A widening scheme on the M25 in Essex has been completed after three years of work.
Two widening schemes on the M25, involving a stretch in Essex and another in Hertfordshire, have been completed after three years of work.
The section between junction 27 at Epping and junction 30 at Thurrock now has four lanes.
An extra, fourth, lane has also been added to the section of the M25 from junction 16 near Uxbridge in west London to junction 23 at South Mimms in Hertfordshire.
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.
"Increasing capacity on the M25 will tackle congestion, help keep traffic moving and improve journey time reliability."