Active Traffic Management (ATM)

Managed Motorways - variable speed limits and hard shoulder running

Managed Motorway - All Lanes Running has no hard shoulder

Managed Motorway - All Lanes Running has no hard shoulder

Compared to some European countries the UK was slow in developing real-time motorway control techniques like variable speed limits, peak-hour hard shoulder use and active traffic management.

The UK's first major real-time traffic control scheme was the M25 'controlled motorway project' introduced in 1995 between junctions 12 and 15. This introduced mandatory variable speed limits at busy times and during incidents.

Initially there was some criticism of the M25 scheme as it often imposed confusing speed limits without any explanation. This has improved with the introduction of the variable message sign system.

M42 pilot - hard shoulder running

The M42 Active Traffic Management 'hard shoulder running' pilot scheme between junctions 3a and 7 near Birmingham aimed to build on the M25 scheme using state-of-the-art, real-time traffic management to improve traffic flow and safety.

Opened in September 2006 the M42 pilot is a fully flexible ‘controlled’ motorway - it has a hard shoulder which can be opened and closed, variable speed limits, lane control, overhead gantries, and emergency refuge areas.

The controlled section of motorway is intensively signed with 50 gantries, 250 variable signs, emergency refuges every 500 metres which detect broken down vehicles, and CCTV.

Results of the M42 pilot

The M42 ATM scheme has proved very successful. It has:

  • Reduced congestion
  • Improved journey times, and
  • Provided a more comfortable driving experience.

Users have said they prefer the system to be switched on all the time and the vast majority say they understand the signs.

However, the safety of the system is totally dependent on drivers adhering to the 'controls' – the most vital of which is the red cross over the hard shoulder which means it is closed to running traffic.

The hard shoulder must also not be used when the ATM system is off i.e. when variable speed limits and congestion signs are not lit.

AA views M42

As the M42 scheme has gained drivers' support, eased congestion and improved journey reliability, the AA supports Active Traffic Management:

  • There have been no operational problems for AA patrols helping members
  • ATM improves capacity and makes driving more comfortable in peak traffic
  • ATM encourages better lane discipline
  • Planners must guard against over development alongside the M42 which will dilute the benefit by adding more traffic

But ATM is not a solution applicable to all UK motorways

  • More robust, traditional widening with hard shoulders is still needed on some overloaded sections of motorway
  • ATM was five times cheaper than widening the M42 so there is no reason to simplify ATM controls to save money if it is to be used elsewhere – ATM works because it has an array of safety systems built in.
  • UK drivers pay £45 billion in road tax and deserve the most robust solutions to motorway congestion – ATM should not be used to save money on proper widening but it has major potential to lock in the benefits of widening and provide relief at specific peak hour hot-spots.

Managed Motorways - All Lanes Running (MM2)

In March 2012 the Highways Agency published a 'concept of operations' for a new type of Managed Motorway scheme - Managed Motorway-All Lanes Running.  This has become known as Managed Motorway 2 - All Lanes Running or MM2(ALR) with schemes like the M42 scheme now being referred to as MM1.

The key feature of MM2(ALR):

  • Permanently removed hard shoulder to provide an additional traffic lane
  • Queue protection system - alerting drivers of congestion ahead
  • Congestion management system - determining speed limits for smooth traffic flow
  • Variable message signs displaying mandatory speed limits, lane closures and other information
  • Gantries at start and end of managed motorway section Refuge areas at a maximum 2,500m

AA views - MM2(ALR)

The Highways Agency says that managed motorways are a great success but this is based on experience of MM1 rather than MM2(ALR). Its risk prediction for MM2 shows it will be less safe than MM1 but will be no less safe than a conventional three lane motorway with hard shoulder and incident detection.

The AA has serious reservations about MM2(ALR) which is a very much pruned back version of MM1. Whilst we are very happy to see congestion reduction effected quickly, we have serious doubts about the resilience of a motorway with no permanent hard shoulder, mandatory traffic management with less signage, gantries and emergency refuge areas.

There will only be gantries at the start and finish of the managed section, key signing will only be on the nearside at greater spacing, and emergency refuges will be spaced at 2.5km not 0.8 km as on M42.  Worse still, the hard shoulder will be scrapped and instead becomes a permanent running lane.  Ten MM2 schemes are already progressing with more in the pipe-line. 

MM2(ALR) will make the motorway hugely vulnerable when accidents and breakdowns occur - any unavoidable stop in lane 1 may well require a full police/traffic officer managed lane closure to resolve.

Anyone broken down at night with a full electrical failure (who couldn't make it to the emergency refuge) will be in a very dangerous situation. Although the motorway will have an incident detection system it does not function in very low traffic flows which are most likely to occur at night.

AA Members' views

AA members will be affected by the new managed motorway design.  In an AA-Populus panel survey:

  • 87% agreed hard shoulders help make motorways safe, and
  • 63% said the new design would make them more nervous about driving on a motorway

But like the AA, 57% thought that use of the hard shoulder made sense as a way of reducing congestion.


(5 August 2013)

 

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