Leading engineering consultancy Mott MacDonald has designed the Highways England (HE) Motorway to Motorway (M2M) metering pilot scheme, which has just started trials as part of what the government-owned agency called its ‘most complex smart motorway project’.
The full Manchester smart motorway scheme stretches 17 miles (27km) between junction 8 of the M60 near Sale and junction 20 of the M62 near Rochdale. Highways England described it as its ‘most complex smart motorway project, affecting the second busiest motorway in the country and covering 13 junctions; an average of one junction every 1.4 miles (2.2km)’.
The US-style ‘ramp metering’ system is being trialed between junction 21A of the M6 and junction 10 of the M62. The pilot system is due to operate during 2018 and will be monitored to evaluate the benefits. The project aims to smooth traffic flows and reduce the number of queues that occur because of congestion.
Large volumes of eastbound traffic on the M62 can cause weaving problems, leading to congestion between junctions 10 and 11. This problem is exacerbated by traffic joining the motorway from the M6 northbound and southbound link roads. This merging traffic causes flow breakdown on the M62 through the Croft Interchange, which in turn causes queues to form along the motorway to junction 9.
The M2M scheme combines the use of two standard technologies in an innovative way. Variable mandatory speed limits on the M62 and metering using traffic signals between the M6 to M62 eastbound are integrated to make best use of the available road capacity. These are set in response to prevailing traffic conditions, with information displayed on overhead gantries, using advanced motorway indicators and variable message signs (VMS).
Mott MacDonald developed the algorithms which coordinate the separate systems. Where no mandatory speed restriction is displayed, the national 70mph (113km/h) speed limit will apply.
“Highways England is committed to building upon the success of its existing smart motorway program. The M2M scheme increases the resilience of the overall network, with the benefit to the road user of smoother traffic flows, improved journey times, and increased quality of information provided,” explained Stuart Scott, Mott MacDonald’s project principal.
“By utilizing the latest technologies and making use of the existing capacity of the link roads, the M2M scheme is a lower cost solution than conventional widening programs. Additionally, it does not require additional road space, leading to a low environmental impact during construction, while delivering a positive impact during operation.”