dmrb volume 9 section 4 part 6 - ta 83/05 - guide to …volume 9 network - traffic control and...

November 2005

DESIGN MANUAL FOR ROADS AND BRIDGES

VOLUME 9 NETWORK - TRAFFICCONTROL ANDCOMMUNICATION

SECTION 4 SYSTEMS DESIGN

PART 6

TA 83/05

GUIDE TO THE USE OF VARIABLEMESSAGE SIGNS FOR STRATEGICTRAFFIC MANAGEMENT ON TRUNKROADS AND TRUNK ROADMOTORWAYS

SUMMARY

This issue of TA 83 introduces a revised Annex A andAnnex D. Annex A incorporates Interim Advice Note27/99 (IAN 27/99) that introduced the Motorway SignalMk 3 (MS3) and Interim Advice Note 43/02(IAN 43/02) that clarifies but does not increase thestandard of provision. Annex D incorporates anamended first bullet point to clause D1.2.14.

INSTRUCTIONS FOR USE

This Advice Note is to be incorporated in the Manual.

1. This document supersedes TA 83/99.

2. Remove Contents pages for Volume 9 datedFebruary 2004.

3. Insert new Contents pages for Volume 9 datedNovember 2005.

4. Remove TA 83/99 from Volume 9, Section 4,Part 6.

5. Insert TA 83/05 into Volume 9, Section 4, Part 6.

6. Archive this sheet as appropriate.

Note: A quarterly index with a full set of VolumeContents Pages is available separately from TheStationery Office Ltd.

TA 83/05

Guide to the Use of VariableMessage Signs for Strategic

Traffic Management onTrunk Roads and Trunk

Road Motorways


Summary: This issue of TA 83 introduces a revised Annex A and Annex D. Annex Aincorporates Interim Advice Note 27/99 (IAN 27/99) that introduced theMotorway Signal Mk 3 (MS3) and Interim Advice Note 43/02 (IAN 43/02) thatclarifies but does not increase the standard of provision. Annex D incorporatesan amended first bullet point to clause D1.2.14.

THE HIGHWAYS AGENCY

SCOTTISH EXECUTIVE

WELSH ASSEMBLY GOVERNMENTLLYWODRAETH CYNULLIAD CYMRU

THE DEPARTMENT FOR REGIONAL DEVELOPMENTNORTHERN IRELAND

Volume 9 Section 4Part 6 TA 83/05

November 2005

REGISTRATION OF AMENDMENTS

Amend Page No Signature & Date of Amend Page No Signature & Date ofNo incorporation of No incorporation of

amendments amendments

Registration of Amendments



PART 6

TA 83/05


Contents

Chapter

1. Introduction

2. Enquiries

Annex A Advice Note for use in England

Annex B Advice Note for use in Scotland

Annex C Advice Note for use in Wales

Annex D Advice Note for use in Northern Ireland


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November 2005 1/1

Chapter 1Introduction

1. INTRODUCTION

1.1 General

1. This Advice Note provides guidance for thefeasibility study, design, implementation and evaluationof Strategic Traffic Management Systems (STMS)using Variable Message Signs (VMS).

1.2 Scope

1. The specific requirements for each OverseeingOrganisation are contained in the relevant Annex to thisAdvice Note. They are as follows:

• Annex A for England

• Annex B for Scotland

• Annex C for Wales

• Annex D for Northern Ireland.

2. This Advice Note is intended to be used byOverseeing Organisation staff, their consultants, Agentsand maintenance contractors.

1.3 Implementation

1. The appropriate Annex should be used forthwithfor all STMS schemes currently in preparation,provided that in the opinion of the OverseeingOrganisation this will not result in additional expense,or delay progress.

2. Design agents should confirm its application toparticular schemes with the Overseeing Organisation.


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2. ENQUIRIES

All technical enquiries or comments on this Advice Note should be sent in writing as appropriate to:

Divisonal Director(Safety & Information)Highways Agency, Room 4BFederated HouseLondon RoadDorking A J PICKETTSurrey RH4 1SZ Divisional Director

Chief Road EngineerScottish ExecutiveVictoria QuayEdinburgh J HOWISONEH6 6QQ Chief Road Engineer

Chief Highway EngineerTransport WalesWelsh Assembly GovernmentCathays Parks M J A PARKERCardiff Chief Highway EngineerCF10 3NQ Transport Wales

Director of EngineeringThe Department for Regional DevelopmentRoads ServiceClarence Court10-18 Adelaide Street G W ALLISTERBelfast BT2 8GB Director of Engineering

Chapter 2Enquiries

November 2005




PART 6

TA 83/05 ANNEX A (ENGLAND ONLY)


SUMMARY

This issue of TA 83 Annex A incorporates CHE Memo73/99 (IAN 27/99) that introduced the MotorwaySignals Mk3 (MS3) and CHE Memo 112/02 (IAN43/02) that clarifies but does not increase the standardof provision.


This is a new document to be incorporated into theManual.

1. Insert TA 83/05 Annex A as Part 6 of Volume 9,Section 4.






Registration of AmendmentsVolume 9 Section 4Part 6 TA 83/05 Annex A (England Only)

November 2005




Registration of AmendmentsVolume 9 Section 4

Part 6 TA 83/05 Annex A (England Only)

November 2005



PART 6

TA 83/05 ANNEX A (ENGLAND ONLY)


Contents

Chapter

A1. Introduction

A2. Scheme Process

A3. Strategic VMS Types

A4. VMS Siting Criteria

A5. VMS Infrastructure

A6. Glossary of Terms

A7. References


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A1. INTRODUCTION

A1.1 General

1. Clause not used.

2. Clause not used.

3. Clause not used.

4. Clause not used.

Glossary

5. A Glossary of Terms is given in Chapter A6.

Standard Drawings and Specifications

6. HA specifications referred to in this TA areavailable from www.tssplansregiustry.org

A1.2 Related Standards and Advice Not

7. TD 33 ‘The Use of Variable Message Signs oAll-Purpose and Motorway Trunk Roads’, providescriteria for the selection, siting and use of all types VMS on all purpose and motorway trunk roads. ThTA relates purely to light emitting VMS. Most VMcurrently used for Strategic Traffic Management arbased on light emitting technology.

8. For VMS based on light emitting technologiethe design criteria and performance standards for roapplications are given in Highways AgencySpecification TR 2516, ‘Performance SpecificationDiscontinuous Variable Message Signs’.

9. Highways Agency Specification TR 2517,‘Performance Specification for ElectromechanicalVariable Message Signs’, covers performancerequirements for that category of sign.

10. Clause not used.

A1.3 Scope



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13. This TA takes precedence in the case of anyconflicting directions given in TD33 and advice inTA60, or other existing Advice Notes in so far as theyrelate to STMS.

VMS Applications

14. VMS are provided for Driver Information,Tactical Control and Strategic Traffic Management. Thescope of these applications are:

• Driver Information Legends - provide themotorist with information of a tactical andstrategic nature, but also with messages relatingto conditions on the network that may affectexpected journey times, but which are not of adirect or instructional nature. This may includeinformation on major events (eg. shows, sportsevents etc.) and inter network connections suchas ferries, tolled roads and crossings.

• Tactical Control - provides supplementaryinformation to complement matrix signals andother traffic control signs for management ofincidents or occurrences on local roads in thearea. Signs set in support of tactical objectivesdisplay messages specifically related to achievingimprovements on localised sections of thenetwork eg. ‘ACCIDENT/SLOW DOWN’.

• Strategic Traffic Management - provide themotorist with information and advice on the roadnetwork ahead. The aim is to improve theperformance of the network by redistributingtraffic efficiently when congestion occurs onsome links and spare capacity is available onothers.

15. This TA covers the application of VMS to STMSonly.

16. Strategic Traffic Management seeks to ensurethat a strategic view of network status and conditions isavailable, and that strategies and decisions which havemore than a local impact can be identified correctly, andeffectively implemented. Signs set in support of theseobjectives offer alternative or diversionary routechoices.

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17. This TA also describes the different types ofVMS currently available for STMS schemes, andoutlines the approach to the feasibility study, schemedesign, implementation and evaluation.

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A2.1 General

1. There are no standard provision criteria forSTMS schemes and each must therefore be individuallyjustified by means of a feasibility study incorporatingan economic analysis.

2. The Scheme Process is illustrated in Figure A2.1The implementation of Strategic Traffic Managementschemes will generally comprise the followingelements:

• Feasibility Study (Chapter A2.2)

• Design and Implementation (Chapter A2.3)

• Scheme Evaluation (Chapter A2.4)

Figure A2.1 Scheme Process

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A2. SCHEME PROCESS

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.2 Feasibility Study

A feasibility study is needed to determine thecticality and value for money of STMS schemes. A

asibility Study Report should be produced at the endthe study period and consider the following:

review of existing systems and trafficmanagement practice

operational objectives

network and traffic analyses

diversion routes and intervention nodes

scheme operation and management

strategic VMS messages and sign type selection

engineering

future Maintenance

economic evaluation

environmental assessment

scheme evaluation requirements

implementation programme

legislation

risk assessment/hazard identification.

view of Existing Systems and Trafficanagement Practice

The feasibility study should consider the extentthe existing and planned facilities within the area of proposed scheme. These include:

Control Office operational boundaries and theirinteraction with respect to the control ofincidents and traffic management

• institutional issues, policy and codes of practicewith respect to the control of incidents and trafficmanagement

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• the location, type and objectives of existing andplanned VMS schemes including, whereappropriate, local authority initiatives

• the location and form of existing Fixed Signs,Signals and Gantries

• the NMCS Infrastructure and its capability tosupport new systems

• extent of CCTV coverage at the relevant point ofthe network

• extent of existing Traffic Data CollectionSystems.

Operational Objectives

5. STMS schemes are likely to deal with themanagement of unusual or unexpected events affectingroad traffic rather than day to day congestion. Designersshould identify the main objectives of the scheme.These might include:

• provision of information in a timely manner

• achievement of reduction in delay

• achievement of local incident management

• supporting diversion routes and controllingtraffic on these routes

• satisfying drivers’ needs for reliability andconsistency in information and legends

• avoiding an adverse impact on safety and theenvironment

• consistency with existing and planned VMSschemes on a national basis

• long term viability in terms of meeting otherobjectives throughout the design life of thesystem.

Network and Traffic Analysis

6. Designers should classify the road networkapplying to the STMS scheme into strategic and non-strategic routes. Aspects to be considered at this stageinclude:

• the disruptive impact of unusual incidents andplanned road works on network operation

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the frequency of route diversions by studyinghistoric records of motorway and trunk roadclosures

traffic characteristics as for network congestionand the capacity of alternative routes to acceptdiverted traffic

the impact of potential diversions on alternativeroutes, especially through towns and villages.

A traffic assignment programme should be usedassess and develop strategic control plans that mayused for the STMS. This programme should have theility to represent traffic diversions that may belied to the road network, and to evaluate thenomic and operational performance of the proposedersion strategies.

The depth and level of the network and trafficlysis should be appropriate to the needs and

jectives of the STMS scheme. The output from thislysis should form the basis for the Economic

aluation.

version Routes and Intervention Nodes

Based on the Network and Traffic Analysis, theort should identify the diversion routes, strategic and

n-strategic intervention nodes and the recommendedations for the provision of VMS.

. The current view is that designers shouldferably restrict diversion strategies to the Trunk andtorway Network. Where this is not possible, thews of the Police and Highway Authorities likely toaffected, must be sought before the strategy is drawn.

Any existing diversion route agreementseloped by the Police and Highway Authorities

thin the scheme area should be considered andiewed for inclusion in the STMS scheme as localersion strategies.

heme Operation and Management

. Options for the operation and management of theeme should be considered. The points to beressed include:

integration with existing and planned control andcommunications systems and any necessaryextension in capability of those systems

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• integration with the existing management of thestrategic network

• implementation of a management structure takinginto account longer term proposals for TrafficControl Centres

• the need to publish traffic data to third partyorganisations and the potential for generatingrevenue

• the need for consultation to develop effectiveCodes of Practice.

13. Designers should assess the suitability of usingexisting control and communications systems for theSTMS scheme in consultation with the OverseeingOrganisation. Existing or planned systems used forVMS control include:

• Stand Alone Control Systems

• NMCS2 - Message Sign subsystem.

14. It is important to consider the effect of thescheme design on STMS and other traffic managementschemes elsewhere on the road network. It is essentialthat different systems provide motorists with accurateand consistent information when moving from one areato another.

15. The feasibility study should address the interestsof all organisations who may be involved in theoperation and management of the proposed STMS andwhere relevant, other existing or planned trafficmanagement and control facilities. These organisationswill include:

• Divisions of the Overseeing Organisation

• the Police

• Highway Authorities

• DBFO Concessionaires

• Traffic Control Centre Operating Company.

VMS Legend and Sign Type selection

16. The feasibility study should identify the type andsize of VMS needed for each location and appropriatecostings should be used in the Economic Evaluation.

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17. The type and range of information to bedisplayed will generally limit the choice of signtechnologies, whereas the sign location, roadclassification and vehicle speeds will all affectcharacter heights and therefore the size of the VMS.

18. Deriving a common strategy for VMS signing isimportant, whatever the technology and application.Chapter A1 describes the scope of VMS applicationscovering Driver Information, Tactical Control andStrategic Traffic Management. The type of VMS andthe range of messages used for STMS applications willtherefore be influenced by the type and extent of anyother VMS signing at a given location.

19. The Feasibility Study must therefore consider insequence:

(i) the information needed in the VMS legend tomeet the scheme objectives

(ii) the content and number of VMS legends for eachlocation

(iii) the VMS technology needed to display therequired legends

(iv) the technology used by other VMS on the samesection of road

(v) the VMS size and performance level needed forthe application, or applications.

20. VMS legends should normally be selected fromthose given in the Traffic Signs Regulations andGeneral Directions (TSRGD). Any other legendsneeded for a specific scheme must be authorised by theOverseeing Organisation.

21. The practice for STMS messages is to state thelocation and cause of the diversion, followed by thesuggested alternative route. Research suggests thatmessages should be restricted to a maximum of sevenwords, or four units of information. The aim should beto use the shortest message possible. Examplescurrently used for STMS applications are:

M40(S) CLOSED J15FOR LONDONUSE M6, M1

M40 ROADWORKSFOR M1 AND M6

USE A46(N)

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23. Where the system will include VMS legendsrelating to more than one application, ie. Tactical andSTMS, the hierarchy must be explicit and designersmust develop setting resolution rules to decide whichlegend to use for each specific set of circumstances.The Highways Agency document ‘Code of Practice forOperation of Motorway and Trunk Road Signals andVariable Message Signs’, prepared with consultationwith the Association of Chief Police Officers (ACPO)gives further guidance on this subject, as does TD 46.

Sign Types

24. If the only information to be provided is a routechange, ie. alternative direction signing, Fixed TextMessage Signs (FTMS) may be adequate. Where thedesigner requires a wider range of options,discontinuous light emitting signs should be used.

25. For most STMS applications, the mostappropriate type of VMS will be the Motorway SignalsMark 3 (MS3), based on light-emitting technology andcomprising 3 lines of 18 characters with the capabilityto display EMI aspects

26. If Motorway Signals Mark 2 (MS2), or MS32x16 are already provided, designers must considermeeting the STMS requirements using these signs. Ifthey are shown to be unsuitable, the study shouldexamine alternatives, and identify a solution that meetsthe needs of all applications.

27. SVMS will normally be provided in pairs on theapproach to a strategic junction. This reinforces thelegend and reduces the potential for it to be obscuredfrom the driver by high-sided vehicles. In selecting theVMS type it is essential that all signs on the approachto a node show the same legend and therefore bothsigns must use the same technology and design.

Engineering

28. The feasibility study should consider theengineering design needed to support the STMS. Avariety of engineering solutions should be consideredand prioritised to decide the most cost effectiveapproach to each particular scheme. Designers shouldaddress the following aspects of engineering design:

(i) Traffic Data Collection

(ii) control system

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iii) signs

iv) infrastructure and transmission.

9. A key factor for STMS is the collection ofccurate real-time traffic information. The study shouldonsider the means by which this is to be achieved costffectively, including on non-motorway roads.

0. The STMS control system as a whole mustupport the operational and management strategy andny development of that strategy over time. The needor any interlocking reaction with, and interaction to,ther existing or planned traffic management andontrol facilities must be identified and the implicationsssessed. This will include such elements as the numbernd type of STMS legends, setting strategies, settingesolution rules between different applications, and theperational Code of Practice.

1. The type(s) of sign should be identified from theuidance in Chapter A3, ‘Strategic VMS Types’.owever the study should also consider the engineering

spects related to possible sign locations and the meansf installation, ie. verge mounted posts or cantilevers, orortal gantries.

2. The requirements for the STMS infrastructurend transmission should be considered and assessed. Its important to identify how the existing infrastructurean be used to reduce the scheme cost, and maximisehe return on previous investments. The standardMCS motorway infrastructure should support theeeds for most STMS applications. Elsewhere, a varietyf solutions should be considered and prioritised. Theseill include cabling, followed by radio and the use ofrivate lines, ISDN or similar links to more remote orifficult locations.

conomic Evaluation and Environmentalssessment

3. Economic Evaluation and Environmentalssessment shall follow the guidelines given in theETR publication ‘A New Deal for Trunk Roads inngland: Guidelines on the New Approach toppraisal’ and HA publication ‘Appraisal ofechnology Projects’. Designers should agree the scopef the evaluation and assessment with the Overseeingrganisation.

4. For conventional means of procurement the studyust include an evaluation to decide the economic

iability of the scheme. The level of detail and the

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evaluation methodology will be scheme-dependent andshould be agreed with the Overseeing Organisation.

35. Whole life costs to be considered should includesystem development, implementation, staffing, serviceand maintenance. The study should seek to prove thatthe provision of a STMS scheme is preferable to analternative traffic solution.

36. The feasibility study must consider the impact ofthe STMS on the environment. This should include:

• consideration of the visual impact of signs/support and ancillary equipment such as cabinets,duct runs and steps etc., viewed from the roaditself and from nearby developments and openspace

• residential properties and consideration of theland classification of adjacent areas

• consideration of the need to fell or reduce thesize of trees on the approach to VMS

• light pollution caused by VMS

• an appreciation of the environmental effects onthe roads receiving diverted traffic as forincreased congestion, noise and air quality.

Designers should agree the scope of the environmentalassessment with the Overseeing Organisation.

Scheme Evaluation Requirements

37. The study should identify the objectives thatneed to be evaluated when the scheme is in operation toassess its effectiveness, optimise performance andconfirm that the economic benefits are being attained.The evaluation should generally include considerationsof accident reduction, speed changes and trafficvolumes leaving the road in response to givenmessages. The reduction in delay costs and driverfrustration leading to risk of accidents should also beconsidered.

Implementation Programme

38. The above study should identify animplementation programme for the preferred schemeoption. The programme should outline the logical stepsof implementation, indicate the likely spend profile, andpresent (where appropriate) the incremental economicbenefit for each stage of the programme.

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39. The programme should also identify appropriatestages for consulting and agreeing design proposals,operational and maintenance boundaries and systemengineering interfaces.

Legislation

40. Many areas of legislation exist which will applyto the various elements of a STMS scheme. Most arecommon to all design, procurement and constructionprojects and guidance is beyond the scope of thisAdvice Note. However two specific areas of legislationwill apply to STMS schemes and these are outlinedbelow.

41. To be legally placed on the highway in Englandall signs, including all VMS legends must be eitherprescribed or authorised. Prescribed signs and VMSlegends are defined in the TSRGD. Any sign not soprescribed must be authorised by the OverseeingOrganisation.

42. VMS that are other than manually operated, willalso need statutory Type Approval. Designers shouldconsult the Overseeing Organisation on this issue.

Risk Assessment/Hazard Identification

43. A Risk/Hazard Assessment should be consideredas it relates to the role of the Highway authority. Thismakes it necessary to maintain the highway in a safecondition and to secure the safe movement of trafficincluding pedestrians. The matters to be consideredtherefore include:

• signs not operating correctly

• reliability

• failure of a legend to appear or the appearance ofan incorrect legend

• maintenance.

44. Depending on the outcome of the assessmentprocess, requirements such as message monitoring,interlocking and/or message sequencing rules may needto be developed during the design stage to ensure safetyintegrity levels are achieved.

A2.3 Scheme Design and Implementation

45. Outline proposals developed during theFeasibility Study should be reviewed, refined and

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developed into the scheme design. This should take intoaccount not only the requirements for implementation,but for effective maintenance and operational supportthroughout the operational life cycle.

46. The scheme design should normally commencewith a consultation, survey and information collectionphase, followed by preparation of preliminary design tobe agreed with the Overseeing Organisation. Thepreliminary design should detail proposals for:

• traffic data and information collection systems

• VMS types

• VMS site locations

• control system

• communications infrastructure and transmission

• structures, geotechnical and civil engineering

• traffic management.

47. Designers should examine existing site records,transmission arrangements and control facilities toestablish the impact of the scheme on existing systems,and the scheme design requirements. This stage willinvolve consultation with relevant divisions of theOverseeing Organisation, the Police and otherorganisations having an interest in the STMS scheme.

General Design of the Works

48. The detailed design and preparation of workingdrawings should not commence until the designproposals have been presented to and agreed with theOverseeing Organisation.

49. The options for collecting accurate real-timetraffic data and information identified during thefeasibility stage may be developed into the overallscheme. On motorways the provision of MIDAS andCCTV will normally deliver this data. Where this is notbeing provided and on other roads, the standard designsmay need to be developed and modified to provideadditional data and information collection sites at keylocations to suit the needs of the scheme.

50. VMS must conform to the OverseeingOrganisation’s standards and will normally be based onthe Highways Agency ‘TR’ series of specifications.These detail the sign design and performancerequirements to be achieved, and standard interfaces to

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the NMCS infrastructure. The designer should consultthe Overseeing Organisation before placing contractsfor VMS procurement as existing contracts may offerbenefits in terms of cost savings and approved designs.

51. The control system requirements must be definedbased on the operational and management objectivesand taking into account the need for integration withexisting and planned systems, and any extension to thefunctionality or capacity of these systems. TheOverseeing Organisation and the Police should beconsulted at an early stage and proposals agreed beforefinalising the design and scope of the STMS contract.

52. Control room and equipment room layouts mustbe examined to ensure the proposed system can beaccommodated in terms of space for equipment andpower supplies etc.

53. Design of the communications infrastructureshould conform to Highways Agency standards definedin the Highway Construction Details ‘MCX’ series andany modifications required by the OverseeingOrganisation.

54. The transmission network should take account ofthe capacity of existing systems. For motorways, cablepairs and channel allocations will need to be agreedwith the Overseeing Organisation and works arrangedto re-configure and provide additional communicationscircuits as required. For other locations, the provisionof circuits by Private Telecommunications Operators(PTOs) must be planned at an early stage in the designprocess.

55. The provision and upgrading of power suppliesfor VMS can be a lengthy process, particularly forremote sites where the Electricity Supply Company(ESC) may need to negotiate wayleaves. Power supplylocations should therefore be identified early in thedesign process, and works orders placed accordingly.

56. VMS will normally be installed on posts orcantilever gantries in the roadside verge, or on new orexisting portal gantries. Standard arrangements exist forsign cantilevers and for modifications to some types ofportal gantry. Designs, technical assessments anddesign checks should be carried out incorporating therequirements as applicable for:

• Post, Cantilever or Portal Gantry sign andsuperstructure

• foundations and holding down arrangements

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• technical assessment/design modifications toexisting gantries

• retaining walls.

57. The design process should include an early deskstudy of available soils data, to establish whether acontract for an additional geotechnical investigation isneeded to complete the scheme design. Designersshould identify any such work early in the programmeas it may have major impact on the implementationtimescale.

58. Safety barrier must be provided at all locationsaccording to the Overseeing Organisation’s standards.Any existing barrier at or near to the sign locationshould be upgraded and extended as necessary.

59. Traffic management systems for STMS schemesmust conform to Chapter 8 of the Traffic Signs Manual.The Overseeing Organisation, Maintaining Agent andthe Police must be consulted to agree localarrangements, lane closure timings and road spacebookings etc. taking into account other programmedworks.

Siting of VMS

60. The locations for VMS should be identified bysite survey according to the criteria given in ChapterA4, ‘VMS Siting Criteria’. A detailed site survey isrequired for each of the VMS locations identifiedduring the feasibility study.

61. When locations have been defined, considerationmust be given to carrying out an Environmental ImpactAssessment study of the STMS scheme.

Notifications

62. If considered necessary by the OverseeingOrganisation, notification of the STMS scheme shouldbe sent to the Planning Authority for information andcomment. This notification should comprise a packageof information, describing the scheme and its objectivesand showing the locations of the signs on a 1:25000scale map of the area.

Legend Authorisation

63. The recommendations for VMS types andlegends identified during the feasibility stage should bereviewed and if necessary further developed.

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64. Any messages not included in the TSRGD mustbe authorised by the Overseeing Organisation asdescribed in Chapter A2.2.

Traffic Modelling and Diversion Strategies

65. The diversion routes and intervention nodesidentified during the feasibility stage should bereviewed and developed in consultation with the Policeand Highway Authority.

Operational Procedures

66. Procedures should be developed and worked intoa Code of Practice for operation of the STMS.Depending on the scope of the scheme, this mayinvolve consultation with the Overseeing Organisationand the Local Police and the Secretary of the NationalMotorway Policing Subcommittee of the Association ofChief Police Officers Traffic Committee.

Safety Audits

67. Safety Audits should be carried out in accordancewith the Highways Agency’s specific requirementsstated in HD 19, ‘Road Safety Audits’.

As-Built Drawings and Records

68. The designer should provide as-built drawingsand records of the completed works for all contracts.All electrical inspection documentation should beprovided at completion of the works. Where required,‘As-Built’ information must be incorporated into theexisting NMCS record drawings. All structuralinformation, both for the signs themselves and thesupports, should be provided on completion of theworks.

Detailed Risk Assessment

69. The safety issues considered during thefeasibility stage should be reviewed and amended asnecessary.

70. The assessment should take into account bestpractice achieved elsewhere on the road network, andthe consequential driver’s expectation and reliance onSTMS information.

71. Requirements such as message monitoring,

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interlocking and/or message sequencing rules must bedeveloped at this stage to ensure safety integrity levelsare achieved.

72. The hazard identification and risk assessmentprocess should consider among other matters thefollowing:

• the signs not operating or operating incorrectly

• possible conflict with signing and/or driverinformation systems

• message priority

• failure of a legend to appear or the appearance ofan incorrect legend - (this must be done on anindividual sign basis and a system and sequencebasis)

• the legends to be displayed and how easily theycan be read and understood

• failure of real time traffic data sources

• maintenance.

A2.4 Scheme Evaluation

73. When the scheme is in operation, the STMSshould be continuously evaluated to assess itseffectiveness, optimise performance, and confirm thatthe economic, operational and other benefits of thescheme are being attained. The evaluation should bepresented in the form of a Scheme Evaluation Report.

74. The evaluation requirements, initially identifiedas part of the feasibility study, should be reviewed andif necessary adjusted when the scheme is in operation.If required, elements of the STMS should be modifiedto ensure maximum benefits are realised.

75. Data from the detection and VMS systems shouldbe collected and analysed to check whether thealgorithm or operational rules select the appropriatestrategy and to assess the actual diversion achieved.Where appropriate rules or algorithms should berefined.

76. Monitoring should continue whether the initial

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results show that refinements are needed or not, so thatchanges in conditions and driver responses over timecan be met with appropriate system responses.

A2.5 System Certification

77. The system certification procedures specified inMCH 1813 should be followed.

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A3.1 Introduction

1. VMS for STMS applications may be of the LightEmitting Technology type or the FTMS types.

2. All Strategic VMS should be fitted with flashingamber lanterns. The lanterns should flash insynchronous horizontal pairs alternating top and bottomto draw the attention of drivers to the messagedisplayed on the VMS. Lantern design requirementsmust comply with the TSRGD.

A3.2 VMS Technologies and Types

Enhanced Message Signs

3. Message Signs are active light emitting signs.Two main technologies are used in such signs, these areLight Emitting Diode (LED) and Optical Fibre. A thirdvariety uses the combination of a reflective disc withlight emitting technology.

4. The arrangements of text most frequently usedfor display purposes are:

• two lines of twelve characters (2x12)

• two lines of sixteen characters (2x16)

• three lines of twelve characters (3x12)

• three lines of eighteen characters (3x18)

5. Each character is formed from a matrix of displaycells 5 wide and 7 deep and has a nominal characterheight of 400mm, although 2x12 signs on gantries use anominal character height of 320mm. CombinedMessage Signs/EMI are now available whereby part ofthe display panel is assigned a continuous matrixcapable of either text or EMI display depending on theparticular need at any given time.

6. Message Signs are usually installed on Cantileveror Portal Gantries.

Fixed Text Message Signs

7. FTMS are any type of VMS that display two ormore fixed legends (or a blank display and one or more

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November 2005

ends). There are currently a number of technologiesed in such signs, the more common being active lightitting (as above), flexible roller blind and rotatingnk or prism, the latter two normally being electrochanical. Of these types the rotating plank or prism

most suitable for strategic use. Because of thewbacks noted below, FTMS are now not widely used

d are generally most suitable for signing diversiontes.

The rotating plank or prism sign normallynsists of a series of planks or prisms that align tom a flat sign face. When required to show a differentect, the planks or prisms realign to present aferent sign face. Either the whole sign face can beanged in this way, or only those parts of the sign facet need to be changed. In this way the number ofend options available can be increased.

The arrangement of text used for displayrposes on rotating plank or prism signs must either beprescribed in the TSRGD or specially authorised by overseeing organisation.

. FTMS are normally mounted on posts installed in motorway verge, or on Portal Gantries. The mainwbacks of FTMS are:

they can not be routinely tested withoutdisplaying the message which may confuse roadusers

unless they are regularly exercised they are proneto electro-mechanical failure.

.3 Applications of Strategic VMS

hanced Message Signs

. It is accepted that under conditions of normalibility, Message Signs are less easily legible thannventional fixed traffic signs. This is a factor thatst be balanced against their ability to display manyferent legends. However, if they comply witharacter height and optical performance requirements,y may actually be more easily legible under poor

nditions. This performance under poor conditionsy influence the choice of technology for a given

plication.

A3/1


Annex AEngland Only

12. Experience suggests that strategic message signson motorways should be provided at the approach tostrategic junctions on the network, upstream ofassociated one-mile and half-mile Advance DirectionSigns (ADS). Strategic junctions are as defined inTD 46.

13. Where there are verge mounted ADS and nosignal gantries any existing one-mile 3x18 strategicVMS should be replaced by a 3x18 MS3 with EMI. Itshould be possible to re-use the existing post andstructure. The two VMS will have the followingpriorities:

• SVMS upstream of the one-mile ADS – tacticallegend priority

• SVMS upstream of the half-mile ADS – strategiclegend priority.

14. Wherever possible SVMS are normally providedin pairs. Both should display either the same strategic ortactical message. In case of conflict between tacticaland strategic legends, the tactical legend is the mostimportant legend to be displayed. The specific use ofsigns in the event of needing to use both a tactical andstrategic legend is as follows:

15. On the SMVS upstream of the one-mile ADS:

• If a tactical legend is displayed it cannot bereplaced by a strategic legend.

• If a strategic legend is displayed a tactical legendshall take priority and shall replace the strategiclegend.

• If no legend is displayed any legend can bedisplayed.

• Once the tactical legend has been removed thestrategic legend shall be displayed (if stillrequired).

16. On the SVMS upstream of the half-mile ADS:

• If a non-strategic legend is displayed a strategiclegend shall take priority and shall replace thenon-strategic legend.

• If a strategic legend is displayed it cannot bereplaced by a non-strategic legend.

• If no legend is displayed any legend can bedisplayed.

•

Fi

17roloefpregdiofDi

18mwebu

19Minthbesesig

20ADbeDiblsaMflaus

A3/2

Once the strategic legend has been removed thenon-strategic legend shall be displayed (if stillrequired).

xed Text Message Signs

. FTMS are more commonly used for diversionuteing and local traffic management where there are aw number of route options. They may mostfectively be used to display messages linking to aedetermined diversionary route, marked by symbols,. “Follow � for London”. Symbols for use onrectional signs are shown in Part VII of Schedule 13 The Traffic Signs Regulations and Generalrections 2002.

. Other FTMS applications include tunnel/bridgeaintenance requiring lane or road closures,ighbridges, tidal flow operations, level crossings ands lane management.

. The use of FTMS for Strategic Trafficanagement is more likely to be on roads approachingtersections with motorways, rather than on motorwaysemselves. However, around major urban areas it may necessary to use FTMS instead of MS3 along certainctions of motorway to achieve a satisfactory level ofning.

. Unlike MS3, FTMS normally replace existingS as the normal sign face contained on the ADS will

incorporated as one of the faces of the FTMS.version destinations, when shown, shall appear inack legends on yellow background, designed to theme rules as set out in Chapter 7 of the Traffic Signsanual. When the diversionary route is displayed,shing amber lanterns, as referred to in A3.1.2 shall beed.

November 2005


Annex AEngland Only

A4.1 General

1. The siting criteria to be used when identifyingVMS locations depends on the sign type selected duringthe feasibility and design stages.

2. For FTMS type signs the criteria to be appliedare the same as for ADS on motorway and trunk roads.Such signs will normally replace the existing ADS andbe installed on posts in the verge or on portal gantriesas appropriate to the scheme design.

3. When siting Light Emitting Technology typesigns, such as MS3 it is important that the sign ispositioned so that the motorist can relate any messagewith the associated ADS downstream of the VMS.

4. The advice given in Chapter A4.2 should befollowed to determine appropriate locations forMessage Signs.

A4.2 Siting Criteria for Message Signs

5. Figure A4.2a and TD 46 cover the generaldecision process and siting arrangements for VMS. Theinformation should be read in conjunction with theadvice given in Chapter A2 of this TA guide,particularly in relation to the selection of VMS sign andlegend types.

6. By definition, MS3 for STMS purposes need tobe on the approaches to road junctions that can bebroadly categorised as either All-Purpose Road orMotorway/Motorway. Whereas the standards for thesewith regard to the type of signing and signalling arequite different, the general arrangement of the directionsigns is usually a one mile, followed by half mile and aFinal ADS on motorways, but the one mile ADS isoften not provided on All-Purpose roads.

7. In deciding locations for Message Signs it isnecessary to consider and balance the following needs:

• all types of information and directional signingand any signals must be in a position where theycan be seen and read by drivers

•

•

•

8hloO

9thMap

1b

•

•

•

•

A4. VMS SITING CRITERIA

November 2005

sign clutter and information overload must beavoided. In this respect, the maximum number ofunits of information presented to the drivershould not exceed seven

STMS signs should be positioned so the drivercan associate the MS3 message with the routeinformation on directional signing

the siting needs of other VMS applications suchas for tactical control purposes.

. Figure A4.2a and TD 46 set out in general termsow this balance might best be achieved in a givencation. Further advice may be obtained from theverseeing Organisation.

. Sign legends should be duplicated to reinforcee information or instructions given. Therefore, twoessage Signs should generally be provided on theproach to the key junctions within any STMS.

0. It is recommended that the following parameterse used in conjunction with Figure A4.2a and TD 46:

Message Signs with 400mm nominal characterheight.

A separation between cantilever strategicmessage signs and the one mile and half mile of200m minimum, 300m desirable and 400mmaximum. However, the downstream MessageSigns should not be closer than 200m to eitherthe upstream or downstream ADS. Where there isno one mile ADS a single Message Sign shouldbe provided, located in advance of the half mileADS in accordance with these sitingrequirements.

A separation between portal strategic MessageSigns and the one mile and half mile ADS of300m minimum and 400m maximum. However,the downstream Message Sign should not becloser to either the upstream or downstreamADS. Where there is no one mile ADS a singleMessage Sign should be provided, located inadvance of the half mile ADS in accordance withthese siting requirements.

A protected sightline to the Message Signs of225m minimum and 400m desirable.

A4/1


Annex AEngland Only

A4.3 Siting Considerations for VMS

11. Factors that need to be taken into considerationwhen locating the VMS include other structures,environmental and other considerations. These arediscussed below.

Location Relative to Structures

12. VMS should be positioned to ensure that bridgesand other structures do not obstruct visibility. It isequally important to ensure that VMS do not obstructthe visibility of other signs and signals, the detectionfield of Fog Detectors, or the view from CCTVsurveillance cameras.

13. Where it is necessary to place a VMSdownstream of an overbridge, the resultant sightlineshould be carefully checked to ensure that the protectedsightline requirements are satisfied.

Location Relative to Lighting Columns

14. Where road lighting is on the verge, VMS shouldbe located at least one column length away from thenearest lighting column. This is to prevent damagebeing sustained by the sign in the event of the lightingcolumn being knocked down by a vehicle. Where aVMS has to be sited between two lighting columns, itshall be placed immediately upstream of a columnwherever possible.

Environmental Considerations

15. All VMS structures should be assessed for theirvisual impact at each sign location. Considerationshould be given to the design and location of thesestructures to take account of the local setting in terms oflandscape, townscape character and conservationdesignations such as National Parks and speciallandscape areas.

16. For new roads and motorways consideration ofthe type, location and degree of visual intrusion, causedby the strategic VMS structures, should be included inthe Environmental Assessment under LandscapeEffects.

17. The procedures set out in Department of theEnvironment Circular 18/84 - Crown Land and CrownDevelopment - do not apply to the provision of VMSwithin the existing highway boundary. However when

sa

O

1in

•

•

•

Oomm

A4/2

iting signs, due consideration should be given tossessing and reducing their visual impact.

ther siting considerations

8. Other design considerations for siting of VMSclude:

proximity of power supplies

available space for communications and powercabinets including paved areas, access steps andwhere necessary retaining walls

access for maintenance including a possible needfor an off-road parking site.

n link roads it is essential that VMS are correctlyriented so that they can be clearly distinguished fromain carriageway VMS. This may be achieved beeans of louvres or narrow angle emitters.

November 2005


Annex AEngland Only

Apply standard separation

Figure A4.2a - Flowchart to determine sign/support arrangements andsiting of VMS related to ADS

Typical solutions areshown in TD 46

Typical solutions areshown in TD 46

Are MS2 or MS3 in place or plannedAre Gantry EMS in place or planned

Can STMS needs be metwith Gantry EMS Provide Cantilever VMS

Provide combined strategicVMS/EMI on cantilever Provide Cantilever VMS

Agree modifications/programmewith Overseeing Organisation

Are existing ADS in 1m, 1/2m or2/3m, 1/3m configuration

Apply desirable separationto both ADS

Is highway a 2/3 lane cross-sectionwith verge mounted ADS or 3/4

lane cross-section with portal gantries

Any obstruction or otherconsideration preventing

use of the location?

Extend towardsmaximum separation

Visability achieved?

Reduce separationtowards minimum


Agree optimumcompromise with

Overseeing Organisation

Fix VMS location

3/4 lane withportal gantries

2/3 lanes with vergemounted ADS

1m, 1/2m

➤➤

➤

➤➤

➤

➤

➤

➤

➤➤

➤➤

➤➤

➤

➤

YES NONOYES

YES

YES

NO

NO

➤

➤➤

NO

YES

YES

➤

➤YES

Can standard 1m 1/2m beimplemented at reasonable cost?

2/3m, 1/3m Single ADS ➤

VMS to upstream ADS➤

Position VMS midwaybetween 2/3 mile ADS and

1/3 mile ADS

Any obstruction or otherconsideration prevent use

of location?

Extend towards2/3 mile ADS


Reduce stowards1/3 mile ADS


➤➤

➤➤

➤

YES

NO

YES

➤

➤➤

YES

VMS to downstream ADS

➤

➤ ➤

➤

NO

NO

➤

NO

November 2005 A4/3


URE

Annex AEngland Only

A5.1 Control Systems

1. VMS can be controlled by all current motorwaycontrol systems. Designers should assess the suitabilityof using existing control and communications systemsfor the STMS scheme in consultation with theOverseeing Organisation. Existing or planned systemsused for VMS control include:

• Stand Alone Control System

• NMCS2 - Message Sign subsystem.

2. The communications infrastructure needed tosupport either an NMCS2 or Stand Alone Controlarrangement is fully described in TRH 1642,‘Motorway Signals Mark 3, Infrastructure DesignGuide’.

A5.2 Roadside Infrastructure

General

3. On motorways, the NMCS infrastructure shouldalso support the majority of STMS applications. Wherenew STMS schemes are introduced within existingsections of motorway, infrastructure works shouldtherefore be limited to civils work and localmodifications to existing cabling and powers supplies.

4. On other roads it will be necessary to develop thesolutions identified during the feasibility study such ascabling to the motorway, or radio, private lines, ISDNor similar links to more remote locations.


5. The infrastructure for a typical Message Sign sitecomprises:

i) a foundation and plinth fitted with a standardholding down arrangement to support thecantilever structure and Message Sign enclosure

or

a Portal Gantry suitably modified to providesupport for the Message Sign and Enclosure

A5. VMS INFRASTRUCT

November 2005

(ii) Communications Cabinet Type 600 and PowerCabinet Type 609 with associated cabling andducts

(iii) safety barrier - double height Open Box Beam

(iv) paving, handrails and retaining walls as requiredby site conditions.

6. A typical Cantilever Message Sign OutstationLayout is shown on Drawing MCX 0582.

7. A Portal Gantry Outstation Layout is shown onDrawing MCX 0800. This shows the arrangementwhere a ducted cable network is provided. At all otherlocations, the cables between the gantry and equipmentcabinets will be directly buried.

8. Further guidance is given in Specification TRH1642, ‘Motorway Signals Mark 3, Infrastructure DesignGuide’.


9. The infrastructure for a typical FTMS sitecomprises:

(i) a foundation, either a reinforced concrete blockwith no holding down arrangement where theFTMS post fixings are drilled into thisfoundation or a similar block with appropriatepost holes

(ii) Communication cabinet Type 600 and a PowerCabinet Type 609 with associated cabling andducts

(iii) safety fencing to suit location


A5/1


Annex AEngland Only

A5.3 Technical Approval

Cantilever Structures

10. Cantilever gantries are designed as two elements:

(i) foundation

(ii) superstructure.

11. The foundation comprises a reinforced concreteplinth incorporating a standard holding downarrangement for the superstructure. Details are given inDrawings MCX 0583.

12. Technical Approval must be sought from theappropriate Technical Approval Authority. If thefoundation and superstructure are designedindependently, or by different design organisations, aTechnical Approval submission must be made for eachelement.

13. Cantilever foundations and superstructures areclassed as Category II structures and, as such willrequire independent checks of the design.

Existing Gantries

14. Existing gantries should already be certified toBD 2. Technical Approval is therefore required for theaddition of VMS sign enclosures and mountingequipment and the effect of these additions on thegantry structure.

15. Detailed designs already exists for the additionalsteelwork to support a 320mm Message Sign to bemounted on certain ‘standard’ gantries. This design andwhere it can be applied is shown on Drawing No.MCX 0584.

16. Where VMS signs other than the 320mm are tobe installed, a new design must be developedspecifically for each situation.

17. The gantry designers should be asked to carry outchecks to ensure there is adequate reserve structuralcapacity to support the VMS, and to establish whetherthe gantry loading on foundations is exceeded.

18. The Technical Approval submission must refer tothe structure number for the existing gantry. Design andcheck certificates must be produced for the additions,and a separate check certificate must be produced bythe gantry designer for the effect on the gantry.

A5/2

A5.4 Holding Down Arrangement

19. When foundations are constructed, it is essentialthe contractor uses a template provided by the supplierof the superstructure.

20. On contracts where different contractors areresponsible for the construction of the base andsuperstructure, steps must be taken to ensure that theinterface between the two elements matches.

A5.5 Optical Alignment

21. When using VMS based on light emittingtechnology, it is particularly important to ensure correctoptical alignment of the sign with the carriageway.Design requirements, and the method to be applied onsite are given in Drawing MCX 0069.

A5.6 Ordering of Equipment

22. A request for Financial Approval and EquipmentOrder shall be made according to MCH 1286.

23. Reference should be made to HighwayConstruction Drawings MCX 0590 and MCX 0591,which show the equipment configuration for VMSoutstation sites.

November 2005


S

Annex AEngland Only

Continuous Sign

A VMS that appears to be made up of solid charactersor symbols. The sign face is changed by removing oneset of symbols/characters and replacing them withanother, or by having a multiple face that can rotate.

Discontinuous Sign

A VMS in which the sign face is made up of individualelements having at least two states. By changing thestate of the individual elements, different characters andsymbols can be created within the same sign area.

Driver Information Legends

Give the motorist information of a tactical and strategicnature, but also with messages relating to conditions onthe network that may affect expected journey times.This may include information on major events eg.shows, sports events etc. and inter network connectionssuch as ferries, tolled roads and crossings.

Fixed Text Message Sign (FTMS)

A type of VMS able to display a limited number offixed messages. Signs for strategic applications use amechanical rotating prism as the mechanism forchanging the sign legend.

NMCS

The Highways Agency’s National MotorwayCommunications System.

Sign

A device carrying directional or other informationalmessage, eg. route information at the approach to ajunction.

Signal

A device used to give advisory or mandatoryinstructions, e.g. stop or 30 mph speed restriction.

A6. GLOSSARY OF TERM

November 2005

Strategic Traffic Management Systems (STMS)

Give the motorist information and advice on the roadnetwork ahead. The aim is to improve the performanceof the network by redistributing traffic efficiently whencongestion occurs on some links and spare capacity isavailable on others.

Tactical Control Systems

Provide supplementary information to complementmatrix signals and other traffic control signs for localmanagement of incidents or occurrences.

Variable Message Sign (VMS)

A generic term for a sign that can display multiplelegends or messages.

Both Motorway Signals Mk3 (MS3) and Fixed TextMessage Signs (FTMS) are different types of VMS.

VMS can display text messages and/or symbols usingany of the following technologies:

a) Rotating Prism

b) Reflecting Cells

c) Light Emitting Cells.

A6/1


Annex AEngland Only

Design Manual for Roads and Bridges

BD 2 Technical Approval of Highway Structures(DMRB 1.1.1).

HD 19 Road Safety Audits (DMRB 5.2.2).

TA 74 Motorway Signalling (DMRB 9.4.3).

TA 60 The Use of Variable Message Signs onAll-Purpose and Motorway Trunk Roads(DMRB 8.2).

TD 33 The Use of Variable Message Signs onAll-Purpose and Motorway Trunk Roads(DMRB 8.2.1).

TD 46 Motorway Signalling (DMRB 9.1.1).

Department for Transport

The Traffic Signs Regulations and General Directions2002 (SI 2002 No 3113).

Traffic Signs Manual Chapter 7 – The Design of TrafficSigns.

Traffic Signs Manual Chapter 8 – Traffic SafetyMeasure and Signs for Road Works and TemporarySituations.

A New Deal for Trunk Roads in England: Guidance onthe New Approach to Appraisal.

Highways Agency Specifications

MCH 1286 Request for Financial Approval (Standardand Non-Standard Schemes) and BulkPurchase Equipment Order.

MCH 1813 System Certification.

TRH 1642 Motorway Signals Mark 3 - InfrastructureDesign Guide.

TR 2517 Performance Specification forElectromechanical Variable MessageSigns.

A7. REFERENCES

November 2005

TR 2516 Performance Specification forDiscontinuous Variable Message Signs.

Highways Construction Details

MCX 0069 Cantilever and Gantry Sign Setting Outand Optical Alignment.

MCX 0582 Installation Drawing NMCS2 MessageSigns Outstation Layout.

MCX 0583 Cantilever Structures and Holding DownArrangements.

MCX 0584 Installation Drawing NMCS2 MessageSigns on Portal Gantry - AdditionalSteelwork.

MCX 0590 Cantilever Site - Typical Arrangement.

MCX 0591 Portal gantry Site - Typical Arrangement.

Other Documents

Department of Environment Circular 18/84 - CrownLand and Crown Development.

HA document - Appraisal of Technology Projects.

A7/1

November 2005




PART 6

TA 83/05 ANNEX B (SCOTLAND ONLY)


SUMMARY

This new Advice Note TA 83/05 provides guidance forthe feasibility study, design, implementation andevaluation of Strategic Traffic Management Systems(STMS) using Variable Message Signs (VMS).



1. Insert TA 83/05 Annex B as Part 6 of Volume 9,Section 4.






Registration of AmendmentsVolume 9 Section 4Part 6 TA 83/05 Annex B (Scotland Only)

November 2005





Part 6 TA 83/05 Annex B (Scotland Only)

November 2005



PART 6

TA 83/05 ANNEX B (SCOTLAND ONLY)


Contents

Chapter

B1. Introduction

B2. Scheme Process

B3. Strategic VMS Types

B4. VMS Siting Criteria

B5. VMS Infrastructure

B6. Glossary of Terms

B7. References


November 2005


Annex BScotland Only

B1. INTRODUCTION

B1.1 General

1. This Annex describes the specific requirementsfor the use and siting of variable message signs inScotland.

DMRB Structure

2. Section 1 of Volume 9 the Design Manual forRoads and Bridges (DMRB) contains TechnicalDirectives (TD) which detail the Standards ofProvision.

3. Section 2 onwards contains Technical Advice(TA) Notes which reflect current practice in the field ofmotorway communications and control.

Design Loop

4. Figure B1.1 shows the ‘Design Loop’ illustratingthe general sequence in the iterative process whichstarts with the design for emergency telephones andsignals followed by transmission and control officedesigns. Last in the cycle is the design of theinfrastructure that will be required to support allcommunications equipment and systems.

Glossary

5. A Glossary of Terms is given in Chapter B6.


6. Standard drawings and specifications referred toin this guide are those issued by The Scottish Office,National Roads Directorate and by the HighwaysAgency.

M

Of

MIn

November 2005

Figure B1.1 Structure of Volume 9 of the DesignManual for Roads and Bridges

Section 1

Standards ofProvision

Sections2 & 3

Introductionand overview

Section 4Part 1

NMCS2SystemsDesign

Section 4

OtherNMCS2

Sub Systems

Section 4Part x

StrategicTraffic

Management

Section 4Part 2

MotorwayEmergencyTelephones

Section 4Part 5

otorwayControlfice Design

Section 4Part 4

MotorwayTransmission

Design

Section 4Part 3

MotorwaySignalling

Section 4Stand Alone

Systemse.g.

CCTV

Section 4

MIDAS

Section 5

otorwayfrastructure

DESIGN

LOO

P

B1/1



B1.2 Related Standards and Advice Notes

7. TD 33/90, ‘The Use of Variable Message Signson All-Purpose and Motorway Trunk Roads’, providescriteria affecting the selection, siting and use of alltypes of Variable Message Signs (VMS) on all purposeand motorway roads. This Advice Note relates purely tolight emitting VMSs and TD 33/90 is due to be updatedto concord with the advice given in this document.Most VMS currently used for Strategic TrafficManagement are based on the light emitting technology.

8. For VMS based on light emitting technologies,the design criteria and performance standards for roadapplications are given in Highways AgencySpecification TR 2136, ‘Functional Specification forContinuous or Discontinuous Variable Message Signs’.

9. Highways Agency Specification TR 0154,‘Electromechanical Variable Message Signs -Functional Specification’, covers performancerequirements for that category of sign. The performancerequirements of sign face materials, where appropriate,is found in BS 873.

10. The following current versions of Advice Notesare of general relevance. Reference should be made tothe National Roads Directorate as to their specificapplication in Scotland.

TA 70/97: Introduction - Motorways - DMRB,Volume 9 Section 2, Part 1.

TA 71/97: Design and Implementation (Overview) -DMRB, Volume 9, Section 3, Part 1.

TA 72/97: National Motorway CommunicationsSystems - DMRB, Volume 9, Section 4,Part 1.

TA 74/97: Motorway Signalling - DMRB, Volume 9,Section 4, Part 3.

TA 75/97: Motorway Transmission Design - DMRB,Volume 9, Section 4, Part 4.

TA 76/97: Motorway Control Offices - DMRB,Volume 9, Section 4, Part 5.

TA 77/97: Motorways: Infrastructure Design -DMRB, Volume 9, Section 5, Part 1.

B1/2

B1.3 Scope

11. The practices and requirements detailed inDMRB, Volume 9, Network - Traffic Control andCommunications, relate to the policies implemented bythe Overseeing Organisations in the UK.

12. The principles in this Advice Note referspecifically to the needs and practices applicable inScotland. Other Overseeing Organisations, should referto Annexes A, C or D as appropriate for advice in linewith their Strategic Traffic Management needs.

13. This Advice Note takes precedence in the case ofany conflicting direction in TD 33/90 or advice inTA 60/90, or other existing Advice Notes in as far asthey relate to Strategic Traffic Management Systems inScotland.

VMS Applications

14. VMS are provided for Driver Information,Incident Signing, Tactical Control and Strategic TrafficManagement. The scope of these applications is asfollows:

• Driver Information - provides the motorist withinformation of a tactical and strategic nature, butalso with messages relating to conditionspertaining on the network which may affectexpected journey times along with safety relatedmessages such as ‘KEEP YOUR DISTANCE’.

• Incident Signing - normally set by the Policeduring emergency conditions but can be set fromthe National Network Control Centre (NNCC) inGlasgow if required.

• Tactical Control - provides supplementaryinformation to complement matrix signals andother traffic control signs for management ofincidents or occurrences on local roads in thearea. Signs set in support of tactical objectivesdisplay messages specifically related to achievingimprovements on the localised sections of thenetwork, eg ‘ACCIDENT/LONG DELAYS’.

• Strategic Traffic Management - set by theNNCC and provides the motorist withinformation and advice on the road networkahead. The aim is to improve the performance ofthe network by redistributing traffic efficientlywhen congestion occurs on some links and sparecapacity is available on others.

November 2005



15. This Advice Note covers the application of VMSto Strategic Traffic Management Systems (STMS) only.

16. Strategic Traffic Management seeks to ensurethat a strategic view of network status and conditions isavailable, and that strategies and decisions which havemore than a local impact can be correctly identified andeffectively implemented. Signs set in support of theseobjectives may offer alternative or diversionary routechoices.

17. This Advice Note describes the different types ofVMS currently available for STMS schemes, andoutlines the approach to be adopted for the feasibilitystudy, scheme design, its implementation and theevaluation of any proposed schemes.

November 2005 B1/3



B2.1 General

1. There are no standard provision criteria forStrategic Traffic Management Systems (STMS)schemes and each must therefore be individuallyjustified by means of a feasibility study incorporatingan economic analysis. However, any proposed STMSscheme must be discussed fully with the NationalNetwork Control Centre (NNCC) beforeimplementation and shown to be compatible with theexisting National Driver Information and ControlSystem (NADICS) system.

2. The Scheme Process is illustrated in Figure A2.1.The implementation of Strategic Traffic Managementschemes will generally comprise the followingelements:

• Feasibility Study (Chapter B2.2)

• Design and Implementation (Chapter B2.3)

• Scheme Evaluation (Chapter B2.4).

Figure B2.1 Scheme Process

B2. SCHEME PROCESS

Considerothersolutions

➤

FEASIBILITY STUDYIs STMS solutioneconomically viable

SCHEME DESIGN

& IMPLEMENTATION

EVALUATIONCan improvementbe made?

➤

Annual Review

NO

NO

YES

YES

November 2005

B2.2 Feasibility Study

3. A Feasibility Study is needed to determine thepracticality and value for money of STMS schemes. AFeasibility Study report should be produced at the endof the study period and should consider the following:

• review of existing systems, including NADICSand traffic management practices

• operational objectives

• network and traffic analyses

• diversion routes and intervention nodes

• scheme operation and management

• Variable Message Signs (VMS) messages

• sign type selection

• engineering

• economic evaluation

• environmental assessment

• scheme evaluation requirements

• implementation programme

• legislation

• risk assessment/hazard identification.

Review of Existing Systems and TrafficManagement Practice

4. The feasibility study should consider the extentof the existing and planned facilities within the area ofthe proposed scheme. These include:

• NNCC and Police Control Office operationalboundaries and their interaction with respect tothe control of incidents and traffic management


B2/1



• the location, type and objectives of existing andplanned VMS schemes where appropriate


• the existing communications infrastructure andits ability to support new systems




5. STMS schemes are likely to deal with themanagement of unusual or unexpected events affectingroad traffic rather than day to day congestion. Designersshould identify the main objectives of the scheme andthese might include:










6. Designers should classify the road networkapplicable to the STMS scheme into strategic and non-strategic routes. Aspects to be considered at this stageinclude:

• the disruptive impact of unusual incidents andplanned roadworks on network operation

B2/2

• the frequency of route diversions by studyinghistoric records of road closures

• traffic characteristics as for network congestionand the capacity of alternative routes to acceptdiverted traffic

• the impact of potential diversions on alternativeroutes, especially through towns and villages.

7. A traffic assignment programme may be used toassess and develop strategic control plans that may beused for the STMS. This programme should have thefacility to represent traffic diversions that may beapplied to the road network, and to evaluate theeconomic and operational performance of the proposeddiversion strategies.

8. The depth and level of the network and trafficanalysis should be appropriate to the needs andobjectives of the STMS scheme. The output from thisanalysis should form the basis for the EconomicEvaluation.

Diversion Routes and Intervention Nodes

9. Based on the Network and Traffic Analysis, thereport should identify the diversion routes, strategic andnon-strategic intervention nodes and the recommendedlocations for the provision of VMS.

10. The current view is that designers shouldpreferably restrict diversion strategies to the Trunk andMotorway Network. Where this is not possible, theviews of the National Roads Directorate (NRD), theNNCC, the Road Authorities and the Police, must besought before the strategy is drawn up.

11. Any existing diversion route agreementsdeveloped by the Road Authority and the Police withinthe scheme area should be considered and reviewed forinclusion in the STMS scheme as local diversionstrategies.

Scheme Operation and Management

12. Options for the operation and management of thescheme should be considered. The points to beaddressed include:

• integration with the existing NADICS system andany future extension of the system

November 2005




• the need to supply traffic data to third partyorganisations and its potential for generatingrevenue


13. Designers should assess the suitability of usingexisting control and communications systems for theSTMS scheme in consultation with the NRD and theNNCC.

14. Appreciation of the effect of the scheme designon STMS and traffic management schemes elsewhereon the road network is important. It is essential thatdifferent systems provide motorists with consistent andaccurate information when moving from one area toanother.

15. The feasibility study should address the interestsof all organisations who may be involved in theoperation and management of the proposed STMSscheme. These organisations include:

• the NRD

• the NNCC

• Local Road Authorities

• the Police

• DBFO Concessionaires.

VMS Messages and Sign Type selection

16. The feasibility study should identify the type andsize of VMS needed for each location and theirappropriate costings should be used in the EconomicEvaluation.

17. The type and range of information to bedisplayed will generally limit the choice of signtechnologies, whilst the sign location, roadclassification and vehicle speeds will affect characterheights and therefore the size of the VMS.

18. Deriving a common strategy for VMS signing isimportant whatever the technology and application.Chapter B1 describes the scope of VMS applicationscovering Driver Information, Tactical Control andStrategic Traffic Management. The type of VMS and

November 2005

the range of messages used for STMS applications willtherefore be influenced by the type and extent of anyother VMS signing at a given location.

19. The Feasibility Study must therefore consider insequence:

(i) the information needed in the VMS legend tomeet the scheme objectives

(ii) the content and number of VMS legends for eachlocation

(iii) the VMS technology needed to display therequired legends

(iv) the technology used by other VMS on the samesection of road

(v) the VMS size and performance level needed forthe application, or applications.

20. VMS legends should normally be selected fromthose given in the Traffic Signs Regulations andGeneral Directions (TSRGD). Any other legendsneeded for a specific scheme must be authorised by theScottish Office.

21. The practice for STMS messages is to state thelocation and cause of the diversion, followed by thesuggested alternative route. Research suggests thatmessages should be restricted to a maximum of eightwords, or four units of information. The aim should beto use the shortest message possible.

22. Further reading on VMS legends is given in theVAMOS WHITE BOOK, produced under the European‘Drive’ Project VAMOS (VAriable Message OptimisedSystems).

23. Where the system will include VMS legendsrelating to more than one application, eg Tactical andSTMS, the hierarchy must be explicit and designersmust develop setting resolution rules to decide whichlegend to use for each specific set of circumstances.This will normally be agreed in conjunction with theNRD via the NNCC, the Police and the Local Authorityconcerned. The Highways Agency document ‘Code ofPractice for Operation of Motorway and Trunk RoadSignals and Variable Message Signs’, prepared inconsultation with the Association of Chief PoliceOfficers (ACPO) gives further guidance on this subject.

B2/3



Sign Types

24. Where the only information to be provided is of aroute change, i.e. alternative direction signing, thenFixed Text Message Signs (FTMS) may be adequate.Where the designer requires a wider range of options,discontinuous light emitting signs should be used.

25. For most STMS applications, the mostappropriate type of VMS will be the Enhanced MessageSign (EMS), based on light-emitting technology.

26. If Motorway Signals Mark 2, or Tactical EMStype signs are already provided on the approach to agiven location, designers must consider meeting theSTMS requirements using these signs. If they areshown to be unsuitable, the study should examinealternatives, and identify a solution that meets the needsof all applications.

27. Depending on proposed usage and location asingle VMS only is provided on the approach to anIntervention Node. Where they can be justified, twosigns may be provided to reinforce the message and toreduce the potential for the VMS to be obscured byhigh-sided vehicles. Where two VMS are beingprovided, it is desirable that both signs on the approachto a node show the same legend and use the sametechnology.

Engineering



(ii) control system

(iii) signs

(iv) infrastructure and transmission.

29. A key factor for STMS is the collection ofaccurate real-time traffic information. The feasibilitystudy should consider the means by which this is to beachieved cost effectively, including that on non-motorway roads.

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B2/4

The STMS control system as a whole mustport the operational and management strategy and development of that strategy over time. The need

any interlocking reaction with, and interaction to,er existing or planned traffic management andtrol facilities must be identified and the implicationsessed. This will include such elements as the number type of STMS legends, setting strategies, setting

olution rules between different applications, and therational Code of Practice.

The type(s) of sign should be identified from thedance in Chapter B3, ‘Strategic VMS Types’.wever the study should also consider the engineeringects related to possible sign locations and the meansnstallation, ie verge mounted posts or cantilevers, ortal gantries.

The requirements for the STMS communicationsastructure should be considered and assessed. It isortant to identify how the existing infrastructure can

used to reduce the scheme cost and maximise thern on previous investments. On most motorways thedard infrastructure should be capable of supporting

needs of most STMS applications. Elsewhere aiety of solutions should be considered andritised. These will include cabling, radio links and

use of private communication links, ISDN orilar, to more remote or difficult locations.

nomic Evaluation

For conventional means of procurement the studyst include an evaluation to decide the economicbility of the scheme. The level of detail and theluation methodology will be scheme-dependent anduld be agreed with the NRD.

Whole life costs should be considered whichlude system development, implementation, staffing,vice and maintenance. The study should seek tove that the provision of an STMS scheme isferable to alternative traffic solutions.

vironmental Assessment

The feasibility study must consider the impact of STMS on the environment. This should include:

consideration of the visual impact of signs/support and ancillary equipment such as cabinets,duct runs and steps, etc viewed from the roaditself and from nearby developments and openspace

November 2005







36. Designers should agree the scope of theenvironmental assessment with the NRD and theNNCC.





39. The programme should also identify appropriatestages for consulting and agreeing design proposals, theoperational and maintenance boundaries and systemengineering interfaces.

Legislation

40. Many areas of legislation exist which will applyto the various elements of an STMS scheme. Most arecommon to all design, procurement and constructionprojects and guidance is beyond the scope of thisAdvice Note. However two specific areas of legislationwill apply to STMS schemes and these are outlinedbelow.

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November 2005

1. To be legally used all traffic signs, including allMS legends, must be either prescribed or authorised.rescribed signs and VMS legends are defined in theSRGD. Any sign not so prescribed must be authorised

or a defined location and period of time by the Scottishffice.

2. VMS which are other than manually operated,ill need statutory Type Approval and designers should

onsult the NRD on this issue.

isk Assessment/Hazard Identification

3. A Risk/Hazard Assessment should be considereds it relates to the role of the Scottish Office. Thisakes it necessary to maintain the highway in a safe

ondition and to secure the safe movement of trafficncluding pedestrians. The matters to be consideredherefore include:

signs not operating correctly

reliability

failure of a legend to appear or the appearance ofan incorrect legend

maintenance.

4. Depending on the outcome of the assessmentrocess, requirements such as message monitoring,nterlocking and/or message sequencing rules may needo be developed during the design stage to ensure safetyntegrity levels are achieved.

2.3 Scheme Design and Implementation

5. Outline proposals developed during theeasibility Study should be reviewed, refined andeveloped into the scheme design. This should take intoccount not only the requirements for implementation,ut for effective maintenance and operational supporthroughout the operational life cycle.

6. The scheme design should normally commenceith a consultation, survey and information collectionhase, followed by preparation of a preliminary designo be agreed with the NRD. The preliminary designhould detail proposals for:

traffic data and information collection systems

VMS types


B2/5



• control system




47. Designers should examine existing site records,data transmission arrangements and control facilities toestablish the impact of the scheme on existing systemsand the scheme design requirements. This stage willinvolve consultation with relevant divisions of theNRD, the NNCC, the Police and other organisationshaving an interest in the STMS scheme.


48. The detailed design and preparation of workingdrawings should not commence until the designproposals have been presented to and agreed with theNRD.

49. The options for collecting accurate real-timetraffic data and information identified during thefeasibility stage may be developed within the overallscheme. On motorways the provision of CCTV andMIDAS (or some other incident detection system), willnormally deliver this data. Where this is not beingprovided standard designs may need to be developedand modified to provide this data to suit the needs ofthe scheme.

50. VMS must conform to NRD standards and arenormally based on the Highways Agency ‘TR’ series ofspecifications. These detail the sign design andperformance requirements to be achieved and thestandard interfaces to the communicationsinfrastructure. The designer should consult the NRDbefore placing contracts for VMS procurement asexisting contracts may offer benefits in terms of costsavings and approved designs.

51. The control system requirements must be basedon current operational and management objectives.They must take into account the need for integrationwith the existing NADICS system and for NRD plannedsystem expansions. They must also take into accountany extension to the functionality or capacity of thesesystems. The NRD and the Police should be consultedat an early stage and proposals agreed before finalisingthe design and scope of the STMS contract.

52. Control room and equipment room layouts mustbe examined to ensure that the proposed system can be

B2/6

accommodated in terms of space for equipment andavailability of suitable power supplies, etc.

53. Design of the communications infrastructureshould conform to Highways Agency standards definedin the ‘MCX’ installation drawings, along with anymodifications required by the NRD as defined in theNADICS series of drawings.

54. The transmission network should take account ofthe available capacity of existing systems. Formotorways, cable pairs and channel allocations willneed to be agreed with the NRD and works arranged tore-configure communications circuits as required. Forother locations, the provision of circuits by PrivateTelecommunications Operators (PTOs) must be plannedat an early stage in the design process.

55. The provision and upgrading of power suppliesfor VMS can be a lengthy process, particularly forremote sites where the Electricity Supply Company(ESC) may need to negotiate wayleaves. Power supplylocations should therefore be identified early in thedesign process and works orders placed accordingly.

56. VMS will normally be installed on posts orcantilever gantries in the roadside verge, or on new orexisting portal gantries. Standard arrangements exist forcantilever signs and for modifications to some types ofportal gantry. Designs, technical assessments anddesign checks should be carried out incorporating therequirements as applicable for:



• technical assessment/ design modifications toexisting gantries


57. The design process should include an early deskstudy of available soil data, to establish whether acontract for a geotechnical investigation is needed tocomplete the scheme design. Designers should identifyany such work early in the programme as it may havemajor impact on the implementation timescale.

58. Safety barrier must be provided at all locationsaccording to NRD standards. Any existing barrier at ornear to the proposed sign location should be upgradedand extended as necessary.

November 2005



59. Traffic management systems for STMS schemesmust conform to Chapter 8 of the Traffic Signs Manual.The NRD, Maintaining Agent and the Police must beconsulted to agree local arrangements, lane closuretimings and road space bookings etc taking into accountother programmed works.

Siting of VMS

60. The locations for VMS should be identified bysite survey according to the criteria given in ChapterB4, ‘VMS Siting Criteria’. A detailed site survey isrequired for each of the VMS locations identifiedduring the feasibility study.


Notifications

62. If considered necessary by the NRD, notificationof the STMS scheme should be sent to the relevantPlanning Authority for information. This notificationshould comprise a package of information describingthe scheme, its objectives and show the locations of thesigns on a 1:25000 scale map of the area.



64. Any messages not included in the TSRGD mustbe authorised by the NRD as described in Chapter B2.2.


65. The diversion routes and intervention nodesidentified during the feasibility stage should bereviewed and developed in consultation with the NRD,NNCC, the Police and the local authorities.


66. Procedures should be developed and worked intoa Code of Practice for operation of the STMS.Depending on the scope of the scheme, this mayinvolve consultation with the NRD, NNCC, localauthorities and the Police.

November 2005

Safety Audits

67. Safety Audits should be carried out in accordancewith the requirements as stated in HD 19/94, ‘RoadSafety Audits’, or as otherwise agreed with the NRD.


68. The designer or contractor should provide as-built drawings and records of the completed works forall contracts. All electrical inspection documentationshould be provided at completion of the works andwhere required, as-built information must beincorporated into the existing communications recorddrawings. All structural information, both for the signsand their supports, shall be provided on completion ofthe works.




71. Requirements such as message monitoring,interlocking and/or message sequencing rules must bedeveloped at this stage to ensure safety integrity levelsare achieved.



• possible conflict with other signing and/or driverinformation systems


• failure of a legend to appear or the appearance ofan incorrect legend - this must be done on anindividual sign basis, and on a system andsequence basis



B2/7




• maintenance.

B2.4 Scheme Evaluation

73. Once the scheme is in operation, the STMSshould be evaluated to assess its effectiveness and tooptimise its performance and to confirm that theeconomic, operational and other benefits of the schemeare being attained. This evaluation should be presentedin the form of a Scheme Evaluation Report.

74. The evaluation requirements initially identifiedas part of the feasibility study, should be reviewed andif necessary adjusted once the scheme is in operation. Ifrequired, elements of the STMS should be modified toensure maximum benefits are realised.

75. Data from the detection and VMS systems shouldbe collected and analysed to check whether thealgorithm or operational rules have selected the mostappropriate strategy and to assess the actual diversionbenefits achieved. Where appropriate rules oralgorithms should be refined.

76. Monitoring should continue whether the initialresults show that refinements are needed or not, so thatchanges in conditions and driver responses over timecan be met with the most appropriate system responses.

B2.5 System Certification

77. The system certification procedures specified inMCH 1813 : System Certification Specification, shallnormally be followed, but this requirement should beclarified with the NRD or the NNCC.

November 2005B2/8


ES


B3.1 Introduction

1. Variable Message Signs (VMS) for StrategicTraffic Management Systems (STMS) applications maybe of the Enhanced Message Sign (EMS) or the FixedText Message Sign (FTMS) types.

2. All Strategic VMS should be fitted with flashingamber lanterns. The lanterns should flash insynchronous horizontal pairs alternating top and bottomto draw the attention of drivers to the messagedisplayed on the VMS. Lantern design and operationalrequirements must comply with the Traffic SignRegulations and General Directions (TSRGD). InScotland only road information related messagesrequire the operation of the amber flashers.

B3.2 VMS Technologies and Types


3. EMS are active light emitting signs and two maintechnologies are used in such signs, these are LightEmitting Diode (LED) and Optical Fibre. A thirdvariety uses a combination of a retro reflective discwith light emitting technology.




• three lines of sixteen characters (3x16)

• three lines of 18 characters (3x18).

This is not an exclusive list and other arrangementsmay be considered.

5. Each character should have a nominal characterheight applicable to the speed of the road, or asotherwise approved by the Scottish Office. EMS 2 x 12signs on gantries use a nominal character size of320mm.

6. EMS are normally installed on Cantilever orPortal Gantries or on mounting posts installed in theverge.

B3. STRATEGIC VMS TYP

November 2005


7. FTMS are any type of VMS that display two ormore fixed legends (or a blank display and one or morelegends). There are currently a number of technologiesused in such signs, the more common being lightemitting, flexible roller blind and rotating plank orprism. The latter two normally being electromechanical. Of these the rotating plank or prism type ismost suitable for strategic use.

8. The rotating plank or prism sign consists of aseries of planks or prisms that are aligned to form arequired message. When required to show a differentmessage, the planks or prisms are realigned. Either thewhole sign face can be changed or only those parts ofthe sign face that need to be changed and in this waythe number of legend options available can beincreased.

9. The arrangement of text used for displaypurposes on rotating plank or prism signs must be asprescribed in the TSRGD.

10. FTMS are normally mounted on posts installed inthe verge, or on Portal Gantries.

B3.3 Applications of Strategic VMS


11. It is accepted that under normal visibilityconditions, EMS type signs may be less legible thanconventional fixed traffic signs, but this factor must bebalanced against their ability to display many differentlegends. However, under poor conditions, provided theycomply with character height and optical performancerequirements, they may actually be more legible. Thisperformance under poor conditions may influence thechoice of technology for a given application.

12. Strategic EMS should be provided at theapproach to key junctions on the network, upstream ofassociated Advance Direction Signs. Positions areselected to suit individual site requirements, such asspeed of the road, local topography and environmentalconsiderations.

B3/1



13. EMS with three lines of eighteen 420mm highcharacters (3x18) are preferred for most applications.However EMS with other formats can also be used,provided that the feasibility study identifies that suchsigns are suitable for the legends needed at a particularlocation.


14. FTMS are more commonly used for diversionrouteing and local traffic management where there are alow number of route options. They may mosteffectively be used to display messages linked topredetermined diversion routes, marked by symbols, eg‘Follow M8 for Edinburgh’.

15. Other FTMS applications include tunnel/bridgemaintenance requiring lane or road closures,weighbridges, tidal flow operations, level crossings andbus lane management and Park and Ride facilities.

16. The use of FTMS for Strategic TrafficManagement is more likely to be on roads approachingintersections with motorways, rather than on motorwaysthemselves. However, around major urban areas it maybe necessary to use FTMS instead of EMS along certainsections of motorway to achieve a satisfactory level ofsigning.

17. Unlike EMS, FTMS normally complement theexisting Advance Direction Signing (ADS), where thenormal ADS sign face will be incorporated as one of thefaces of the FTMS. Diversion destinations shall appearin black legends on a yellow background, as set out inChapter 7 of the Traffic Signs Manual. When thediversionary route is displayed, flashing amber lanterns,as referred to in B3.1.2 shall be used.

November 2005B3/2


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B4.1 General

1. The siting criteria to be used when identifyingVariable Message Sign (VMS) locations depends on thesign type and size selected during the feasibility anddesign stages.

2. For Fixed Text Message Signs (FTMS) typesigns the criteria to be applied are the same as forAdvance Direction Signing (ADS). Such signs willnormally replace or complement the existing ADS andbe installed on posts in the verge or on portal gantriesas appropriate to the scheme design.

3. When siting Enhanced Message Sign (EMS) typesigns, it is important that the EMS is positioned so thatthe motorist can relate any message with the associatedADS downstream of the VMS.

4. The advice given in Chapter B4.2 should befollowed to determine appropriate locations for EMStype signs.

B4.2 Siting Criteria for EMS Type Signs

5. The following information should be read inconjunction with the advice given in Chapter B2 of thisguide, particularly in relation to the selection of VMSsign and legend types.

6. By definition, EMS for Strategic TrafficManagement Systems (STMS) purposes need to be onthe approaches to road junctions that can be broadlycategorised as either All-Purpose Road/Motorway orMotorway/Motorway. Whereas the standards for thesewith regard to their type of signing and signalling arequite different, the general arrangement of the ADS isusually at one mile, followed by half mile (or two-thirdsmile and one-third mile respectively on dual two lanemotorways) with a final confirmation ADS.

7. In deciding locations for EMS it is necessary toconsider and balance the following needs:

• all types of information and directional signingand any signals must be in a position where theycan be clearly seen and read by drivers

B4. VMS SITING CRITERI

November 2005

• sign clutter and information overload must beavoided. In this respect, the maximum number ofunits of information presented to the driver inany message should not exceed eight

• STMS signs should be positioned so the drivercan associate the EMS message with the routeinformation on fixed directional signing

• the siting needs of other VMS applications suchas for tactical control purposes.

8. The following points should be considered whenselecting sign locations:

• the separation between strategic EMS and theone mile or half mile ADS should be 200mminimum, 300m desirable and 400m maximum.However, the downstream EMS should not becloser than 200m to either the upstream ordownstream ADS

• a protected uninterrupted sightline to the EMS of225m minimum and 400m is desirable.

B4.3 Siting Considerations for VMS

9. Factors that need to be taken into considerationwhen locating the VMS include other structures andenvironmental considerations. These are discussedbelow.


10. VMS should be positioned to ensure that bridgesand other structures, including signs and signals, do notmutually obstruct visibility. Equally important is toensure that VMS do not obstruct the visibility of othersigns and signals, the detection field of Fog Detectors,or the view from CCTV surveillance cameras.

11. VMS installed adjacent to existing structuresshould not be located closer than a distance of at leasttwice the height of the proposed VMS. Where it isnecessary to place a VMS downstream of anoverbridge, the resultant sightline should be carefullychecked to ensure that the protected sightlinerequirements are satisfied.

B4/1




12. Where road lighting is in the verge, the VMSshould be located at least one column length away fromthe nearest lighting column. This is to prevent damagebeing sustained by the sign in the event of the lightingcolumn being knocked down by a vehicle. Where aVMS has to be sited between two lighting columns, itshall be placed immediately upstream of a columnwherever possible, but without affecting the sightlinerequirements.



14. For new roads and motorways consideration ofthe type, location and degree of visual intrusion causedby the VMS structures, should be included in theEnvironmental Assessment under Landscape Effects.

Other siting considerations

15. Other design considerations for siting of VMSinclude:

• proximity of power supplies

• availability of communication services

• available space for communications and powercabinets including paved areas, access steps andwhere necessary retaining walls

• access for maintenance including a possible needfor an off-road parking site

• on link roads it is essential that VMS arecorrectly oriented so that they can be clearlydistinguished from main carriageway VMS. Thismay be achieved be means of louvres or narrowangle emitters.

November 2005B4/2



Figure B4.2a

FLOW CHART TO DETERMINE SIGN/SUPPORT ARRANGEMENTAND SITING OF VMS RELATIVE TO ADS

Typical solutions areshown in Figure B4.2b

Typical solutions areshown in Figure B4.2c

Are MS2 in place or plannedAre Gantry EMS in place or planned

Can STMS needs be metwith Gantry EMS Provide Cantilever VMS

Provide combined strategicVMS/EMI on cantilever Provide Cantilever VMS

Agree modifications/programmewith Overseeing Organisation Are existing ADS in 1m, 1/2m or

2/3m, 1/3m configuration

Apply desirable separationto both ADS

Is highway a 2/3 lane cross sectionwith verge mounted ADS or 3/4

lane cross-section with portal gantries

Any obstruction or otherconsideration preventing

use of the location?

Extend towardsmaximum separation


Reduce separationtowards minimum


Agree optimumcompromise with

Overseeing Organisation

Fix VMS location

3/4 lane withportal gantries

2/3 lane with vergemounted ADS

1m, 1/2m

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November 2005 B4/3


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B5.1 Control Systems

1. Most Variable Message Signs (VMS) can becontrolled by all current motorway control systems.Designers should assess the suitability of using existingcontrol and communications systems for the StrategicTraffic Management Systems (STMS) scheme inconsultation with the National Roads Directorate(NRD) and the National Network Control Centre(NNCC).

2. Reference should be made to the NRD todetermine if the existing communications infrastructurecan support proposed STMS applications

B5.2 Roadside Infrastructure

General

3. On motorways, the existing communicationsinfrastructure should support the majority of STMSapplications. Where new STMS schemes are to beintroduced within existing sections of motorway theinfrastructure works should therefore be limited to civilengineering works and local modifications to existingcabling and power supplies.

4. In other areas, it will be necessary to develop thesolutions identified during the feasibility study, such ascabling to the site and radio paths, private lines, orsimilar links to remote locations.


5. The infrastructure for a typical EnhancedMessage Sign (EMS) site comprises:

(i) a foundation and plinth fitted with a standardholding down arrangement to support thecantilever structure and EMS enclosure

or

a Portal Gantry suitably modified to providesupport for the EMS and Enclosure

(ii) communications cabinet Type 600 and PowerSupply Cabinet with associated cabling and ducts

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November 2005

iii) safety fencing - double height Open Box Beam

iv) paving, handrails and retaining walls as requiredby site conditions.

. For typical Cantilever and Portal Gantry EMSutstation Layouts for use in Scotland designers should

ontact the NRD or the NNCC.

ixed Text Message Signs

. The infrastructure for a typical Fixed Textessage Signs (FTMS) site comprises:

i) a foundation, either a reinforced concrete blockwith no holding down arrangement where theFTMS post fixings are drilled into thisfoundation or a similar block with appropriatepost holes

ii) Communication Cabinet Type 600 and a PowerCabinet with associated cabling and ducts

iii) safety fencing to suit location


5.3 Technical Approval

antilever Structures

. Cantilever gantries are designed as two elements:

i) foundation

ii) superstructure.

. The foundation comprises a reinforced concretelinth incorporating a standard holding downrrangement for the superstructure. Details are given inrawings MCX 0583.

0. Technical Approval must be sought from theppropriate Technical Approval Authority. If theoundation and superstructure are designedndependently, or by different design organisations, aechnical Approval submission must be made for eachlement.

B5/1




Existing Gantries

12. Existing gantries should already be certified toBD 2/89. Technical Approval is therefore required forthe addition of VMS sign enclosures and mountingequipment and the effect of these additions on thegantry structure.

13. Detailed designs already exists for the additionalsteelwork to support 320mm EMS to be mounted oncertain ‘standard’ gantries. This design and where it canbe applied is shown on Drawing No. MCX 0584.


15. The gantry designers should be asked to carry outchecks to ensure there is adequate reserve structuralcapacity to support the VMS, and to establish whetherthe gantry loading on the foundations is exceeded.


B5.4 Holding Down Arrangement


18. On contracts where different contractors areresponsible for the construction of the base andsuperstructure, steps must be taken to ensure that theinterface between the two elements is agreed and thetemplate supplied by the superstructure supplier is usedto mark off the gantry’s final orientation.

B5.5 Optical Alignment

19. When using VMS based on light emittingtechnology, it is particularly important to ensure correctoptical alignment of the sign with the carriageway.Design requirements, and the method to be applied onsite are given in Drawing MCX 0069.

November 2005B5/2



1. A glossary of general terms applying toMotorway Communications is given in TA 70/97.

2. Definitions for additional terms used in thecontext of this Advice Note are as follows:

Cantilever

An overhead structure which extends from the verge. Itcomprises a single column and an arm supporting anEnhanced Message Sign (EMS) or Motorway SignalMark 2.

Continuous Sign

A VMS that appears to be made up of solid charactersor symbols. The sign face is changed by removing oneset of symbols/characters and replacing them withanother, or by having a multiple face that can rotate.

Discontinuous Sign

A Variable Message Signs (VMS) in which the signface is made up of individual elements having at leasttwo states. By changing the state of the individualelements, different characters and symbols can becreated within the same sign area.

Driver Information Systems

Gives the motorist information of a tactical andstrategic nature, but also displays messages relating toconditions on the network that may affect expectedjourney times.

Enhanced Message Sign

A type of VMS based on light emitting technology. TheEMS can display a variety of legends that may beconfigured and controlled remotely from an instation.

Fixed Text Message Sign

A type of VMS able to display a limited number offixed messages. VMS for strategic applications use amechanical rotating prism as the mechanism forchanging the sign legend.

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B6. GLOSSARY OF TERMS

November 2005

ntervention Node

road junction that offers alternative routes, whereMS legends can be used to intervene and modify orlock the normal journey route as shown on fixedirectional signing.

ortal Gantry

n overhead structure that spans the carriageway and issed to support combinations of signals, variableessage signs and conventional fixed signs.

ign

device carrying directional or other informationalessage, eg route information at the approach to anction.

ignal

device used to give advisory or mandatorystructions, eg stop or 30 mph speed restriction.

trategic Traffic Management Systems

ive the motorist information and advice on the roadetwork ahead. The aim is to improve the performancef the network by redistributing traffic efficiently whenongestion occurs on some links and spare capacity isvailable on others.

actical Control Systems

rovide supplementary information to complementatrix signals and other traffic control signs for localanagement of incidents or occurrences.

ariable Message Sign

generic term for a sign that can display multiplegends or messages.

oth EMS and FTMS are different types of VMS.

B6/1




(a) Rotating Prism

(b) Reflecting Cells

(c) Light Emitting Cells.

NMCS

The Highways Agency’s National MotorwayCommunications System (NMCS) which in Scotlandhas been adopted in a slightly modified form for use inthe National Driver Information and Control System(NADICS) system.

NADICS

The National Driver Information and Control System.

NNCC

The National Network Control Centre (NNCC) inGlasgow which operates the NADICS system on behalfof the NRD.

November 2005B6/2




BD 2/89: Technical Approval of HighwayStructures on Motorways and OtherTrunk Roads. Part 1: GeneralProcedures – DMRB, Volume 1,Section 2, Part 2.

HD 19/94: Road Safety Audits – DMRB,Volume 5, Section 2, Part 2.

TA 60/90: The Use of Variable Message Signs onAll-Purpose and Motorway TrunkRoads – DMRB, Volume 8, Section 2,Part 1.

TA 70/97: Introduction - Motorways – DMRB,Volume 9, Section 2, Part 1.

TA 71/97: Design and Implementation(Overview) – DMRB, Volume 9,Section 3, Part 1.

TA 72/97: National Motorway CommunicationsSystems – DMRB, Volume 9, Section 4,Part 1.

TA 74/97: Motorway Signalling – DMRB,Volume 9, Section 4, Part 3.

TA 75/97: Motorway Transmission Design –DMRB, Volume 9, Section 4, Part 4.

TA 76/97: Motorway Control Offices – DMRB,Volume 9, Section 4, Part 5.

TA 77/97: Motorways: Infrastructure Design –DMRB, Volume 9, Section 5, Part 1.

TD 33/90: The Use of Variable Message Signs onAll-Purpose and Motorway TrunkRoads – DMRB, Volume 8, Section 2,Part 1.

Department of Transport/Scottish Office

Traffic Signs Regulations and General Directions(TSRGD).

Traffic Signs Manual.

B7. REFERENCES

November 2005


TR 0154: Electromechanical Variable MessageSigns - Functional Specification

TR 2136: Functional Specification forContinuous or Discontinuous VariableMessage Signs

Highways Agency NMCS Installation Drawings(TRH 1239)

MCX 0069: Cantilever and Gantry Sign Setting Outand Optical Alignment.

MCX 0583: Cantilever Structures and HoldingDown Arrangements.

MCX 0584: EMS on Portal Gantry - AdditionalSteelwork.

Other Publications


European Drive Project VAMOS (VAriable MessageOptimised Systems) - VAMOS White Book.

B7/1

November 2005




PART 6

TA 83/05 ANNEX C (WALES ONLY)


SUMMARY

This new Advice Note TA 83/05 provides guidance forthe feasibility study, design, implementation andevaluation of Strategic Traffic Management Systems(STMS) using Variable Message Signs (VMS).



1. Insert TA 83/05 Annex C as Part 6 of Volume 9,Section 4.






Registration of AmendmentsVolume 9 Section 4Part 6 TA 83/05 Annex C (Wales Only)

November 2005





Part 6 TA 83/05 Annex C (Wales Only)

November 2005



PART 6

TA 83/05 ANNEX C (WALES ONLY)


Contents

Chapter

C1. Introduction

C2. Scheme Process

C3. Strategic VMS Types

C4. VMS Siting Criteria

C5. VMS Infrastructure

C6. Glossary of Terms

C7. References


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C1. INTRODUCTION

C1.1 General

1. This Annex is for the specific requirements ofmotorway communications in Wales.

DMRB Structure



Design Loop

4. Figure C1.1 shows the ‘Design Loop’ illustratingthe general sequence in the iterative process whichstarts with the design for emergency telephones andsignals followed by transmission and control officedesigns. Last in the cycle is the design of theinfrastructure that will be required to support allcommunications equipment and systems.

Glossary

5. A Glossary of Terms is given in Chapter C6.


6. Standard drawings and specifications referred toin this guide are issued by the Welsh Office and/or theTraffic Systems and Signing (TSS) Division of the

FM

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Highways Agency.

Section 1


Sections2 & 3


Section 4Part 1

NMCS2SystemsDesign

Section 4

OtherNMCS2

Sub Systems

Section 4Part x

StrategicTraffic

Management

Section 4Part 2


Section 4Part 5

MotorwayControl

Office Design

Section 4Part 4


Design

Section 4Part 3

MotorwaySignalling


Systemse.g.

CCTV

Section 4

MIDAS

Section 5

MotorwayInfrastructure

DESIGN

LOO

P

igure C1.1 Structure of Volume 9 of the Designanual for Roads and Bridges

C1/1


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C1.2 Related Standards and Advice Notes

7. TD 33/90, ‘The Use of Variable Message Signson All-Purpose and Motorway Trunk Roads’, providescriteria affecting the selection, siting and use of alltypes of Variable Message Signs (VMS) on all purposeand motorway trunk roads. This Advice Note relatespurely to light emitting VMS and TD 33/90 is due to beupdated to concord with the advice given in thisdocument. Most VMS currently used for StrategicTraffic Management are based on light emittingtechnology.



10. Enhanced Message Signs (EMS) and MotorwaySignals Mark 2 are defined in Highways AgencySpecification TR 2141 ‘Motorway Signals Mark 2,Requirements for Signal Equipment’.

11. The following current versions of Advice notesare of relevance to motorways:








C1/2

C1.3 Scope

12. The practices and requirements detailed inDMRB, Volume 9, Network - Traffic Control andCommunications relate to the policies implemented byOverseeing Organisations in the UK.

13. The principles in this Advice Note may not beentirely applicable to Strategic Traffic ManagementSchemes of other Overseeing Organisations.

14. This Advice Note takes precedence in the case ofany conflicting advice given in Advice Note TA 60/90,or other existing Advice Notes in as far as they relate toStrategic Traffic Management Systems (STMS).

VMS Applications

15. VMS are provided for Driver Information,Tactical Control and Strategic Traffic Management. Thescope of these applications are:

• Driver Information Systems - provide themotorist with information of a tactical andstrategic nature, but also with messages relatingto conditions on the network which may affectexpected journey times. This may includeinformation on major events, eg shows, sportsevents, etc and inter network connections such asferries, tolled roads and crossings.

• Tactical Control - provides supplementaryinformation to complement matrix signals andother traffic control signs for management ofincidents or occurrences on local roads in thearea. Signs set in support of tactical objectivesdisplay messages specifically related to achievingimprovements on the localised sections of thenetwork eg ‘ACCIDENT/LONG DELAYS’.

• Strategic Traffic Management - provide themotorist with information and advice on the roadnetwork ahead. The aim is to improve theperformance of the network by redistributingtraffic efficiently when congestion occurs onsome links and spare capacity is available onothers.

16. This Advice Note covers the application of VMSto STMS only.

17. Strategic Traffic Management seeks to ensurethat a strategic view of network status and conditions isavailable, and that strategies and decisions which have

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more than a local impact can be identified correctly andimplemented effectively. Signs set in support of theseobjectives offer alternative or diversionary routechoices.

18. This Advice Note also describes the differenttypes of VMS currently available for STMS schemes,and outlines the approach to the feasibility study,scheme design, implementation and evaluation.

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C2.1 General

1. There are no standard provision criteria forStrategic Traffic Management Systems (STMS)schemes and each must therefore be individuallyjustified by means of a feasibility study incorporatingan economic analysis.

2. The Scheme Process is illustrated in Figure C2.1.The implementation of Strategic Traffic Managementschemes will generally comprise the followingelements:

• Feasibility Study (Chapter C2.2)

• Design and Implementation (Chapter C2.3)

• Scheme Evaluation (Chapter C2.4).

Figure C2.1 Scheme Process

C2. SCHEME PROCESS

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•

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•

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SCHEME DESIGN

& IMPLEMENTATION


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Annual Review

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YES

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2.2 Feasibility Study

. A feasibility study is needed to determine theracticality and value for money of STMS schemes. Aeasibility Study Report should be produced at the endf the study period and consider the following:




diversion routes, junctions and nodes


Variable Message Signs (VMS) legends and signtype selection

sign types

engineering

future maintenance

economic evaluation




legislation


eview of Existing Systems and Trafficanagement Practice

. The feasibility study should consider the extentf the existing and planned facilities within the area of

the proposed scheme. These include:

• Control Office operational boundaries and theirinteraction with respect to the control ofincidents and traffic management

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• the location, type and objectives of existing andplanned VMS schemes including, whereappropriate, local authority initiatives


• the NMCS Infrastructure and its capability tosupport new systems




5. STMS schemes are likely to deal with themanagement of unusual or unexpected events affectingroad traffic rather than with day to day congestion.Designers should identify the main objectives of thescheme. These might include:











C2/2


• the frequency of route diversions by studyinghistoric records of motorway and trunk roadclosures

• traffic characteristics as for network congestionand the capacity of alternative routes to acceptdiverted traffic

• the impact of potential diversions on alternativeRoutes, especially through towns and villages.

7. A traffic assignment programme should be usedto assess and develop strategic control plans that maybe used for the STMS. This programme should have thefacility to represent traffic diversions that may beapplied to the road network and to evaluate theeconomic and operational performance of the proposeddiversion strategies.

8. The depth and level of the network and trafficanalysis should be appropriate to the needs andobjectives of the STMS scheme. The output from thisanalysis should form the basis for the EconomicEvaluation.

Diversion Routes, junctions and nodes

9. Based on the Network and Traffic Analysis, thereport should identify the diversion routes, strategic andnon-strategic intervention nodes and the recommendedlocations for the provision of VMS.

10. The current view is that designers shouldpreferably restrict diversion strategies to the Trunk andMotorway Network. Where this is not possible, theviews of Police and Highway Authorities likely to beaffected must be sought before the strategy is drawn up.

11. Any existing diversion route agreementsdeveloped by the Police and Highway Authoritieswithin the scheme area should be considered andreviewed for inclusion in the STMS scheme as localdiversion strategies.

Scheme Operation and Management

12. Options for the operation and management of thescheme should be considered. The points to beaddressed include:

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• integration with existing and planned control andcommunications systems and any necessaryextension in capability of those systems


• implementation of a management structure takinginto account longer term proposals for RegionalTraffic Control Centres



13. Designers should assess the suitability of usingexisting control and communications systems for theSTMS scheme in consultation with the OverseeingOrganisation. Existing or planned systems used forVMS control include:

• NMCS2 - Message Sign subsystem

• NMCS2 - Traffic Management subsystem

• Stand Alone Control Systems.

14. Considering the effect of the scheme design onSTMS and other traffic management schemeselsewhere on the road network is important. It isessential that different systems provide motorists withaccurate and consistent information when moving fromone area to another.


• divisions of the Overseeing Organisation

• the Police

• Highway Authorities

• DBFO Concessionaires

• members of the M4NTAIS CYMRU TrafficControl Centre Consortium.

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MS Legend and Sign Type selection

6. The feasibility study should identify the type andize of VMS needed for each location and appropriateostings should be used in the Economic Evaluation.

7. The type and range of information to beisplayed will generally limit the choice of signechnologies, whereas the sign location, roadlassification and vehicle speeds will all affectharacter heights and therefore the size of the VMS.

8. Deriving a common strategy for VMS signing ismportant, whatever the technology and application.hapter C1 describes the scope of VMS applicationsovering Driver Information, Tactical Control andtrategic Traffic Management. The type of VMS and

he range of messages used for STMS applications willherefore be influenced by the type and extent of anyther VMS signing at a given location.

9. The Feasibility Study must therefore consider inequence:

i) the information needed in the VMS legend tomeet the scheme objectives

ii) the content and number of VMS legends for eachlocation

iii) the VMS technology needed to display therequired legends

iv) the technology used by other VMS on the samesection of road

v) the VMS size and performance level needed forthe application or applications.

0. VMS legends should normally be selected fromhose given in the Traffic Signs Regulations andeneral Directions (TSRGD). Any other legendseeded for a specific scheme must be authorised by theverseeing Organisation.

1. The practice for STMS messages is to state theocation and cause of the diversion, followed by theuggested alternative route. Research suggests thatessages should be restricted to a maximum of sevenords, or four units of information. The aim should be

o use the shortest message possible. Examplesurrently used for STMS applications are:

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M4 CLOSEDUSE A48

M4 CLOSEDLEAVE AT J41

22. Further reading on VMS legends is given in theVAMOS WHITE BOOK, produced under the EuropeanDrive Project VAMOS (VAriable Message OptimisedSystems).

23. Where the system will include VMS legendsrelating to more than one application, ie Tactical andSTMS, the hierarchy must be explicit and designersmust develop setting resolution rules to decide whichlegend to use for each specific set of circumstances.The Highways Agency document ‘Code of Practice forOperation of Motorway and Trunk Road Signals andVariable Message Signs’, prepared with consultationwith the Association of Chief Police Officers (ACPO)gives further guidance on this subject.

Sign Types

24. If the only information to be provided is a routechange, ie alternative direction signing, Fixed TextMessage Signs (FTMS) may be adequate. Where thedesigner requires a wider range of options,discontinuous light emitting variable message signsshould be used.

25. For STMS applications in Wales, the usual typeof VMS is the Enhanced Message Sign (EMS), basedon light-emitting technology and comprising 2 lines of12 characters. However, EMS of other sizes such as3x18, 2x16, 3x16, etc may also be used.


27. VMS will normally be provided in pairs on theapproach to a junction or node and it is preferable thatboth these signs show the same legend. This is toreinforce the legend and to reduce the chance of driversmissing the information presented due to obscuration ofa sign by high-sided vehicles. To allow identicallegends to be displayed, both signs must use the sametechnology and design and this must be borne in mindwhen selecting the sign type.

C2/4

Engineering



(ii) control system

(iii) signs

(iv) infrastructure and transmission.

29. A key factor for STMS is the collection ofaccurate real-time traffic information. The study shouldconsider the means by which this is to be achieved costeffectively, including on non-motorway roads.

30. The STMS control system as a whole mustsupport the operational and management strategy andany development of that strategy over time. The needfor any interlocking reaction to, and interaction with,other existing or planned traffic management andcontrol facilities must be identified and the implicationsassessed. This will include elements such as the numberand type of STMS legends, setting strategies, settingresolution rules between different applications, and theoperational Code of Practice.

31. The type(s) of sign should be identified from theguidance in Chapter C3, ‘Strategic VMS Types’.However the study should also consider the engineeringaspects related to possible sign locations and the meansof installation, ie verge mounted posts/cantilevers orportal gantries.

32. The requirements for the STMS infrastructureand transmission should be considered and assessed. Itis important to identify how the existing infrastructurecan be used to reduce the scheme cost, and maximisethe return on previous investments. The standardNMCS motorway infrastructure should support theneeds for most STMS applications. Elsewhere, a varietyof solutions should be considered and prioritised. Thesewill include cabling, followed by radio and the use ofprivate lines, ISDN or similar links to more remote ordifficult locations.

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Economic Evaluation

33. For conventional means of procurement the studymust include an evaluation to decide the economicviability of the scheme. The level of detail and theevaluation methodology will be scheme-dependent andshould be agreed with the Overseeing Organisationbeforehand.

34. Whole life costs to be considered should includesystem development, implementation, staffing, serviceand maintenance. The study should seek to prove thatthe provision of a STMS scheme is preferable to analternative traffic solution.

Environmental Assessment


• consideration of the visual impact of signs/support and ancillary equipment such as cabinets,duct runs and steps, etc viewed from the roaditself and from nearby developments and openspace




• an appreciation of the environmental effects onthe roads receiving diverted traffic with regard toincreased congestion, noise and air quality.

36. Designers should agree the scope of theenvironmental assessment with the OverseeingOrganisation beforehand.


37. The study should identify the objectives thatneed to be evaluated when the scheme is in operation toassess its effectiveness, optimise performance andconfirm that the economic benefits are being attained.The evaluation should generally include considerationsof accident reduction, speed changes and trafficvolumes leaving the road in response to givenmessages. The reduction in delay costs and driverfrustration leading to risk of accidents should also beconsidered. Quantifiable performance indicators that

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ay be used to demonstrate the effectiveness of theTMS might include:

reduced number of incidents

reduced number of congestion events notified

regular/reduced average journey time

increased traffic throughput

increased number of visits to M4NTAISCYMRU website (could be deemed to indicateincrease in public’s faith in the system).

mplementation Programme

8. The above study should identify anmplementation programme for the preferred schemeption. The programme should outline the logical stepsf implementation, indicate the likely spend profile andresent (where appropriate) the incremental economicenefit for each stage of the programme.

9. The programme should also identify appropriatetages for consulting and agreeing design proposals,perational and maintenance boundaries and systemngineering interfaces.

egislation

0. Many areas of legislation exist which will applyo the various elements of an STMS scheme. Most areommon to all design, procurement and constructionrojects and guidance is beyond the scope of thisdvice Note. However two specific areas of legislationill apply to STMS schemes and these are outlinedelow.

1. To be legally placed on the highway in Wales alligns, including all VMS legends must be eitherrescribed or authorised. Prescribed signs and VMSegends are defined in the TSRGD. Any sign not sorescribed must be authorised by the Overseeingrganisation.

2. VMS which are other than manually operatedill also need statutory Type Approval. Designers

hould consult the Overseeing Organisation on thisssue.

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Risk Assessment/Hazard Identification

43. A Risk/Hazard Assessment should be consideredas it relates to the role of the Highway Authority. Thismakes it necessary to maintain the highway in a safecondition and to secure the safe movement of trafficincluding pedestrians. The matters to be consideredtherefore include:

• signs not operating correctly

• reliability

• failure of a legend to appear or the appearance ofan incorrect legend

• maintenance.

44. Depending on the outcome of the assessmentprocess, requirements such as message monitoring,interlocking and/or message sequencing rules may needto be developed during the design stage to ensure thatsafety integrity levels are achieved.

C2.3 Scheme Design and Implementation

45. Outline proposals developed during theFeasibility Study should be reviewed, refined anddeveloped into the scheme design. This should take intoaccount the requirements not only for implementationbut for effective maintenance and operational supportthroughout the operational life cycle.

46. The scheme design should normally commencewith a consultation, survey and information collectionphase, followed by preparation of preliminary design tobe agreed with the Overseeing Organisation. Thepreliminary design should detail proposals for:

• traffic data and information collection systems

• VMS types


• control system




47. Designers should examine existing site records,transmission arrangements and control facilities to

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C2/6

ablish the impact of the scheme on existing systemsd the scheme design requirements. This stage willolve consultation with relevant divisions of theerseeing Organisation, the Police and otheranisations having an interest in the STMS scheme.

neral Design of the Works

. The detailed design and preparation of workingwings should not commence until the designposals have been presented to and agreed with theerseeing Organisation.

. The options for collecting accurate real-timeffic data and information identified during thesibility stage may be developed into the overalleme. On motorways the provision of MIDAS andTV will normally deliver this data. On other roads

d motorways where MIDAS and CCTV are not beingvided, the standard designs may need to be

veloped and modified to provide additional data andormation collection sites at key locations to suit theeds of the scheme.

. VMS must conform to the Overseeingganisation’s standards and will normally be based on Highways Agency ‘TR’ series of specifications.ese detail the sign design and performanceuirements to be achieved and standard interfaces to NMCS infrastructure. The designer should consult Overseeing Organisation before placing new

ntracts for VMS procurement as existing contractsy offer benefits in terms of cost savings and

proved designs.

. The definition of the control system requirementsst be based on the operational and management

jectives, taking into account the need for integrationth existing and planned systems and any extension to functionality or capacity of these systems. Theerseeing Organisation and the Police should be

nsulted at an early stage and proposals agreed beforealising the design and scope of the STMS contract.

. Control room and equipment room layouts must examined to ensure the proposed system can becommodated in terms of space for equipment andwer supplies etc.

. Design of the communications infrastructureould conform to the Welsh Office standards andwings available, as supplemented by the Highwaysency standards defined in the ‘MCX’ installationwings series.

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stated in HD 19/94.

54. The transmission network should take account ofthe capacity of existing systems. For motorways, thecable pairs and channel allocations on the PCMnetwork (where applicable) will need to be agreed withthe Overseeing Organisation beforehand and worksshould be arranged to re-configure and provideadditional communications circuits as required. Forother locations, the provision of circuits by PrivateTelecommunications Operators (PTOs) must be plannedat an early stage in the design process.

55. The provision and upgrading of power suppliesfor VMS can be a lengthy process, particularly forremote sites where the Electricity Supply Company(ESC) may need to negotiate wayleave. Power supplylocations should therefore be identified early in thedesign process and works orders placed accordingly.

56. VMS will normally be installed on posts orcantilever gantries in the roadside verge or on new orexisting portal gantries. Standard arrangements exist forsign cantilevers and for modifications to some types ofportal gantry. Designs, technical assessments anddesign checks should be carried out incorporating therequirements as applicable for:






58. Safety barrier must be provided at all locationsaccording to the Overseeing Organisation’s standards.Any existing barrier at or near to the sign locationshould be upgraded and extended as necessary.

59. Traffic management systems for STMS schemesmust conform to Chapter 8 of the Traffic Signs Manual.The Overseeing Organisation, Maintaining Agent andthe Police must be consulted to agree localarrangements, lane closure timings and road spacebookings, etc taking into account other programmedworks.

November 2005

Siting of VMS

60. The locations for VMS should be identified bysite survey according to the criteria given in ChapterC4, ‘VMS Siting Criteria’. A detailed site survey isrequired for each of the VMS locations identifiedduring the feasibility study.


Notifications

62. If considered necessary by the OverseeingOrganisation, notification of the STMS scheme shouldbe sent to the Planning Authority for information andcomment. This notification should comprise a packageof information, describing the scheme and its objectivesand showing the locations of the signs on a 1:25000scale map of the area.



64. Again any messages not included in the TSRGDmust be authorised by the Overseeing Organisation asdescribed in Chapter C2.2.


65. The diversion routes, junctions and nodesidentified during the feasibility stage should bereviewed and developed in consultation with the Policeand Highway Authority.


66. Procedures should be developed and worked intoa Code of Practice for operation of the STMS.Depending on the scope of the scheme, this mayinvolve consultation with the Overseeing Organisationand the Police including representatives of the relevantACPO committee.

Safety Audits

67. Safety Audits should be carried out in accordancewith the Highways Agency’s specific requirements

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68. The designer should provide as-built drawingsand records of the completed works for all contracts.All electrical inspection documentation should beprovided at completion of the works. Where required,‘As-Built’ information must be incorporated into theexisting NMCS record drawings. All structuralinformation, both for the signs themselves and thesupports, should be provided on completion of theworks.



70. The assessment should take into account bestpractice achieved elsewhere on the road network andthe driver’s consequential expectation and reliance onSTMS information.




• possible conflict with other signing/signallingand/or other driver information systems

• legend priority

• failure of a legend to appear or the appearance ofan incorrect legend (this must be done withregard to an individual sign, the message planaffected and the system as a whole)



• maintenance.

C2/8

C2.4 Scheme Evaluation

81. When the scheme is in operation, the STMSshould be continuously evaluated to assess itseffectiveness, optimise performance, and confirm thatthe economic, operational and other benefits of thescheme are being attained. The evaluation should bepresented in the form of a Scheme Evaluation Report,including the performance indicators detailed abovewherever possible.


83. Data from the detection and VMS systems shouldbe collected and analysed to check whether thealgorithm or operational rules select the appropriatestrategy and to assess the actual diversion achieved.Where appropriate, rules or algorithms should berefined.

84. Monitoring should continue whether the initialresults show that refinements are needed or not, so thatchanges in conditions and driver responses over timecan be met with appropriate system responses.

C2.5 System Certification

85. The system certification procedures specified inMCH 1813 : System Certification Specification, shouldbe followed.

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C3.1 Introduction


2. All Strategic VMS should be fitted with flashingamber lanterns. The lanterns should flash insynchronous horizontal pairs alternating top and bottomto draw the attention of drivers to the messagedisplayed on the VMS. Lantern design requirementsmust comply with the Traffic Signs Regulations andGeneral Directions (TSRGD).

C3.2 VMS Technologies and Types


3. EMS are active light emitting signs. Two maintechnologies are used in such signs: these are LightEmitting Diode (LED) and Optical Fibre (OF). A thirdvariety uses the combination of a reflective disc withlight emitting technology.






5. Each character is formed from a matrix of displaycells 5 wide and 7 deep and has a nominal characterheight of either 320mm or 420mm, depending on theapplication. EMS installed on all purpose roads mayhave characters of smaller dimensions, in accordancewith TD 33/90.

6. EMS are usually installed on Cantilever or PortalGantries.

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C3. STRATEGIC VMS TYPE

November 2005

ed Text Message Signs

FTMS are any type of VMS that display two orre fixed legends (or a blank display and one or moreends). There are currently a number of technologiesd in such signs, the more common being active lightitting (as above), flexible roller blind and rotatingnk or prism, the latter two normally being electro-chanically operated. Of these type the rotating plankrism is most suitable for strategic use.

The rotating plank or prism sign normallysists of a series of planks or prisms that align to

m a flat sign face. When required to show a differentect, the planks or prisms rotate and realign to presenifferent sign face. Either the whole sign face can benged in this way, or only those parts of the sign facet need to be changed. In this way the number ofend options available can be increased.

The arrangement of text used for displayposes on rotating plank or prism signs must be asscribed in the TSRGD.

FTMS are normally mounted on posts installed in motorway verge, or on Portal Gantries.

.3 Applications of Strategic VMS

hanced Message Signs

It is accepted that under conditions of normalibility, EMS type signs are less easily legible thanventional fixed traffic signs. This is a factor thatst be balanced against their ability to display manyerent legends. However, if they comply withracter height and optical performance requirements,y may actually be more easily legible thanventional fixed text signs under poor visibilityditions. This performance under poor conditionsy influence the choice of technology for a givenlication.

Experience suggests that strategic EMS ontorways should be provided at the approach to keyctions on the network, upstream of associated onee and half mile Advance Direction Signs (ADS).

ile and _ mile respectively on dual two lanemotorways).

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13. EMS with two lines of twelve characters (2x12)are preferred for most motorway applications. HoweverEMS with 2x16, 3x16 or 3x18 characters can also beused, provided that the feasibility study identifies thatsuch signs are necessary for the legends required at aparticular location. EMS with smaller characters mayalso be used, depending on the type of road and theparticular application. In such cases, the character eightshould be determined from the guidelines given in TD33/90.


14. FTMS are more commonly used for diversionrouteing and local traffic management where there are alow number of route options. They may mosteffectively be used to display messages linking to apredetermined diversionary route marked by symbols,eg ‘Follow _ for London’.

15. Other FTMS applications include tunnel/bridgemaintenance requiring lane or road closures,weighbridges, tidal flow operations, level crossings andbus lane management.


17. Unlike EMS, FTMS normally replace existingADS as the normal sign face contained on the ADS willbe incorporated as one of the faces of the FTMS.Diversion destinations, when shown, shall appear inblack legends on yellow background, designed to thesame rules as set out in Chapter 7 of the Traffic SignsManual. When the diversionary route is displayed,flashing amber lanterns, as referred to in C3.1.2 shall beused.

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C4.1 General

1. The siting criteria to be used when identifyingVariable Message Sign (VMS) locations depends on thesign type selected during the feasibility and designstages.

2. For Fixed Text Message Sign (FTMS) type signsthe criteria to be applied are the same as for AdvanceDirection Signing (ADS) on motorway and trunk roads.Such signs will normally replace the existing ADS andbe installed on posts in the verge or on portal gantriesas appropriate to the scheme design.

3. When siting Enhanced Message Sign (EMS) typesigns, it is important that the EMS is positioned so thatthe motorist can correlate the legend displayed with theassociated ADS downstream of the EMS.

4. The advice given in Chapter C4.2 should befollowed to determine appropriate locations for EMStype signs.

C4.2 Siting Criteria for EMS Type Signs

5. Figures C4.2 a, b and c cover the generaldecision process and siting arrangements for EMS onmotorway. The use of cantilevers indicated in FigureC4.2b assumes signs of 3 lines of 18 characters asstandard, which are too large to accommodate on portalgantries. However, where signs of 2 lines of 12characters are to be used, portal gantries should be usedin preference to cantilevers, as described in TD 33/90and MCH 1643. The information should be read inconjunction with the advice given in Chapter C2 of thisguide, particularly in relation to the selection of VMSsign and legend types.

6. By definition, EMS for Strategic TrafficManagement Systems (STMS) purposes need to be onthe approaches to road junctions that can be broadlycategorised as either All-Purpose Road/Motorway orMotorway/Motorway. Whereas the standards for thesewith regard to the type of signing and signalling arequite different, the general arrangement of the directionsigns is usually one mile, followed by half mile (_ mileand _ mile respectively on dual two lane motorways)and a final ADS.

C4. VMS SITING CRITER

November 2005

7. In deciding locations for EMS it is necessary toconsider and balance the following needs.


• sign clutter and information overload must beavoided. In this respect, the maximum number ofunits of information presented to the drivershould not exceed seven

• STMS signs should be positioned so the drivercan associate the EMS message with the routeinformation on directional signing


8. Figures C4.2 a, b and c set out in general termshow this balance might best be achieved in a givenlocation. If however a particular situation is notdefined, reference should be made to the OverseeingOrganisation.

9. Sign legends should be duplicated to reinforcethe information or instructions given. Therefore, twoEMS should generally be provided on the approach tothe key junctions within any Strategic TrafficManagement Scheme.

10. It is recommended that the following parametersbe used in conjunction with Figures C4.2 a, b and c:

• EMS with 420mm (nominal) character height oncantilevers or 320mm (nominal) character heighton gantries

• separation distances as described in MCH 1643

• a protected sightline to the EMS of 225mminimum and 400m desirable.

C4.3 Siting Considerations for VMS


C4/1


Annex CWales Only


12. VMS should be positioned to ensure that bridgesand other structures do not obstruct visibility. Equallyimportant is to ensure that VMS do not obstruct thevisibility of other signs and signals, the detection fieldof Fog Detectors, or the view from CCTV surveillancecameras.



14. Where road lighting is in the verge, VMS shouldbe located at least one column length away from thenearest lighting column. This is to prevent damagebeing sustained by the sign in the event of the lightingcolumn being knocked down by a vehicle. Where aVMS has to be sited between two lighting columns, itshall be placed immediately upstream of a columnwherever possible.



16. For new roads and motorways, consideration ofthe type, location and degree of visual intrusion causedby the strategic VMS structures, should be included inthe Environmental Assessment under LandscapeEffects.

17. The procedures set out in Department of theEnvironment Circular 18/84 - Crown Land and CrownDevelopment do not apply to the provision of VMSwithin the existing highway boundary. However whensiting signs, due consideration should be given toassessing and reducing their visual impact.

C4/2






• on link roads it is essential that VMS arecorrectly oriented so that they can be clearlydistinguished from main carriageway VMS: thismay be achieved be means of louvres or narrowangle emitters.

November 2005


Novem

Annex CWales Only

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ber 2005 C4/3

Volum

e 9 Section 4P

art 6 TA

83/05

Novem

ber 2005

Annex C

Wales O

nly

C4/4

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Volum

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art 6 TA

83/05

Nove

Annex C

Wales O

nly

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GNALLING.

nal gantries will apply to other diverge arrangements.

ed.

SE TRUNKAL GANTRIES

mber 2005

C4/5 Figure C4.2c

9 * 2 3 �

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NOTES

1. The layout and separation for the sign/signal gantries is taken from DMRB Vol9, Section 4, Part 3 TA74/97. MOTORWAY SI

2. To determine the separation distance 'S' refer to Paragraph C4.2 and Figure C4.2a.

3. The diagram shown is for a parallel deceleration lane. However a similar relationship between the strategic EMS and sign/sig

4. The sign/signal granties should comprise lane signal matrices supported by 2x12 EMS (320mm character height) plus ADS.

5. The cantilever VMS should comprise 3x18 400mm characters. If it comprises an integral matrix, this facility should be disabl

PROVISION OF STRATEGIC EMS ON ALL PURPOROADS AND MOTORWAYS WITH SIGN/SIGNAL PORT


RE

Annex CWales Only

C5.1 Control Systems

1. Variable Message Signs (VMS) can be controlledby all current motorway control systems. Designersshould assess the suitability of using existing controland communications systems for the Strategic TrafficManagement Systems (STMS) scheme in consultationwith the Overseeing Organisation. Existing or plannedsystems used for VMS control include:

• NMCS2 - Message Sign subsystem

• NMCS2 - Traffic Management subsystem

• Stand Alone Control System.

2. The communications infrastructure needed tosupport either an NMCS2 or Stand Alone Controlarrangement is fully described in TRH 1642,‘Motorway Signals Mark 2, Infrastructure DesignGuide’.

C5.2 Roadside Infrastructure

General

3. On motorways, the existing NMCS infrastructureshould be able to support the majority of STMSapplications. Where new STMS schemes are introducedwithin existing sections of motorway, infrastructureworks should therefore be limited to civils work andlocal modifications to existing cabling and powerssupplies.

4. On other roads it will be necessary to develop thesolutions identified during the feasibility study such ascabling to the motorway, or radio/private lines/ISDN/similar links to more remote locations.


5. The infrastructure for a typical EnhancedMessage Signs (EMS) site comprises:


(

(

(

6s

7Dwlc

81G

F

9M

(

(

(

(

C5. VMS INFRASTRUCTU

November 2005

or


ii) Communications Cabinet Type 600 and PowerCabinet Type 609 with associated cabling andducts

iii) safety fencing - double height Open Box Beam


. A typical Cantilever EMS Outstation Layout ishown on Drawing MCX 0582.

. A Portal Gantry Outstation Layout is shown onrawing MCX 0800. This shows the arrangementhere a ducted cable network is provided. At all other

ocations, the cables between the gantry and equipmentabinets will be directly buried.

. Further guidance is given in Specification TRH642, ‘Motorway Signals Mark 2, Infrastructure Designuide’.

ixed Text Message Signs

. The infrastructure for a typical Fixed Textessage Signs (FTMS) site comprises:

i) a foundation (either a reinforced concrete blockwith no holding down arrangement where theFTMS post fixings are drilled into thisfoundation or a similar block with appropriatepost holes)

ii) Communication cabinet Type 600 and a PowerCabinet Type 609 with associated cabling andducts

iii) safety fencing to suit location


C5/1


Annex CWales Only

C5.3 Technical Approval



(i) foundation



12. Technical Approval must be sought from theappropriate Technical Approval Authority. If thefoundation and superstructure are designedindependently, or by different design organisations, aTechnical Approval submission must be made for eachelement.

13. Cantilever foundations and superstructures areclassed as Category II structures and, as such, willrequire independent checks of the design.

14. Note that, in Wales, offset tee cantilevers havebeen used in place of full cantilevers. The amount ofoffset is defined for individual contracts.

Existing Gantries

15. Existing gantries should already be certified toBD 2/89. Technical Approval is therefore required forthe addition of VMS sign enclosures and mountingequipment and the effect of these additions on thegantry structure.

16. Detailed designs already exist for the additionalsteelwork to support 320mm EMS to be mounted oncertain “standard” gantries. This design and where itcan be applied is shown on Drawing No MCX 0584.

17. Where VMS signs with character sizes other than320mm are to be installed, a new design must bedeveloped specifically for each situation.


C5/2


C5.4 Holding Down Arrangement


21. On contracts where different contractors areresponsible for the construction of the base andsuperstructure, steps must be taken to ensure that theinterface between the two elements matches.

C5.5 Optical Alignment

22. When using VMS based on light emittingtechnology, it is particularly important to ensure correctoptical alignment of the sign with the carriageway, so asto present the optimum viewing time to drivers. Designrequirements and the method to be applied on site aregiven in Drawing MCX 0069.

C5.6 Ordering Equipment

23. Requests for Welsh Office issued equipment forspecific schemes should be made in accordance withthe current procurement procedures in place at the time.

November 2005


S

Annex CWales Only



Cantilever


Continuous Sign

A Variable Message Signs (VMS) that appears to bemade up of solid characters or symbols. The sign face ischanged by removing one set of symbols/characters andreplacing them with another, or by having a multipleface that can rotate.

Discontinuous Sign



Systems which give the motorist information of atactical and strategic nature, but also with messagesrelating to conditions on the network that may affectexpected journey times. This may include informationon major events, eg shows, sports events, etc and internetwork connections such as ferries, tolled roads andcrossings.




A type of VMS able to display a limited number offixed messages. Signs for strategic applications use amechanical rotating prism as the mechanism forchanging the sign legend.

C6. GLOSSARY OF TERM

November 2005

Portal Gantry

An overhead structure that spans the carriageway and isused to support combinations of signals, variablemessage signs and conventional fixed signs.

Sign

A device carrying directional or other informationalmessage, eg route information at the approach to ajunction.

Signal

A device used to give advisory or mandatoryinstructions, eg stop or 30 mph speed restriction.

Strategic Traffic Management Systems

Systems which give the motorist information andadvice on the road network ahead. The aim is toimprove the performance of the network byredistributing traffic efficiently when congestion occurson some links and spare capacity is available on others.

Tactical Control Systems

Systems which provide supplementary information tocomplement matrix signals and other traffic controlsigns for local management of incidents or occurrences.

Variable Message Sign

A generic term for a sign that can display multiplelegends or messages.

EMS and Fixed Text Message Signs (FTMS) aredifferent types of VMS.


(a) Rotating Prism



NMCS


C6/1


Annex CWales Only




TA 72/97: National Motorway CommunicationsSystems – DMRB, Volume 9, Section 4Part 1.





Department of Transport

Traffic Signs Regulations and General Directions(TSRGD).

Chapter 8 of the Traffic Signs Manual.

Highways Agency Specifications and Standards

MCH 1286: Request for Financial Approval:Standard and Non-Standard Schemes.

MCH 1288: Request for Financial Approval forBulk Purchase Equipment only.

MCH 1643: Motorway Signals Mark 2 - DesignGuide

MCH 1813: System Certification Specification.

TRH 1642: Motorway Signals Mark 2 andEnhanced Message Signs -Infrastructure Design Guide.

C7. REFERENCES

November 2005

,

TR 0154: Electromechanical Variable MessageSigns - Functional Specification

TR 2136: Functional Specification forContinuous or Discontinuous VariableMessage Signs

TR 2141: Motorway Signals Mark 2,Requirements for Signal Equipment

TA 33/90: The Use of Variable Message Signs onAll Purpose and Motorway TrunkRoads



MCX 0582: EMS Outstation Layout.



MCX 0590: Cantilever Site - Typical Arrangement.

MCX 0591: Portal gantry Site - TypicalArrangement.

Other Publications

Department of Environment Circular 18/84 - CrownLand and Crown Development

C7/1

November 2005




PART 6

TA 83/05 ANNEX D (NORTHERNIRELAND ONLY)


SUMMARY

This issue of Annex D incorporates an amended firstbullet point to clause D1.2.14.



1. Insert TA 83/05 Annex D as Part 6 of Volume 9,Section 4.






Registration of AmendmentsVolume 9 Section 4Part 6 TA 83/05 Annex D (Northern Ireland Only)

November 2005





Part 6 TA 83/05 Annex D (Northern Ireland Only)

November 2005



PART 6

TA 83/05 ANNEX D (NORTHERNIRELAND ONLY)


Contents

Chapter

D1. Introduction

D2. Scheme Process

D3. Strategic VMS Types

D4. VMS Siting Criteria

D5. VMS Infrastructure

D6. Glossary of Terms

D7. References


November 2005


Annex DNorthern Ireland Only

D1. INTRODUCTION

D1.1 General

1. This Annex is for the specific requirements ofmotorway communications in Northern Ireland.

DMRB Structure



Design Loop

4. Figure D1.1 shows the ‘Design Loop’ illustratingthe general sequence in the iterative process whichstarts with the design for emergency telephones andsignals followed by transmission and control officedesigns. Last in the cycle is the design of theinfrastructure that will be required to support allcommunications equipment and systems.

Glossary

5. A Glossary of Terms is given in Chapter D6.


6. Standard drawings and specifications referred toin this guide are issued by Roads Service.

November 2005

Figure D1.1 – Structure of Volume 9 of the DesignManual for Roads and Bridges

Section 1


Sections2 & 3


Section 4Part 1

NMCS2SystemsDesign

Section 4

OtherNMCS2

Sub Systems

Section 4Part x

StrategicTraffic

Management

Section 4Part 2


Section 4Part 5

MotorwayControl

Office Design

Section 4Part 4


Design

Section 4Part 3

MotorwaySignalling


Systemse.g.

CCTV

Section 4

MIDAS orOther AID

System

Section 5

MotorwayInfrastructure

DESIGN

LOO

P

D1/1



D1.2 Related Standards and Advice Notes

7. TD 33/90, ‘The Use of Variable Message Signson All-Purpose and Motorway Trunk Roads’, providescriteria affecting the selection, siting and use of alltypes of Variable Message Signs (VMS) on all purposeand motorway trunk roads. This Advice Note relatespurely to light emitting VMS and TD 33/90 is due to beupdated to concord with the advice given in thisdocument. Most VMS currently used for StrategicTraffic Management are based on light emittingtechnology.



10. The following current versions of Advice Notesare of general relevance to motorways. Referenceshould be made to Roads Service as to their specificapplication in Northern Ireland.








D

11DMCoOv

12spNoshwi

13anTAth(S

VM

14Tasc

•

•

•

15to

16

D1/2

1.3 Scope

. The practices and requirements detailed inRB, Volume 9, Network - Traffic Control and

mmunications relate to the policies implemented byerseeing Organisations in the UK.

. The principles in this Advice Note referecifically to the needs and practices applicable inrthern Ireland. Other Overseeing Organisations,

ould refer to annexes A, B or C, for advice in lineth their Strategic Traffic Management needs.

. This Advice Note takes precedence in the case ofy conflicting direction in TD 33/90 or advice in 60/90, or other existing Advice Notes in as far as

ey relate to Strategic Traffic Management SystemsTMS).

S Applications

. VMS are provided for Driver Information,ctical Control and Strategic Traffic Management. Theope of these applications is:

Driver Information Systems - provide themotorist with information of a tactical andstrategic nature, but also with messages relatingto conditions on the network which may affectexpected journey times.

Tactical Control - provides supplementaryinformation to complement matrix signals andother traffic control signs for management ofincidents or occurrences on local roads in thearea. Signs set in support of tactical objectivesdisplay messages specifically related to achievingimprovements on the localised sections of thenetwork, eg ‘ACCIDENT/LONG DELAYS’.

Strategic Traffic Management - provide themotorist with information and advice on the roadnetwork ahead. The aim is to improve theperformance of the network by redistributingtraffic efficiently when congestion occurs onsome links and spare capacity is available onothers.

. This Advice Note covers the application of VMS STMS only.

. Strategic Traffic Management seeks to ensurethat a strategic view of network status and conditions isavailable, and that strategies and decisions which have

November 2005



more than a local impact can be identified correctly, andeffectively implemented. Signs set in support of theseobjectives offer alternative or diversionary routechoices.

17. This Advice Note also describes the differenttypes of VMS currently available for STMS schemes,and outlines the approach to the feasibility study,scheme design, implementation and evaluation.

November 2005 D1/3



D2.1 General

1. There are no standard provision criteria forStrategic Traffic Management Systems (STMS)schemes and each must therefore be individuallyjustified by means of a feasibility study which mayincorporate an economic analysis.

2. The Scheme Process is illustrated in Figure D2.1The implementation of Strategic Traffic Managementschemes will generally comprise the followingelements:

• Feasibility Study (Chapter D2.2)

• Design and Implementation (Chapter D2.3)

• Scheme Evaluation (Chapter D2.4).

Figure D2.1 Scheme Process

D2. SCHEME PROCESS

D

3pFo

•

•

•

•

•

•

•

•

•

•

•

•

•

•

RM

4ot

•


➤


SCHEME DESIGN

& IMPLEMENTATION


➤

Annual Review

NO

NO

YES

YES

November 2005

2.2 Feasibility Study

. A feasibility study is needed to determine theracticality and value for money of STMS schemes. Aeasibility Study Report should be produced at the endf the study period and consider the following:




diversion routes and intervention nodes


Variable Message Signs (VMS) messages andsign type selection

engineering

future maintenance

economic evaluation




legislation


eview of Existing Systems and Trafficanagement Practice

. The feasibility study should consider the extentf the existing and planned facilities within the area ofhe proposed scheme. These include:

Control Office operations with respect to thecontrol of incidents and traffic management


D2/1



• the location, type and objectives of existing andplanned VMS schemes where appropriate


• the motorway communications infrastructure andits capability to support new systems




5. STMS schemes are likely to deal with themanagement of unusual or unexpected events affectingroad traffic rather than day to day congestion. Designersshould identify the main objectives of the scheme.These might include:












•

•

•

7.asusfaapecdi

8.anobanEv

Di

9.renolo

10prMvibe

11descinstr

Sc

12scad

•

D2/2

the frequency of route diversions by studyinghistoric records of motorway and trunk roadclosures

traffic characteristics as for network congestionand the capacity of alternative routes to acceptdiverted traffic

the impact of potential diversions on alternativeroutes, especially through towns and villages.

A traffic assignment programme may be used tosess and develop strategic control plans that may beed for the STMS. This programme should have thecility to represent traffic diversions that may beplied to the road network, and to evaluate theonomic and operational performance of the proposedversion strategies.

The depth and level of any network and trafficalysis should be appropriate to the needs andjectives of the STMS scheme. The output from thisalysis should form the basis for any Economicaluation that may be required.

version Routes and Intervention Nodes

Based on the Network and Traffic Analysis, theport should identify the diversion routes, strategic andn-strategic intervention nodes and the recommendedcations for the provision of VMS.

. The current view is that designers shouldeferably restrict diversion strategies to the Trunk andotorway Network. Where this is not possible, theews of Roads Service and the Police, must be soughtfore the strategy is drawn up.

. Any existing diversion route agreementsveloped by Roads Service and the Police within theheme area should be considered and reviewed forclusion in the STMS scheme as local diversionategies.

heme Operation and Management

. Options for the operation and management of theheme should be considered. The points to bedressed include:

integration with existing and planned control andcommunications systems and any necessaryextension in capability of those systems

November 2005




• implementation of a management structure takinginto account longer term proposals of a RegionalTraffic Control Centre



13. Designers should assess the suitability of usingexisting control and communications systems for theSTMS scheme in consultation with Roads Service.Existing or planned systems used for VMS controlinclude:

• Motorway Control System

• Urban Traffic Control subsystem

• Automatic Incident Detection Subsystem

• Ramp Metering Systems

• Remote Monitoring Systems

• Other Stand Alone Systems.

14. Considering the effect of the scheme design onSTMS and other traffic management schemeselsewhere on the road network is important. It isessential that different systems provide motorists withaccurate and consistent information when moving fromone area to another.


• Roads Service

• the Police

• DBFO Concessionaires.

VMS Legend and Sign Type selection

16. The feasibility study should identify the type andsize of VMS needed for each location and appropriatecostings should be used in the Economic Evaluation.

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November 2005

7. The type and range of information to beisplayed will generally limit the choice of signechnologies, whereas the sign location, roadlassification and vehicle speeds will all affectharacter heights and therefore the size of the VMS.

8. Deriving a common strategy for VMS signing ismportant, whatever the technology and application.hapter D1 describes the scope of VMS applicationsovering Driver Information, Tactical Control andtrategic Traffic Management. The type of VMS and

he range of messages used for STMS applications willherefore be influenced by the type and extent of anyther VMS signing at a given location.

9. The Feasibility Study must therefore consider inequence:

i) the information needed in the VMS legend tomeet the scheme objectives

ii) the content and number of VMS legends for eachlocation

iii) the VMS technology needed to display therequired legends

iv) the technology used by other VMS on the samesection of road

v) the VMS size and performance level needed forthe application, or applications.

0. VMS legends should normally be selected fromhose given in the Traffic Signs Regulations (Northernreland). Any other legends needed for a specificcheme must be authorised by Roads Service.

1. The practice for STMS messages is to state theocation and cause of the diversion, followed by theuggested alternative route. Research suggests thatessages should be restricted to a maximum of sevenords, or four units of information. The aim should be

o use the shortest message possible.

2. Further reading on VMS legends is given in theAMOS WHITE BOOK, produced under the European

Drive’ Project VAMOS (VAriable Message Optimisedystems).

3. Where the system will include VMS legendselating to more than one application, ie Tactical andTMS, the hierarchy must be explicit and designersust develop setting resolution rules to decide which

egend to use for each specific set of circumstances.he Highways Agency document ‘Code of Practice for

D2/3



Operation of Motorway and Trunk Road Signals andVariable Message Signs’, prepared with consultationwith the Association of Chief Police Officers (ACPO)gives further guidance on this subject.

Sign Types

24. If the only information to be provided is a routechange, ie alternative direction signing, Fixed TextMessage Signs (FTMS) may be adequate. Where thedesigner requires a wider range of options,discontinuous light emitting signs should be used.

25. For most STMS applications, the mostappropriate type of VMS will be the Enhanced MessageSign (EMS), based on light-emitting technology.


27. Depending on proposed usage and location, VMSmay be provided in pairs on the approach to anIntervention Node. This is to reinforce the legend, andto reduce the potential for it to be obscured from thedriver by high-sided vehicles. In selecting the VMStype it is essential that all signs on the approach to anode show the same legend and therefore both signsmust use the same technology and design.

Engineering



(ii) control system

(iii) signs

(iv) infrastructure and transmission

29. A key factor for STMS is the collection ofaccurate real-time traffic information. The study shouldconsider the means by which this is to be achieved costeffectively, including on non-motorway roads.

D2/4

30. The STMS control system as a whole mustsupport the operational and management strategy andany development of that strategy over time. The needfor any interlocking reaction with, and interaction to,other existing or planned traffic management andcontrol facilities must be identified and the implicationsassessed. This will include such elements as the numberand type of STMS legends, setting strategies, settingresolution rules between different applications, and theoperational Code of Practice.

31. The type(s) of sign should be identified from theguidance in Chapter D3, ‘Strategic VMS Types’.However the study should also consider the engineeringaspects related to possible sign locations and the meansof installation, ie verge mounted posts or cantilevers, orportal gantries.

32. The requirements for the STMS infrastructureand transmission should be considered and assessed. Itis important to identify how the existing infrastructurecan be used to reduce the scheme cost, and maximisethe return on previous investments. The standardmotorway infrastructure should support the needs formost STMS applications. Elsewhere, a variety ofsolutions should be considered and prioritised. Thesewill include cabling, followed by radio and the use ofprivate lines, ISDN or similar links to more remote ordifficult locations.

Economic Evaluation

33. For conventional means of procurement the studymay include an evaluation to decide the economicviability of the scheme. The level of detail and theevaluation methodology will be scheme-dependent andshould be agreed with Roads Service.

34. Whole life costs to be considered should includesystem development, implementation, staffing, serviceand maintenance. The study should seek to prove thatthe provision of an STMS scheme is preferable to analternative traffic solution.

Environmental Assessment


• consideration of the visual impact of signs/support and ancillary equipment such as cabinets,duct runs and steps etc., viewed from the roaditself and from nearby developments and openspace

November 2005







36. Designers should agree the scope of theenvironmental assessment with Roads Service.





39. The programme should also identify appropriatestages for consulting and agreeing design proposals,operational and maintenance boundaries and systemengineering interfaces.

Legislation

40. Many areas of legislation exist which will applyto the various elements of an STMS scheme. Most arecommon to all design, procurement and constructionprojects and guidance is beyond the scope of thisAdvice Note. However two specific areas of legislationwill apply to STMS schemes and these are outlinedbelow.

41. To be legally used all Traffic Signs, including allVMS legends must be either prescribed or authorised.

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November 2005

escribed signs and VMS legends are defined in theaffic Signs Regulations (Northern Ireland). Any signt so prescribed must be authorised for a definedation and period of time by Roads Service.

. VMS which are other than manually operated,ll also need statutory Type Approval. Designersould consult Roads Service on this issue.

sk Assessment/Hazard Identification

. A Risk/Hazard Assessment should be consideredit relates to the role of Roads Service. This makes itcessary to maintain the highway in a safe conditiond to secure the safe movement of traffic includingdestrians. The matters to be considered thereforelude:

signs not operating correctly

reliability

failure of a legend to appear or the appearance ofan incorrect legend

maintenance.

. Depending on the outcome of the assessmentcess, requirements such as message monitoring,

erlocking and/or message sequencing rules may needbe developed during the design stage to ensure safetyegrity levels are achieved.

.3 Scheme Design and Implementation

. Outline proposals developed during theasibility Study should be reviewed, refined andveloped into the scheme design. This should take intocount not only the requirements for implementation,t for effective maintenance and operational supportoughout the operational life cycle.

. The scheme design should normally commenceth a consultation, survey and information collectionase, followed by preparation of preliminary design to agreed with Roads Service. The preliminary designould detail proposals for:

traffic data and information collection systems

VMS types

VMS site locations

control system

D2/5






47. Designers should examine existing site records,transmission arrangements and control facilities toestablish the impact of the scheme on existing systems,and the scheme design requirements. This stage willinvolve consultation with relevant divisions of RoadsService, the Police and other organisations having aninterest in the STMS scheme.


48. The detailed design and preparation of workingdrawings should not commence until the designproposals have been presented to and agreed withRoads Service.

49. The options for collecting accurate real-timetraffic data and information identified during thefeasibility stage may be developed within the overallscheme. On motorways the provision of MIDAS, orother incident detection systems, and CCTV willnormally deliver this data. Where this is not beingprovided and on other roads, the standard designs mayneed to be developed and modified to provideadditional data and information collection sites at keylocations to suit the needs of the scheme.

50. VMS must conform to Roads Service standardsand will normally be based on the Highways Agency‘TR’ series of specifications. These detail the signdesign and performance requirements to be achieved,and standard interfaces to the motorwaycommunications infrastructure. Also, signs may berequired to be interfaced to the Urban Traffic ControlSystem. The designer should consult Roads Servicebefore placing contracts for VMS procurement asexisting contracts may offer benefits in terms of costsavings and approved designs.

51. The control system requirements must be definedbased on the operational and management objectivesand taking into account the need for integration withexisting and planned systems, and any extension to thefunctionality or capacity of these systems. RoadsService and the Police should be consulted at an earlystage to enable consultations with the police. Proposalsshould be agreed before finalising the design and scopeof the STMS contract.

D2/6

52. Control room and equipment room layouts mustbe examined to ensure the proposed system can beaccommodated in terms of space for equipment andpower supplies, etc.

53. Design of the communications infrastructureshould conform to Highways Agency standards definedin the ‘MCX’ installation drawings series and anymodifications required by Roads Service.

54. The transmission network should take account ofthe capacity of existing systems. For motorways, cablepairs and channel allocations will need to be agreedwith Roads Service and works arranged to re-configureand provide additional communications circuits asrequired. For other locations, the provision of circuitsby Private Telecommunications Operators (PTOs) mustbe planned at an early stage in the design process.

55. The provision and upgrading of power suppliesfor VMS can be a lengthy process, particularly forremote sites where the Electricity Supply Company(ESC) may need to negotiate wayleaves. Power supplylocations should therefore be identified early in thedesign process, and works orders placed accordingly.

56. VMS will normally be installed on posts orcantilever gantries in the roadside verge, or on new orexisting portal gantries. Standard arrangements exist forsign cantilevers and for modifications to some types ofportal gantry. Designs, technical assessments anddesign checks should be carried out incorporating therequirements as applicable for:




• retaining walls


58. Safety barrier must be provided at all locationsaccording to Roads Service standards. Any existingbarrier at or near to the sign location should beupgraded and extended as necessary.

November 2005



59. Traffic management systems for STMS schemesmust conform to Chapter 8 of the Traffic Signs Manual.Roads Service, Maintaining Agent and the Police mustbe consulted to agree local arrangements, lane closuretimings and road space bookings, etc taking intoaccount other programmed works.

Siting of VMS

60. The locations for VMS should be identified bysite survey according to the criteria given in ChapterD4, ‘VMS Siting Criteria’. A detailed site survey isrequired for each of the VMS locations identifiedduring the feasibility study.


Notifications

62. If considered necessary, by Roads Service,notification of the STMS scheme should be sent to thePlanning Authority for information. This notificationshould comprise a package of information, describingthe scheme and its objectives and showing the locationsof the signs on a 1:25000 scale map of the area.



64. Again any messages not included in the TrafficSigns Regulations (Northern Ireland) must beauthorised by Roads Service as described in ChapterD2.2.


65. The diversion routes and intervention nodesidentified during the feasibility stage should bereviewed and developed in consultation with the Policeand Roads Service.


66. Procedures should be developed and worked intoa Code of Practice for operation of the STMS.Depending on the scope of the scheme, this mayinvolve consultation with Roads Service and the Police.

November 2005

Safety Audits

67. Safety Audits should be carried out in accordancewith the requirements as stated in HD 19/94, ‘RoadSafety Audits’, or as otherwise agreed with RoadsService.


68. The designer or contractor should provide as-built drawings and records of the completed works forall contracts. All electrical inspection documentationshould be provided at completion of the works. Whererequired, ‘As-Built’ information must be incorporatedinto the existing motorway communications recorddrawings. All structural information, both for the signsthemselves and the supports, should be provided oncompletion of the works.







• possible conflict with signing and/or driverinformation systems


• failure of a legend to appear or the appearance ofan incorrect legend - (this must be done on anindividual sign basis and a system and sequencebasis)


D2/7




• maintenance.

D2.4 Scheme Evaluation

73. When the scheme is in operation, the STMSshould be evaluated to assess its effectiveness, optimiseperformance, and confirm that the economic,operational and other benefits of the scheme are beingattained. The evaluation should be presented in theform of a Scheme Evaluation Report.


75. Data from the detection and VMS systems shouldbe collected and analysed to check whether thealgorithm or operational rules select the appropriatestrategy and to assess the actual diversion achieved.Where appropriate rules or algorithms should berefined.

76. Monitoring should continue whether the initialresults show that refinements are needed or not, so thatchanges in conditions and driver responses over timecan be met with appropriate system responses.

D2.5 System Certification

77. The system certification procedures specified inMCH 1813 : System Certification Specification, shouldbe followed.

November 2005D2/8


PES


D3.1 Introduction


2. All Strategic VMS should be fitted with flashingamber lanterns. The lanterns should flash insynchronous horizontal pairs alternating top and bottomto draw the attention of drivers to the messagedisplayed on the VMS. Lantern design requirementsmust comply with the Traffic Signs Regulations(Northern Ireland).

D3.2 VMS Technologies and Types


3. EMS are active light emitting signs. Two maintechnologies used in such signs, these are LightEmitting Diode (LED) and Optical Fibre. A thirdvariety uses the combination of a reflective disc withlight emitting technology.






5. Each character is formed from a matrix of displaycells 5 wide and 7 deep and has a nominal characterheight of 420mm or as otherwise approved by RoadsService. EMS 2x12 signs on gantries use a nominalcharacter size of 320mm.

6. EMS are usually installed on Cantilever or PortalGantries.


7. FTMS are any type of VMS that display two ormore fixed legends (or a blank display and one or more

D3. STRATEGIC VMS TY

November 2005

legends). There are currently a number of technologiesused in such signs, the more common being active lightemitting (as above), flexible roller blind and rotatingplank or prism, the latter two normally being electromechanical. Of these type the rotating plank or prism ismost suitable for strategic use.

8. The rotating plank or prism sign normallyconsists of a series of planks or prisms that align toform a flat sign face. When required to show a differentaspect, the planks or prisms realign to present adifferent sign face. Either the whole sign face can bechanged in this way, or only those parts of the sign facethat need to be changed. In this way the number oflegend options available can be increased.

9. The arrangement of text used for displaypurposes on rotating plank or prism signs must be asprescribed in the Traffic Signs Regulations (NorthernIreland).

10. FTMS are normally post mounted and located inthe footway, or the motorway verge, or installed onPortal Gantries.

D3.3 Applications of Strategic VMS


11. It is accepted that under conditions of normalvisibility, EMS type signs are less easily legible thanconventional fixed traffic signs. This is a factor thatmust be balanced against their ability to display manydifferent legends. However, if they comply withcharacter height and optical performance requirements,they may actually be more easily legible under poorconditions. This performance under poor conditionsmay influence the choice of technology for a givenapplication.

12. Experience suggests that strategic EMS onmotorways should be provided at the approach to keyjunctions on the network, upstream of associated onemile and half mile or two-thirds mile and one-third milerespectively Advanced Direction Signs as appropriate.

13. EMS with three lines of eighteen 420mm highcharacters (3x18) are preferred for most applications.However EMS with 2x12, 2x16 or 3x16 characters canalso be used, provided that the feasibility study

D3/1



identifies that such signs are suitable for the legendsneeded at a particular location.


14. FTMS are more commonly used for diversionrouteing and local traffic management where there are alow number of route options. They may mosteffectively be used to display messages linking to apredetermined diversionary route, marked by symbols,eg ‘Follow _ for Belfast’. Symbols incorporated insigns are indicated in the Traffic Signs Regulations(Northern Ireland).

15. Other FTMS applications include tunnel/bridgemaintenance requiring lane or road closures,weighbridges, tidal flow operations, level crossings andbus lane management.


17. Unlike EMS, FTMS normally replace existingAdvance Direction Signing (ADS) as the normal signface contained on the ADS will be incorporated as oneof the faces of the FTMS. Diversion destinations, whenshown, shall appear in black legends on yellowbackground, designed to the same rules as set out inChapter 7 of the Traffic Signs Manual. When thediversionary route is displayed, flashing amber lanterns,as referred to in D3.1.2 shall be used.

November 2005D3/2


A


D4.1 General

1. The siting criteria to be used when identifyingVariable Message Signs (VMS) locations depends onthe sign type and size selected during the feasibility anddesign stages.

2. For Fixed Text Message Signs (FTMS) typesigns the criteria to be applied are the same as forAdvance Direction Signing (ADS) on motorway andtrunk roads. Such signs will normally replace theexisting ADS and be installed on posts in the verge oron portal gantries as appropriate to the scheme design.

3. When siting Enhanced Message Signs (EMS)type signs, it is important that the EMS is positioned sothat the motorist can relate any message with theassociated ADS downstream of the VMS.

4. The advice given in Chapter D4.2 should befollowed to determine appropriate locations for EMStype signs.

D4.2 Siting Criteria for EMS Type Signs

5. Figures D4.2a, b and c cover the general decisionprocess and siting arrangements for EMS. Theinformation should be read in conjunction with theadvice given in Chapter D2 of this guide, particularly inrelation to the selection of VMS sign and legend types.

6. By definition, EMS for Strategic TrafficManagement Systems (STMS) purposes need to be onthe approaches to road junctions that can be broadlycategorised as either All-Purpose Road or Motorway/Motorway. Whereas the standards for these with regardto the type of signing and signalling are quite different,the general arrangement of the direction signs is usuallya one mile and half mile, or two-thirds mile and one-third mile Advanced Direction Signs as appropriate.

7. In deciding locations for EMS it is necessary toconsider and balance the following needs:


D4. VMS SITING CRITERI

November 2005

• sign clutter and information overload must beavoided. In this respect, the maximum number ofunits of information presented to the drivershould not exceed seven

• STMS signs should be positioned so the drivercan associate the EMS message with the routeinformation on directional signing


8. Figures D4.2 a, b and c set out in general termshow this balance might best be achieved in a givenlocation. If however a particular situation is notdefined, reference should be made to Roads Service.

9. Where considered necessary by Roads Service,sign legends should be duplicated to reinforce theinformation or instructions given. Therefore, two EMSmay be provided on the approach to the key junctionswithin any Strategic Traffic Management Scheme.

10. For the purposes of Figures D4.2 a, b and c thefollowing parameters have been assumed:

• EMS with 420mm character height

• for the cases shown in the above figures aseparation between strategic EMS and the onemile and half mile ADS (or two-thirds mile andone-third mile ADS as appropriate) of 200mminimum, 300m desirable and 400m maximum.However, the downstream EMS should not becloser than 200m to either the upstream ordownstream ADS

• a protected sightline to the EMS of 225mminimum and 400m desirable.

D4.3 Siting Considerations for VMS


D4/1




12. VMS should be positioned to ensure that bridgesand other structures, including signs and signals, do notobstruct visibility. Equally important is to ensure thatVMS do not obstruct the visibility of other signs andsignals, the detection field of Fog Detectors, or the viewfrom CCTV surveillance cameras.



14. Where road lighting is on the verge, VMS shouldbe located at least one column length away from thenearest lighting column. This is to prevent damagebeing sustained by the sign in the event of the lightingcolumn being knocked down by a vehicle. Where aVMS has to be sited between two lighting columns, itshall be placed immediately upstream of a columnwherever possible.



16. For new roads and motorways consideration ofthe type, location and degree of visual intrusion, causedby the strategic VMS structures, should be included inthe Environmental Assessment under LandscapeEffects.

17. When siting signs, due consideration should begiven to assessing and reducing their visual impact.

D4/2






• on link roads it is essential that VMS arecorrectly oriented so that they can be clearlydistinguished from main carriageway VMS. Thismay be achieved be means of louvres or narrowangle emitters.

November 2005


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� 6 3 3 � � 4 � � � � 5

� � ( �

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Figure D4.2b

Volum

e 9 Section 4P

art 6 TA

83/05

Novem

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Annex D

Northern Ireland O

nly

D4/5

IGNALLING.

gnal gantries will apply to other diverge arrangements.

bled.

SE TRUNKTAL GANTRIES

) � � � � % � � � � �

� � �

� � "

� �

�

� � � � � � � �

2 � 3 �

4 � � � � � � 5

7 3 3 �

4 � � � � � � 5

� � � � � �

1 � � � � "

� �

Figure D4.2c

NOTES

1. The layout and separation for the sign/signal gantries is taken from DMRB Vol9, Section 4, Part 3 TA74/97. MOTORWAY S

2. To determine the separation distance 'S' refer to Paragraph D4.2 and Figure D4.2a.

3. The diagram shown is for a parallel deceleration lane. However a similar relationship between the strategic EMS and sign/si

4. The sign/signal granties should comprise lane signal matrices supported by 2x12 EMS (320mm character height) plus ADS.

5. The cantilever VMS should comprise 3x18 400mm characters. If it comprises an integral matrix, this facility should be disa

PROVISION OF STRATEGIC EMS ON ALL PURPOROADS AND MOTORWAYS WITH SIGN/SIGNAL POR

9 * 2 3 �

�

' � �

� � �

1 � � � � "

� � � � � � � � � � "

' � � � � � � � � �

1 � � � � "

' � �

� � � � � �

1 � � � � "

� � �

1 � �

� � � � � � � �

�

7 3 3 �

4 � � � � � � 5

2 � 3 �

4 � � � � � � 5

2 � 3 �

4 � � � � � � 5

7 3 3 �

4 � � � � � � 5


RE


D5.1 Control Systems

1. Variable Message Signs (VMS) can be controlledby all current motorway control systems. Designersshould assess the suitability of using existing controland communications systems for the Strategic TrafficManagement Systems (STMS) scheme in consultationwith Roads Service. Existing or planned systems usedfor VMS control include:

• Motorway Control System

• Urban Traffic Control System.

• Automatic Incident Detection Systems.

• Ramp Metering Systems

• Remote Monitoring Systems

• Other Stand Alone Systems.

2. Reference should be made to Roads Service todetermine if the existing communications infrastructurecan support proposed STMS applications

D5.2 Roadside Infrastructure

General

3. Roads Service should be consulted to determinewhether the existing motorway communicationsinfrastructure can support proposed STMS applications.Where new STMS schemes are to be introduced onsections of motorway with a suitable communicationsinfrastructure, works should be limited to civil worksand local modifications to existing cabling and powersupplies.

4. In other areas, it will be necessary to develop thesolutions identified during the feasibility study such ascabling to the motorway, or radio, private lines, ISDNor similar links to more remote locations.


5. The infrastructure for a typical EnhancedMessage Signs (EMS) site comprises:

D5. VMS INFRASTRUCTU

November 2005


or


(ii) Communications Cabinet Type 600 and PowerCabinet Type 609 with associated cabling andducts

(iii) safety fencing - double height Open Box Beam


6. A typical Cantilever EMS Outstation Layout isshown on Drawing MCX 0582.

7. A Portal Gantry Outstation Layout is shown onDrawing MCX 0800. This shows the arrangementwhere a ducted cable network is provided. At all otherlocations, the cables between the gantry and equipmentcabinets will be directly buried.

8. Further guidance is given in Specification TRH1642, ‘Motorway Signals Mark 2, Infrastructure DesignGuide’.


9. The infrastructure for a typical Fixed TextMessage Signs (FTMS) site comprises:

(i) a foundation, either a reinforced concrete blockwith no holding down arrangement where theFTMS post fixings are drilled into thisfoundation or a similar block with appropriatepost holes

(ii) Communication cabinet Type 600 and a PowerCabinet Type 609 with associated cabling andducts

(iii) safety fencing to suit location


D5/1



D5.3 Technical Approval



(i) foundation



12. Technical Approval must be in accordance withRoads Service procedures. If the foundation andsuperstructure are designed independently, or bydifferent design organisations, a Technical Approvalsubmission must be made for each element.


Existing Gantries

14. Existing gantries should already be certified toNIRS 7/82. Technical Approval is therefore required forthe addition of VMS sign enclosures and mountingequipment and the effect of these additions on thegantry structure.

15. Detailed designs already exist for the additionalsteelwork to support 320mm EMS to be mounted oncertain ‘standard’ gantries. This design and where it canbe applied is shown on Drawing No. MCX 0584.




D

1to

2rsi

D

2toDs

D

2OPs

210E

D5/2

5.4 Holding Down Arrangement

9. When foundations are constructed, it is essentialhe contractor uses a template provided by the supplierf the superstructure.

0. On contracts where different contractors areesponsible for the construction of the base anduperstructure, steps must be taken to ensure that thenterface between the two elements matches.

5.5 Optical Alignment

1. When using VMS based on light emittingechnology, it is particularly important to ensure correctptical alignment of the sign with the carriageway.esign requirements, and the method to be applied on

ite are given in Drawing MCX 0069.

5.6 Ordering of Equipment

2. A request for Financial Approval and Equipmentrder shall be made according to MCH 1286. Bulkurchase Equipment Order and Financial Approvalhall be made according to MCH 1288.

3. Reference should be made to Specification TRH239, in particular Drawings MCX 0590 and MCX591, which show the equipment configuration forMS outstation sites.

November 2005





Cantilever


Continuous Sign

A Variable Message Sign (VMS) that appears to bemade up of solid characters or symbols. The sign face ischanged by removing one set of symbols/characters andreplacing them with another, or by having a multipleface that can rotate.

Discontinuous Sign



Give the motorist information of a tactical and strategicnature, but also with messages relating to conditions onthe network that may affect expected journey times.




A type of VMS able to display a limited number offixed messages. Signs for strategic applications use amechanical rotating prism as the mechanism for

I

Avun

P

Aum

S

Amj

S

Ai

S

Gnoca

T

Pmm

V

Al

Bd

D6. GLOSSARY OF TERMS

November 2005

changing the sign legend.

ntervention Node

road junction that offers alternative routes, whereariable message signs and appropriate legends can besed to intervene traffic, and modify or block theormal journey route as shown on directional signing.

ortal Gantry

n overhead structure that spans the carriageway and issed to support combinations of signals, variableessage signs and conventional fixed signs.

ign

device carrying directional or other informationalessage, eg route information at the approach to a

unction.

ignal

device used to give advisory or mandatorynstructions, e.g. stop or 30 mph speed restriction.

trategic Traffic Management Systems

ive the motorist information and advice on the roadetwork ahead. The aim is to improve the performancef the network by redistributing traffic efficiently whenongestion occurs on some links and spare capacity isvailable on others.

actical Control Systems

rovide supplementary information to complementatrix signals and other traffic control signs for localanagement of incidents or occurrences.

ariable Message Sign

generic term for a sign that can display multipleegends or messages.

oth EMS Fixed Text Message Signs (FTMS) areifferent types of VMS.


D6/1



(a) Rotating Prism



NMCS


November 2005D6/2




BD 2/89: Technical Approval of HighwayStructures on Motorways and OtherTrunk Roads. Part 1: GeneralProcedures – DMRB, Volume 1,Section 1, Part 1.

HD 19/94: Road Safety Audits – DMRB,Volume 5, Section 2, Part 2.

TA 60/90: The Use of Variable Message Signs onAll-Purpose and Motorway TrunkRoads – DMRB, Volume 8, Section 2,Part 1.



TA 72/97: National Motorway CommunicationsSystems – DMRB, Volume 9, Section 4,Part 1.





TD 33/90: The Use of Variable Message signs onAll-Purpose and Motorway TrunkRoads – DMRB, Volume 8, Section 2,Part 1.

Department of Transport

Traffic Signs Regulations (Northern Ireland).

Chapter 8 of the Traffic Signs Manual.

D7. REFERENCES

November 2005


MCH 1286: Request for Financial Approval:Standard and Non-Standard Schemes.

MCH 1288: Request for Financial Approval forBulk Purchase Equipment only.

MCH 1813: System Certification Specification.

TRH 1642: Motorway Signals Mark 2 andEnhanced Message Signs -Infrastructure Design Guide.

TR 0154 Electromechanical Variable MessageSigns - Functional Specification.

TR 2136 Functional Specification forContinuous or Discontinuous VariableMessage Signs.



MCX 0582: EMS Outstation Layout.



MCX 0590: Cantilever Site - Typical Arrangement.

MCX 0591: Portal gantry Site - TypicalArrangement.

Other Publications


European ‘DRIVE’ Project ‘VAMOS’ (VAriableMessage Optimised Systems) – ‘VAMOS’ White Book.

D7/1



Code of Practice for Operators of Motorway and TrunkRoad Signals and Variable Message Signs (prepared byHighways Agency in consultation with the Associationof Chief Police Officers (ACPO).

November 2005D7/2