The Highways Agency is adding capacity to the M25 between junctions 5 and 7 by making the hard shoulder available to drivers as an extra lane.
Main construction work for the so-called ‘managed motorway’ is expected to start next spring – the first of its kind in he southeast.
The contractor will be Connect Plus, which is a consortium of Balfour Beatty, Skanska, Atkins and Egis. The current is estimated to be in the range of £137.2m to £247.4m.
Managed motorways use a range of technology combined with new operating procedures to control traffic flow. Techniques such as varying the speed limits and opening up the hard shoulder to traffic are designed to improve traffic flow and reduce congestion. Such schemes already operate on the M42 and M6 in the West Midlands.
Mobilisation work starting on Monday 17 September will lay the groundwork for the M25 scheme.
Highways Agency project manager John Martin said: “The preparatory work is vital if we are to deliver this important road upgrade as soon as possible and realise its benefits for the economy. As well as installing important equipment that will be used during the scheme, we are preparing key parts of the road infrastructure for the upgrade, including checking and refurbishing more than 1,000 drainage gulleys and chambers under the hard shoulder to minimise the risk of unplanned disruption once the roadworks get underway.”
The work, which will be carried out overnight, will include clearing some vegetation from the hard shoulder and work to relocate protected wildlife from the road verge. The hard shoulder and sections of the verge will be strengthened, drainage will be upgraded and the breakdown recovery stations and cameras that will be used during the roadworks will be prepared.
The work will be completed using overnight lane and slip road closures, with all restrictions removed outside working hours. It will be followed by an upgrade to the central reservation barrier, which will begin in November, using 24-hour narrow lanes and a reduced 50 mph speed limit.