The Connect Plus joint venture will start the latest design, build, finance, and operate contract on the London orbital route tomorrow.
Preparation work will start Tuesday with main construction work expected to start in the spring.
The team will be responsible for constructing the infrastructure for Managed Motorways on 46km of the M25 in two sections between junctions 5 to 7 and junctions 23 to 27 through Kent, Surrey, Essex and Hertfordshire.
Managed Motorways add extra capacity by converting the hard shoulder to a traffic lane and control traffic more effectively using variable speed limits.
Work includes the upgrade of the central reservation to a concrete barrier and the installation of road management technology including electronic matrix signs, CCTV cameras and emergency refuge areas for vehicles.
The 25 month contract is scheduled for completion by February 2015.
Ian Tyler, Balfour Beatty Chief Executive, said: “We are very pleased to have been awarded this new contract on the M25.
“It builds on our existing contracts across the UK roads network and strengthens our position in the transportation arena, which is a core strategic sector for us globally.”
Greg Craig, Managing Director of Civil Engineering, Skanska UK, said: “This contract is a natural progression for our Skanska Balfour Beatty joint venture, having successfully delivered ahead of schedule the £1 billion widening of the M25 in 2012.
“Our very positive relationship with the Highways Agency has helped set new standards in contributing to meeting the government objectives of delivering growth while also reducing costs by 20 per cent across public construction projects.”