M3 'smart' motorway opens in Hampshire and Surrey
A £174m upgrade to turn the M3 into a "smart" motorway in Surrey and Hampshire has opened.
The 13.4-mile stretch between Farnborough and the M25 is now a four-lane carriageway after the main construction work was completed.
Motorists have faced years of disruption since work began in 2014.
Ongoing roadworks and some overnight restrictions will continue to affect motorists with speed limits in place as the system is tested.
Technology is being used to manage traffic flows with variable speed limits and use of the hard shoulder.
Speed limits will remain in place until later this month.
The M3 passes through Chobham Common, an area of heathland in Surrey.
Before work began, the government said the M3 smart motorway would improve journey times by 15%, but the then Highways Agency raised concerns extra traffic would cause EU air quality rules to be broken.
In June 2014, a plan to impose a 60mph speed limit on that part of the M3 to cut air pollution was put on hold by the then Transport Secretary Patrick McLoughlin, with the Highways Agency asked to look at other ways of tackling pollution.
Maintenance work on the motorway is still to be completed, including the rebuilding of the Woodlands Lane bridge over the motorway near Windlesham, which will continue until later in the year, Highways England said.
Pranav Devale, project manager for Highways England, said: "This new stretch of smart motorway will tackle congestion and improve journey times for the 130,000 drivers who use it every day."
Back in 2014, Highways England said the main project work would be completed by December 2016.
But James Wright of Highways England said: "The reason we are finishing construction now rather than last December is that, shortly after we started work and after a bit of local lobbying, we agreed to do a large amount of maintenance work at the same time as the smart motorway upgrade."
He said the extra work included fully resurfacing the road and replacing a bridge over it.
"This is extra work with extra benefits and we do not consider it a delay," he added.