Motorists are being allowed to drive on the hard shoulder of a motorway in a bid to beat peak-hour congestion.
Drivers move across to use the hard shoulder of the M42
Drivers are directed to use the hard shoulder on an 11-mile stretch of the M42, from south of Birmingham and through Warwickshire, at certain times.
A 50mph speed limit warning over the hard shoulder between junctions 3a and 7 shows when the lane is in use.
Drivers first moved on to the hard shoulder at 0745 BST. The Highways Agency said everything "went well".
Traffic build up
Regional director Graham Bowskill said traffic started to build up during the morning at the northern end of the section, close to the M6.
"By 7.45am the systems were saying we needed to put traffic on to the hard shoulder between junctions along most of the length of the motorway affected by the scheme. That operated very well."
"The information goes onto gantry boards asking people to use the hard shoulder, then they move across and it allows them to go up to the next junction with less congestion."
The system had been a success, he added.
The agency has said signs on the gantries can be changed within seconds in case of emergency.
But Roger Vincent, spokesman for the Royal Society for the Prevention of Accidents, said he did have some concerns, primarily in terms of safety because of the distances between refuges and in terms of people breaking down in one of the most dangerous places on the motorway.
"There are also concerns about whether the systems for getting emergency services to help people in terms of accidents will operate well," he added.