Two widening schemes on Britain's busiest motorway were completed today after three years of work.
An extra, fourth, lane has been added to the section of the M25 from junction 16 near Uxbridge in west London to junction 23 at South Mimms in Hertfordshire.
And the section between junction 27 at Epping in Essex and junction 30 at Thurrock in Essex also now has four lanes.
The widening projects have seen more than 11 million hours worked and the installation of 125 gantries, including the largest single span gantry in Europe.
Around 130,000 trees, shrubs and plants have been planted and more than 2,800 animals moved to new habitats.
Roads Minister Mike Penning said: "The delivery of these major improvement schemes is part of the Government's £3 billion investment in the strategic road network. Significantly, these improvements have been completed ahead of the London 2012 Games.
"Our motorways are the backbone of Britain, getting people to and from work, powering the economy and keeping families connected.
"Increasing capacity on the M25 will tackle congestion, help keep traffic moving and improve journey time reliability."