TRAFFIC congestion will be reduced on the M4 as a result of a smart motorway scheme - it is claimed - after the government approved the measure last week, but campaigners say safety fears remain.

The hard shoulder on the M4 motorway will be permanently changed into an extra carriageway for traffic after the Department for Transport gave permission for the scheme to go ahead on Friday last week.

The all-lane running smart motorway will be between Junctions 3 (Hayes) and 12 (Theale), including turn offs for Langley, Slough, Windsor and Maidenhead. It will see emergency refuge areas, similar to lay-bys, installed for vehicles to stop in, in place of the hard shoulder for vehicles to stop in.

Labour’s Louise Ellman, chair of the Commons Transport Committee, has criticised the plan and has said that she thinks lives could be put at risk.

She said: “It ignores the need for a three-year trial period for safety considerations. The Transport Committee produced a highly critical report on this.

“Breakdown operators say they will not go to cover broken down vehicles as they are concerned about safety. There is also concern that there will be too few emergency refuges.”

The committee published a report in June which recommended the immediate halt of all-lane running due to safety concerns, but the Secretary of State for Transport Chris Grayling disagreed.

His decision letter read: “The Secretary of State has considered the road safety implications of the proposed development, in particular the applicant’s choice of all lane running as opposed to dynamic hard shoulder running (peak time) for the smart motorways programme.

“The Secretary of State agrees that taking into account the Road Safety Audit for the proposed development and the evidence of the first 12 months’ performance of all-lane running on the M25, the proposals for the M4 would achieve a good level of safety which is greater than that achieved under existing conditions between Junctions 3 and 12.”

A Highways England spokesperson added: “We look forward to bringing the benefits of less congested and more reliable journeys to users of the M4.

“Each of our smart motorway schemes has been designed with safety in mind. This upgrade will maintain or improve the M4’s strong safety record.”

The 32-mile stretch of road will have new technology installed which will help to keep the traffic flowing and tackle congestion, with overhead gantries displaying variable speed limits and cameras controlling speeds and feeding information about traffic conditions.

The scheme, which will cost more than £500 million, is expected to be completed by March 2022, after the plans were initially put forward in March last year.