Managed motorways in the United Kingdom

Managed motorways are motorways with technology to allow variable speed limits to be applied and hard shoulder running.

Contents 1 History 1.1 Background 1.2 In use 1.2.1 Expansion 2 Techniques 3 Current schemes 4 Proposed schemes 5 Criticisms 6 References 7 External links

History

Background

The first section of motorway in the UK to use this technique was the M42 in the West Midlands.^[1] The Highways Agency's road building budget was £3 billion over budget^[2] and widening a motorway in the UK costs around £79 million as opposed to implementing ATM at a cost of around £5-£15 million.^[3] It was estimated that widening this stretch of motorway would cost £500 million, whereas implementing ATM would cost £100 million.^[2] It is estimated that it takes 10 years to implement a widening scheme as opposed to 2 years for ATM.^[4] Traffic has increased by 80% between 1980 and 2005 whilst road capacity has increased by 10%.^[5]

In use

Installation of the first scheme began in November 2004. The first phase, the variable speed limit, came into use on the 29 November 2005.^[6] The final stage of ATM began operation on the M42 on 12 September 2006 between junction 3A for the M40 motorway and junction 7 for the M6 motorway, a distance of 12 miles (19 km).^[7] This part of the motorway carries 120,000 vehicles each day^[8] made up of long distance traffic, local traffic, customers of Birmingham International Airport and visitors to the National Exhibition Centre (NEC) as well as higher number of accidents than the national average.^[9]

The M42 scheme was initially run as an experiment and a Highways Agency report into the first six months of the scheme scheme showed a reduction in journey times of up to 25%^[10][11] The journey time statistics can be broken down to show that northbound journey times were reduced by 26%, equating to an average reduction of 4 minutes as compared to the period when the variable speed limits were on but the hard shoulder was not being used and 9% southbound (equating to 1 minute) during the afternoon rush hour.^[8] The report also indicated a fall in the number of accidents from over 5 a month to 1.5 per month on average.^[10][11] The Agency did state that normally accident statistics should be compared over a 3 year period, so the initial results should be treated with caution. They also stated that no accidents had been caused by hard shoulder use as a normal lane.^[8] The report also stated that there had been a 10% fall in pollution and 4% fall in fuel consumption.^[10] The report also indicated a compliance rate of 98% to the indicated speed limits when using the hard shoulder.^[8] For comparison before the introduction of mandatory speed limits at road works, the compliance rate was 10% as opposed to 89% afterwards, showing a similar effect.^[5]

The Highways Agency surveyed drivers, stating that 84% felt confident using the hard shoulder, 68% felt better informed about traffic conditions and that around 66% wanted the scheme expanding to other roads.^[8]

In 2008 and as part of the pilot a section of the southbound carriage way between junctions 4 and 3A began operating using the hard shoulder with a speed limit of 60 miles per hour (97 km/h), a 10 miles per hour (16 km/h) increase on the previous maximum permissible speed.^[12]

Expansion

The Secretary of State for Transport has announced that the government is to introduce the scheme onto two sections of the M6 by 2011 for £150 million.^[10] The emergency refuges will be extended to every 800 metres (0.50 mi) on the roll out.^[11] A further study into the use of ATM on the M1, M4, M20 and M25 motorways was also announced,^[10] however the Department for Transport has confirmed that the scheme will not be used on the M25 where the motorway is planned to be widened.^[13]

Techniques

Managed Motorways is a ‘tool-box’ which facilitates the dynamic control of traffic for congestion and incident management which includes:^[14]

• Hard Shoulder Running: Controlled use of the Hard Shoulder during times of heavy congestion or during incident management
• Controlled Motorways: The dynamic management of traffic in the designated running lanes using Variable Mandatory Speed Limits (VMSL)
• Queue Protection: Automatic protection of incidents and queues
• Lane Specific Signalling: Protection of incidents and on-road resources
• Ramp Metering: Controlling traffic entering the main carriageway from slip-roads or connector roads to maintain the flow on the main carriageway
• Integrated Traffic Management: Management of traffic on the motorway and local road network

Current schemes

The following schemes are in operation:

• M6 motorway 4-5^[15]
• M6 motorway 8-10a^[15]
• M25 motorway 9-16 (variable speed limits)^[16]
• M42 motorway 3A-7^[17]

Proposed schemes

The following schemes have been proposed:

• M1 motorway 28-31,^[18] 32-35a^[19] and 39-42^[20]
• M4 motorway: 19-20^[19]
• M5 motorway: 15-17^[19]
• M6 motorway: 5-8^[19]
• M25 motorway: 5-7^[21] and 23-27^[20]
• M60 motorway: 8-12^[19] and 12-15^[20]
• M62 motorway: 18-20^[19] and 25-30^[20]

Criticisms

The scheme was initially criticised for exposing people to potentially higher risks in the event of a breakdown or emergency. Environmental campaigners also argued that the scheme would not reduce the environmental impact of motoring. The government was also criticised for introducing the scheme as a cheaper alternative to proper widening.

The Campaign for Better Transport argued that whilst it would reduce the need for widening schemes, it did nothing to reduce traffic and CO2 emissions. Friends of the Earth criticised the scheme as "widening on the cheap" and also pointed to a possible increase in vehicle emissions.^[10] The Highways Agency argue that ATM reduces the environmental impact in regards to widening as it is carried out within the existing boundaries of the motorway as well as a possible improvement in local air quality due to smoother traffic flow.^[22]

The RAC cited a study in the Netherlands that showed drivers using the hard shoulder when they were not permitted, increasing the risk of a collision for vehicles stopped. The Royal Society for the Prevention of Accidents also expressed concern that emergency services would take longer to reach an incident.^[4] The Highways Agency rejected this concern based on the 5,000 miles of dual carriageway which doesn't have a hard shoulder.^[7] Disability groups were concerned that some drivers would not be able to access the emergency phones or even exit their vehicles, leaving them at increased risk.^[7]

Ruth Kelly, Secretary of State for Transport stated in an interview that this would not necessarily replace motorway widening in all circumstances, but would be another option and that the government were not using it simply a cheaper method of widening roads.^[4]

References

External links

• M42 ATM Monitoring and Evaluation - Project Summary Report