Highways England has appointed a consortium of WSP Parsons Brinckerhoff, Steer Davies Gleave and GL Hearn to study options for adding capacity to the M25 west of London. The work will look at how best to improve traffic flow on one of the most congested sections of the orbital motorway between the M25 Junction 10 with the M3 in Surrey and Junction 16 joining with the M40 in Buckinghamshire.

This is the sixth major road study launched by Highways England to inform the Department for Transport's Roads Investment Strategy 2 for projects to be built between 2021 and 2026. The M25 is already four lanes wide with a hard shoulder in both directions from Junctions 10 to 12, then five lanes in width to Junction 14, widening further to six lanes in both directions between the Heathrow junction and the M4 at Junction 15. One option likely to be under consideration will be conversion of hard shoulders to create all lane running (ALR) along all but the widest section near Heathrow. ALR is already in place on the M25 between junctions 5-7 and J23-27.

The other five studies for RIS2 include evaluation of the feasibility of options for a new Trans Pennine tunnel linking Manchester and Sheffield awarded to Mouchel and Arcadis, plus a study looking at ways of adding capacity to the A1 or M11 between the M25 and Peterborough awarded to Arup. A new east-west link between the M6 in Cumbria and the A1(M) in the north-east is being studied by WSP Parsons Brinckerhoff, Ch2m, TRL and Steer Davies Gleave, which are also drawing up options for an Oxford-Cambridge Expressway. Arup is also evaluating ways of improving the M60-M62 corridor from Trafford to Bury.