post opening project evaluation m25 junction 28/a12...

M25 Junction 28/A12 Brook Street Junction Improvement – Post Opening Project Evaluation

One Year After

M25 J28 OYA Report v3.docx i

Post Opening Project Evaluation

M25 Junction 28/A12 Brook Street Junction Improvement

One Year After Study

April 2011 Notice This report was produced by Atkins for the HA for the specific purpose of POPE. This report may not be used by any person other than the HA without HA's express permission. In any event, Atkins accepts no liability for any costs, liabilities or losses arising as a result of the use of or reliance upon the contents of this report by any person other than HA.


One Year After

M25 J28 OYA Report v3.docx ii

Contents Section Page

Executive Summary 8

1. Introduction 11

Purpose of this Report 11

Scheme Background 11

Other Schemes in the Area 14

History of the Scheme 15

Summary of the TIS Report 16

Report Structure 16

Sources 17

2. Traffic Analysis 18

Traffic Count Data Collection 18

Seasonality/ Background Growth 20

Traffic Count Analysis 22

Journey Time Surveys 26

Other Traffic Impacts 30

3. Safety Evaluation 32

Introduction 32

Accident Analysis 34

4. Economic Evaluation 40

Introduction 40

Journey Time Benefits 40

Safety Benefits 44

Scheme Costs 45

Benefit Cost Ratio (BCR) 46

Reliability 47

5. Environment Evaluation 50

Introduction 50

Noise 52

Local Air Quality 53

Greenhouse Gases 54

Landscape 55

Townscape 58

Heritage 58

Biodiversity 60

Water 62


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Physical Fitness 64

Journey Ambience 68

6. Accessibility and Integration Evaluation 74

Introduction 74

Accessibility 74

Integration 75

7. Other Issues 77

Splitter Island 77

Signing / Lane Allocation 78

Other Improvements 79

8. Appraisal & Evaluation Summary Tables 80

Appraisal Summary Table (October 2006) 80

Evaluation Summary Table (July 2009) 82

9. Conclusion 85 Appendices

Appendix A – NTM 2007/ TEMPRO Growth Factors 87

A.1 Growth Factors for Traffic Counts 88

A.2 Traffic Count Data 89

Appendix B – Journey Times 90

B.1 Journey Time Intermediate Timing Points 91

B.2 Number of Runs Undertaken for Journey Time Surveys 93

Appendix C – Environment 94

C.1 Environmental Tables 95

C.2 Environmental Pictures 106

Appendix D – Economic Analysis 109

D.1 Introduction 110

D.2 Methodologies 110

D.3 Summary 112


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Glossary

Term Definition

AADT Annual Average Daily Traffic. Average of 24 hour flows, seven days a week, for all days within the year.

AAWT Annual Average Weekday Traffic. As AADT but for five days, (Monday to Friday) only.

A/C Anti-Clockwise

Accessibility

Accessibility can be defined as ‘ease of reaching’. The accessibility objective is concerned with increasing the ability with which people in different locations, and with differing availability of transport, can reach different types of facility.

AM denoting the morning peak period

AQMA Air Quality Management Areas

AST Appraisal Summary Table. This records the impacts of the scheme according to the Government’s five key objects for transport, as defined in DfT guidance contained on its Transport Analysis Guidance web pages, WebTAG

ATC Automatic Traffic Count, a machine which measures traffic flow at a point in the road.

AWT Average Weekday Traffic. Average of Monday to Friday 24 hour flows.

COBA

COst Benefit Analysis – a computer program which compares the costs of providing road schemes with the benefits derived by road users (in terms of time, vehicle operating costs and accidents), and expresses the results in terms of a monetary valuation. The COBA model uses the fixed trip matrix.

CRF Congestion Reference Flow - AADT flow at which a road is likely to be congested in the peak periods of an average day.

C/W Clockwise

DfT Department for Transport

DMRB Design Manual for Roads and Bridges

DR The Department’s Representative is a consultant acting on behalf of the Highways Agency with regard to particular schemes.


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Discounting Discounting is a technique used to compare costs and benefits that occur in different time periods and is the process of adjusting future cash flows to their present values to reflect the time value of money, e.g. £1 worth of benefits now is worth more than £1 in the future. A standard base year needs to be used which is 2002 for the appraisal used in this report.

Do-Minimum In scheme modelling, this is the scenario which comprises the existing road network plus improvement schemes that have already been committed.

Do-Something In scheme modelling, this is the scenario detailing the planned scheme plus improvement schemes that have already been committed.

E & C OFT Engineering and Construction Open for Traffic. A provision for costs occurring after the scheme opened.

ES Environmental Statement. This must be submitted with the initial planning application and covers all potential significant impacts that the road project may have.

EST Evaluation Summary Table. In POPE studies, this is a summary of the evaluations of the TAG objectives using a similar format to the forecasts in the AST.

HATRIS Highways Agency Traffic Information System

HGV Heavy Goods Vehicle.

Highways Agency

An Executive Agency of the Department for Transport, responsible for operating, maintaining and improving the strategic road network in England.

IP Inter Peak, the time between the AM and PM peaks

JUICE Junction User Interface Cost Evaluation. A spreadsheet model used to calculate delay costs at a junction.

KSI Killed or Seriously Injured

Light vehicle Not a HGV. For traffic flow data, it is a vehicle less than 5.2m in length.

Managing Agent

A Managing Agent is responsible for the operation, maintenance, and improvement of the motorway and trunk road network of a Highways Agency area.

MTC Manual Turning Count. A survey of the turning movements of vehicles at a junction undertaken by human observers, normally on a single day.


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NMU Non Motorised User. A generic term covering pedestrians, cyclists and equestrians, more recently known as vulnerable users.

NRTF /NTM National Road Traffic Forecast / National Traffic Model. This document defines the latest forecasts produced by the Department of the Environment, Transport and the Regions of the growth in the volume of motor traffic. NRTF 1997 has now been replaced by NTM 2007.

OGV1, OGV2 Other Goods Vehicle. OGV1 = Goods Vehicles with 2 or 3 axles, OGV2= Goods Vehicles with 4 or more axles

OPR Order Publication Report

PAR Project Appraisal Report These are undertaken, for Highways Agency improvement schemes which are not major schemes

PIA Personal Injury Accident. A road traffic accident in which at least one person required medical treatment.

PM evening peak period

POPE Post Opening Project Evaluation, before & after monitoring of all major highway schemes in England.

PVB

Present Value Benefits. Value of a stream of Benefits accruing over the appraisal period of a scheme expressed in the value of a single ‘present’ year. For this scheme this is 2002.

PVC Present Value Cost. As for PVB but for a stream of costs

Route Stress This is used as a proxy for journey time reliability. It is described as the stress level of a road and is calculated as the ratio of flow to capacity: AADT / CRF.

Screenline

An imaginary line drawn across a transport corridor used to determine flows between areas on either side. Each road crossed by the screenline is monitored by a traffic count (ATC).

Seasonality Seasonality is the variation in traffic behaviour across the year due to varying daylight levels, weather conditions, school holidays, etc.

Severance Community severance is the separation of adjacent areas by road or heavy traffic, causing negative impact on non-motorised users, particularly pedestrians.


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STATS19 A database of injury accident statistics recorded by police officers attending accidents

TEE Transport Economic Efficiency

TIS Traffic Impact Study

TAG Transport Analysis Guidance, as defined in WebTAG.

TEMPRO Trip End Model Presentation PROgram, DfT software which provides forecast data on trips for transport planning purposes.

TfL Transport for London

TPI

Targeted Programme of Improvements. (Now Known as Programme of Major Schemes). The Highways Agency’s programme of investment in improvements to the Trunk road and Motorway road network comprised of a number of major schemes each costing more than £5m.

TRADS Traffic Flow Data System

Vehicle hours

Vehicle hours refers to the total time spent by all vehicles using a road and is expressed normally as a yearly value. For example, if 10,000 vehicles a day used a route with a 6 minute journey time, then the route’s vehicle hours for the year would be 365,000.

VISSIM Micro-simulation modelling software

VOT Value Of Time

vpd Vehicles Per Day

WebTAG Department for Transport’s website for guidance on the conduct of transport studies at http://www.WebTAG.org.uk/

M25 Junction 28/A12 Brook Street Junction Improvement – Post Opening Project Evaluation One Year After

M25 J28 OYA Report v3.docx 8

Executive Summary The M25 Junction 28 / A12 Brook Street scheme opened in March 2008 and comprised the following elements:

A new dedicated left turn lane from the M25 clockwise exist slip road to the A12 eastbound.

Extension of the A12 merge lane towards Ipswich; Widening of the A12 London bound exit slip road to four lanes; Realignment of the A1023 Brook Street to M25 clockwise; Widening of the M25 anticlockwise exit slip road to four lanes; and Other minor works to improve junction safety.

Objectives (Non Technical Summary, October 2006) Objective Achieved?

Improve safety at the junction Not at this stage

Improve circulation of the junction to deliver a reduction in vehicle queuing and journey times. Yes

Key Findings

The objectives of the scheme were to improve circulating flows at the junction to reduce queuing and journey times, and to improve safety. Journey times have improved but the number of accidents has increased.

A number of methodologies have been used to analyse the 60 year outturn benefits, giving a wide range of results. Given the high level of benefits predicted to occur from 2023 onwards and the very low benefits predicted for the first year after opening, it is considered that it is too early at the ‘one year after’(OYA) stage to conclude whether the scheme will achieve the predicted level of benefits. It is noted that only 0.2% of the entire scheme benefits are predicted to occur in the opening year.

Given that the outturn journey time benefits cannot be accurately determined using the evidence currently available, it is not possible to derive a BCR at the OYA stage.

The scheme has had no major impact on traffic flows, and journey times through the junction have improved as predicted.

There has been an increase in accidents at the junction with a high proportion due to poor lane discipline. A number of remedial measures have been implemented since the scheme opened including reflective marker post on the splitter island, and additional signing on the circulatory carriageway.

The scheme cost is 35% lower than forecast. The traffic model used for the original scheme appraisal did not include the signalised

Wigley Bus Lane junction on Brook Street. The observed delays at this junction causing queues back onto the roundabout were therefore not considered in the appraisal.

Severance is likely to be slightly worse as expected due to NMU’s having to cross an increased number of lanes. However, the number of NMU’s is so low this is not considered to be significant.

Current work to upgrade the M25 between Junctions 27 and 30, including the installation of VMS (Variable Message Signs) will improve the ability of the HA to respond to major incidents and reduce the likelihood of severe congestion events at Junction 28 which have been known to occur.



Summary of Scheme Impacts

Traffic

The scheme has had no major impact on traffic flows through the junction as predicted.

There is potentially a small amount of re-routing of traffic accessing the M25 from north east of the scheme. Traffic may have therefore swapped from using Brook Street to the A12 Brentwood Bypass due to the widening of the A12 westbound offslip.

Traffic frequently queues back onto the roundabout from Brook Street in peak periods due to congestion at the nearby traffic signals. The modelling undertaken for the scheme did not cover this junction, and therefore the issue was not identified during the appraisal.

Journey times through the junction have generally improved since the scheme opened. Safety

The annual rate of Personal Injury Accidents (PIA’s) has increased from 15.6 pre scheme opening to 23.0 post opening. This is worse than the forecast reduction of 3 accidents in the opening year.

However, the observed changes in accident numbers are not statistically significant, therefore the change in accident rate is not necessarily due to the implementation of the scheme.

There has been a decrease of around 8% in damage only accidents since the scheme opened, however, this data includes a large amount of the construction period and therefore the results should not be overstated.

Since the opening of the scheme new permanent reflective posts at the splitter island and a new lane allocation sign has been implemented. Environment

Evaluation based on traffic flows indicates that the schemes effect on the local noise and air quality climate is slightly better than expected at most locations.

The greenhouse gas impact of the scheme is considered neutral due to the negligible changes in traffic flows.

The landscaping and mitigation measures implemented are in line with those outlined in the Environmental Statement. The impact can therefore be considered as expected.

Limited heritage and townscape impacts were predicted due to the location of the scheme.

The majority of the biodiversity mitigation measures appear to have been implemented as expected. However, slightly less woodland planting has been undertaken.

The water mitigation measures recommended in the ES appear to have been implemented and there is no evidence to suggest they are not operating as intended. The evaluated impact is therefore neutral as expected.

New footways have been implemented and improved as part of the scheme. The numbers of Non Motorised Users (NMU’s) using the paths in the vicinity of the



junction are low; therefore the neutral impact predicted has been achieved by the minor improvements made.

The impact on journey ambience is slightly worse than expected due to congestion on Brook Street blocking the roundabout at peak times. Accessibility

The scheme has had no impact on option values as expected. Severance is likely to be slightly worse as expected due to NMU’s having to cross an

increased number of lanes. However, the number of NMU’s is so low this is not considered to be significant. Integration

The scheme is consistent with a number of the policies outlined in the Essex Local Transport Plan 2, East of England Plan, and Havering Unitary Development Plan.

Summary of Scheme Economic Performance

Pre Scheme Forecast

(2002 Prices)

Post Opening Reforecast

(2002 Prices)

Journey Time Benefit £259.6m N/A

Safety Benefit £4.7m £-11.7m

Total 60 Year Benefits (PVB) £264.3m N/A

Costs (PVC) £14.8m £9.5m

Benefit Cost Ratio (BCR) 17.9 N/A

The original appraisal predicted costs and benefits over a 60 year period and used

VISSIM microsimulation modelling and JUICE economic evaluation software. Most of the monetised benefit was predicted to arise from savings in journey times.

Also, the vast majority of these savings were predicted to occur in the PM peak from 2023 onwards, with little benefit expected in the opening year.

It is considered too early to accurately determine the level of outturn journey time benefits of the scheme, given the high level of benefits which are predicted to occur from 2023 onwards.

The increase in accidents results in a safety disbenefit of £-11.7m. However, it is noted that the increase is not statistically significant and this will be revisited in the Five Years After evaluation, when more data is available.

The outturn scheme cost is £9.5m which is 35% lower than predicted. Given the above limitations, the evidence available at the OYA stage does not provide

conclusive evidence of the long term economic impact of this scheme and hence its value for money.



1. Introduction Purpose of this Report

1.1 This report represents the One Year After (OYA) post opening study for the M25 Junction 28 Brook Street scheme. The study was undertaken as part of the Highways Agency’s Post Opening Project Evaluation (POPE) of all major schemes. POPE is undertaken One Year and Five years after the opening of all major schemes. This report builds on the Traffic Impact Study (TIS) prepared for the Highways Agency (HA) in October 2008.

1.2 The purpose of the POPE OYA study is to evaluate whether the original objectives of the scheme have been achieved, and to provide a comparison of predicted and actual scheme impacts. POPE is based on an evaluation of the schemes impact according to the five New Approach to Appraisal (NATA) objectives; economy, safety, environment, accessibility and integration.

1.3 More specifically, the report sets out the following:

A comparison of the Do-Minimum (Without Scheme) and Do-Something (With Scheme) traffic volumes and journey times;

An outline of changes in accident rates at the junction in the year post opening of the scheme;

A monetised comparison of the predicted and best estimated outturn benefits and costs of the scheme; and

An evaluation of the scheme’s impact upon the environment, accessibility and integration sub-objectives.

Scheme Background

Location

1.4 The scheme is located on Junction 28 of the M25 where it crosses the A12. It is a three tier grade separated junction, with the A12 and M25 running under and over the roundabout respectively. The junction consists of a five arm roundabout that connects the M25, A12 and the A1023 (Brook Street).

1.5 The junction is located between Brentwood and Romford, and is situated on the boundary of HA Area 5 (for the M25 J28) and Area 6 (for the A12 North of the scheme). Figure 1.1 illustrates the location of the scheme.

1.6 The M25 is the key route at this junction; however the A12 is also a strategic route that connects Chelmsford and Ipswich with London.

1.7 The A1023 is a local authority road that connects Junction 28 with Brentwood.



Figure 1.1 – Scheme Location

Scheme Description

1.8 Opening in March 2008, the M25 Junction 28 Brook Street scheme was implemented to relieve congestion and unreliable journey times experienced at the junction, which is particularly evident during peak periods. The main turning flow is between the A12 north-east and the M25 south-east, which regularly results in significant congestion at the junction.

1.9 A recommendation of the London to Ipswich Multi-Modal Study (November, 2002) was that major improvements to the junction should be implemented involving dedicated free flow slip roads.

1.10 To resolve the problems at the junction, the following improvements were implemented (as shown in Figure 1.2):

1) A new dedicated left turn lane with splitter island from the M25 clockwise exit slip road to the A12 eastbound;

2) Extension of the A12 merge lane towards Ipswich (eastbound);

3) Widening of the A12 London-bound exit slip road to four lanes;

4) Realignment of the A1023 Brook Street to M25 clockwise on-slip as a result of widening of circulatory carriageway at this point;

5) Widening of the M25 anticlockwise exit slip road to four lanes; and

6) Other minor works to improve junction safety.



Figure 1.2 – M25 Junction 28 Scheme Improvements



1.11 As a result of implementing the changes described previously several mitigation measures were also implemented including:

The retaining wall proposed in the Environmental Statement (ES) adjacent to the M25 anti-clockwise exit slip was not required which allowed sufficient space for a new embankment to be provided at this location to replace the embankment that existed pre-scheme;

The lay-by on the A12 eastbound was left unchanged, but barriered across;

The proposed auxiliary lane on the A12 eastbound was reduced in length from 1km to 650m; and

The new retaining wall proposed in the ES was not required in the central reservation of the A12.

1.12 A more detailed description of these changes can be found in the Section 5 of this report.

Scheme Objectives

1.13 The main objectives of the scheme obtained from the HA Non-Technical Summary (October 2006) and agreed with the Project Manager were to:

Improve safety at the junction; and

Improve circulation of the junction to deliver a reduction in vehicle queuing and journey times.

Other Schemes in the Area

1.14 Local projects implemented in the locality of the scheme area can sometimes have an impact on traffic counts, journey times or accident figures. There are two other major schemes which are in the vicinity of M25 Junction 28, which are detailed in Table 1.1.



Table 1.1 – Nearby Schemes

Name Date Scheme

Description Relation to M25 J28 Brook

Street Scheme

M25 J27 – J30 Widening

Construction began in July 2009, and the

scheme is intended to be

complete in July 2012

Carriageway widening from dual 3 lanes to

dual 4 lanes

The M25 J28 scheme has been designed to compliment the M25

widening scheme. All OYA surveys were conducted before

construction of this scheme begun. However, this scheme

will have a significant impact on any further surveys undertaken

during this period.

M25 J28 – J27 Speed

Harmonisation Trial

Work began in March 2007

Automatic Number Plate Recognition

(ANPR) cameras and roadside

portable Variable Message Signs

(VMS) used to set temporary speed

limits to ease congestion

None

History of the Scheme

1.15 The history of events leading up to the scheme improvements are summarised in Table 1.2.

Table 1.2 – Chronology of the M25 J28 Brook Street Scheme

Date Event

November 2002 One of several measures suggested by London to Ipswich Multi-Modal Study

March 2005 Added to Programme of Major Schemes (formally known as TPI)

November 2006 Environmental Statement for the scheme was published

February 2007 Comments from the Environmental Statement and improvement proposals were submitted to the Secretary of State for Transport

April 2007 Approval of scheme by Secretary of State

May 2007 Start of construction period

10th March 2008 Opening of the scheme



Date Event

August 2008 Permanent reflective posts erected on the new splitter island

Summary of the TIS Report

1.16 The TIS report produced in October 2008 drew the following conclusions:

Between 2003 and 2008, traffic using the junction increased by around 8.3%, which is close to the expected background growth of 9.2% derived from the National Road Traffic Forecasts (NRTF). This suggests that the scheme has not induced any extra traffic to the junction. However there were larger increases in traffic for the following movements:

- M25 CW to A12 E/B – Peak period increase of 34%

- A12 W/B to M25 ACW – Peak period increase of 44%

The M25 CW to A12 E/B (via the new splitter lane) route is now the most utilised route through the junction.

Journey times have significantly decreased, especially in the PM peak where journey times across the junction have decreased by 30-50%.

A visit to the site found that queues were still backing onto the roundabout from the A1023, having a knock-on effect further around the roundabout. This was also happening before the scheme was implemented. Also, the splitter island was perceived by some drivers as a ghost island rather than a physical one, especially when heading for the A12 E/B on slip from the circulatory carriageway.

On the 1st July 2008 cones were put up on the island as a temporary measure. In August 2008 these were replaced with permanent reflective posts along the length of the splitter island.

Report Structure

1.17 The remainder of the report is structured as follows:

Section 2 – Traffic Analysis: A comparison of the traffic impacts of the scheme compared to those forecast.

Section 3 – Safety Analysis: This section contains the analysis of the key safety impacts of the scheme and discusses whether changes in accident patterns have occurred at this stage as a result of the scheme.

Section 4 – Economic Assessment: This section examines the economic impacts of the scheme in comparison with those that were forecast.

Section 5 – Environmental Assessment: A review of the environmental impacts of the scheme is given in this section. This includes an evaluation of the mitigation measures described within the scheme’s Environmental Statement.



Section 6 – Accessibility and Integration: This section reviews the accessibility and integration impacts of the scheme.

Section 7 – Other Issues: This section discusses any other issues with the scheme that have not already been raised.

Section 8 – Appraisal and Evaluation Summary Tables: This includes the original Appraisal Summary Table and the Evaluation Summary Table for the scheme.

Sources

1.18 The evaluation is based upon the following sources:

Appraisal Summary Table (October 2006). An amended AST was produced in May 2007 but no supporting information was made available at the time of this evaluation and therefore this OYA report has been based upon the October 2006 AST;

Environmental Statement (October 2006);

Traffic Impact Study (October 2008);

Minutes of POPE OYA Meeting (April 2009);

As Built Drawings;

Handover Environmental Management Plan (April 2008);

HA Non-Technical Summary (October 2006);

A12/ M25 Brook Street Junction Improvement Traffic Survey Report (February 2005);

M25 J28/ A12/ Brook Street Junction Improvement Economics Report THMTJT-R010 (September 2006);

M25 J28/ A12/ Brook Street Junction Improvement Traffic Analysis and Review Report THMTJT – R008 (September 2006);

HA Website;

www.statistics.gov.uk;

WebTAG;

Atkins site visits;

Traffic and journey time surveys;

NTM 2007;

TEMPRO; and

HA TRADS Database.



2. Traffic Analysis Traffic Count Data Collection

2.1 Traffic data for this report has been collected from two main sources; Highways Agency (HA) TRADS (Traffic Flow Data System) database sites and data collected from counts commissioned by Atkins. Surveys were also commissioned to collect journey times at the junction.

2.2 Traffic count data has been obtained for all on/off-slip roads, Brook Street and A12/M25 through movements on Junction 28 with the exception of the A12 E/B On-Slip. Turning counts were also commissioned to assess the movement of traffic on the junction.

2.3 A full summary of the source of traffic data can be found in Appendix A.

Highways Agency Traffic Count Sites

2.4 The HA TRADS database provides traffic data on several arms and routes on/ through M25 Junction 28. All data obtained from TRADS in this report excludes bank holidays, days with bad weather and any other abnormal conditions or events.

2.5 To avoid using data collected during the construction period, data was obtained from April 2007 and April 2009 for the pre-scheme and One Year After (OYA) stages respectively.

2.6 TRADS data was collected from the following sites:

Site 30013284 (Area 5): M25 Clockwise Off-Slip;

Site 30013283 (Area 5): M25 Clockwise Within Junction;

Site 30013282 (Area 5): M25 Anti Clockwise Off-Slip;

Site 30013281 (Area 5): M25 Anti Clockwise Within Junction;

Site 2806 (Area 5): M25 Anti Clockwise On-Slip1;

Site 30014653 (Area 5): A12 Eastbound Within Junction;

Site 30013187 (Area 6): A12 Westbound Off-Slip (Pre-scheme only) 2; and

Site 30010186 (Area 6): A12 Westbound Within Junction.

2.7 Data was also obtained from TRADS immediately after scheme opening for analysis in the Traffic Impact Study (TIS).

1 No data was available in April 2007 so data was collected from April 2006. This will be factored later in the report using the appropriate factor given in Appendix A. 2 No data was available in April 2007 so data was collected from April 2005. This will be factored later in the report using the appropriate factor given in Appendix A.



Atkins Counts

2.8 Atkins have commissioned a combination of turning counts and Automatic Traffic Counts (ATCs) to compare with data collected before the scheme was built and to fill in gaps in the data available from the TRADS database.

Turning Counts

2.9 Atkins commissioned a turning count on 1st July 2008 to compare with a pre-scheme turning count undertaken on 26th June 2003 as described in the Traffic Survey Report3. The count covers all possible turning movements across the junction, the same movements that were surveyed in the Traffic Impact Study.

2.10 The turning counts took place over one day and covered the AM (07:00-10:00), Inter (12:00-15:00) and PM peak periods (16:00-19:00).

2.11 Since they are 9 hour counts recorded on one day, any difference between the pre-scheme and post-scheme survey should not be regarded as statistically significant. For this reason this report will use the turning counts to estimate the proportion of traffic making each movement through the junction and wherever possible avoid using them for estimating general traffic levels across the junction.

2.12 These turning counts have already been analysed in the Traffic Impact Study. This report will use these turning counts, traffic data collected in 2009 and Journey Time surveys to estimate the delay occurring on the junction.

Automatic Traffic Counts (ATCs)

2.13 Atkins commissioned ATCs for a period of one week between 27th June 2009 and 3rd July 2009. Data was collected using a mixture of temporary tubes (Brook Street) and radar counts (all other counts) due to the busy nature of the junction. The 7 sites were chosen to fill in the gaps in the TRADS data and consist of:

All 4 A12 Slip Roads (2 Off-Slips and 2 On-Slips);

M25 Clockwise On-Slip; and

Both directions on the A1023 (Brook Street) close to Junction 28.

2.14 Unfortunately data collected for the A12 E/B On-Slip was not suitable for analysis due to an error with the counting equipment.

Other Pre-scheme Counts

2.15 Pre-scheme traffic data was not available for all On/Off-Slips or Brook Street at Junction 28. Therefore traffic data used for the environmental appraisal base scenario from the Traffic Analysis and Review Report 4 has been used to complete the data set on the following slip roads:

A12 Eastbound Off-Slip;

3 Traffic Survey Report – 25 February 2005 4 Traffic Analysis and Review Report – September 2006



A12 Eastbound On-Slip;

A12 Westbound On-Slip; and

M25 Clockwise On-Slip.

2.16 Data was also obtained from Essex County Council at the following locations:

A1023 Brook Street Eastbound (between J28 and Wigley Bush Lane junction); and

A1023 Brook Street Westbound (between J28 and Wigley Bush Lane junction).

Seasonality/ Background Growth

2.17 Traffic flow data varies from month to month, and year to year due to several factors such as seasonality and natural or background traffic growth. It is imperative that data is collected to ensure a fair comparison between the pre-scheme and post-scheme stages and factored where appropriate to ensure any changes are caused by the scheme and not enhanced or concealed by seasonality or background growth. This section examines the seasonality and yearly growth experienced on the M25 Junction 28.

Monthly seasonality

2.18 Traffic and journey time data used in this report was collected or obtained for various dates including April, May, June and July, for both the pre-scheme and post-scheme stages. This range in dates was due to limitations in available data on the TRADS database and the need to avoid using data during the construction period of the scheme.

2.19 It is therefore important to consider the seasonal difference in traffic between these months to investigate whether data may be influenced by any seasonal variation of traffic in the area and if it is apply a factor to account for this.

2.20 To assess this, traffic data has been obtained from the HA TRADS database. It is important that any data used to assess this variation must be complete to ensure its accuracy. There are a limited number of sites where sufficient data is available; namely the:

A12 W/B Off-Slip;

M25 C/W Off-Slip;

M25 A/C On-Slip; and

M25 A/C Off-Slip.

2.21 Figure 2.1 shows the factors required to convert a monthly flow into AADT.



1.09

1.04

1.01

0.97

0.96 0.

97

0.97

0.96 0.

98

0.98

1.02

1.06

0.9

0.95

1

1.05

1.1

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Fac

tor

to c

on

vert

to

AA

DT

Figure 2.1 – Monthly Breakdown of traffic using M25 J28 2.22 Figure 2.1 shows there is a negligible difference between the proportion of April,

May, June and July traffic flows and therefore all counts quoted in this report have not been factored for any kind of monthly seasonality unless stated otherwise.

Yearly Growth

2.23 Data has been obtained from the 2007 National Traffic Model (NTM)5 and adjusted by the Trip End Model Presentation Program (TEMPRO) to estimate the yearly background traffic growth expected around M25 J28.

2.24 Background traffic growth occurs independently of the scheme and therefore should be taken into consideration when assessing traffic data.

2.25 Appendix A displays the expected background growth on M25 J28 between the various years during which traffic data was collected. The post-opening counts were expected to be up to 9% higher than the after counts solely due to background growth.

5 Formally known as the National Road Traffic Forecasts (NRTF)



Traffic Count Analysis

Automatic Traffic Count Analysis

2.26 Figure 2.2 compares the before scheme construction and the after scheme opening observed traffic counts on all approaches to the junction 28 circulatory carriageway with the exception of the A12 E/B On-Slip (as explained in the data collection section).

Figure 2.2 – M25 & A12 Slip Road & Brook Street Observed ADT

2.27 Figure 2.3 compares the before scheme construction and the after scheme opening observed traffic counts on the A12 and M25 through routes.



Figure 2.3 – M25, A12 Through Traffic Observed ADT 2.28 The key points to note from Figure 2.2 and Figure 2.3 are:

Traffic levels at most of the locations above have changed by 5% or less, and therefore it can be concluded that the scheme has not induced or suppressed traffic. Background growth between the pre-scheme and post-scheme counts was expected to be up to 9%. The data above also suggests this level of background growth may not have materialised;

One reason for background growth in the area being less than expected is the recent downturn in traffic caused by the current economic climate. A recession is widely defined as two consecutive quarters of negative growth in Gross Domestic Product (GDP); this criterion was met in late 2008.



Any traffic survey has a certain margin for error involved, most of the differences shown are relatively small and therefore not significant enough to draw any firm conclusions; and

Two of the larger differences were experienced on Brook Street and the A12 W/B Off-Slip (Shown in Figure 2.4), where traffic decreased by 5% and increased by 15% respectively. Part of the scheme involved the widening of the A12 W/B slip road from 3 to 4 lanes in an attempt to stop traffic queuing back onto the A12.

Figure 2.4 – A12 W/B Off-Slip

It is possible that this improvement has encouraged a small amount of traffic originating from North-East of the scheme to switch from using the A1023 Brook Street to the A12 Brentwood Bypass. It is suggested that this is looked at in more detail in the Five Years After (FYA) Report.

2.29 Overall the small differences in traffic levels coupled with the reasons outlined above suggest the scheme has not induced any extra traffic.

Predicted vs. Actual Traffic Flows

2.30 Traffic forecasts for both the Do-Minimum (without the scheme) and Do-Something (with the scheme) scenarios are given the Traffic Analysis and Review Report, published in September 2006.

2.31 Data was collected for a 2003 base scenario and forecasts were made for an opening year of 2008, and future years of 2010 and 2023. The scheme was not

“Economic growth during the fourth quarter of 2008 contracted by 1.5 per cent. This marks the second successive quarter of negative growth so, according to the widely-held technical definition, the UK is now officially in recession” Source: http://www.statistics.gov.uk/downloads/theme_economy/EconReview_0209.pdf



expected to induce any extra traffic; therefore DM and DS traffic predictions were the same.

2.32 This section will compare the predicted opening year traffic flows with the observed data already displayed earlier in this chapter.

2.33 The observed data has been collected from the sources shown in Appendix A. It was noted that several of these counts were conducted over one month. To allow a comparison to be made with the predicted flows these counts were annualized using factors displayed in Appendix A; thus converting counts into Average Annual Daily Traffic (AADT).

2.34 Due to the relatively short amount of time between the appraisal and opening date (around two years) and the possible lack of background growth occurring in the area it has been deemed unnecessary to include a comparison between the predicted DM and observed factored before traffic counts in this report.

2.35 Table 2.1 shows a comparison between DS predicted and observed after scheme opening counts.

Table 2.1 – Predicted Vs. Observed Do-Something Traffic AADT

Location Direction Predicted AADT

Observed AADT

% Difference

Brook Street E/B 10,300 10,000 -3%

Brook Street W/B 9,200 10,400 12%

A12 Off-Slip E/B 11,200 10,100 -10%

A12 Off-Slip W/B 21,100 21,100 0%

A12 On-Slip E/B 22,400 - -

A12 On-Slip W/B 10,800 10,300 -4%

A12 Through E/B 10,600 9,700 -9%

A12 Through W/B 10,000 9,900 -1%

M25 Off-Slip C/W 18,100 19,400 7%

M25 Off-Slip A/C 16,800 16,000 -5%

M25 On-Slip C/W 15,300 14,800 -3%

M25 On-Slip* A/C (15,400) 18,700 18%

M25 Through C/W 46,800 44,000 -6%

M25 Through A/C 51,100 43,900 -16%

M25 On-Slip* A/C 19,100 18,700 -2% *See comments after this Table

2.36 Table 2.1 shows that traffic flows are generally fairly close to predicted, any differences can be explained by reasons already outlined in this section, such as the lack of background growth and a slight margin of error in traffic surveys.

2.37 The relatively large difference shown between the predicted and observed 2009 AADT for the M25 A/C On-Slip can be explained by the predicted 2003 base flows which appear to be too low. To check this, the base year 2003 count for the



M25 A/C On-Slip was compared with data available on the HA TRADS database. This showed a sizeable difference in 2003 AADT, as shown Table 2.2.

Table 2.2 – M25 On-Slip 2003 AADT Inconsistency

Traffic Analysis and Review Report TRADS

2003 (Base Year) AADT 15,000 18,600

2009 DM AADT 15,600 19,300

2.38 When the TRADS data is considered and factored up using the same rate as the Traffic Report the predicted 2009 DS AADT appears to be very close to prediction as shown at the bottom of Table 2.1.

Journey Time Surveys

Data Collection

2.39 Journey time surveys using the moving observer method have been undertaken at the pre-scheme, immediately after opening (For the Traffic Impact Study) and One Year After opening stages to analyse the effect of the scheme on journey times for a selection of routes through the junction.

2.40 In order to ensure a fair comparison the specification of each survey was kept exactly the same except a slight variation in dates. The date of each journey time survey is displayed in Table 2.3.

Table 2.3 – Dates of Journey Time Surveys

Pre-scheme Post-scheme (TIS) Post-scheme (OYA)

Wednesday 23rd May 2007

Tuesday 1st July 2008 Tuesday 30th June

2009 2.41 All journey time surveys were carried out over 6 routes. Runs were broken down

into AM peak (07:00-10:00), Inter peak (12:00-15:00) and PM peak periods (16:00-19:00). For presentation purposes the routes have been divided into those heading towards London and those heading away from London.

2.42 Figure 2.5 shows 3 of the routes that were covered:

Route 1 – Running clockwise on the M25 from the Chequers Road overbridge, departing the M25 at J28, and finishing at the end of the A12 on slip heading east.

Route 2 – Starting anti-clockwise on the M25 from the Nags Head Lane overbridge, departing the M25 at J28 and leaving J28 on the A12 eastbound, and finishing at the Spital Lane overbridge.



Route 3 – Heading east along the A12 from the Petersfield Avenue junction, crossing the M25 J28 roundabout and finishing on the A1023 at Nags Head Junction.

Figure 2.5 – Journey Time Routes (JTRs) – Heading away from London

2.43 Figure 2.6 shows the other three routes covered:

Route 4 – Starting at the A12 westbound off slip at M25 J28 and heading anti-clockwise on the M25 until the Chequers Road overbridge.

Route 5 – Running west along the A12 starting at the Spital Lane overbridge, departing at the M25 J28 roundabout and heading clockwise along the M25 until the Nags Head Lane overbridge.

Route 6 – Heading west along the A1023 from the Nags Head Junction, leaving the M25 J28 roundabout on the eastbound A12 and finishing at the Petersfield Avenue junction.



Figure 2.6 – Journey Time Routes (JTRs) – Heading towards London

2.44 The exact intermediate points used for each of the journey time run can be found in Appendix B, as can the number of runs undertaken for each route.

Journey Time Analysis

2.45 The OYA journey time survey was completed successfully but the survey company that carried out the surveys notified Atkins that there were unusually high traffic levels and congestion on the M25 on the day of the surveys. This is reflected in the data received with a wide variation of journey times for routes which include a part of the M25 (Routes 1,2,4 and 5).

2.46 While any outliers can be removed, the remaining data is not considered to be reliable enough to draw any conclusions about the scheme. For this reason the analysis of Routes 1,2,4 and 5 will be undertaken using data collected for the purpose of the TIS.

2.47 The OYA data for Routes 3 and 6 will however be analysed in this report as they do not include the M25 and results appear to be more consistent than the routes mentioned above.



-50%

-40%

-30%

-20%

-10%

0%

10%

20%

30%

40%

50%

1 2 3 4 5 6

Route

Diff

ere

nce

AM Peak IP Peak PM Peak

Figure 2.7 – Comparison between percentage changes in Pre and Post-scheme Journey Times across J28

Table 2.4 – Actual Journey Time Savings

Journey Time (seconds) Route Number AM IP PM

Distance (km)

1 46 54 29 3

2 6 13 45 1.7

3 58 47 40 2.3

4 12 28 69 3.5

5 -8 8 75 1.5

6 -17 -6 7 2.3

2.48 Figure 2.7 suggests that journey times across the junction have generally improved since the scheme opened. The main points to note from Figure 2.7 are as follows:

Journey times in the PM peak have improved for all 6 routes by between 10 and 50%;



Journey times in the AM peak have improved on most routes, with the exception of routes 5 and 6 towards London. It is however worth noting that route 6 showed around a 40% improvement in journey times across all three time periods at the TIS stage. It is therefore possible that the survey may have been affected by the high levels of traffic experienced on the M25 on the day of the survey; and

Route 1 which makes use of the new free flow lane on the M25 C/W off-slip to A12 E/B showed savings of around 35-45%; suggesting the new free flow lane has delivered significant journey time benefits to vehicles making this movement.

2.49 The large difference shown between the OYA and TIS journey time surveys demonstrates that due to the busy nature of the junction, and especially the M25, journey times can vary vastly from day to day. For this scheme a substantial journey time survey conducted over several days or weeks would be needed to draw any firm conclusions about any journey time improvements at the junction. Based upon the data available it appears as if the scheme has delivered some journey time benefit.

Other Traffic Impacts

2.50 This section analyses other traffic impacts based upon information obtained from both the OYA meeting and various site visits to the scheme.

2.51 Atkins carried out site visits on M25 Junction 28 for the pre-scheme, TIS and OYA opening stages. A summary of the pre-scheme and TIS site visit was given in the TIS with the key points being as follows:

Site Visit – Pre-Scheme

AM queues on M25 CW off slip, A12 W/B off slip and backing onto roundabout from A1023; and

PM queues backing onto roundabout from A1023.

Site Visit – After (TIS)

All improvements seem to have been completed;

Queues still backing onto roundabout from the A1023, having a knock-on effect further around the roundabout;

AM queues on the A12 W/B off slip on inside two lanes, with other two lanes relatively empty; and

AM queues on circulatory blocked access from the M25 CW off-slip on to the roundabout and blocked access to the A12 E/B on-slip.



2.52 The OYA site visit was undertaken towards the end of the AM peak period. Most of the issues identified above were not evident during this site visit, possibly suggesting the above issues only occur during the AM and PM Peak periods.

Peak Period Queuing from Brook Street

2.53 One of the key issues identified from the site visits was traffic queuing back from Brook Street onto the J28 circulatory carriageway. Several attendees at the OYA meeting agreed this was a problem, especially in the AM Peak period. It appears as if this is caused by queuing from the signalised Wigley Bush Lane Junction further along Brook Street.

2.54 The VISSIM model used to appraise this scheme does not include this junction and the model does therefore not appear to simulate these key problems.

2.55 It is therefore recommended that when appraising schemes more consideration should be given about issues occurring in the base scenario and adjacent junctions should be included in the model where necessary.

KEY POINTS FROM SECTION 2 – TRAFFIC ANALYSIS

Traffic Counts

Traffic Data was primarily collected from TRADS and counts commissioned by Atkins;

There was shown to be a negligible difference between the months over which data was collected;

The traffic data around M25 J28 shows negligible change. This is partially due to the current economic climate. It was therefore concluded that the scheme has had no significant impact on traffic levels as was predicted; and

Observed Do-Something traffic levels in were generally close to predictions.

Journey Times

The journey time surveys showed journey times had improved on most routes but it was noted that this was based upon a relatively limited data set due to the day to day variation in journey times likely on such a busy junction. Several of the OYA results were discounted due to the unusually high levels of traffic on the M25 on the day of the survey.

Other Traffic Impacts

The main issue identified on the site visits was traffic queuing back onto the roundabout from Brook Street during the peak periods. This problem does not appear to have been modelled in the original appraisal.



3. Safety Evaluation Introduction

3.1 This section examines the safety impacts associated with the scheme and examines how the scheme is performing against the WebTAG safety objective:

3.2 More specifically this chapter:

Establishes whether the scheme has achieved its objective to improve safety at the roundabout as set out in Section 1 of this report;

Contains analysis of the numbers of Personal Injury Accidents (PIAs) and damage only accidents;

Compares the causation of PIAs pre and post-scheme opening; and

Details the other safety measures that have been implemented at the site.

Study Area

3.3 It is not clear over what area safety was originally appraised, so for the purpose of this study, only accidents that occurred on the roundabout or on the slip roads of Junction 28 have been included in the analysis. The same accident area has been used for analysis of pre and post-scheme accidents to ensure a fair comparison of safety impacts.

Original Appraisal

3.4 The Economics Report predicted a saving of three PIAs in the opening year consisting of one shunt type PIA at each of the following locations, where new measures were installed as part of the scheme (see Figure 1.2 for details):

M25 N/B Off-Slip (widened to 4 lanes at stop line);

A12 S/B Off-Slip (widened to 4 lanes at stop line); and

M25 S/B Off-Slip to A12 N/B On-Slip dedicated left turn.

Data Collection

3.5 Five years of pre-scheme PIA data and one year of post-scheme PIA data has been obtained from Essex County Council and Transport for London (TfL) over the time period shown in Figure 3.1.

3.6 The scheme took approximately ten months to construct (May 2007 – March 2008). Accidents occurring during this period have been omitted from the analysis. It should be noted that the accident data obtained for this study has not yet been validated by the DfT and may be subject to change. Although it is not

To reduce the loss of life, injuries and damage to property resulting from transport accidents and crime.



anticipated that this would be significant in terms of analysis of the analysis of accident numbers presented in this report.

Figure 3.1 – PIA Data Timeline

3.7 Damage only accidents have also been analysed for a limited period. This data covered the period between March 2007 and March 2009, and was obtained from the HA due to the nature of this scheme. This represents one year of pre-scheme and one year of post-scheme data. It should be noted that this data coincides with the construction period and hence results should not be overstated.

3.8 The accident data referred to in this report has not necessarily been derived from the national validated accident statistics produced by DfT. As such, the data may subsequently be found to be incomplete or contain inaccuracies. The requirement for up-to-date information and site specific data was a consideration in the decision to use un-validated data and, as it is sourced from Local Processing Units through the HA’s Managing Agency Contractors, it is sufficiently robust for use in this context.



Accident Analysis

PIA Analysis

3.9 As stated previously, PIA data was provided for five years pre-scheme opening and one year post-scheme opening.

3.10 Table 3.1 shows a comparison between PIAs during these time periods.

Table 3.1 – Comparison of PIAs Pre and Post-Scheme Opening

Period No. of Years

No. of Accident

s/Rate Slight Serious Fatal TOTAL

Severity Index

No. of PIAs

70 6 2 78 Pre-scheme Opening

5 PIAs per

year 14 1.2 0.4 15.6

10.3%

No. of PIAs

21 1 1 23 Post-scheme Opening

1 PIAs per

year 21 1 1 23

8.7%

3.11 The key points to note from Table 3.1 are:

The number of PIAs per year has increased from 15.6 to 23.

The severity of PIAs has decreased slightly from 10.3% to 8.7% due to an increase in the number of slight PIAs compared to serious / fatal PIAs; and

The fatal post-scheme opening PIA was attributed to excessive speed and may not necessarily been caused by the scheme itself.

3.12 Figure 3.2 compares the number of PIAs for 12 month periods for both before scheme construction and after scheme opening stages.

3.13 The following points can be observed from Figure 3.2:

In the year post opening of the scheme there has been an increase in the number of PIAs; and

After a general decrease in the number of slight accidents (except 2005/6), this has increased post opening of the scheme.



0

5

10

15

20

25

2002/3 2003/4 2004/5 2005/6 2006/7 2008/9

Before After

PIA

s Fatal

Serious

Slight

Figure 3.2 – PIAs by 12 month period 3.14 The causation (as recorded by the attending police officer) of PIAs has also been

monitored pre-scheme construction (May 2002 – April 2007) and post-scheme opening (March 2008 – February 2009). The differences in the causation of PIAs between the pre and post-scheme stages are illustrated in Figure 3.3.

0 2 4 6 8 10 12

Poor lane discipline

Poor judgement ofvehicle(s) position /

speed

Skidding / Loss of control

Collision of opposingvehicles

PIAs per year

Pre schemeopening

Postschemeopening

Figure 3.3 – PIA Causation Analysis



3.15 The key findings from Figure 3.3 are:

There has been an increase in the number of collisions of opposing vehicles from 0.2 to 5 PIAs per year. This includes drivers pulling out onto the roundabout and colliding with vehicles already on the circulatory carriageway.

Skidding / loss of control PIAs and poor judgement of vehicle position / speed PIAs (e.g. ‘shunts’) have decreased post opening of the scheme.

The number of poor lane discipline related PIAs has increased from 2 PIAs per annum to 7 PIAs per annum post opening of the scheme. This could be attributed to drivers being unfamiliar with the new road layout. At this stage there is not enough evidence to prove that this is the case and therefore this will be re-examined in the Five Year After report when more data will be available. It was noted by the Project Manager that a large number of learner drivers used routes through this junction. However, since this was the case both before and after the scheme opened this is unlikely to have had a significant influence on the results.

PIA Significance Testing

3.16 To determine whether the differences in accident numbers observed in the safety analysis is likely to have occurred by chance or directly as a result of the scheme, the Chi-squared test has been used. From this test result we can be 95% confident that the change in accident rate could have occurred by chance alone and therefore the change in PIA numbers is not necessarily a direct impact of the scheme.

3.17 Due to the relatively random nature of PIAs, it is difficult to draw any conclusions with only one year of post-scheme data. Additional PIA analysis in the POPE Five Years After report (due in 2013) will offer a more accurate reflection of PIA trends and will study the safety impacts in greater detail.

Damage Only Accidents

3.18 Damage only accidents refer to those accidents where no injuries were reported but where there was damage to vehicles.

3.19 Damage only accidents are not usually considered as part of the POPE evaluation, however due to the nature of the scheme and the readily available data, it was agreed with the Project Manager that analysis of this data would be included in this report.

3.20 Data was provided for one year pre opening of the scheme (March 2007 – February 2008) and twelve months post opening of the scheme (March 2008 – February 2009). This pre-opening period includes the construction period and therefore analysis of damage only accidents should be considered representative only. Table 3.3 gives a comparison of the pre and post-scheme opening data.



Table 3.2 – Total Damage Only Accidents

Pre-Scheme Opening

Post-Scheme Opening

% Difference

Total Damage Only Accidents

660 608 -8%

3.21 The annual rate of damage only accidents decreased from 660 pre-scheme opening to 608 after scheme opening, representing an 8% decrease.

Additional Measures

3.22 Since the opening of the scheme, reflective posts have been installed with the aim of improving the visibility of the splitter island (Figure 3.4). These posts were implemented in August 2008 following a meeting between the Highways Agency (HA), Essex police and Metropolitan police.

Figure 3.4 - Splitter Island with New Permanent Reflective Posts

3.23 A new lane allocation sign on the outside of the roundabout immediately after the M25 anti clockwise on-slip has been introduced (Figure 3.5). This sign was erected as a result of the post-scheme opening Stage 3 Road Safety Audit.



Figure 3.5 – New Lane Allocation Sign

Security

3.24 The scheme proposed new dedicated lighting would be installed on the junction footway between the M25 clockwise entry and anti-clockwise exit slip roads. However, a site visit by Atkins found that new lighting had not been provided. Existing lights were present on the footpath, although these are of varying condition.



KEY POINTS FROM SECTION 3 – SAFETY ANALYSIS

PIAs

The annual PIA rate has increased from 15.6 pre-scheme opening to 23.0 post-scheme opening;

There has been an increase in the number of collisions of opposing vehicles from 0.2 per year pre-scheme to 5.0 post-scheme opening;

The rate of skidding / loss of control PIAs and poor judgement of vehicle position / speed PIAs (e.g. ‘shunts’) has decreased post opening of the scheme; and

The number of poor lane discipline related PIAs has increased from 2 accidents per year to 7 post-scheme opening.

A Chi-Squared test determined that we can be 95% confident that the difference in accident rate could have occurred by chance alone and thus the change in accident rate is not necessarily due to the implementation of the scheme.

Damage Only Accidents

There has been a decrease of around 8% in damage only accidents since the scheme opened, however this data includes a large amount of the construction period and therefore this result should not be overstated.

Additional Measures

Since the opening of the scheme new permanent reflective posts at the splitter island and a new lane allocation sign have been implemented; and

A site visit by Atkins found proposed lighting on the footway had not been implemented.



4. Economic Evaluation Introduction

4.1 This section will evaluate the economic costs and benefits of the M25 J28 Brook Street improvements by use of the following sources:

Economics Report (September 2006);

AST (October 2006); and

Outturn as-spent costs provided by the regional finance manager within the Highways Agency in June 2009.

4.2 It should be noted that the AST was updated in May 2007. In particular a higher scheme cost and lower journey time benefits were quoted, but it was unclear how these figures were obtained, and hence this report will use figures from the October 2006 AST which match the Economics Report.

Journey Time Benefits

Appraisal Methodology

4.3 The Economics Report predicted the level of delay in the years 2008, 2014 and 2023 for both the AM and PM peak periods, and for the scenarios:

Do-Minimum (DM) without the scheme and

Do-Something (DS) with the scheme.

4.4 These forecasts were based on scheme modelling undertaken using the VISSIM micro-simulation software. The model covered the Junction 28 circulatory, the M25 and A12 either side of the junction, and a small section of Brook Street. It should be noted that the signalised junction at Wigley Bush Lane on Brook Street (0.6km from J28) has not been modelled.

4.5 Delay and traffic levels output from VISSIM were then fed through a spreadsheet model called JUICE-9 which uses COBA and TUBA parameters to convert these delays into a monetary value.

4.6 The Economics Report predicted a 60 year benefit of £259.564m (2002 prices discounted to 2002) as a result of a reduction in delays on, and around Junction 28 due to the scheme being implemented. A significant proportion of benefit occurs in the PM peak from 2023 onwards when delay time was expected to triple unless the scheme was built, as shown in Table 4.1. The Economics Report predicts the first year rate of return to be only 0.2%.



Table 4.1 – Predicted Average Delay time (min/vehicle)

Forecast Year Period DM DS Saving

AM 1.27 1.25 0.02 2008

PM 1.27 1.26 0.01

AM 1.08 1.02 0.06 2014

PM 1.52 0.99 0.53

AM 1.25 1.10 0.15 2023

PM 3.87 1.24 2.63

4.7 The VISSIM model’s forecast time savings for specified years are illustrated in Figure 4.1. Clearly, the junction was forecast to become very congested in the PM period, when a certain traffic level is reached, if the scheme is not implemented. As the M25 is due to be widened between junctions 27 and 30 in the near future, extra traffic is likely to add to congestion at junction 28 in the longer term.

0

0.5

1

1.5

2

2.5

3

20

08

20

09

20

10

20

11

20

12

20

13

20

14

20

15

20

16

20

17

20

18

20

19

20

20

20

21

20

22

20

23

De

lay

Sa

vin

gs

(m

inu

tes

pe

r v

eh

icle

)

AM

PM

Figure 4.1 – VISSIM Forecast delay time savings by year

4.8 The pre-scheme construction (representing the DM scenario) and OYA (representing the DS scenario) journey time survey results have been used to



estimate a 2008 outturn delay saving on Junction 28 using the following methodology:

From all the journey time surveys, the quickest time to each stop line (from the previous checkpoint) was used as a proxy for the free-flow time up to that stop line; in the majority of cases this occurred in the Inter Peak. To ensure consistency the same free flow times were used for the DM and DS scenarios;

The journey times up to each stop line were then assessed for the OYA and pre-scheme stages, with anything above the free-flow time considered to be a delay;

The 2003 (representing the DM scenario) and 2008 (representing the DS scenario) turning counts described in Section 2 of this report were used to estimate the amount of traffic passing each stop line. Since Section 2 of this report shows the scheme does not appear to have induced extra traffic, the 2003 counts were factored up to 2008 levels to represent DM flows;

Any vehicles travelling through the junction on the M25 or the A12 have been assumed as having no benefit; and

Using the amount of traffic and delay at all 9 stop lines on Junction 28 (shown in Figure 4.2) the total DM and DS delay on the junction was calculated. This was then converted into delay per vehicle (for the same area as the VISSIM model) by dividing the total delay at the junction by the number of vehicles using the junction and M25 and A12 through routes.

Figure 4.2 – Junction 28 Stop Line Locations



Monetised Benefits

4.9 Table 4.2 shows the predicted and outturn delay savings in 2008 as a result of the scheme.

Table 4.2 – Predicted vs. Outturn Delay Savings (Mins/Vehicle)

Forecast Year

Period Predicted

Saving Observed

Saving

AM 0.02 0.135 2008

PM 0.01 0.300

4.10 The observed data shows a greater than predicted delay saving per vehicle. However these results should be viewed as indicative and not overstated due to a number of reasons, including:

The journey time surveys were carried out over one day and only consisted of a minimum of 6 runs. The results are therefore dependant on a number of external factors including:

- Weather conditions.

- Traffic levels on that day.

- Any incidents in the surrounding area.

- A margin for error in data collection.

- Since the junction has several traffic signals, journey times could differ greatly from one run to another depending on the phase of the traffic signals at the time of the run.

The majority of the scheme benefit was predicted to occur later on in the 60 year appraisal period, with only a small impact expected in the opening year of 2008 compared to that in the design year of 2023 and beyond.

There appears to be less traffic in the modelled area during the AM and PM peaks than predicted in 2008. Whilst Error! Reference source not found.Table 4.2 suggests greater benefit at this OYA stage, the lower traffic levels may mean it takes longer for the scheme to achieve the large benefits expected from 2023 onwards. This would reduce the total benefit of the scheme over the 60 year period.

4.11 A number of methodologies have been used to analyse the outturn benefits of the scheme over a 60 year appraisal period, as detailed in Appendix D. These methodologies include:

Utilising PAR guidance to convert observed opening year daily vehicle hour savings into 60 year benefits;



Using the JUICE-9 program, assuming a higher level of benefits occurring sooner than predicted; and

Using the JUICE-9 program, assuming lower traffic flows than predicted.

4.12 The analysis demonstrates that the various methodologies give a wide range of total outturn benefits. Given the high level of benefits predicted to occur from 2023 onwards and the very low benefits predicted for the first year after opening, it is considered that it is too early at the ‘one year after’ stage to conclude whether the scheme will achieve the predicted level of benefits.

Safety Benefits

Evaluation Methodology

4.13 The Economics Report predicted a saving of three PIAs in the opening year resulting in a 60 year monetary benefit of £4.73m in 2002 prices discounted to 2002. The scheme was predicted to achieve these savings by saving one shunt type PIA in the opening year at each of the following locations, where new measures were installed as part of the scheme (see Figure 1.2 for details):

M25 N/B Off-Slip (widened to 4 lanes at stop line);

A12 S/B Off-Slip (widened to 4 lanes at stop line); and

M25 S/B Off-Slip to A12 N/B On-Slip dedicated left turn.

4.14 The POPE methodology applies the ratio between the predicted PIA saving in the opening year and the resulting 60 year monetised benefit to the observed opening year saving in order to get an estimate of the outturn safety benefit.

4.15 To calculate a best estimate of outturn 60 year safety benefit for the M25 Brook Street scheme the POPE methodology has been applied to the observed opening year saving obtained in Section 3 of this report.

Monetised Benefits

4.16 The POPE methodology has been applied to an observed opening year increase of 7.4 PIAs with the resultant monetised benefit shown in Table 4.3.

Table 4.3 – Forecast and Best Estimated Outturn Safety Benefits

2002 Prices Discounted to 2002 Forecast Best Estimate of Outturn

Opening Year PIA Saving 3 -7.4

Monetary Accident Benefit (Over 60 Years)

£4.73m -£11.67m



4.17 Table 4.3 suggests that based upon the limited data available so far, the predicted safety benefits have not materialised. In fact the increase in PIAs appears to show a slight disbenefit as a result of the scheme which equates to £11.67m.

4.18 It should be noted that this based upon only one year of post-scheme data which is relatively limited considering that accidents are relatively rare events; furthermore Section 3 showed that this increase was statistically insignificant through the use of a Chi-Squared test. This shows that we can be 95% confident that this change has occurred by chance and not as a result of the scheme itself; the £11.67m disbenefit cannot therefore be attributed to the scheme.

Scheme Costs

4.19 The predicted scheme costs have been obtained directly from the Economics Report produced in September 2006.

4.20 The predicted costs are given in Q1 2005 Prices; these have been re-based and Table 4.4 displays the predicted costs of the scheme in 2002 Prices.

Table 4.4 – Predicted Scheme Costs (2002 Prices Undiscounted)

Component Cost (£m)

Works 5.765

Statutory Undertakers 0.577

Supervisor 0.718

Risk 0.799

Optimum Bias 1.067

Inflation 1.163

Land Costs 0.379

Total 10.467

4.21 The total predicted scheme cost displayed in Table 4.4 of £10.5m equates to £10.3m when discounted to 2002. To avoid delays during the Inter Peak it was intended to use overnight working to construct the scheme. This attracted an additional cost and resulted in a final Present Value Cost (PVC) of £14.8m in 2002 prices discounted to 2002.

4.22 The scheme is also likely to require an additional maintenance cost to renew the infrastructure 30 years after opening.



4.23 Outturn as-spent costs were provided by the regional finance manager within the Highways Agency in June 2009 and have been subsequently converted into 2002 prices.

4.24 Table 4.5 gives a breakdown of these outturn costs. E & C OFT Provision accounts for an estimate of other costs occurring after the scheme opened (March 2008). At the time this report was published actual E & C OFT Provision costs were only available up to and including May 2009. A small estimated provision for future E & C OFT costs has also been included.

4.25 Table 4.5 also includes an estimate for costs between June 2009 and March 2010. Although this is not strictly an outturn cost, it accounts for such a small proportion of the overall cost that for the purpose of this report it has been included in the final outturn costs of the scheme.

Table 4.5 – Outturn Scheme Costs (2002 Prices Undiscounted)

Component Cost (£m)

Works/ Preparation/ Supervision 10.581

Land 0.151

E & C OFT Provision 08/09 Actual 0.373

E & C OFT Provision April/May 09 Actual 0.014

E & C OFT Provision Jun 09 - Mar 10 Forecast 0.052

Total 11.170

4.26 Comparing figures in Table 4.4 and Table 4.5 shows the outturn scheme costs at this stage are around £0.7m higher than predicted.

4.27 The total outturn scheme cost displayed in Table 4.5 of £11.2m equates to a PVC of £9.5m when discounted to 2002.

Benefit Cost Ratio (BCR)

4.28 Benefit Cost Ratio (BCR) is a value for money measurement applied to highways schemes measuring a scheme’s return for each unit of cost to public accounts6.

4.29 Table 4.6 shows a comparison between the forecast and outturn costs and benefits of the scheme, quoted earlier in this section. As previously discussed, it is considered too early to accurately determine the level of outturn journey time benefits of the scheme, given the high level of benefits which are predicted to occur from 2023 onwards. It is not possible, therefore, to derive an outturn BCR at this stage.

6 As defined in WebTAG 6.1.4



Table 4.6– Predicted vs. Best Estimate of Outturn BCR

(2002 Prices Discounted to 2002) Forecast Best Estimate of Outturn

Journey Time Benefit £259.6m N/A

Safety Benefit £4.7m -£11.7m

Total PVB £264.3m N/A

Total PVC £14.8m £9.5m

BCR 17.9 N/A

4.30 It should be noted that although the data demonstrates a safety disbenefit, it was shown that we can be 95% confident that this occurred by chance and therefore the £11.7m disbenefit shown in Table 4.6 cannot be attributed to the scheme itself.

Reliability

4.31 Reliability of journey times is an important economic factor for travellers but is not simple to measure. WebTAG guidance uses the measurement of the route stress as a reasonable proxy for measuring the reliability sub-objective.

4.32 However, this method is not appropriate for assessing the reliability of a junction, and the AST therefore stated that is was not possible to quantify the impact of the scheme on the reliability sub-objective. The AST also stated that a predicted reduction in accidents and delays would lead to improved reliability of trips through the junction.

4.33 Data analysed earlier in this report suggested the scheme has reduced delays but on the other hand has increased accidents, albeit by an insignificant amount. Therefore the change in journey reliability is inconclusive.

4.34 The fact that the OYA and TIS journey time surveys (analysed in Section 2) are so different would appear to suggest the journey times are quite unreliable. However, it is impossible to quantify this or say this if is due to the scheme itself, in fact in this instance the slow journey times experienced in the OYA survey appeared to be caused by slow-moving traffic on the M25, the cause of which is unknown.



KEY POINTS FROM SECTION 4 – ECONOMIC ASSESSMENT

All monetary values in this summary box are given in 2002 prices discounted to 2002.

Appraisal Methodology The original appraisal predicted costs and benefits over a 60 year

period with forecast years of 2008 (Opening Year), 2014 and 2023.

The scheme was assessed through use of the VISSIM micro-simulation software; and

Delay and traffic levels output from VISSIM were then fed through a spreadsheet model called JUICE-9 which uses COBA and TUBA to convert these delays into a monetary value.

Journey Time PVB 60 year journey time benefits of £259.6m were predicted as a result of

this scheme. This was based upon reducing delays at the junction;

A number of issues were identified with trying to calculate a best estimate of outturn benefits including:

- Forecast opening year savings of around 1 second per vehicle were too small to estimate

- The vast majority of the benefit from reduction in delay was predicted to occur 15 years after opening and beyond;

- Hence according to the scheme modelling, the observations in the opening year were expected to be weak evidence of the longer term delay benefits.

A number of methodologies have been used to analyse the 60 year outturn benefits, giving a wide range of results. Given the high level of benefits predicted to occur from 2023 onwards and the very low benefits predicted for the first year after opening, it is considered that it is too early at the ‘one year after’ stage to conclude whether the scheme will achieve the predicted level of benefits.

Safety PVB

A 60 year safety benefit of around £4.7m was predicted as a result of implementing the scheme;

Using the POPE methodology and PIA data analysed earlier in the report a 60 year best estimate of outturn benefit of -£11.7m was



obtained; and

However, it was shown this change was statistically insignificant and therefore we cannot say that this disbenefit was due to the scheme itself.

Scheme Costs /PVC

The outturn scheme costs at this stage of £11.2m are around £0.7m higher than predicted; and

The predicted PVC was around £14.8m, a best estimate of outturn costs as of May 2009 was around £9.5m.

BCR

Given that the outturn journey time benefits cannot be accurately determined using the evidence currently available, it is not possible to derive a BCR at the OYA stage.

Reliability

The usual measurement of route stress is not appropriate for a junction scheme; and

The reliability of the scheme was instead judged upon journey time and PIA results (same method used in the AST), which does not allow a conclusive view to be derived.

M25 Junction 28/A12 Brook Street Junction Improvement– Post Opening Project Evaluation

One Year After


5. Environment Evaluation Introduction

5.1 This section documents the findings of the One Year After evaluation for the Environmental sub-objectives.

Documents Obtained

5.2 Copies of the following documents have been used in the compilation of this section:

Appraisal Summary Table (May 2007);

Environmental Statement (October 2006);

As Built Drawings;

Handover Environmental Management Plan (April 2008);

Traffic Impact Study (October 2009); and

Minutes of OYA Meeting held on 16/04/2009.

Changes to the Scheme

5.3 The retaining wall proposed in the Environmental Statement (ES) adjacent to the M25 anti-clockwise exit slip was not required after local negotiations resulted in some additional land being transferred to the Highways Agency. This allowed sufficient space for a new embankment to be provided at this location to replace the embankment that existed pre-scheme.

5.4 The lay-by on the A12 eastbound was left unchanged, but barriered across to deny any access as a result of Value Engineering to save construction costs, rather than being removed, grass seeded and shrub planted. The barriered off lay-by would also provide a potential location for a mobile VMS.

5.5 The proposed auxiliary lane on the A12 eastbound was reduced in length from 1km to 650m because re-analysis of the traffic model during the detail design phase found that 650m of auxiliary lane would be sufficient for the design year 2023.

5.6 Following a detailed levels survey it was found that the new retaining wall proposed in the ES was not required in the central reservation of the A12.

Site Inspection

5.7 A site inspection for the purpose of this study was undertaken in May 2009.

Consultations

5.8 Three statutory environmental organisations (Natural England, English Heritage and the Environment Agency), the local authorities and relevant scoping consultees have been contacted regarding their views on the impacts they


One Year After


perceive the road scheme has had on the environment, and whether they feel that the mitigation measures implemented have been effective. Table C.1 (found in Appendix C) lists the organisations contacted, their area of interest, and the responses received.

5.9 The HA Part 1 team has also been contacted and it is understood that the scheme is in the early stages of the 6 year claim period and it is not yet clear how many of the claims are likely to be successful. Therefore this information will be requested as part of the Five Years After evaluation.

Traffic

5.10 Three of the environmental sub-objectives (noise, local air quality and greenhouse gases) are directly related to traffic flows. The ES predicted traffic flows (AADT) with the scheme in the forecast opening year of 2008, this has been factored to 2009 for comparison with observed traffic flows.

Table 5.1 – Predicted Vs. Observed Do-Something Traffic 2009 AADT

Location Direction Predicted AADT

Observed AADT

% Difference

Brook Street E/B 10,500 10,000 -5%

Brook Street W/B 9,300 10,400 10%

A12 Off-Slip E/B 11,300 10,100 -11%

A12 Off-Slip W/B 21,300 21,100 -1%

A12 On-Slip E/B 22,700 - -

A12 On-Slip W/B 10,900 10,300 -6%

A12 Through E/B 10,700 9,700 -10%

A12 Through W/B 10,200 9,900 -3%

M25 Off-Slip C/W 18,300 19,400 5%

M25 Off-Slip A/C 17,000 16,000 -6%

M25 On-Slip C/W 15,500 14,800 -5%

M25 On-Slip A/C 15,600 18,700 17%

M25 Through C/W 47,400 44,000 -8%

M25 Through A/C 51,800 43,900 -18%

5.11 Observed traffic flows are lower than predicted at all locations except for Brook Street westbound, M25 clockwise off-slip and the M25 anti-clockwise on-slip.


One Year After


Noise

Forecast Noise

5.12 The AST stated that a total of 460 sensitive properties lay within 300m of the scheme. Barely perceptible changes in traffic noise levels would arise as a result of the scheme. Noise level changes at the closest properties would be <2dB. The estimated population annoyed was 144 with the scheme and 144 for the Do-minimum scenario. The AST estimated that no additional residents would be annoyed by noise in the design year.

5.13 The ES assessed the effects of the scheme on noise levels as follows:

Traffic noise predictions indicated that noise level changes with the scheme would be imperceptible and no specific mitigation measures were considered necessary. However, in line with the HA’s policy when carrying out all new road schemes, a low noise road surfacing would be used;

The scheme would have no vibration impact over and above that expected through traffic growth, were the scheme not to proceed; and

No properties would be eligible for noise insulation.

Consultation

5.14 Brentwood District Council was consulted and stated it had not received any comments from local residents in respect of road traffic noise.

5.15 The London Borough of Havering was consulted and stated that no monitoring had been undertaken and therefore it was unable to comment on whether the impact of the scheme on local noise was as expected and it did not have any evidence of changes in noise levels as a result of the scheme.

Evaluation

5.16 The designers confirmed that low noise road surfacing had been provided and that noise insulation had been discussed for three properties. It is understood that a final decision for noise insulation will be made from the Part 1 Claims process.

5.17 From Table 5.1 it appears that at most locations observed traffic flows are between 1% and 18% lower than forecast and it is considered that the local noise climate at these locations is likely to be slightly better than predicted.

5.18 For Brook Street westbound, M25 clockwise off-slip and M25 anti-clockwise on-slip the observed traffic flows are between 5% and 17% higher than forecast and it is considered that the local noise climate at these locations could be slightly worse than predicted.


One Year After


NOISE SUMMARY

AST Barely perceptible changes in traffic noise levels would arise as a result of the scheme, with no additional residents annoyed by noise in the design year.

EST Low noise surfacing has been provided and traffic volumes are very slightly lower than predicted. Assessment: Slightly beneficial.

Local Air Quality

Local Air Quality Forecasts

5.19 The AST stated that the scheme would have a negligible benefit to air quality within three Air Quality Management Areas (AQMA). The small magnitude of the scores indicated that the overall reduction in public exposure would be slight. Air quality would improve for 787 properties and worsen at 221 properties and there would be no change at three properties.

5.20 The ES assessed the effects of the scheme on air quality as follows:

There are three Local Authority declared AQMA immediately adjacent to the Scheme. The two key traffic related pollutants most relevant for the AQMA are nitrogen dioxide (NO2) and particulates (PM10). Other pollutants fell significantly below the EU Limit Values and National Air Quality Objectives.

Using a detailed air quality model, concentrations of these two pollutants were estimated at sensitive locations in the study area, and compared with the national air quality objectives and the EU Limit Values.

The ES predicted that implementation of the Scheme would cause no overall worsening of air quality in the local area. A generalised assessment showed that when the scheme opened in 2008 approximately 20% of properties would experience a slight reduction in air quality, but the majority (80%) would experience an improvement.

5.21 In summary, the ES assessed the scheme demonstrated an overall improvement in air quality.

Consultation

5.22 Brentwood District Council was consulted and stated it had not received any comments from local residents in respect of local air quality.

5.23 The London Borough of Havering was consulted and stated that no monitoring had been undertaken and therefore it was unable to comment on whether the impact of the scheme on local air quality was as expected and it did not have any evidence of changes in local air quality as a result of the scheme.


One Year After


Evaluation

5.24 For the M25 anti-clockwise Observed traffic flows (AADT) in 2009 (shown in Table 5.1) are lower than the ES forecast growthed flows for 2009 and the difference between the observed and forecast growthed flows is greater than 5000 AADT. It is likely that local air quality is better than expected at this location

5.25 For the remaining locations in Table 5.1, Observed Traffic Flows (AADT) in 2009 were within +/- 5000AADT of those predicted in the Environmental Statement and it is therefore considered that air quality is as expected.

LOCAL AIR QUALITY SUMMARY

AST Negligible benefit to air quality within three AQMA’s.

EST Traffic volumes slightly lower than predicted but generally within 5,000 vehicles. Assessment: As expected.

Greenhouse Gases

5.26 The scheme was predicted to reduce congestion and not induce any extra traffic. Despite this the AST predicted there would be an increase in CO2 of 0.4% in the opening year as a result of implementing the scheme. 50,891 tonnes CO2 were predicted for the 2008 Do Minimum scenario and 51,100 tonnes CO2 were predicted for 2008 Do Something scenario. The AST therefore implies that traffic will be travelling at a less efficient speed as a result of the scheme.

5.27 The ES predicted that CO2 emissions would increase by 5.6% between 2003 and 2008 (opening year), and by 12.4% between 2003 and 2023 (design year) if a ‘Do Minimum’ approach was adopted. With the scheme in place, CO2 emissions were predicted to increase by an additional 0.4% in the opening year and 3.0% in the design year.

Evaluation

5.28 The evaluation of outturn Carbon impacts is usually carried out using one of the following two methodologies:

COBA 11 R7 modelling software; or

Design Manual for Roads and Bridges (DMRB) regional emissions worksheet.

5.29 However this scheme was not assessed using COBA and the link based DMRB worksheet is not compatible with junction schemes. A quantitative evaluation of Carbon can therefore not be carried out for this scheme.


One Year After


5.30 Based upon data in Section 2 of this report, which appears to show the scheme has not induced any extra traffic and flows are close to predicted, it can be said that the impact on Greenhouse Gases is as expected.

5.31 Furthermore, the predicted 5.6% and 12.4% increase in Carbon by 2008 and 2023 respectively is likely to be overestimated due to the less than expected background growth experienced around the country as a whole (and described in Section 2).

GREENHOUSE GASES SUMMARY

AST Negligible increase in greenhouse gases due to traffic travelling at less efficient speeds.

EST The scheme does not appear to have induced traffic. Assessment: As expected.

Landscape

Forecast Landscape Impacts

5.32 The AST stated that an existing, established, well vegetated landscape of local importance was present. Restricting improvement works to within the existing highway boundary minimised wider impacts and the impact on landscape character. There would be some localised loss of vegetation beside the Ingrebourne River. A neutral impact was predicted.

5.33 The ES assessed the effects of the scheme on landscape as follows:

5.34 Local landscape designations within the study area included:

Areas of Green Belt within the boundaries of London Borough of Havering and Brentwood Borough Council;

A Special Landscape Area, Childerditch SLA;

A strategic Green Wedge to the northeast of the study area, and a playground and allotments off River Road designated as Protected Urban Space;

The Havering Ridge of Special Character; and

The Thames Chase Community Forest.

5.35 Mitigation measures included:


One Year After


Minimising loss or damage to mature trees and vegetation belts and minimising the footprint of the scheme;

Minimising the visual impact of the scheme on properties, footpaths and places of public access as far as practicable;

Ensuring landscape planting proposals were consistent with the character of the surrounding and/or lost landscape or provided an enhancement of the existing landscape where possible,

Use of locally appropriate native plant species, specified for maximum growth rates, in order to be able to screen and integrate the new works as soon as possible; and

Seeking opportunities for local nature conservation enhancement.

5.36 The landscape design comprised tree, shrub and grass planting works within the road corridor principally surrounding the motorway Junction with some planting along the A12 eastbound of the Junction. The design would take account of proposed ecological mitigation measures.

5.37 The scheme was expected to have a slight adverse effect on the existing landscape character in the vicinity of the proposed retaining wall beside the A12 eastbound entry slip road due to the removal of existing trees and vegetation. Overall the scheme would have a neutral effect on the existing landscape character due principally to the small footprint of the works within the existing road corridor which was surrounded by a strong landscape structure.

5.38 The proposed retaining wall and extended culvert beside the A12 eastbound entry slip road would open up views to the carriageway from the neighbouring field and woodland beyond. Elsewhere views were not predicted to change appreciably and there would be no significant long-term residual impact on views from receptor locations.

5.39 Most of the 140 properties with views towards the scheme were located along the southern side of the A12 through Brook Street and could not see the Junction. Commercial properties were noted as the Holiday Inn Hotel, Brentwood Garden Centre, Total Garage and Bibby’s Diner. The remaining receptors were walkers or cyclists on the overbridges along the eastern portion of the A12 and using the unmarked pedestrian routes around the southern side of the Junction. The key visual receptors all had existing views of the road corridors. All the viewpoints would experience no change, with the exception of two residences, which would experience moderate effects with improved screening made possible by improved field boundary planting along the highway edge beside the A12 London-bound exit slip road.

5.40 All the road corridors including the Junction were well lit and there was a noticeable night time glow from the road corridors. The existing lighting system would be replaced with high pressure low cut-off lights on 10m or 12m columns where adjustments to the lighting layout were required to accommodate the


One Year After


scheme. This would give a reduction in light spillage, improve existing road lighting conditions and would result in visual improvement to those over-looking the scheme.

Consultation

5.41 Brentwood District Council was consulted, and comments received are summarised below:

The impact is as expected for Areas of Green Belt, The Thames Chase, landscape features such as woodlands and hedgerows, public rights of way and the setting of Brook Street;

The impact is better than expected for the Special Landscape Area (Childerditch SLA), the strategic Green Wedge to the northeast of the A12, a playground and allotments off River Road designated as Protected Urban Space, local landscape character, and views to and from the road improvements;

The effect that mitigation measures have had on reducing visual impacts and integrating the scheme into the surrounding landscape has been as expected for new landscape planting, earthworks and ground modelling and retention of existing vegetation; and

The use of materials and finishes on new retaining walls is very appropriate.

5.42 Essex County Council was consulted and was unable to comment as it had not been involved in the scheme’s landscape sub-objective.

Evaluation

5.43 Observations made during the site visit for this report are provided in Table C.2 and Table C.4 (found in Appendix C).

5.44 In summary, most vegetation lost has been offset by replanting in line with the mitigation proposals except for a few minor variations including slightly less tree planting than proposed and no grass and shrub planting over the former lay-by on the A12. The lay-by was left in place and barriered across as a result of Value Engineering to save construction costs and to provide a potential location for a mobile VMS. Tree and shrub planting appears to be establishing well although ongoing maintenance will be required to ensure that planting continues to establish. Overall evaluation indicates a ‘neutral’ impact as expected.

5.45 Landscape planting has generally been implemented in line with the mitigation proposals detailed in the ES. A detailed evaluation of the mitigation proposals is provided in Table C.4.


One Year After


LANDSCAPE SUMMARY

AST Neutral impact predicted as improvements were made within the highway boundary minimising negative impacts.

EST Landscaping and mitigation measures implemented in line with the proposals. Assessment: As expected.

Townscape

5.46 The AST stated that the suburban townscapes of Brook Street, Harold Hill and Harold Park were located within 1km of the scheme. Areas located close to the scheme were considered to be of no distinctive appearance and existing screening would not be altered. A neutral impact was predicted on townscape character.

5.47 The ES described ‘Townscape Character A: Suburban’ which bordered the southern edge of the A12 corridor and was part of Brook Street which formed a residential area on the western fringes of Brentwood.

5.48 The impacts for ‘Townscape Character A: Suburban’ were considered to be neutral for day and night-time effects in the opening year and design year.

Consultation

5.49 No comments specifically relating to Townscape have been received.

Evaluation

5.50 No environmental enhancements were proposed in the ES to be undertaken as part of the scheme in adjacent settlements.

5.51 It is considered that the impact of the scheme on the townscape character of Brook Street and other nearby settlements is neutral as expected.

TOWNSCAPE SUMMARY

AST Neutral impact predicted due to location of the scheme.

EST Assessment: As expected.

Heritage

Heritage Forecast Impacts

5.52 The AST stated that the only known feature within scheme footprint was the undesignated line of the London–Colchester Roman road which had been


One Year After


previously disturbed and no further impact was expected as result of scheme. A neutral impact was predicted overall.

5.53 The ES assessed the effects of the scheme on heritage as follows and stated that:

5.54 Baseline Conditions:

There were three Grade II listed buildings, one Area of Ancient Woodland and one Archaeological Priority Area within 250m of the scheme. These are all of Local Value;

The Roman Road from London to Colchester passes through the Junction on the line of the former A12 but this area has already been heavily disturbed by the construction of the A12 and M25, which would have damaged or destroyed the Roman Road to such a degree that it would now be of Negligible Value;

A World War II spigot mortar emplacement and Alan Williams Tower once stood in the town of Brentwood, to the northeast of the scheme but neither now survives above ground; and

Based on the extremely limited number of known remains in the area and the likelihood of previous impacts upon any archaeological remains due to the original construction of the A12 and M25, the ES assessed that there was very little potential of recovering currently unknown sub-surface archaeological deposits within the land-take of the scheme. Any remains that may be identified were likely to be of Negligible Value due to past damage.

5.55 Construction Phase Impacts:

There would be a Negligible Visual Impact upon the Area of Ancient Woodland, which would equate to a Neutral Significance of Effect.

There would be at most a Negligible Direct Impact on the Roman Road which passes through the Junction. As this feature was assessed as being of Negligible Value, due to the previous impacts, there would be a Neutral Significance of Effects.

There would be Neutral Impact (directly or indirectly) on the three listed buildings, the Spigot Gun and Tower, the Archaeological Priority Area and most likely on any hitherto unknown archaeological features.

5.56 Mitigation and Enhancement:

The ES stated there were limited known archaeological and cultural heritage features within the study area and the scheme area had already been heavily disturbed by the construction of the A12/M25. As no known Cultural Heritage features were to be directly impacted and only a slight area of the Area of Ancient Woodland fell within the Visual Limits of works a Neutral assessment of significance was predicted overall and it was considered that no mitigation was required. No further archaeological works were proposed.


One Year After


Consultation

5.57 Essex County Council was consulted and commented that due to previous highways developments in the area it was thought the survival of the London to Colchester Roman Road or any other unknown archaeological activity, would be remote. Therefore there were no recommendations for archaeological works. Impacts were judged to be negligible

5.58 Brentwood District Council was consulted and commented that it had little information available to be able to make judgements on the scheme but given the nature and scale of the works and the distance to the Heritage resources identified it was not aware of any impacts that had been worse than expected.

Evaluation

5.59 The new retaining wall and extended culvert beside the A12 eastbound entry slip road has opened up views to the carriageway from the Area of Ancient woodland beyond although it is considered that this is not particularly significant as this area was relatively open previously and with time the new planting should screen views of the carriageway.

5.60 The site visit for this report confirmed that the impact on the setting of the three listed buildings is considered to be neutral as expected.

5.61 Overall evaluation indicates a neutral impact as expected.

HERITAGE SUMMARY

AST No impact on heritage predicted as a result of the scheme.

EST Assessment: As expected.

Biodiversity

Biodiversity Forecast Impacts

5.62 The AST predicted the scheme would result in loss of habitat within the highway boundaries with low to medium importance at the local scale, including habitat along the Ingrebourne River due to extension of existing culvert, and some reptile habitat. There would be an indirect adverse impact on foraging/commuting bats through increased risk of collisions with road traffic as a result of the reduced verge width. A slight adverse impact was predicted overall.

5.63 The ES assessment of the effects of the scheme on biodiversity is provided in Table C.3 and the text below.

5.64 The mitigation proposals are summarised below:


One Year After


Management of habitats retained and re-instated to compensate for potential impacts and to maximise wildlife potential;

Implementation of Construction Environmental Management Plan (CEMP) to prevent damage to protected species and valuable habitats; and

Implementation of Landscape and Ecological Management Plan (LEMP) during the operational phase to enhance habitats and their potential for protected species.

5.65 There would be an inevitable net loss of habitat and subsequent impact on species because the proposals are located within the existing highway boundary, but following mitigation the ES predicted an overall slight adverse impact.

Consultation

5.66 Brentwood District Council was consulted, and comments received are summarised below:

The impact of the scheme on protected species and other areas of ecological interest e.g. breeding birds, Ingrebourne River, broadleaved woodland, scrub, grassland, appears to be as expected; and

Brentwood District Council considered that mitigation measures including the provision of new habitats and landscape planting alongside the scheme and the use of species rich grass mixes had been effective in avoiding / reducing impacts on biodiversity.

5.67 Essex County Council was consulted and was unable to comment as it had not been involved in the scheme’s biodiversity sub-objective.

Evaluation

5.68 An evaluation of the impacts of the scheme on biodiversity is provided in Table C.3 and the text below.

5.69 Construction of the scheme started in late May 2007 and the scheme was opened to traffic in March 2008.

5.70 The Area 5 MAC responsible for M25 J28 reported four roadkills between March 2006 and May 2007, three roadkills between May 2007 and March 2008 and three roadkills between March 2008 and May 2009. All roadkills were deer.

5.71 The Area 6 MAC responsible for the A12 was only able to provide roadkill data for 2009 during which a total of three dead deer were reported.

5.72 Area 6 MAC were not aware of a Highways Agency policy for deer fencing on this section of the A12. However, Area 6 MAC are due to undertake a deer study in 2009/10 which will identify risk sites based on personal and non personal injury accident data and will propose mitigation measures.

5.73 In summary most mitigation measures recommended in the ES appear to have been implemented. Very slightly less new woodland planting was present than


One Year After


expected. One badger sett which showed no signs of activity during the survey for the ES was later found to be occupied and therefore a Badger License was issued by Natural England permitting work close to the sett. A number of deer deaths have been reported but there is no obvious increase in deer deaths as a result of the scheme. Deer were not mentioned in the ES. The Highways Agency has confirmed that prior to construction the Highways Agency deer specialist was consulted and deer were not considered to be an issue because the scheme was small and within an existing road corridor where deer deaths had already occurred. Large areas of species rich grassland have been created throughout the scheme which were not mentioned in the ES. Overall evaluation indicates a ‘slight adverse’ impact as expected.

5.74 The impact on protected species was considered to be relatively minor and therefore no post opening monitoring for protected species has been undertaken and no monitoring requirements for protected species were included in the HEMP. The Handover Environmental Management Plan (HEMP) stated that ‘the main issue for future environmental care and maintenance was that of landscaping aftercare upon project construction phase completion.’

BIODIVERSITY SUMMARY

AST AST predicted that the scheme would result in loss of habitat within the highway boundaries with a slight adverse impact overall.

EST Less woodland planting than expected. Assessment: Slight Adverse as expected.

Water

Water Forecast Impacts

5.75 The AST stated that there would be no significant change in the water quality of the Ingrebourne River due to the modified existing road drainage system and additional 30m length of culverting. There would be no adverse affect on the existing flooding regime and groundwater would be unaffected. A neutral impact was predicted overall.

5.76 The ES assessed the effects of the scheme on water as follows:

The local water environment comprising the Ingrebourne River, its floodplain and shallow groundwater in the superficial deposits associated with the river valley could potentially be affected by the scheme;

The Flood Risk Assessment demonstrated that the scheme would have no adverse effect on the Ingrebourne River’s existing flood flow regime;

Risks to groundwater in shallow deposits included contamination by accidental spillage during construction and below ground structures interfering with groundwater flow during the operational phase. These risks


One Year After


were considered very minor and would have no significant implications for the local water environment;

Before the scheme local road drainage from the M25, A12 and their slip roads was discharged either directly to Ingrebourne River (most), or to field ditches which join the river. There were no pollution prevention measures, aside from gully traps. The assessment of the effects of routine road drainage upon the Ingrebourne River, and the spillage risk assessment, demonstrated that no pollution prevention measures needed to be incorporated in the new road drainage system, however, the EA wished to see incorporation of measures to improve protection of the Ingrebourne River from road drainage related contamination, as part of the scheme;

During construction, the Ingrebourne River would be protected by implementation of the CEMP. The risk of contamination could not be entirely eliminated, although the effect of any incident would be temporary;

Regular monitoring of the Ingrebourne River would be carried out if required by the EA;

The road sections to be improved almost directly abut the river and so the choice of pollution prevention measures was restricted and the measure that was applicable to the Junction was penstocks on existing or new drains; and

Where widening was proposed for the junction approaches it would be necessary to replace the existing drainage with a new system in the new verge. For the widened three-lane section of the A12 it would be necessary to upgrade the existing drainage system where it does not have sufficient flow capacity.

5.77 The ES predicted that all potential impacts fell into the Neutral category, except for water quality risks to the Ingrebourne River during construction which would be (potentially) Slight Adverse.

Consultation

5.78 The Environment Agency was consulted, and comments received are summarised below:

The impact on the local water environment is as expected for ground water and hydrology, local aquifers, River Ingrebourne and water meadows;

The effect that mitigation measures have had on reducing/avoiding impacts on the water environment is as expected for improvements to the existing highway drainage system, pollution control measures and new highway drainage; and

The Environment Agency was not aware of any changes to water quality in local watercourses as a result of the improvement scheme although this stretch of the River Ingrebourne is no longer monitored under the


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Environment Agency’s general quality assessment (GQA) scheme so a change in trend would not be seen as the Environment Agency have no data.

5.79 Brentwood District Council was consulted, but was not able to comment as it had no water quality data and had not seen the design details for the scheme.

5.80 London Borough of Havering was consulted and stated it was unable to comment on whether the impact of the scheme on the local water environment was as expected.

Evaluation

5.81 The As Built Drainage Drawings show:

Three manholes within the scheme have a Penstock fitted to the outlet pipe;

The existing drainage has been replaced with a new system where the junction approaches have been widened; and

Some of the existing drainage system adjacent to the widened three-lane section of the A12 has been upgraded.

5.82 The Designers confirmed the following:

There were no known incidents of contamination of the Ingrebourne River during construction. The River was physically dammed to enable construction works with a pipe system through the dam to allow water to pass; and

During construction the Ingrebourne River was regularly monitored for contamination and for possible approaching storm waters when the in-river works would have been removed to mitigate potential flooding.

5.83 Impacts on the water environment are considered to be as expected based on the information which has been made available for this report.

WATER SUMMARY

AST No adverse effect affect on the existing flooding regime and groundwater would be unaffected. A neutral impact was therefore predicted.

EST As expected.

Physical Fitness

Physical Fitness Forecast Impacts

5.84 The AST predicted no change in physical fitness would be expected as a result of the scheme and a neutral impact was predicted overall.

5.85 The ES assessed the effects of the scheme on physical fitness as follows:


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Users of all routes experienced difficulties from traffic. The journey experience and amenity of crossing points was considered as very poor and cyclists were required to travel on the main carriageway with no segregation from traffic;

Where footways were provided on the A1023, A12 and around the Junction their width ranged from 0.5 to 2 metres and the condition of the footways, in general, was acceptable. No safety fencing or pedestrian guard-railing was present along any of the footways to separate users from the high volume of traffic using these routes;

There were no signalised at-grade crossings with pedestrian facilities provided along any of the existing pedestrian routes of the A1023, A12 and around the Junction. Due to high traffic volumes, crossing the carriageways was difficult and users were forced to cross the road during breaks in the traffic. In particular, users originating from Brook Street village whose destination was onward to Harold Hill were required to cross the high traffic volumes of the M25 clockwise entry and anti-clockwise exit slip road, the latter had traffic signals but no pedestrian facilities. No warning signs were provided to motorised users indicating that there may be pedestrians crossing the carriageway;

The NMU survey results indicated relatively low pedestrian and cyclist numbers around the Junction. The ‘Do Minimum’ (baseline) severance impact on residents was defined as Severe because users were required to cross a number of roads carrying large numbers of traffic and therefore were likely to be deterred from making journeys.

5.86 The proposed improvements are described below:

From the A1023 southern footway to M25 clockwise entry slip road, a new footway, including tactile paving, would replace the existing footway of poor condition;

Dedicated lighting would be installed on the Junction footway between the M25 clockwise entry and anti-clockwise exit slip roads. If necessary due to utilities diversions, a new footway with tactile paving would be constructed;

Between the M25 anti-clockwise exit slip road and the A12 London-bound entry slip road a new footway, including tactile paving, would replace the existing;

There would be improved amenity for NMUs from improved carriageway lighting; and

The traffic signals to be implemented around the Junction would be appropriate for later upgrading to Toucan crossings for the potential cycle route between Romford and Brentwood which may be promoted by Transport for London (TfL) in the future.


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5.87 In summary, no additional severance to pedestrians and cyclists would be caused by the scheme. As a result of the scheme there would be a few amenity and safety benefits for NMUs that could encourage increased usage and therefore reduce severance. However, in the context of relatively low users the overall effect on users of public routes was assessed as neutral.

Consultation

5.88 Brentwood District Council was consulted, and commented that it was not aware that any additional provision had been made for cyclists and pedestrians as part of the scheme.

5.89 Sustrans was consulted and did not provide any comments.

Evaluation

5.90 No formal NMU post opening survey has been undertaken however informal observations made during Road Safety Audit 3 noted occasional cyclists and pedestrians present in similar numbers to the Environmental Statement NMU survey.

5.91 The Designers stated there had been proposals in the Environmental Statement which were never part of the Highways Agency’s scheme, to replace the existing NMU route which crosses the M25 clockwise entry slip road and M25 anti -clockwise exit slip road with a new NMU route which crossed into the central roundabout area and required four toucan crossings. It was decided not to proceed with this proposal as it was thought to create too much of a detour and there were not enough NMUs to justify the expense.

5.92 The Designers confirmed that the scheme design does not impede future upgrade to toucan crossings. No additional toucan crossings were provided as the stop lines would have needed relocating if this option had been adopted which would have impacted on vehicle queuing capacities and made the junction less efficient. New traffic signal heads had been upgraded the year before scheme construction commenced and these were retained except where new pole locations were required as a result of kerb-line adjustments. The facility that was implemented was agreed with the cycle-route promoting authority, TfL and the Highways Agency.

5.93 The following observations were made during the site visit and from the As Built Drawings:

The uncontrolled pedestrian crossing at the M25 clockwise entry slip road continues to be difficult and dangerous to cross due to high volumes of traffic;

New footways, including tactile paving have been constructed at all three locations proposed in the ES. Some cracking was visible in the new footway between the M25 anti-clockwise exit slip road and the A12 London-bound entry slip road. The Highways Agency have confirmed this footway has been repaired since the site visit for this report. See Figure 5.1;


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New dedicated lighting has not been provided on the footway which passes under the M25 between the M25 clockwise entry and anti-clockwise exit slip roads. The footway is located beneath the bridge shown on Figure 5.1. Existing lights are present at this location although these are of varying condition;

Two signs warning of drivers of ‘cycle route ahead’ are present at the uncontrolled pedestrian crossing on the M25 clockwise entry slip road;

A safety barrier was present at most locations between the new footways and

the road; and

Improved carriageway lighting has been implemented.

5.94 In summary, new footways and improved carriageway lighting have been provided as proposed. New dedicated lighting has not been provided on the footway between the M25 clockwise entry and anti-clockwise exit slip roads although existing lights in varying condition were present at this location. The scheme design does not impede future upgrade to toucan crossings. The uncontrolled pedestrian crossing at the M25 clockwise entry slip road continues to be difficult to cross. In the context of relatively low users the overall evaluation indicates a ‘neutral’ impact as expected

Figure 5.1 – Footway between M25 Anti-Clockwise Exit Slip Road and A12 London-bound Entry Slip Road


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PHYSICAL FITNESS SUMMARY

AST No change in physical fitness, therefore neutral impact predicted.

EST As expected.

Journey Ambience

Journey Ambience Forecast Impacts

5.95 The AST predicted improved traffic flows and reduction in congestion would result in improved route certainty, reliability and safety, reduced driver frustration and stress. A large beneficial impact was predicted overall.

5.96 The ES assessed the effects of the scheme on journey ambience as follows:

Traveller Views

5.97 The overall effect on traveller’s views would be neutral. The scale of the works, set in a well vegetated landscape, would not alter the views for travellers on the various road corridors. Mitigation would include incorporation of planting for screening and to reinforce existing boundaries and hedgerows;

M25 Motorway - The views from the M25 would remain unaltered and the existing open views would not be impacted on by the small footprint of the scheme. One small change would be the window opened up by the clearance of trees and vegetation beside the A12 east-bound on-slip due to the construction of the retaining wall. At the opening year new planting would be unnoticed by travellers on the M25, but at the 15th year any tree planting would have established. However, it would be hard to recognise to motorists passing at speed at a higher elevation, set in the context of the overall landscape;

A12 - At the opening year, views would remain intermittent and would be restricted beyond the corridor as no alterations were proposed to the road corridor boundary planting. New planting and grassing would be evident on the newly formed cut slopes and in the central reserve and at the 15th year the planting would have merged with the existing planting;

M25 / A12 Junction Roundabout - New planting would be evident close to the junction. At the opening year the views would be more open where the construction works have taken place but new planting would be positioned to


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reinforce existing boundaries and hedgerows. By the 15th year the planting would be sufficiently established to merge with the existing planting and any views resulting from the works would be closed up. Views would remain restricted; and

A1023 – At the opening year, alterations at the junction of the A1023 with the roundabout would have some very minor opening of views, principally to The Poplars but replacement planting would be evident along the road boundary. At the 15th year, the boundary planting and reinforcement of hedgerows would have established to re-form a strong boundary screen. Views would remain intermittent.

Driver Stress

5.98 Driver stress was assessed as continuing to be high for the M25 and A1023 and moderate for the A12, however, the likely impact of the scheme on driver stress was predicted to be beneficial when compared to the existing situation due to the significant improvement in terms of reduced congestion, enhanced highway design and safer driving conditions. Slip road widening and dedicated turnings would improve the flow of traffic and reduce congestion around the junction, resulting in an increase in route certainty, reliability of journey times and therefore reducing driver frustration. Fear of accidents would decrease with a reduction in the erratic starting and stopping of vehicular movements and increased awareness of hazards by strategically placed warning signs of the potential hazards within the junction.

Traveller Care

5.99 As part of the scheme a 1km widening of the A12 east-bound would be implemented. As a result of this change the east-bound lay-by situated approximately 1km from the Junction would be closed permanently early-on in the construction programme. Signing would be used to provide advance warning of the lay-by closure. The closure of this lay-by would increase the usage of the other three lay-bys on the A12 between the Junction and Mountnessing Junction. A survey was conducted which concluded that the other three lay-bys had sufficient capacity to accommodate the extra usage resulting from the closed lay-by. Traveller facilities were considered to be worse when compared to the existing situation as a result of the loss of a lay-by.

Evaluation

Traveller views

5.100 The site visit for this report concluded that traveller’s views are generally as predicted except that:

The former lay-by on the A12 is less visually attractive than expected because it has been barriered across and left in place rather than being removed, grass seeded and shrub planted as proposed in the ES. The lay-by


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was left in place as a result of Value Engineering to save construction costs and to provide a potential location for a mobile VMS;

No new planting was visible in the A12 central reserve although this is not considered significant as most of the existing vegetation appears to have been retained at this location; and

Most of the existing hedgerow has been retained along the boundary with the Poplars and therefore views have not been opened up particularly at this location.

Driver Stress

5.101 Observed traffic flows are generally lower than predicted except for Brook Street west bound, M25 clockwise off-slip and M25 anti-clockwise on-slip where observed traffic flows are slightly higher than predicted. The junction was not congested at the time of the site visit for this report however queuing back from the A1023 arm onto the roundabout resulting in other entrances and exits to the roundabout being blocked, is known to be a problem particularly during the AM Peak. The traffic lights at Wigley Bush Lane Junction may be optimised to improve this congestion problem.

5.102 Since the scheme was constructed reflective posts have been installed on the splitter island after several incidents relating to visibility of the splitter island.

5.103 On 9 July 2008 the Brentwood Gazette expressed some negative views about the scheme, mainly aimed at the lane allocations.

5.104 Various warning signs of the potential hazards within the junction have been provided. The Highways Agency confirmed the junction signing meets the required standards.

Traveller Care

5.105 The east bound lay-by on the A12 has been closed. The designers have confirmed that during the construction phase signing was used to provide warning of the lay-by closure. These warning signs are no longer required and therefore have been removed.

5.106 In summary, travellers views are slightly worse than expected because the former lay-by on the A12 has been barriered across and left in place. The lay-by was left in place as a result of Value Engineering to save construction costs and to provide a potential location for a mobile VMS. Driver stress appears worse than expected due to queuing back from the A1023 arm onto the roundabout during the AM Peak and concerns about signing and lane allocations. The impact on traveller care is as expected in the ES.

5.107 The journey time surveys collected in Section 2 appear to suggest a slight reduction in congestion, however as mentioned previously there still appears to be some congestion from Brook Street onto the roundabout. Therefore, journey


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ambience is likely to be slightly worse than expected and has been scored as slightly beneficial.

JOURNEY AMBIENCE SUMMARY

AST Improved traffic flows and reduction in congestion leading to a large beneficial impact.

EST Assessment: Slightly Beneficial. I.e. worse than expected due to congestion on Brook Street blocking the roundabout at peak times.

KEY POINTS FROM SECTION 5 – ENVIRONMENT EVALUATION

Noise

Low noise road surfacing has been provided. Evaluation based on traffic flows indicates that the scheme’s effect on the local noise climate is slightly better than expected at most locations. For Brook Street west bound, M25 clockwise off-slip and M25 anti-clockwise on-slip the local noise climate is slightly worse than expected.

Local Air Quality

Evaluation based on traffic flows indicates that the scheme’s effect on air quality is likely to be as expected in the ES except for the M25 anti-clockwise where Observed traffic flows (AADT) in 2009 are lower than the ES forecast growthed flows for 2009 and it is likely that local air quality is better than expected at this location.

Greenhouse Gases

A quantitative re-evaluation of Carbon impacts was not possible for this scheme. Based upon traffic flows the scheme has had a negligible impact on Greenhouse Gases as predicted.

Landscape

Most vegetation lost has been offset by replanting in line with the mitigation proposals except for a few minor variations including slightly less tree planting than proposed and no grass and shrub planting over the former lay-by on the A12. This lay-by was left in place and barriered across as a result of Value Engineering to save construction costs and to provide a potential location for a mobile VMS. Tree and shrub planting appears to be establishing well although ongoing maintenance will be required to ensure that planting continues to establish. Overall evaluation indicates


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a ‘neutral’ impact as expected; and

It is recommended that night time lighting is considered further during the five years after evaluation.

Townscape

Overall evaluation indicates a ‘neutral’ impact as expected.

Heritage

Overall evaluation indicates a ‘neutral’ impact as expected.

Biodiversity

Most mitigation measures appear to have been implemented. Slightly less new woodland planting was present than expected. One badger sett which showed no signs of activity during the survey for the ES was later found to be occupied and a Badger License was issued by Natural England permitting work close to the sett. A number of deer deaths have been reported but there is no obvious increase in deer deaths as a result of the scheme. The Highways Agency deer specialist did not consider deer to be an issue because the scheme was relatively small. Large areas of species rich grassland have been created which were not mentioned in the ES. Overall evaluation indicates a ‘slight adverse’ impact as expected;

It is recommended that consultation is extended to the Local Wildlife Trust or Badger group as part of the five years after evaluation who might have some local knowledge of habitats and species.

Water

Mitigation measures recommended in the ES appear to have been implemented and there is nothing to suggest that they are not operating as intended. Based on the information available it is considered that the overall evaluation indicates a ‘neutral’ impact as expected.

Physical Fitness

The new footways were in place and improved carriageway lighting has been implemented. New dedicated lighting has not been provided on the footway between the M25 clockwise entry and anti-clockwise exit slip roads although existing lights in varying condition were present. The scheme design does not impede future upgrade to toucan crossings. The uncontrolled pedestrian crossing at the M25 clockwise entry slip road continues to be difficult to cross. In the context of relatively low users the overall evaluation indicates a ‘neutral’ impact as expected.

Journey Ambience

Traveller’s views are slightly worse than expected because the former lay-by on the A12 has been barriered across and left in place. The lay-by was left in place as a result of Value Engineering to save construction costs and to provide a potential location for a mobile VMS;

Driver stress appears worse than expected due to queuing back from the A1023 arm onto the roundabout during the AM Peak and concerns about signing and lane allocations. Reflective posts have been installed on the splitter island after several


One Year After


incidents;

The impact on traveller care is as expected in the ES; and

Overall the slight improvements in journey times resulted in this sub-objective being scored as slightly beneficial (slightly worse than expected).


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6. Accessibility and Integration Evaluation Introduction

6.1 This section of the report assesses the accessibility and integration impacts of the M25 Junction 28 Brook Street scheme. Two of the five Government objectives for transport, Accessibility and Integration, were covered as part of the scheme’s appraisal included in the AST.

Accessibility

Option Values

6.2 WebTAG defines Option Values as measures arising from a scheme which will substantially change the availability of transport services within the study area. The AST for this scheme states that no additional public transport was included as part of this scheme, therefore this sub-objective is not applicable to this scheme.

Severance

6.3 The AST stated that there would be no relief to or additional severance to pedestrians and cyclists moving around or accessing local facilities. A cycle / pedestrian path is already place. A site visit by Atkins in June 2009 found that chevron signs have been implemented to assist cyclists and warn them of the M25 off-slip (Figure 6.1). This not believed to be part of the scheme. However severance is likely to be slightly worse due to the increased number of lanes cyclists and pedestrians now have to cross. The low number of Non Motorised Users (NMUs) using this junction however means that this is not a significant impact.

Figure 6.1 – Chevron Warning for Cyclists


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Access to the Transport System

6.4 Bus route 498, operated by Transport for London, is the only route which passes through the junction. This route runs between Romford and Brentwood and passes through the M25 Junction 28 interchange.

6.5 The journey time surveys showed that journey times had improved on most routes and therefore this may have had a positive impact on bus route 498 travelling through the junction. However it should be noted that the journey time analysis was based upon a relatively limited data set due to the day to day variation in journey times likely on such a busy junction.

6.6 The scheme did not include any additional public transport.

Integration

Transport Interchange

6.7 There are no passenger or freight interchanges within the scheme.

Land Use and Policy Integration

6.8 The AST reports that the scheme is supported by key policies relating to reducing congestion, including PPG13, the draft East of England Plan and Policy TRN4 of the Havering Unitary Development Plan. The limited land take of the scheme and proposed mitigation measures ensure that there is no significant affect on local land use policies.

Essex Local Transport Plan 2 (2006 – 2011)

6.9 The Essex Local Transport Plan 2 (LTP2) identifies the severe congestion experienced during peak times at M25 Junction 28 Brook Street. The document also recognises that the network is constrained from junctions such as J28 operating at near capacity. The Essex LTP2 states how the M25 Brook Street scheme is one of a series of schemes aimed at reducing congestion in the region including the widening of M25 J27 – J30.

6.10 The scheme also contributes to one of the five objectives given in the LTP2 – ‘Tackling Congestion’ in Essex.

East of England Plan (May 2008)

6.11 The East of England Plan contains a summary of the M25 Brook Street scheme and notes that this scheme has now been implemented. This scheme helps to achieve one of the objectives in the plan – to manage travel behaviour and the demand for transport to reduce the rate of traffic growth. This objective will lead to improved journey reliability as a result of tackling congestion.

Havering Unitary Development Plan

6.12 The scheme helps meet objective TRN4 of the Havering Unitary Development Plan. This objective states that ‘the Council will press the Department of Transport to discharge its responsibilities for the provision of facilities to ease the


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flow of through traffic on trunk roads in the borough’. The document states how improvements to the Trunk Road network will allow the Council to implement traffic management schemes on Borough Roads and improve conditions for residents.

KEY POINTS FROM SECTION 6 – ACCESSIBILITY AND INTEGRATION

The scheme had no impact on option values. Severance is likely to be slightly worse due to NMUs having to cross an increased number of lanes; however the number of NMUs is so low this is not considered to be significant;

Bus route 498 is the only route which passes through the junction. This route runs between Romford and Brentwood and passes through the M25 Junction 28 interchange. The journey time surveys showed that journey times had improved on most routes and therefore this may have had a positive impact on bus route 498 travelling through the junction; and

The scheme is supported by the Essex Local Transport Plan 2 (2006 – 2011), East of England Plan (2008) and Havering Unitary Development Plan.


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7. Other Issues 7.1 This section summarises any other issues with the M25 Brook Street Scheme

based upon information from the following sources:

Site Visits;

OYA meeting; and

Any other publicity.

Splitter Island

7.2 According to information obtained in the OYA meeting there were two options for the original design of the splitter island; one being a vertical element and the other being use of a conspicuous colour. The second option was chosen but soon after opening a number of incidents involving the splitter island were reported.

7.3 On the 1st July 2008 during the PM peak Atkins staff7 who carried out the site visit felt that the splitter island was difficult to see, especially for circulatory traffic heading for the A12 E/B on slip. From some angles and in some lighting conditions it appeared to look more like a ghost island rather than a physical raised island.

Figure 7.1 – Splitter Island with Temporary Coning (July 2008)

7 This represents personal opinions. However the views seem to be backed up by incidents involving the island and also the placement of cones on the island.


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7.4 A meeting took place on Monday 30th June 2008, between the Highways

Agency, Metropolitan police and Essex police to discuss the Splitter Island. As a result, cones were put up on 1st July 2008 (shown in Figure 7.1) as temporary measure, and the possibility of putting reflective posts on the island was also discussed.

7.5 In August 2008 these reflective posts were installed as shown in Figure 7.2. These have improved the visibility of the segregated lane splitter island.

Figure8 7.2 – Splitter Island with new Permanent Reflective Posts

7.6 It was also noted in the OYA meeting that incidents involving the island has reduced dramatically since the new permanent reflective posts were erected. However, due to the limited amount of PIA data available it will not be possible to verify this.

Signing / Lane Allocation

7.7 Several attendees of the OYA meeting expressed concern over signing on the junction, but the Scheme Designer confirmed that the signing meets all the required standards.

8Photograph supplied by the Highways Agency.


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7.8 One new lane allocation sign (shown in Figure 3.5) was erected immediately after the M25 A/C On-Slip exit as a result of the Stage 3 Road Safety Audit.

7.9 On the 9th July 2008 the Brentwood Gazette9 published an article about a fatality at the junction and also expressed some negative views about the scheme, mainly aimed at the lane allocations.

Other Improvements

7.10 It was noted on the OYA site visit that maintenance work was being undertaken on the M25 overbridge. It was confirmed in the OYA meeting that this was water-proofing work being undertaken on weekends. The surveys will not have been affected by this work.

7.11 After a number of incidents where J28 has become gridlocked the Metropolitan Police commented in the OYA meeting that it is crucial to divert traffic off the M25 before J29 in the event of an incident. This is currently difficult due to the lack of VMS signs between J27 and 30; however these are due to be installed as part of the M25 widening scheme between these junctions.

KEY POINTS FROM SECTION 7 – OTHER ISSUES

Reflective posts were added to the splitter island after a number of incidents occurred immediately after opening; and

Concern has been raised about both signing and lane allocations. However the signing meets the required standard.

9http://www.thisistotalessex.co.uk/searching/Motorist-say-8m-Brook-Street-junction-revamp-failure/article-213820-detail/article.html


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8. Appraisal & Evaluation Summary Tables Appraisal Summary Table (October 2006)

30.10.06Option

M25 Junction 28 / A12 /

Brook Street Improvement Scheme

Description Introduction of dedicated left-hand turning lane

from M25 clockwise off-slip road onto A12 eastbound on-slip road; widening of A12

eastbound on-slip road and additional carriageway widening for approx. 1km; widening of slip roads at Junction itself.

Problems Congestion at

Junction: reduced

safety and journey time

reliability

Present Value of Costs to Public

Accounts (£13.6m)

OBJECTIVE SUB-

OBJECTIVE QUALITATIVE IMPACTS

QUANTITATIVE ASSESSMENT

ASSESSMENT

Noise

A total of 460 sensitive properties lie within 300m of the Scheme. Barely perceptible changes in traffic noise levels will arise as a result of the Scheme. Noise level changes at closest properties would be <2dB.

Est. population annoyed by traffic

noise: Do minimum = 144; Do something =

144.

Estimated net 0 additional

residents will be annoyed by

noise in design year

Local Air Quality

The Scheme will have a negligible benefit to air quality within three Air Quality Management Areas. The small magnitude of the scores indicates that the overall reduction in public exposure would be slight.

Properties with: improvement =

787; deterioration = 221, no change

= 3 (same for NO2 and PM10)

Net total assessment for:

PM10 = -8.51; NO2 = -4.62

Greenhouse Gases

Calculations show an increase in CO2 with Scheme of 0.4% compared to the Do Minimum in first year.

2008 Do min - 50,891 tonnes

CO2 2008 Do

Something – 51,100 tonnes

CO2

+ 209 tonnes CO2

Landscape

Existing, established, well vegetated landscape of local importance. Restricting improvement works to within existing highway boundary minimises wider impacts and impact on landscape character. Some localised loss of vegetation beside the Ingrebourne River.

Not applicable Neutral

Townscape

Suburban townscapes of Brook Street, Harold Hill and Harold Park within 1km of Scheme. Areas close to Scheme of no distinctive appearance, existing screening would not be altered. No impact on townscape character.


Heritage of Historic

Resources

Only known feature within Scheme footprint is undesignated line of London–Colchester Roman road: previously disturbed and no further impact expected as result of Scheme.


Biodiversity

Scheme would result in loss of habitat within highway boundaries with low to medium importance at the local scale, including habitat along the Ingrebourne River due to extension of existing culvert, and some reptile habitat. Indirect adverse impact on foraging/commuting bats through increased risk of collisions with road traffic through reduced verge width.

Not applicable Slight Adverse

Water Environment

No significant change in water quality of Ingrebourne River due to modified existing road drainage system and additional 30m length of culverting. No adverse affect on existing flooding regime, groundwater unaffected


Physical Fitness

No change in physical fitness is expected as a result of the Scheme.


Environment

Journey Ambience

Improved traffic flows and reduction in congestion would result in improved route certainty, reliability & safety,

Not applicable Large Beneficial


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reduced driver frustration & stress.

Accidents Traffic queues removed from affecting A12 and M25 main carriageways. Reduction in shunt-type accidents.

Not applicable £4.7m Safety

Security Upgraded road lighting and footway under M25 flyover to be lit

Not applicable Slight Beneficial

Public Accounts

PV of Construction costs of scheme including allowance for night-time working, also includes renewal costs in the 30th year.

Central Govt PVC, Local Govt

PVC

£14.8m BCR = 17.9

Transport Economic Efficiency: Business Users &

Transport Providers

PV of benefits accruing to business users and transport providers resulting from reduced delays at junction.

Users PVB, Transport

Providers PVB, Other PVB

£157.4m

Transport Economic Efficiency: Consumers

PV of benefits accruing to consumer users and transport providers resulting from reduced delays at junction.

Users PVB £102.1m

Reliability Reduction in accidents and delays would lead to improved reliability of trips through the junction. However it has not been possible to quantify this.

Not applicable Beneficial

Economy

Wider Economic Impacts

Improved accessibility to/from major national and regional economic centres by journey time savings.


Option values

No additional public transport included as part of the Scheme.


Severance No relief to or additional severance to pedestrians and cyclists moving around or accessing local facilities.

Neutral Accessibility Access to the

Transport System

No additional public transport included as part of the Scheme


Transport Interchange

There is no inclusion of passenger or freight interchanges within the Scheme.

Not applicable -

Land-Use Policy

The Scheme is supported by key policies relating to reducing congestion, including PPG13, the draft East of England Plan and Policy TRN4 of the Havering Unitary Development Plan. The limited land take of the Scheme and proposed mitigation measures ensure that there is no significant affect on local land use policies.


Integration

Other Government

Policies

Improvements to transport infrastructure reduce public exposure to pollutants and provide the opportunity for improved regional and local economic performance. However, no government policies are significantly affected by the scheme.



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Evaluation Summary Table (July 2009)

OBJECTIVE SUB-OBJECTIVE QUALITATIVE IMPACTS QUANTITATIVE MEASURE ASSESSMENT

SCORE

Noise

The scheme’s effect on the local noise climate is slightly better than expected at most locations. For Brook Street west bound, M25 clockwise off-slip and M25 anti-clockwise on-slip the local noise climate is slightly worse than expected

- Better than expected

Local Air Quality (LAQ)

Likely to be Neutral except for the M25 anti-clockwise where Observed traffic flows (AADT) in 2009 are lower than the ES forecast growthed flows for 2009.

- As expected

Greenhouse Gases Neutral - As expected

Landscape Most vegetation lost has been off-set by replanting in line with mitigation proposals

- As expected

Townscape Neutral - As expected

Heritage of Historic Resources Neutral - As expected

Biodiversity Mitigation measures have been implemented except very slightly less new woodland planting was present.

- As expected

Water Environment Mitigation measures have been implemented.

- As expected

Physical Fitness New footways and improved carriageway lighting have been provided.

- As expected

ENVIRONMENT

Journey Ambience

Traveller’s views and driver stress are worse than expected. Impact on traveller care is as expected. Journey Time surveys appear to suggest a slight reduction in delays.

Worse than expected


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Accidents Negative 60 year benefits, however this change is statistically insignificant.

PVB £-11.7m Worse than expected

SAFETY Security Proposed lighting on the footpath was not implemented. -

Worse than expected

Public Accounts PVC £9.5m Better than expected

Transport Economic Efficiency

It is considered too early to accurately determine the level of outturn journey time benefits of the scheme, given the high level of benefits which are predicted to occur from 2023 onwards and the very low level of benefits predicted for the opening year.

PVB N/A Not comparable

to AST

Reliability

The scheme has marginally reduced delays but has also marginally increased accidents. Therefore it is not possible to give an assessment as to the outturn impact on reliability.

- -

ECONOMY

Wider Economic Impacts Not assessed - -

Option Values Not assessed - -

Severance No change - As expected ACCESSIBILITY

Access to the Transport System Not assessed - -

Transport Interchange Not assessed - - INTEGRATION

Land-Use Policy

The scheme is supported by key policies relating to reducing congestion, including PPG13, the draft East of England Plan and Policy TRN4 of the Havering Unitary Development Plan.

- As expected


One Year After


Other Government Policies Not assessed - -


One Year After


9. Conclusion 9.1 Opening in March 2008, the M25 Junction 28 Brook Street scheme was

implemented to relieve congestion and unreliable journey times experienced at the junction, which is particularly evident during peak periods. To resolve the problems at the junction, the following improvements were implemented:

1) A new dedicated left turn lane with splitter island from the M25 clockwise exit slip road to the A12 eastbound;

2) Extension of the A12 merge lane towards Ipswich (eastbound);

3) Widening of the A12 London-bound exit slip road to four lanes;

4) Realignment of the A1023 Brook Street to M25 clockwise on-slip as a result of widening of circulatory carriageway at this point;

5) Widening of the M25 anticlockwise exit slip road to four lanes; and

6) Other minor works to improve junction safety.

Assessment of Scheme Objectives

9.2 It is important to assess if the scheme has achieved what it was intended to do. The Table below gives an assessment on whether the scheme objectives have been achieved based upon the data available at this OYA stage.

HA Scheme Objective OYA Evaluation Achieved at OYA stage

Improve safety at the junction.

At this stage, the PIA data shows there has been a statistically insignificant rise in

accidents. More PIA data is required to draw any firm conclusions.

Too early to conclude.

Improve circulation of the junction to deliver a reduction in vehicle queuing and journey

times.

The surveys generally show a reduction in journey times. But the OYA survey times show journey times can vary from day to day and therefore more data would be required to draw any firm conclusions.

Variable success (More data required).

9.3 The Table above shows that due to the limited amount of data available at the time of this OYA study it is not possible to draw any firm conclusions on the success of the scheme objectives. These objectives will be evaluated again at the FYA stage in 2013.

9.4 An assessment of all other NATA objectives can be found in the Evaluation Summary Table (EST).


One Year After


Key Issues

9.5 The following bullet points summarise the key points of this One Year After study:

It is too early to draw any firm conclusions on whether the scheme has met its objectives;

The majority of environmental impacts were assessed to be as expected; and

Based upon data available at the time of this study the forecasted BCR was 17.9, although the predicted first year rate of return was only 0.2%. Using data collected for this study the outturn BCR has been estimated as 0.4. However, it is vital to point out that this based upon a worst case estimate of the PVB which does not include the large journey time benefits expected to occur from 2023 onwards in the PM Peak. These large benefits were not included as this evaluation considers actual data and hence no assumptions regarding congestion beyond the opening year have been considered.

Five Years After Study

This report will be followed by the Five Years After (FYA) study due in 2013 which will evaluate the impacts of the scheme against the NATA sub-objectives and the HA scheme objectives in more detail.


One Year After


Appendix A – NTM 2007/ TEMPRO Growth Factors


One Year After


A.1 Growth Factors for Traffic Counts

Period Background Growth Expected

2003 to 2009 + 9.71%

2005 to 2009 + 5.69%

2006 to 2009 + 3.82%

2007 to 2009 + 2.47%

2008 to 2009 + 1.25%


One Year After


A.2 Traffic Count Data

Before After Environmental Link No. Route Direction AWT ADT DATE SOURCE AWT ADT DATE SOURCE

23 Brook Street E/B - 10893 Apr-05 Essex CC 10655 10342 Jun/Jul 2009 COUNT ON US 24 Brook Street W/B - 11337 Apr-05 Essex CC 11096 10764 Jun/Jul 2009 COUNT ON US

6 A12 Offslip E/B - 10227 2003 EBF 10689 10504 Jun/Jul 2009 COUNT ON US - Site 5 22 A12 Offslip W/B 19259 18851 Apr-05 TRADS 21541 21805 Jun/Jul 2009 COUNT ON US - Site 2 21 A12 Onslip E/B - 19416 2003 EBF #ERROR #ERROR Jun/Jul 2009 COUNT ON US - Site 1

3 A12 Onslip W/B - 10015 2003 EBF 10997 10662 Jun/Jul 2009 COUNT ON US - Site 4 5 A12 Through E/B 11169 10645 Apr-07 TRADS 10502 10061 Apr-09 TRADS 4 A12 Through W/B 11266 10667 Apr-07 TRADS 10717 10225 Apr-09 TRADS

17 M25 Offslip CW 20598 19282 Apr-07 TRADS 21033 19997 Apr-09 TRADS 10 M25 Offslip AC 17231 16466 Apr-07 TRADS 17366 16539 Apr-09 TRADS

7 M25 Onslip CW - 14943 2003 EBF 15396 15270 Jun/Jul 2009 COUNT ON US - Site 3 14 M25 Onslip AC 19594 18401 Apr-06 TRADS 20230 19305 Apr-09 TRADS 16 M25 Through CW 49588 46802 Apr-07 TRADS 48272 45483 Apr-09 TRADS

15 M25 Through AC 49042 46583 Apr-07 TRADS 48011 45323 Apr-09 TRADS

#Error – No data available due to error with the counting equipment used in the survey


One Year After


Appendix B – Journey Times


One Year After


B.1 Journey Time Intermediate Timing Points

Exact intermediate points used for each of the journey time run. The section highlighted in yellow represent the portion of the journey covering the M25 J28 roundabout.

.

Figure B.1 – Journey Time Routes (JTRs) – Intermediate Timing Points


One Year After


Figure B.2 – Journey Time Routes (JTRs) – Intermediate Timing Points


One Year After


B.2 Number of Runs Undertaken for Journey Time Surveys B.2.1 The following tables show the number of runs that were completed on each of the 6 routes for

each time period and each of the Pre-Scheme, TIS and OYA surveys.

Table B.1 – Number of Runs in AM Period

Route Pre-scheme TIS OYA

1 11 8 6

2 6 9 13

3 16 17 38

4 10 8 6

5 6 8 12

6 15 19 36

Table B.2 – Number of Runs in IP Period


1 7 9 8

2 6 10 18

3 29 18 53

4 8 9 10

5 6 8 20

6 29 22 52

Table B.3 – Number of Runs in PM Period


1 6 8 6

2 10 8 16

3 23 15 46

4 6 8 8

5 10 7 16

6 23 20 43


One Year After


Appendix C – Environment


One Year After


C.1 Environmental Tables

Table C.1 – Summary of Environmental Consultation Responses

Organisation Field of Interest Comments

Natural England Biodiversity, Landscape

No response as very little involvement in scheme

English Heritage Heritage No response as very little involvement in

scheme

Environment Agency Water Commented on Water

Essex County Council General Commented on Heritage

Brentwood District Council General Commented on Landscape, Biodiversity,

Heritage, Local Access, Water, Air Quality and Noise

London Borough of Havering General Commented on Water, Air Quality, Noise No response for cultural heritage as no

involvement in scheme.

Greater London Authority Biodiversity No response as no involvement in scheme

Essex Ecology Services Ltd Biodiversity No response because EESL do not

comment on developments.

Sustran Physical Fitness No response as no recent involvement

Landscape Science Consultancy

Biodiversity No response as no recent involvement

Greenspace Information for Greater London

Biodiversity, Landscape

No response because GIGL do not comment on developments.


One Year After


Table C.2 – Evaluation of Existing Vegetation, Vegetation Establishment, Landscape Character and Visual Impact

Aspect Evaluation

Exi

stin

g V

eget

atio

n Existing vegetation generally appears to be retained as proposed.

The ES mentioned reinstatement of the boundary hedge for Area 4 but this hedge has been retained and this is considered better than expected.

One additional small tree appears to have been removed where the retaining wall proposed in the ES adjacent to the M25 anti-clockwise exit slip was replaced by an embankment. This is not considered to be significant.

Existing vegetation has been retained and coppiced along some stretches of the south side of the Ingrebourne River rather than being removed as suggested in the Environmental Statement.

Existing vegetation generally appears to be in good condition.

Veg

etat

ion

E

stab

lish

men

t

New landscape planting is establishing well.

Species rich verge has been created along most of the scheme and is establishing well.

Lan

dsc

ape

Ch

arac

ter

As expected the scheme has had minimal impact on the local landscape and local landscape designations within the study area because of the small footprint of the works within the existing road corridor which is surrounded by a strong landscape structure.

As expected the scheme has had a slight adverse effect on the existing landscape character in the vicinity of the new retaining wall beside the A12 eastbound entry slip road due to the removal of existing trees and vegetation but with time new planting will establish at this location and should screen the retaining wall and accompanying metal post and rail fence. See figure C.1.

The retaining wall proposed in the ES adjacent to the M25 anti-clockwise exit slip has been replaced by an embankment which blends well with the surrounding rural landscape and is considered better than expected. The new embankment replaces the embankment that existed pre scheme at this location. See figure C.2.

Vis

ual

Imp

act

The visual impacts of the scheme on visual receptors appear similar to that predicted in the ES.

As expected, the new retaining wall and extended culvert beside the A12 eastbound entry slip road have opened up views to the carriageway from the neighbouring field and woodland beyond but with time the new planting should screen views of the carriageway. See figure C.1.

There are views of the metal post and rail fence on the retaining wall from a few properties on Brook Street including the Holiday Inn and 61-63 Brook Street. The views of the railings are not particularly significant especially as there are crash barriers adjacent to the A12 at this point, but the railings were not specifically mentioned in the ES. See figure C.3.

Existing lights have been replaced with new high pressure low cut-off lights on 10m or 12m columns at locations immediately adjacent to new carriageway construction. The existing carriageway was already lit and it is likely that the impact from the replacement lighting system would be similar to predicted. It is suggested that night time lighting should be considered further at the FYA stage.


One Year After


Table C.3 – Biodiversity Mitigation, Forecast Effects and Site Visit Findings

Aspect Predicted Impact Mitigation Measures Evaluation

Veg

etat

ion

Trees removed along A12 side of Ingrebourne River.

Broadleaved woodland removed from M25 clockwise exit slip road and from A12 central reservation. Slight adverse impact for broadleaved woodland. Hedgerows removed for access/egress points. Scrub removed along M25 anti-clockwise exit slip road. Neutral impact for scrub. Loss of small areas of semi-improved grassland. Slight adverse impact for semi-improved grassland.

Replacement planting of trees over the newly culverted section of river. Woodland will be replanted with a similar area if possible although some shrub planting may be required due to sight lines. Hedgerows replanted with similar species. Replacement planting with similar species. Little scope to create new habitat within the highway boundary although existing semi-improved grassland along the A12 and around the junction could be enhanced via suitable management.

The site visit for this report made the following observations: Landscape planting had generally been implemented in line with the

mitigation proposals

A small number of trees have been planted adjacent to the Ingrebourne River next to the new extended culvert.

Only a small number of trees had been planted throughout the scheme. Most of the planting consists of two rows of native shrubs. There is therefore very slightly less ‘woodland’ planting than proposed but plenty of new ‘hedgerow’ planting present.

Two rows of native shrubs have been planted at the toe of the embankment along M25 anti-clockwise exit slip road and the rest of this area seeded with a species rich grassland mix (Area 1, Planting Location).

Large areas of species rich grassland have been created throughout the scheme.


One Year After



Ingr

ebou

rne

Riv

er a

nd In

greb

ourn

e V

alle

y S

ite o

f Met

ropo

litan

Impo

rtan

ce (

SM

I)

Risk of contamination of Ingrebourne River during construction would impact on flora and fauna, water vole, bats and the Ingrebourne Valley (SMI) downstream. Assessed as minor adverse impact.

Operational impacts which could impact on the Ingrebourne

River, and consequently the Ingrebourne Valley SMI would be:

Discharge of additional highway drainage;

Increased scouring of the river banks and bed through additional drainage and the effects of structures within the floodplain or stream channel;

Increased potential for pollution incidences through accidental spillage or hazardous substances as the highway will run nearer to the Ingrebourne River at the junction; and

Leaching of contaminants from concrete structures immediately adjacent to the river.

Assessed as slight adverse impact.

Risk of contamination during construction reduced to a minimum through implementation and adherence of CEMP.

Penstocks would be fitted on existing or new drains to reduce the chance of pollution during the operational phase.

No obvious pollution or damage to Ingrebourne River adjacent to the A12 east bound, was visible during the site visit for this report. The Designers have confirmed there were no known contamination incidents of the Ingrebourne River during construction. The As Built Drainage Drawings show three manholes within the scheme have a Penstock fitted to the outlet pipe.


One Year After



Ingr

ebou

rne

Riv

er

Loss of habitat due to 30m of Ingrebourne River replaced by culverting.

Removal of bank side features and associated ecology as a result of piling to stabilise the river bank for the widening scheme.


Habitat loss will be compensated by enhancing retained riverine features within Ingrebourne River which may include opening up the southern bank to enhance opportunity for use by water voles.

The site visit for this report confirmed that part of the southern bank of the Ingrebourne River adjacent to the A12 east bound, has been opened up. See Figure C.6.

Bad

gers

Low population of badgers found to be using the area. One outlier sett identified in soft estate adjacent to A12 east-bound but it had no signs of badger activity. Assessed as lower value.

Potential closure of one outlier sett.

Loss of seasonal foraging and sub-optimal foraging areas.

Assessed as neutral impact.

Pre-construction monitoring of badger activity to identify new setts, or recent use of setts previously identified as not active. All construction activities likely to disturb badger setts to be carried out under licence from English Nature (now Natural England). The closure of setts would only be undertaken where necessary and under licence from English Nature.

The Designers confirmed that the badger sett adjacent to the works had been unoccupied throughout 2005 and 2006 surveys but was found to be reoccupied at the end of February 2007 and therefore a Badger License was issued by Natural England permitting work close to the sett. The sett was not destroyed and it is unknown whether the sett is now (post works) re-occupied. It is recommended that consultation is extended to the Local Wildlife Trust or Badger group as part of the five years after evaluation who might have some local knowledge of habitats and species. The HEMP included a copy of the Badger Licence which was in force during construction permitting work within five metres of the badger sett.


One Year After



Bat

s

Common pipistrelle bat present in low numbers. Many areas of favourable foraging habitat present in local landscape. Assessed as lower value.

Reduction of width of bat commuting corridor and increased proximity of traffic could make bats more vulnerable to collisions with traffic.

Potential impacts on water quality would impact on invertebrates upon which bats feed.


1-2m grass strip to be created along the A12 east-bound and A12 east-bound on slip to keep bats further away from traffic and reduce risk of collisions. Maintain commuting corridor used by bats by retaining a continuous strip of trees, shrubs and coarse vegetation along the A12 east-bound.

The site visit for this report found that the 1-2m grass strip was present and that a continuous strip of vegetation was present along the A12 east-bound.

Bre

edin

g B

irds

Area supports bird species typical of woodland, farmland and urban areas. Breeding birds assessed as negligible value. Loss of bird breeding habitat assessed as not significant and of neutral impact.

Little scope to replace habitat lost within the highway boundary. Habitat lost could be compensated by improved management of the soft estate.

The site visit for this report found that landscape planting had generally been implemented in line with the mitigation proposals and should in time provide replacement habitat for breeding birds.


One Year After



Wat

er V

oles

Evidence of water vole activity in Ingrebourne River downstream of scheme. Low population status on the stretch of Ingrebourne River adjacent to Scheme. Assessed as medium value.

Water vole habitat not directly impacted by the Scheme. Potential impacts on water quality would effect water vole populations downstream.


Opening up the southern bank of the Ingrebourne River by clearance of trees and scrub to enhance habitat for water voles.

The site visit for this report confirmed that part of the southern bank of the Ingrebourne River adjacent to the A12 eastbound, had been opened up.

Rep

tiles

Small population of slow worm and common lizard were identified in an area of grassland on the verge of the M25 anti-clockwise exit slip road. Assessed as lower value.

Minor loss of habitat.


A reptile mitigation strategy would be prepared which would set out how killing and injury of reptiles would be avoided during the Scheme. Any captured reptiles would be moved into suitable adjacent habitat on the soft estate. Following completion of the works the verge habitats of semi-improved grassland and scrub mosaic would be recreated.

The opportunity existed to enhance areas for reptiles elsewhere within the soft estate, via the provision of artificial hibernacula and refugia, and the implementation of a habitat management regime which would benefit reptiles.

The grassland/scrub mosaic habitat proposed for the M25 anti-clockwise slip road, has not been recreated. Instead two rows of native shrubs have been planted at the toe of the embankment and the rest of this area seeded with a species rich grassland mix (Area 1, Planting Location). This change is not considered particularly significant. Artificial hibernacula and refugia were not provided because they were not considered necessary. The ES proposed artificial hibernacula and refugia because the retaining wall proposed on the verge of the M25 anti-clockwise exit slip road would have affected reptiles identified at this location. As a result of additional land being transferred to the Highways Agency the embankment that existed pre scheme adjacent to the M25 anti-clockwise exit slip road was replaced with a similar embankment and the retaining wall proposed in the ES was not constructed at this location. With this effective like for like replacement further enhancements for reptiles were not considered necessary.


One Year After


Table C.4 – Evaluation of Landscape Mitigation Proposals

Planting Location in ES

Landscape Mitigation Evaluation

Area 1

Tree, shrub and grassing to embankment. Trees to be planted where space allows.

The ecological mitigation proposals indicated re-creation of grassland/scrub mosaic habitat for Area 1.

Two rows of native shrubs have been planted at the toe of the embankment. The location of the planting some distance away from the new fence looks slightly awkward and the planting appears rather sparse in the wide verge although this will improve with time as the planting matures. The Designers have confirmed that the location for the planting was restricted by underground services in the top of the verge, ground anchors in the embankment batter and a drain located between the toe of the embankment and the boundary fence. No trees were planted because of planting restrictions. See figure C.2.

Species rich grass is present.

Area 2

Tree, shrub and grassing to embankment and beside the Ingrebourne River. Tree planting beside river where space allows. There is likely to only be space for shrub planting adjacent to the new retaining wall and extended culvert. Off site planting may be required if works access is sought and agreed through neighbouring farm and woodland.

The ecological mitigation proposals indicated re-planting of trees, shrubs and grass as space permits, for Area 2.

A small number of trees have been planted adjacent to the Ingrebourne River next to the new extended culvert. Two rows of shrubs have been planted along the boundary fence at the junction and also along the south side of the Ingrebourne River from retaining wall No. 1 to the south west end of retaining wall No. 2. There was very little room to carry out planting at other locations beside the Ingrebourne River. Existing vegetation has been coppiced along some stretches of the south side of the Ingrebourne River where shrub planting was not undertaken, see figure C.4. Trees have not been planted at the location identified on Outline Landscape Mitigation Figure C.3 between retaining wall No. 1 and No. 2, because maintenance access is required for the Ingrebourne River.


Offsite planting was not required.

Area 3 Regeneration of grass and scrub mosaic and tree planting along embankment.

No trees were planted although there was little room present for new tree planting and existing vegetation was not removed from this area.


Area 4 Planting along highway boundary including thickening and reinstatement of hedgerow.

Two rows of plants consisting of shrubs and trees have been planted along the highway boundary where there was a gap in the existing hedge. The existing hedge was retained.


Area 5

Planting along boundary with Poplars Farm including reinstatement of existing hedgerow particularly along the M25 clockwise entry slip road.

A short section of hedge has been planted along the Poplars Farm boundary where there was a gap in the existing hedge. The existing hedge was retained elsewhere.

Area 6 Grass and shrub planting over area The layby has been barriered across and left in


One Year After


Planting Location in ES

Landscape Mitigation Evaluation

of former lay-by. place as a result of Value Engineering to save construction costs and to provide a potential location for a mobile VMS, and is therefore is less visually attractive than the landscape mitigation proposed for this area. See figure C.5.

Area 7

Grass and shrub planting to central reservation of A12 where reinstatement is required following construction of retaining wall.

Following a detailed levels survey it was found that the retaining wall was not required at this location and therefore most existing vegetation appeared to have been retained in the central reservation.


One Year After


Table C.5 – Standard list of information required to evaluate the environmental sub-objective

Information Requested Information Received

Environmental Statement (ES)

Appraisal Summary Table (AST)

Amendments, updates or addendums to the ES or relevant further studies or reports.

'As Built' drawings for landscape, ecological mitigation measures, drainage, fencing, earthworks etc.

Landscape and Ecology Management Plans HEMP received

Relevant contact names, of people with knowledge of the scheme at:

the Statutory Consultees (Environment Agency, English Heritage and Natural England);

the local authorities;

the designer or environmental coordinators for the scheme and for the MAC; and,

any other relevant specialist consultees that were contacted

Archaeological reports (popular and academic) No archaeological reports were produced.

List of properties eligible for noise insulation Designers provided some information but Part 1 Claims will decide properties eligible for noise insulation.

List of Part 1 Claims regarding noise, air quality or lighting (from HA National Part 1 Team)

HA Part 1 Team advised that it was too early in the claims period for successful claims to be advised

Results of any post opening survey or monitoring work e.g. ecology surveys, water quality surveys pre- and post- construction

No monitoring surveys carried out and no monitoring requirements for protected species were included in the HEMP.

Animal mortality data, pre and post-scheme construction (from MAC)


One Year After


Information Requested Information Received

Scheme newsletters or publicity material for the scheme.

Available on HA website.

Copy of the Non-motorised User (NMU) post opening survey

No formal NMU post opening survey. Informal observations were made during Road Safety Audit 3.

Information available regarding environmental enhancements to streetscape/townscape for bypassed settlements

No environmental enhancements required to streetscape/townscape for nearby settlements.


One Year After

C.2 Environmental Pictures

Figure C.1 – Retaining Wall and Culvert Adjacent to A12 Eastbound Entry Slip Road

Figure C.2 – Planting and Boundary Fence Adjacent to M25 Anti-Clockwise Exit Slip Road


One Year After

/M25 J28 OYA Report v3.docx 107

Figure C.3 – View from Holiday Inn of Railings on Retaining Wall

Figure C.4 – Coppiced Vegetation on South Side of Ingrebourne River


One Year After


Figure C.5 – Former Lay-by on A12 Eastbound

Figure C.6 – Opening up of south bank of Ingrebourne River


One Year After


Appendix D – Economic Analysis


One Year After


D.1 Introduction

This analysis considers a range of methodologies for estimating the outturn benefits for the M25 Junction 28/A12 Brook Street junction improvement, utilising observed data from the One Year After study.

Three methodologies have been assessed, namely:

PAR Guidance;

JUICE-9 with time-shift; and

JUICE-9 with reduced traffic flows.

These methodologies and the resultant scheme benefits are discussed in the following section.

It should be noted that traffic frequently queues back onto the Junction 28 roundabout from Brook Street in peak periods due to congestion at the nearby signals. The modelling undertaken for the scheme did not include this junction, and therefore the issue was not identified during the appraisal. The proposed methodologies do not address the impact of this queuing back on the scheme benefits.

D.2 Methodologies

Table D.1 shows the predicted 60 year monetised benefits for the proposed junction improvements for the original economic assessment and for the three methodologies discussed below.

Table D.1– Scheme Benefits

Methodology 60 Year Monetised Benefits in 2002 Prices and Values

Original Economic Assessment £260m

PAR Guidance £16m

JUICE-9 with Time Shift £270m

JUICE-9 with Reduced Traffic Flows £165m

The cumulative scheme benefits over the 60 year appraisal period, for each of the methodologies, are shown in Figure D.1.

PAR Guidance

This methodology is based on the following process:

Delays at M25 Junction 28 for the Do-Minimum (i.e. without the improvements) and for the Do-Something (i.e. with the improvements) scenarios have been determined using journey time surveys;

Traffic counts from 2003 (growthed to 2008) and 2008 (post scheme opening) have been used to determine the Do-Minimum and Do-Something turning flows, respectively;


One Year After


The observed delay per vehicle and total vehicle delay has been derived using the above data;

The observed delay savings between the Do-Minimum and Do-Something scenarios have been monetised using annualisation factors, the value of time and a capitalisation factor (based on PAR guidance) to give 60 year benefits in 2002 prices and values.

Table D.2 shows the observed daily vehicle hour savings in the opening year and a 60 year monetised benefit based on PAR Guidance10.

Table D.2– Monetised Benefits using PAR Guidance

Forecast Year

Period Observed Daily Vehicle

Hour Saving

60 Year Monetised Benefit in 2002 prices

and values

AM 30 £4.81m

PM 67 £10.75m 2008

Total £15.56m

The scheme benefits obtained using this method are considerably lower than the original economic assessment as the large increase in benefits expected from 2023 onwards are not taken into account. This methodology, therefore, represents a “worst case scenario”.

JUICE-9 with Time Shift

The original economic assessment for this scheme utilised the spreadsheet program JUICE-9 to determine benefits for the proposed scheme. A comparison between the observed benefits achieved in the opening year 2008 (using the PAR Guidance methodology above) and the predicted benefits from JUICE-9 indicates that the observed benefits were not predicted to occur until 2009 (i.e. one year later).

The ‘JUICE-9 with Time Shift’ methodology, therefore, assumes that the benefits of the scheme occur one year earlier than predicted (i.e. 2011 year benefits occur in 2010). This methodology gives a higher level of overall benefits as higher scheme benefits occur sooner, with greater benefits included within the appraisal period, and these higher benefits are discounted less.

It should be noted, however, that this methodology may give too much significance to observed delay savings in the opening year which are based on journey time surveys that are subject to a number of external factors, including weather conditions, traffic levels on the day, incidents and data collection margins of error.

10 Project Appraisal Report Guidance Note V4.1d. TEE benefits have been calculated based on the value of time for an opening year of 2008 at 1286 pence and a capitalisation factor of 49.88 for 60 years of benefits assuming NRTF growth over 60 years.


One Year After


JUICE-9 with Reduced Traffic Flows

Analysis of traffic flows in the modelled area shows that there has been less traffic growth between 2003 and 2008 than predicted. Traffic levels at most locations have changed by 5% or less whilst background growth was expected to be up to 9%.

For this methodology, the JUICE-9 program is utilised with traffic flows in 2008 reduced by 5% to reflect lower traffic growth up to this year. Future year traffic growth factors have not been changed as they are considered to be reasonable. Junction delays for the Do-Minimum and Do-Something scenarios for the future years have been estimated using the modelled delays for different levels of traffic flow in the original assessment.

This methodology reduces the scheme benefits compared to the original assessment as traffic flows are lower, resulting in lower delay savings in future years.

D.3 Summary

Three potential methodologies for assessing the outturn benefits of the M25 Junction 28 scheme improvements have been assessed.

The PAR guidance method produces significantly lower benefits compared to the original economic assessment as it does not consider high benefits occurring in later years when congestion levels are higher.

The ‘JUICE-9 with Time Shift’ method assumes that higher benefits will occur sooner, based on observed benefits in the opening year, resulting in a slight increase in overall scheme benefits.

The ‘JUICE-9 with Reduced Traffic Flows’ method considers the impact of reduced traffic flows due to lower than expected traffic growth up to 2008. This method results in lower scheme benefits than the original economic assessment as lower traffic flows result in reduced vehicle delay saving.

This analysis demonstrates that the various methodologies give a wide range of total outturn benefits. Given the high level of benefits predicted to occur from 2023 onwards and the very low benefits predicted for the first year after opening, it is considered that it is too early at the ‘one year after’ stage to conclude whether the scheme will achieve the predicted level of benefits.


One Year After


Figure D.1– Monetised Benefits over 60 year appraisal period