The UK's Highways Agency has completed the widening of two sections of the M25 motorway in Hertfordshire and Essex as part of a £6.2bn programme.
The two sections between junctions 16 (Uxbridge/M40) and 23 (South Mimms/A1) and between junctions 27 (Epping/M11) and 30 (Thurrock/A13) have been widened with an additional fourth lane in each direction to improve travel time and to reduce traffic congestion.
Roads Minister Mike Penning described the motorways as 'the backbone of Britain', as they are used to get people to and from work, power the economy and keep families connected.
"Increasing capacity on the M25 will tackle congestion, help keep traffic moving and improve journey time reliability," Penning added.
Highways Agency Chief Executive Graham Dalton said congestion on major roads is frustrating for road users, bad for the economy and damaging to the environment - and that is why the agency is doing everything it can to tackle congestion.
"Overall these schemes will reduce congestion, improving the reliability of journey times and safety for road users," Dalton added.
The agency awarded the design, build, finance and operate (DBFO) contract of the M25 to a private sector consortium of Skanska, Balfour Beatty, Atkins and Egis called Connect Plus.
Connect Plus, under the DBFO contract, will widen the M25 to four-lanes between the two junctions and refurbish the Hatfield Tunnel on the A1 (M).
The consortium will also operate and maintain the M25 motorway and the associated stretches and trunk roads, as well as the Dartford Crossing, for a period of 30 years.
The project has used recycled aggregates for over 90% of the widening of junctions.