M25 Motorway widening

This £6.2 billion project saw an extensive programme of road widening and improvements to increase capacity and enhance safety and reliability of one of Europe's busiest motorways.

The M25 carries more than 220,000 vehicles per day on some sections. In May 2009, the Highways Agency (now known as National Highways) awarded Balfour Beatty a 30-year Design, Build, Finance and Operate (DBFO) contract to manage the M25 and its key arterial link roads.

The scope of works included routine maintenance, the delivery of lifecycle works and improvement schemes, constructing 62km of motorway widening prior to the 2012 Olympic Games and a further 46km of Smart motorway.

The Smart motorway upgrades enable the hard shoulder to be used permanently as an extra running lane improving the reliability of journey times. The works included the installation of new infrastructure and technology including motorway spanning gantries, a contiguous piled retaining wall installed by Balfour Beatty Ground Engineering, refuge areas, emergency telephones, overhead signals, verge mounted signs and CCTV cameras.

The final section of roadworks was completed fourteen weeks ahead of schedule following the earlier completion of Junctions 23 to 25 in Hertfordshire, and Junctions 5 to 7 between Kent and Surrey - which also opened twenty-two weeks ahead of schedule in the spring of 2014.

The early completion was achieved through the extensive use of Building Information Modelling (BIM), which enabled the early detection of design issues while at the same time providing the customer, the Highways Agency, and stakeholders, such as Network Rail, with real-time information on design and implementation.

Balfour Beatty continue to work in a joint venture with Skanska on the motorway at Junction 30 to improve capacity and traffic flow.

Today, Balfour Beatty works alongside AtkinsRéalis and Egis to operate and maintain the whole M25 under the ConnectPlus brand. As part of the consortium’s maintenance of the M25, a custom-designed, vehicle-mounted vacuum litter picker was developed by our in-house team. The new machine is more efficient and helps to keep our workforce safe by removing the need for litter picking by hand.

30 years

contract length


contract value


of landfill removed from the entire site


of the M25 through Kent, Surrey, Essex and Hertfordshire improved

Related content:

Balfour Beatty's patented King Sheet Piling system was used extensively during the M25 widening and has since gone on to be incorporated in many of our Smart motorway contracts. Find out more in the short film below.


Revolutionising 120 years of sheet piling

Inventor David Baker explains how Balfour Beatty's patented King Sheet Piling system (KSP) is already reaping rewards. David's revolutionary earth-retaining wall system typically saves 35% to 40% of the materials while reducing the noise and installation time, yet achieves the same result. Subtitles available. For more information, please visit the KSP website at: http://www.balfourbeatty.com/ksp #expertengineers