The first section of the newly-refurbished M25 has opened - and next month the Surrey stretch will also be reopened.
An eight mile section of the motorway in Hertfordshire is the first in the country of a new style of 'smart motorway' schemes - which will also come to Surrey.
Pioneering technology and use of the hard shoulder as a permanent running lane have been combined to reduce congestion and ease traffic flow, improving the reliability of journeys.
One more section on the southern part of the M25 is due to open next month, with a third later in the year on the northern section, with similar schemes being rolled out across the country including the M1, M3, and M62.
Smart motorways deliver additional road capacity more quickly and at less cost than traditional road widening schemes, while remaining at least as safe.
Roads minister Robert Goodwill said: "The additional capacity on the M25 is part of the government's record investment in the strategic road network, with £15.1 billion being invested to add over 400 lane miles of capacity on our busiest motorways by 2021.
"Our motorways are the backbone of Britain and vital to building the UK economy, with approximately four million vehicles using them each day."
Graham Dalton, Highways Agency chief executive said: "The Highways Agency is a world class roads operator and we have built upon our experience of operating the M42 pilot scheme.
"The design changes have meant that smart motorways are quicker to build, more intuitive for drivers and more efficient to operate, while maintaining safety."
The improvement work on the M25 has been carried out by Connect Plus.
A similar scheme, between junctions 5 and 6/7 has completed construction and after a period of essential testing and commissioning of systems, is due to open next month.
The hard shoulder will be a permanent running lane between junctions 5 and 6 with a traditional hard shoulder between junctions 6 and 7 where there are already four lanes available to traffic.
The new technology has been added to the road to provide drivers with safe and reliable journeys.
This includes infra-red CCTV, being used for the first time by the Highways Agency, to enable staff in the control centres to have increased visibility of the network and will be able to respond even quicker to incidents.
