active traffic management on the m42

LT3204

Traffic and Transport Engineering

Active Traffic Management on the M42

Thomas Birch

SUN – 096695173

Transport Management

Aston University – School of Engineering and Science

21 January 2013

Contents

1 Introduction...........................................................................................................................4

1.1 Active traffic management..............................................................................................4

1.1.1 Difference with Controlled Motorways.....................................................................4

1.1.2 Managed Motorways................................................................................................4

2 M42 Active Traffic Management Pilot Scheme.....................................................................4

2.1 Location..........................................................................................................................4

2.2 Objectives.......................................................................................................................6

2.3 Operational Regimes......................................................................................................6

2.3.1 No Variable Speed Limits (NO-VSL)........................................................................6

2.3.2 Three Lane Variable Mandatory Speed Limits (3L-VMSL)......................................6

2.3.3 Four Lane Variable Mandatory Speed Limits (4L-VMSL)........................................6

2.3.4 Ramp Metering........................................................................................................7

2.3.5 Timeline...................................................................................................................7

2.4 Physical and technological features...............................................................................8

2.4.1 Gantries...................................................................................................................8

2.4.2 Motorway Incident Detection and Automatic Signalling (MIDAS)............................8

2.4.3 Emergency Refuge Areas (ERAs)...........................................................................9

2.4.4 Closed Circuit Television Cameras (CCTV).............................................................9

2.4.5 Semi-automatic Control System (SCS)....................................................................9

2.4.6 Highways Agency Digital Enforcement Camera System (HADECS).......................9

2.4.7 Road markings and signage..................................................................................10

2.5 Operational procedure..................................................................................................10

2.5.1 3L-VMSL....................................................................................................................10

2.5.2 4L-VMSL....................................................................................................................10

2.5.3 Incident management................................................................................................11

3 Relation to Theory...............................................................................................................12

3.1 Traffic Flow Theory.......................................................................................................12

3.2 Traffic Management......................................................................................................14

4 Impact Studies....................................................................................................................14

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4.1 Journey Time................................................................................................................15

4.1.1 Before and after the introduction of hard shoulder running...................................15

4.1.2 Before and after the increase to 60 mph hard shoulder running...........................15

4.2 Safety...........................................................................................................................16

4.3 Environment.................................................................................................................16

4.4 Noise............................................................................................................................17

5 Comparable Schemes.........................................................................................................17

5.1 Cost of widening motorway..........................................................................................17

5.2 Overseas Schemes......................................................................................................17

5.2.1 Denmark, Copenhagen..........................................................................................17

5.2.2 The Netherlands....................................................................................................18

6 Concerns.............................................................................................................................18

6.1 Technological...............................................................................................................18

6.2 Compliance...................................................................................................................19

6.3 Environmental...............................................................................................................19

7 Similar Schemes.................................................................................................................20

8 Future Schemes..................................................................................................................21

8.1 All Lanes Running........................................................................................................21

8.2 Car-share Lanes...........................................................................................................21

8.3 High Occupancy or Tolled (HOT) Lanes......................................................................22

9 Conclusions.........................................................................................................................23

10 Reference List...................................................................................................................24

11 Appendices.......................................................................................................................26

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1 INTRODUCTIONIn 2000, the government launched the 10 Year Plan for Transport promising public and private funding of £180 billion over road, rail and other public transport schemes (DETR, 2000). Of this, £59 billion was allocated toward road transport to reduce congestion levels on motorways through widening schemes, improve traffic information for drivers, respond quicker to incidents and link speed limits to traffic levels to improve the smoothness of flow.

The Highways Agency was expected to achieve these aims as a network operator, excluding the standard practice of trunk road widening, through the method of Active Traffic Management (Highways Agency, 2009). This was driven partly because of growing public opposition to road widening due to environmental and land use concerns (Kamnitzer & Simpson, 2012).

1.1 ACTIVE TRAFFIC MANAGEMENTActive Traffic Management (ATM) is a broadly used term which the majority of sources define as the utilisation of technology and innovation to maximise road space (Highways Agency, 2008a; Highways Agency, 2009; Bennett et al., 2010). The Department for Transport (DfT, 2008b) further explained that the existing road space should be optimised through the use of the hard shoulder as a running lane and through the dynamic variation of the speed limit. This would respond in real time to the level of traffic and reduce the speed limit with the intention of maintaining a steady flow.

1.1.1 Difference with Controlled MotorwaysConquest (2009) warned of the possibility of mistaking ATM with the term “Controlled Motorways”. Variable speed limits and increased levels of driver information provision are used in both concepts but ATM extends this to utilise the hard shoulder in times of congestion. Controlled Motorways do not extend to that level.

1.1.2 Managed MotorwaysDuring 2009, the term “Active Traffic Management” was seemingly replaced by the Highways Agency by the term “Managed Motorways”, with no discernable difference between the two (Highways Agency, 2009; 2011).

For the purposes of this report, the concept of hard shoulder running and varying speed limits will be referred to as Active Traffic Management (ATM), as defined by the brief for this report. The report will aim to make no further reference to Managed Motorways so as to avoid confusion.

2 M42 ACTIVE TRAFFIC MANAGEMENT PILOT SCHEMEWith no previous experience of running vehicles through the hard shoulder, except during road works, the then Secretary of State requested, in 2001, that the Highways Agency trial ATM on the M42 between junctions 3A and 7 (DfT, 2008a). Construction began in March 2003.

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2.1 LOCATIONThe M42 was chosen as it is one of the busiest motorways in the UK as it is part of a major strategic route through the country, joining the North and the South of the UK, with around 50,000 to 75,000 vehicles per direction each day (Highways Agency, 2008a). This is highlighted also in Appendix 11.1, which highlights the congestion on the various motorways forming the “Birmingham motorway box”. Congestion is particularly bad during the peak hours of the day and was envisaged that running traffic in the hard shoulder could help to alleviate this congestion

The specific stretch of the M42, from junction 3A to junction 7, passes to the east of Birmingham, connecting the M40 and the M6, totalling 17km. This can be seen, as well as the length between each junction, in Figure 1.

Figure 1: Location map of the M42 ATM Pilot Scheme and the associated link lengths, (Highways Agency, 2008a)

A number of the junctions see heavy usage by local traffic. This is especially true of Junction 6; the connecting point from Birmingham International Airport and the National Exhibition Centre (NEC) to the motorway network (Highways Agency, 2009). Utilisation of

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ATM through this junction is logical due to the heavy demand these venues place on the network, especially for special events in the NEC’s case.

There has also been development work at Birmingham Business Park near to junction 7, seeing an increase in demand for the motorway capacity (Conquest, 2009). The completion of the M6 Toll Road in 2004 has also led to higher vehicle numbers as the M42 feeds traffic from the M40 to the Toll Road.

2.2 OBJECTIVESThe DfT (2008a) defines the objectives of the pilot scheme to:

Optimise performance and safety through the volume of traffic Provide more consistent journey times Minimise emissions and fuel consumption Reduce delays due to accidents Provide improved warnings to drivers

2.3 OPERATIONAL REGIMESThe Highways Agency (2008b) explain that operational regimes are scenarios or plans which are implemented in response to a traffic situation, whether congestion or an incident, in real time.

2.3.1 No Variable Speed Limits (NO-VSL)Strictly speaking, this is not an operational regime as there is nothing being implemented on the motorway because flow conditions are not suffering and congestion is not present. In this situation, the national speed limit is observed and the hard shoulder is not used.

2.3.2 Three Lane Variable Mandatory Speed Limits (3L-VMSL)This operational regime uses variable mandatory speed limits along a motorway to help regulate and maintain flow during periods of congestion. Whilst the system is reliant on predetermined and entered flow and speed threshold, the system will operate automatically, introducing a lower speed limit across all lanes (Highways Agency, 2008a). Officers at the West Midlands Regional Control Centre could intervene if necessary.

This is the system that operates on Controlled Motorways which is mentioned in section 1.1.1. The need to implement a variable speed limit due to flow conditions is detected using MIDAS; explained in section 2.4.2. The variable speed limit is then displayed using AMI; explained in section 2.4.1.

This system can also be implemented in ATM schemes where there has been an accident.

2.3.3 Four Lane Variable Mandatory Speed Limits (4L-VMSL)The Highways Agency (2008a) explains that this operational regime uses the variable mandatory speed limits as well as hard shoulder running during times of congestion, mostly the peak hours in a weekday. This can only occur however when a check has been completed of the hard shoulder, using technology explained in section 2.4.4. Once staff have completed a check to confirm the hard shoulder is clear then it can be opened for usage at a variable mandatory speed limit, which will be less than the national limit for motorways (70mph). Like 3L-VMSL, flows and speed thresholds are predetermined but in

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the case of 4L-VMSL, the process is not fully automatic due to the check process which has to be completed manually by an operator (Highways Agency, 2008a).

Kamnitzer & Simpson (2012) refer to the M42 ATM Pilot scheme as dynamic hard shoulder running (DSR). The significance of the term “dynamic” is that the hard shoulder opens in response to certain conditions; the predetermined flow and speed levels. There is little, if any difference between the definitions of DSR and 4L-VMSL.

2.3.4 Ramp MeteringRamp metering utilises traffic signals on the entry slip roads to the M42, to control and regulate the flow of traffic (DfT, 2008a). It is recognised that managing access to the motorway could cause delays into the local road network, hence the acknowledgement by the DfT that the Highways Agency has worked closely with local authorities to design and implement integrated management approaches.

The DfT (2008a) justifies the introduction of ramp metering due to findings in Minnesota. Here in 2000, the Department of Transport turned off all ramp metering sites because of public protests. As a result speeds on the freeway dropped by 14%, overall journey time grew, journey time reliability doubled and accident rates increased by 26%. However, it is also acknowledged that such results cannot blindly be applied in the UK, but, like all elements of a scheme, should be assessed on a case by case basis.

2.3.5 TimelineConstruction began in March 2003. The NO-VSL period indicated in Table 1 was the period of time where data was collected by Mott MacDonald to conduct the “before” study for their before and after evaluation work (Highways Agency , 2009). In practice there was no variable speed limits in place before March 2002 and not until the scheme was completed and became operation in December 2005.

Operational Regime DatesNO-VSL March 2002 – February 20033L-VMSL December 2005 – August 20064L-VMSL (50mph maximum) September 2006 – March 20084L-VMSL (60mph maximum) March 2008 – presentRamp metering October 2008 – present

Table 1: Operational regime timeline, (Highways Agency, 2009)

The 3L-VSL operational regime was operated for 8 months following project completion to assess the success of operating a Controlled Motorway scheme, before the 4L-VSL operational scheme began in September 2006, utilising the hard shoulder for the first time. Until March 2008, the maximum VMSL was 50 mph to ensure safety during the early stages of operation. The Highways Agency (2009) decided that studies were correct in showing that a speed of 60 mph could be achieved safely, hence the current situation of a 60 mph maximum VMSL operating.

Ramp metering was introduced in October 2008 on the slip roads at Junctions 4, 5 and 6 which are the busiest for local road users (Highways Agency, 2009).

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2.4 PHYSICAL AND TECHNOLOGICAL FEATURESThis section of the report will discuss and explain many of the features, both physical and technological, which make up the M42 ATM pilot scheme. Many can be seen in Figure 2.

Figure 2: Physical and technological features for the M42 ATM Pilot scheme (Highways Agency, 2009)

2.4.1 GantriesGantries need to be positioned regularly within an ATM scheme so as to provide the road user with a regular amount of information. In the case of the M42 ATM pilot scheme, these gantries are placed every 800 metres approximately (Kamnitzer & Simpson, 2012). Kamnitzer & Simpson go on to explain that the gantries need to be “inter-visible”; drivers need to be able to see the next gantry before passing underneath the preceding one. This ensures that the driver always has a line of sight to the information about the appropriate VMSL.

Advanced Motorway Indicators (AMI) are positioned on the gantries and display the mandatory variable speed limits when in place (DfT, 2008a). They are modern light emitting diode (LED) signs which are linked to the enforcement system, HADECS, which is discussed in section 2.4.8. The AMI will follow the standard Highways Agency signalling policy of “all-on, all-off”, mentioned by Kamnitzer & Simpson (2012). This means that road users know that if there is nothing on display then the standard speed limit of 70mph applies and the hard shoulder is closed for usage. To that end, the AMI also indicates whether the hard shoulder is open for traffic.

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2.4.2 Motorway Incident Detection and Automatic Signalling (MIDAS)The “Sensors” referenced in Figure 2, are actually MIDSA loops. The MIDAS detector loops work in a similar way as discussed by O’Flaherty (1997) and detect vehicle presence or flow if placed a set distance part. This will be further explored in Section 3.2.

The MIDAS loops are spaced at 500 metre intervals and measure traffic flow. They can be set so that, at a certain level of traffic flow, a variable speed limit is introduced and displayed above the lanes on the AMI, as explained in section 2.4.1. Indeed if traffic is actually stationary then the system automatically displays “Queue Ahead” on signs on MS4 signs (see section 2.4.11). This protects the rear of a queue of traffic from secondary collisions when traffic behind has not slowed down sufficiently (DfT, 2008a). If congestion levels have led to a reduction in the speed limit, then the hard shoulder can also be opened to traffic.

2.4.3 Emergency Refuge Areas (ERAs)Given that the scheme would, at times where there was congestion, use the hard shoulder as a running lane, there needed to be a provision of emergency stopping areas in case of a vehicle breakdown or incident. The DfT (2008a) stipulate that these need to be approximately every 500 metres so that there is a safe area away from the flow of traffic. If a vehicle is unable to enter or move to the ERA then the control room system would allow traffic officers to close the affected lane using the overhead gantries and signs. This capability could also be used to shut a lane for emergency vehicles to travel down, rather than contending with other vehicles (DfT, 2008a).

Each ERA needs to have an emergency roadside telephone, as well as a fixed CCTV camera trained on it, as discussed in section 2.4.4. Induction loops (see section 2.4.2 and 3.2) are also present so that any vehicle entry or exit can be detected in the ERA (Kamnitzer & Simpson, 2012).

2.4.4 Closed Circuit Television Cameras (CCTV)The West Midlands Regional Control Centre is provided with real time traffic flow and incident information through live footage from CCTV cameras. The DfT (2008a) says that this improves the response time of the emergency services, most likely because of the accuracy that an incident’s location can be given.

The cameras are also crucial in the opening of the hard shoulder for traffic because it needs to be manually checked by a Traffic Officer before it is opened; this ensures that there are no obstructions that could lead to an accident. Pan Tilt and Zoom (PTZ) Cameras provide coverage of the whole area of the road space and can be moved from the Regional Control Centre to focus in on a certain area. Fixed CCTV Cameras are trained on the hard shoulder for the purpose of manual checked, as mentioned above. These cameras are not used for the enforcement but merely monitoring (DfT, 2008a).

2.4.5 Semi-automatic Control System (SCS)This process assists the officers in the Regional Control Centre in inspecting the hard shoulder for obstructions before opening it to traffic (DfT, 2008a). This ensures that there is no possibility of the hard shoulder being opened when there any stationary vehicles.

2.4.6 Highways Agency Digital Enforcement Camera System (HADECS)For an ATM scheme to be successful, compliance of the road user with the variable speed limits is crucial. The Highways Agency corresponds with the police on this matter, who

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provide enforcement through HADEC cameras (DfT, 2008a). The DfT (2008b) also discuss policing priorities and whether enforcement of a traffic management scheme is optimal. Given the use of radar speed detection cameras rather than manual speed gun checks by officers, it can be taken that police time is not unduly spend enforcing the variable speed limit.

2.4.7 Road markings and signageMS4 signs can display images, using the same LED technology as AMI (DfT, 2008a). This can be set manually by a Traffic Officer in the Regional Control Centre or automatically based on flow detection by the MIDAS system, as discussed in section 2.4.2.

2.5 OPERATIONAL PROCEDUREThis section will briefly explain and show through figures how the ATM scheme is operated.

2.5.1 3L-VMSLKamnitzer & Simpson (2012) explain how the hard shoulder is opened to traffic to ensure safety and establish a smooth flow of traffic. Figure 3 shows 3L-VMSL operational regime, discussed in section 2.3.2., where traffic in the open three lanes is brought to the lower VMSL.

Figure 3: The 3L-VMSL operational regime on the M42 ATM Pilot scheme (Kamnitzer & Simpson, 2012)

The AMI show the VMSL of 60mph in the three open lanes of traffic, with the hard shoulder showing a red cross to indicate that it is not open to traffic.

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2.5.2 4L-VMSLOnce the smooth flow of traffic is established and the officers at the West Midlands Regional Control Centre have utilised the fixed CCTV cameras, in accordance with the SCS (explained in section 2.4.5), to check that the hard shoulder is clear of obstructions, then it can be opened for usage. This is show in Figure 4.

Figure 4: The 4L-VMSL operational regime on the M42 ATM Pilot scheme (Kamnitzer & Simpson, 2012)

The AMI above the hard shoulder now also displays a VMSL of 60mph, showing that it is open for traffic usage. This is the 4L-VMSL operational regime, explained in section 2.3.3. It is interesting to note in Figure 4 the variable message sign which is providing further information to road users.

2.5.3 INCIDENT MANAGEMENTAnother major purpose of the ATM scheme is the responsiveness of the operators in the West Midlands Regional Control Centre to an accident (Highways Agency, 2008b). Figure 5 shows how the ATM scheme would look if a lane were to be closed due to an accident.

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Figure 5: Management of accident using the M42 ATM pilot scheme (Highways Agency, 2008b).

The AMI shows an arrow, indicating that users should move into the left hand lane and the hard shoulder, with a 40 mph VMSL. The right hand lane is closed, as indicated by the red cross in the AMI over that lane. The variable message sign provides further information to road users. The closing of the right hand lane will serve to protect the accident site and also allow the emergency services to attend the scene more easily (Highways Agency, 2008b).

3 RELATION TO THEORYTo understand what ATM is attempting to achieve, it is important to understand some basic traffic flow and management theory.

3.1 TRAFFIC FLOW THEORYO’Flaherty (1997) explains that road space is scarce and, like any scarce resource, needs to be nurtured to maximise its capacity.

For clarification, flow is defined as the rate of vehicles travelling past a point per unit time. Concentration is defined as the number of vehicles per unit distance. Speed is classed as the distance travelled per unit time. These three parameters, states O’Flaherty (1997), are directly related; flow is the concentration of vehicles multiplied by their speed. Figure 6 shows this relationship, as well as the maximum capacity, qm.

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Figure 6: Flow-concentration, speed-flow and speed-concentration curves (Gerlough & Huber, 1975).

If the speed-concentration graph is considered from Figure 6, then is can be seen that, as speed drops from uf to 0, and as concentration increases from 0 to kj, flow begins to increase before decreasing again. This indicates that flow will increase to a theoretical maximum capacity of um before being overcapacity until concentration is so high that no movement can take place.

Ultimately the key point is that a reduction in speed leads to an increase in the overall flow experienced for all road users. In practice this is what the ATM scheme is trying to achieve.

By looking at Figure 7, this could be seen as successful.

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Figure 7: Speed-flow graph for the M42 ATM pilot scheme, upstream of a bottleneck (Highways Agency, 2008a).

The general shape of Figure 7 matches the shape of the speed-flow graph in Figure 6, with flow increasing to a maximum capacity with a reduction of speed, before falling away. The green plots in Figure 7 show the result of running in the hard shoulder; a greater flow rate achieved with a reduction in speed to 50 mph. It should be noted that the information from the Highways Agency (2008a) is from the period where the maximum allowed speed limit on the hard shoulder was 50 mph. Now that the maximum is 60 mph, it could be expected that capacity and flow rate would be even higher.

3.2 TRAFFIC MANAGEMENTMIDAS utilises the inductive loop, discussed by O’Flaherty (1997). This operates as a coil of wire just below the road surface which has an alternating current sent through it, creating an alternating magnetic field. When a vehicle drives over the loop it induces additional currents which are detected by the loop and recorded. If two loops are placed a set distance apart (which in the case of the M42 ATM pilot scheme is 500 metres) then the speed can be calculated and flow deduced. With this information, the MIDAS system can automatically set the VMSL to begin and, with user confirmation from the Regional Control Centre, open the hard shoulder.

4 IMPACT STUDIESOne of the main impacts which is desired by the Highways Agency (2008b) is that drivers are more aware of the situation around them and the traffic situation. As O’Flaherty (1997) stated, the nature of human behaviour means that every reacts differently to a situation. Providing more information through AMI and variable message signs allows drivers to be better informed and, the Highways Agency hopes, reduces driver stress.

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For the purposes of before and after studies, data was collected and evaluated by Mott MacDonald (Highways Agency, 2008a). Figure 8 shows when the data for each of the operational regimes was collected.

Figure 8: Timeline of variable speed limit periods during and after construction (Highways Agency, 2008a)

4.1 JOURNEY TIME

4.1.1 Before and after the introduction of hard shoulder runningKamnitzer & Simpson (2012) report that there has been a 22% reduction in journey time variability. This fulfils another major objective; making journey predictability much more reliable.

Friday afternoon peak journey times, normally the worse time for users to travel, shows a significant improvement when the 4L-VMSL operational regime is in place, utilising the hard shoulder (DfT, 2008a). Equally, in the afternoon peak for Tuesdays to Thursdays, average journey times have dropped by around 26% for northbound journeys and 9% for southbound journeys, relative to the 3L-VNSL operational regime. This equates to an average reduction of 4 minutes northbound and 1 minute southbound (DfT, 2008a).

4.1.2 Before and after the increase to 60 mph hard shoulder runningComparing the results between the hard shoulder running at 50 mph, between September 2006 and March 2008, and for those at 60 mph, since March 2008, it can be seen that there average journey time is reduced by 4% (Highways Agency, 2009). This confirms the

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hypothesis stated in section 3.1., that increasing the speed on the hard shoulder would allow a greater flow of traffic. The average traffic speed has also increased by 5%.

However, there was an increase in the variability of journey times (Highways Agency, 2009). This is not unexpected as the ability to offer a 60 mph VMSL offers the West Midlands Regional Control Centre more options (40 mph, 50 mph and 60 mph) to suit various levels of congestion.

4.2 SAFETYA key focus and objective of the ATM pilot scheme was the improvement or at least maintenance of safety standards. It is clear that the Highways Agency is not willing to compromise on such a key area and has dedicated a detailed 3 year safety report (Highways Agency, 2011) to it.

Table 2: M42 ATM pilot scheme accident data (Highways Agency, 2011).

Table 2 shows that, on average, the number of accidents has fallen since the implementation of both 3L-VMSL and 4L-VMSL. The small number of months of data for the 3L-VMSL operational regime means the information needs to be handled with care. Another issue would be approximate four year gap between the collection of the NO-VSL data and the 4L-VMSL data. As the Highways Agency (2011) points out, national trends point toward an overall reduction in accident rates, so this drop would be expected anyway.

Whilst the severity of accidents seems to be decreasing after the implementation of ATM, the number of rear shunt collisions has remained fairly constant. This seems to imply that whilst accidents are happening as often, the warning signs on the overhead gantries are preventing accidents from being as serious. The Highways Agency (2011) admitted that the number of side on collisions in the 4L-VMSL operational regime has increased. This potentially is to be expected as there is, effectively an additional traffic lane for vehicles to collide with.

4.3 ENVIRONMENTConquest (2009) seems impressed with the performance of the ATM pilot scheme, stating that fuel consumption has dropped by 4% and that vehicle emissions have lowered by 10%. (Kamnitzer & Simpson, 2012).

The information provided by the Highways Agency (2008a) could be called into question due to the long period of time between the before and after study on the M42. In that time, it has been accepted that technological advances have led to an increased number of more environmentally friendly cars. It could be argued that any decreases claimed could be due to the modernising of the UK’s car fleet.

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However the smoothing of traffic flow which the ATM scheme accomplishes does bring environmental benefits (Highways Agency, 2008a). Having less occasions of deceleration and acceleration due to congestion and erratic traffic flow, means that there are less stop/start journeys making vehicles more fuel efficient.

4.4 NOISEAfter the implementation of the M42 ATM pilot scheme, average noise levels have dropped by between 0.8 – 1.4dB, which the Highways Agency (2011) admit is a borderline benefit. It is also stated that due to wind speeds and directional variations, the collection of data was difficult and could not be easily assessed. This does not make for a particularly convincing argument, especially given the normalising of data, which seems to indicated that the 4L-VMSL operational regime sees a larger fall in noise level than the equivalent for 3L-VMSL. As with other comparisons, the short period of time data was collected for the 3L-VMSL operational regime needs to be taken into account.

Equally, any reduction claimed could also be offset by the significant increases in traffic which the pilot scheme generates (DfT, 2008a).

5 COMPARABLE SCHEMES

5.1 COST OF WIDENING MOTORWAYIn terms of the cost of the M42 ATM pilot scheme, the information can be seen in Table 3.

Table 3: M42 Pilot Scheme costs (DfT, 2008a)

Over the 17km that the scheme operates, the cost per km was £5.6 million for both directions. This compares very favorably to the estimated costs of widening the motorway along the same section, which were between £18 million and £25 million per km (DfT, 2008a). This before considering the environmental and land use issues that widening a motorway brings as well.

5.2 OVERSEAS SCHEMES

5.2.1 Denmark, CopenhagenBetween 2002 and 2003, the Koge Bugt Motorway near Copenhagen had a variable speed limit scheme put in place, aiming to reduce congestion during construction works (Wendelboe, 2003). However there were significant issues which plagued the project, such as displaying the incorrect speed limits and being slow to respond to changes in demand. The scheme did make traffic flow more predictable which shows that, even if implemented

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badly, a traffic management scheme can still fulfil some of its aims. The M42 scheme has not suffered with the same technical issues as its Danish counterpart, making it more successful.

5.2.2 The NetherlandsThere were 17 schemes of hard shoulder running in the Netherlands in 2007 (DfT, 2008b) and they have increased overall capacity at individual sites by between 7% and 22%, with not negative impact on safety and improved journey reliability times. The schemes were popular with drivers, as it improved their journey times, but were unpopular with the emergency services. This is an area where closing lanes for emergency services to get to the scene of an accident may need further investigation in the UK.

6 CONCERNS

6.1 TECHNOLOGICALThere are concerns that MIDAS does not actually detect accidents, but merely the aftermath and slow moving or stationary traffic that is caused (Olds, 2010). This is potentially a biased source as they make the radar detector system called HASMOS (hard shoulder monitoring system). However the flaws with MIDAS are somewhat concerning in the hard shoulder. For instance, if a vehicle comes to a stop between inductive loops, then potentially its presence will not automatically be detected. The HASMOS solution is to fuse the MISAS technology with CCTV Video Image Processing (VIP) and radar detectors in the hard shoulder. A screen shot of the VIP interface can be seen in Figure 9.

Figure 9: VIP interface for HASMOS (Olds, 2010).

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However HASMOS had its own limitations during trial which meant that blind spots and difficulties maintain a line of sight down the hard shoulder meant it has not been implemented as yet. Concerns still remain with MIDAS detection in the hard shoulder though.

6.2 COMPLIANCEWhilst general compliance for variable mandatory speed limits of 50 mph and above is over 95%, there is a concern that the compliance 40 mph limits is much lower. This can be seen clearly in Figure 10.

Figure 10: Monthly compliance with speed limits for two operational regime (Highways Agency, 2008a).

The lack of compliance for the 40 mph limit is striking relative to the others speed limits. The DfT (2008b) recognise this and speculate about the enforcement of average speed cameras throughout the scheme area to improve compliance.

6.3 ENVIRONMENTALThe Campaign for Better Transport seems to support the idea of ATM in principle but does clearly harbour reservations (Blub, 2008). An initial concern is the long term strategy of the DfT. If the idea of ATM is a short term one to “create a little extra capacity” then their view would be a negative one. The suspicion seems to be the fact that ultimately expanding capacity will encourage further usage of the road network rather than encouraging modal split. Blub (2008) admits that ATM is better than widening in an environmental sense but does not make the observation that any ATM project will have more of an environmental impact than the “do –nothing approach”.

Two other concerns revolve around the exclusion of the M25 for consideration for an ATM scheme and the raising of the maximum speed limit to 60 mph. The exclusion of the M25 is

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confirmed by the DfT (2008a) and that widening work will continue to go ahead. The DfT counter argue about raising the speed limit to 60 mph, stating that it encourage an improved flow of traffic meaning that emissions improve relative to the stop-start nature of the lower speed limits.

The DfT (2008a) themselves admit that the visual intrusion of gantries and the energy requirements of the technology used to run the schemes are both causes for concern and will need monitoring on a case-by-case basis.

7 SIMILAR SCHEMESSince the successful M42 ATM pilot trial, numerous other ATM schemes have been implemented. A summary of some of these can be seen in Figure 10, which shows the Birmingham motorway box, made up of the M6, M5 and the M42.

Figure 10: Birmingham motorway box ATM schemes (Highways Agency, 2008b).

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The extension of the Birmingham motorway box was split into phases. Phase 1 included extending the M42 scheme to Junction 9, adding ATM from junction 16 of the M40 to the existing scheme on the M42 and the M6 between junction 4 and 5. Due to the expertise gathered on the M42 pilot scheme, the elements of Phase 1 of the Birmingham Box project were all delivered ahead of schedule. Bennet et al. (2010) think that this is because the same design team worked on Phase 1, as worked on the pilot scheme. They also state that the project has become operationally and safety led, meaning that design decisions were made quickly and the procedures and legislation to implement them followed later.

Crawford (2009) states that the investment in the Birmingham box scheme is £150 million; cheaper than an equivalent widening scheme for the M25 (DfT, 2008a). This continues to imply that the Highways Agency and the DfT will, where possible, utilise the hard shoulder rather than pay to widen a motorway. Crawford’s list of other schemes to being built over the next number of years, including two on the M62 and a number on the M1, justify that point.

8 FUTURE SCHEMES

8.1 ALL LANES RUNNINGFuture schemes planned for the UK seem to be focussing on the MM-ALR design; Managed Motorways – All Lanes Running. This is discussed at length by the DfT (2012) and Kamnitzer & Simpson (2012) after the Coalition Government’s spending review has reduced the Highways Agency budget.

The concept of MM-ALR is to permanently remove the hard shoulder and replace it with a permanent running lane. The DfT (2012) states that having a permanent running lane will remove the difficulty of opening and closing the dynamic hard shoulder as well as the need to monitor it so closely. It is clear that there is a wide school of thought that there is no need for a hard shoulder, especially if the technology is there to close lanes if there is a breakdown or accident. Further cost savings would arise from, as Kamnitzer & Simpson (2012) state, a less dense placement of overhead gantries; approximately every 1500 metres instead of the dynamic running lane 800 metre equivalent.

8.2 CAR-SHARE LANESCar-share lanes, or high-occupancy vehicle lanes have had a presence in the United Kingdom since 1998, with the A647 car-share lane in Leeds, (DfT, 2008b). That scheme saw journey times drop by 4 minutes in the morning peak for a journey which normally took 10 minutes. The non-car-share lane users also saw a reduction in journey time as some traffic that previously used the normal lane switched to the car-share lane.

Car sharing has obvious other environmental benefits; less cars being used – less emissions.

The first motorway scheme opened in 2008 on the junction between the M62 and M606. If at least two people were in a vehicle then they could utilise the 2 mile car-share lane. A plan of the scheme can be seen in Appendix 11.2.

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8.3 HIGH OCCUPANCY OR TOLLED (HOT) LANESA further area that the DfT (2008b) are considering for the future is high occupancy or tolled (HOT) lanes. These have been successfully implemented in the United States. The concept is that car-sharers get to utilise the lane for free, but other users (non-sharers) can pay to use it if they wish to have a more reliable journey time. The technology used to charge tolls is in place, for instance the M6 Toll Road, and could be utilised on a HOT lane.

In America, a successful scheme operates in Minneapolis, on the I-394 toll lane (DfT, 2008b). This has been operational since 2005 and the toll charged fluctuates throughout the day based on the demand placed on the road. This has meant that traffic flows at the speed limit 95% of the time. Figure 11 shows the scheme.

Figure 11: I-394 Toll Lane in Minneapolis (DfT, 2008b).

A number of issues would need to be resolved before implantation could take place in the UK. The payment of the toll in itself presents a number of challenges including the operator needing to be able to collect the toll and the user knowing what toll they owe and how to pay it. Distinguishing the toll lane would also be necessary and the DfT would prefer not to have a fixed barrier for safety reasons. Paint markings seem like the more obvious choice in this instance. Enforcement would need altering from the United States model from Minneapolis as they utilise police officers to pull over non-compliant users. The DfT (2008b) have stated that they are concerned about police priorities so enforcement would need to be automated, similarly to the M6 Toll Road.

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9 CONCLUSIONSActive traffic management through hard shoulder running has been successful on the M42 Pilot Trial, with reduced levels of congestion, environmental improvements, costs savings as well as journey reliability and predictability. Safety has also, crucially, not worsened but seen a decrease in severity of accidents.

Clearly, both the DfT and Highway Agency have rethought the need for hard shoulders, given the expansion of the scheme around the Birmingham Box Network. Given that public response has generally been positive and that capacity expansion can occur without the usual public environmental outcry, the number of new schemes is hardly a surprise.

The use of technology such as Advanced Motorway Indicators, Semi-automatic Control Systems and Ramp Metering shows that there is a clear understanding that just adding capacity does not solve the problem; sophisticated management is needed to ensure congestion does not build up once again. The technology helps drivers with more information as they use the road network. It is crucial that the drivers understand the system and comply with the speed limits; otherwise the scheme will not serve its purpose of slowing down traffic to improve the flow rate. Enforcement is important but police priorities also need to be recognised, so the introduction of radar cameras on overhead gantries is sensible relative to the American model of police road-side enforcement.

The future seems to be heading toward permanently removing the hard shoulder on motorways and using innovate technology to manage a four lane system. The evidence so far suggests it is possible.

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10 REFERENCE LISTBennett, T., Dhanda, H., Goddard, J. and Lord G., 2010. Accelerated Delivery of Managed Motorways: Birmingham Box Phase 1. In: Road Transport Information and Control Conference. London, United Kingdom.

Blum, R. L., 2008. Submission to the Active Traffic Management (ATM) feasibility study from Campaign for Better Transport. London.

Conquest, J., 2009. ATM – coming to a motorway near you soon. Traffic Engineering & Control, 50(4), pp.159-161.

Crawford, D., 2009. DfT fires starting gun on ATM roll out. Traffic Engineering & Control, 50(2), pp.54-56.

Department of the Environment, Transport and the Regions, 2000. Transport 2010: The 10 Year Plan. [pdf] London: Department of the Environment, Transport and the Regions. Available at: < http://webarchive.nationalarchives.gov.uk/+/http:/www.dft.gov.uk/about/strategy/whitepapers/previous/transporttenyearplan2000> [Accessed 16 January 2013].

Department for Transport, 2008a, Advanced motorway signalling and traffic management feasibility study: A report to the Secretary of State for Transport. [pdf] London: Department for Transport. Available at: <http://webarchive.nationalarchives.gov.uk/20081109085418/http://www.dft.gov.uk/pgr/roads/network/policy/mtorsigntrafmanagement/advancedmotorwaysignal.pdf> [Accessed 14 January 2013].

Department for Transport, 2008b. Road – Delivering Choice and Reliability. [pdf] London: Department for Transport. Available at: <http://webarchive.nationalarchives.gov.uk/+/http:/www.dft.gov.uk/pgr/roads/introtoroads/roadcongestion/roadscommandpaper1.pdf> [Accessed 16 January 2013].

Department for Transport, 2012. Managed Motorways All Lanes Running: Concept of Operations. [pdf] London: Department for Transport. Available at: <http://www.dft.gov.uk/ha/standards/tech_info/files/MM-ALR_Concept_of_Operations_v1_0.pdf> [Accessed 16 January 2013].

Gerlough, D. L. and Huber, M. J., 1975., Traffic Flow Theory: A Monograph. Washington DC: Transportation Research Board.

Highways Agency, 2008a. ATM Monitoring and Evaluation: 4-Lane Variable Mandatory Speed Limits, 12 Month Report (Primary and Secondary Indicators). [pdf] London: Highways Agency. Available at: <http://webarchive.nationalarchives.gov.uk/20120810121037/http://www.highways.gov.uk/knowledge_compendium/assets/documents/Portfolio/M42%204LVMSL%20Performance%2012%20Month%20Report%20D%20Final%20-%20613.pdf> [Accessed 16 January 2013].

Highways Agency, 2008b. Consultation Paper – Birmingham Box Active Traffic Management: Phase 1 and 2. [pdf] London: Highways Agency. Available at:

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<http://webarchive.nationalarchives.gov.uk/20120810121037/http://www.highways.gov.uk/roads/documents/081222_Consultation_Paper_-_Issue_B.pdf> [Accessed 15 January 2013].

Highways Agency, 2009. M42 ATM Monitoring and Evaluation – Project Summary Report. London: Highways Agency.

Highways Agency, 2011. M42 MM Monitoring and Evaluation: Three Year Safety Review. [pdf] London: Highways Agency. Available at: <http://webarchive.nationalarchives.gov.uk/20120810121037/http://www.highways.gov.uk/knowledge_compendium/assets/documents/Portfolio/HCG-HRG_264763_001b_V2__2_.doc.pdf> [Accessed 15 January 2013].

Highways Agency, 2012. Freedom of Information Request. [pdf] Available at: <http://assets.highways.gov.uk/freedom-of-information/disclosure-log/M42-managed-motorway-scheme-677305/CRS_677305_Response-letter.pdf> [Accessed 15 January 2013].

Kamnitzer, D. and Simpson, A., 2012. Managed Motorways – Experience from the UK. In: 2012 Conference of the Transportation Association of Canada. [pdf] Fredericton, Canada. 14-17 October 2012. Available at: <http://www.tac-atc.ca/english/annualconference/tac2012/docs/session12/kamnitzer.pdf> [Accessed 8 January 2013].

O’Flaherty, C. A. ed., 1997. Transport Planning and Traffic Engineering. London: Arnold.

Olds, A. R., 2010. Development of a Hard Shoulder Monitoring System (HASMOS). In: Road Transport Information and Control Conference. London, United Kingdom.

Wendelboe, J. T., 2003. Traffic management application on the Koge Bugt Motorway, Denmark. Transportation Research Board.

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11 APPENDICES

Appendix 11.1: Congestion levels on the trunk road network (2000), (DETR, 2000)

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Appendix 11.2: Plan of M606/M62 car-share lane (DfT, 2008b).

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active traffic management on the m42

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