A national rollout of smart motorways has been put on hold by transport secretary, Grant Shapps, after they were linked with an increase in the number of road deaths.
Shapps said there would be no new stretches of smart motorway until the government has completed a review announced last year.
“For me, we must make them at least as safe, if not safer [than ordinary motorways], otherwise they cannot continue,” he said.
The freeze comes days after new figures revealed that the schemes, designed to increase capacity, had led to a dramatic 20-fold increase in the number of near misses.
But while work will stop on several schemes that were due to finish this year, sections of smart motorway that are already in use – including on the M1, M4, M6 and M62 – will remain open.
The trial schemes help increase capacity without the need for road widening, by allowing drivers to use the hard shoulder when directed to do so by electronic signs mounted on gantries above the road. About 200 miles of motorway in Britain have already been converted.
Shapps announced a review in October last year, amid concern about accidents involving drivers who break down on sections of motorway with no hard shoulder.
Earlier this week, an investigation by BBC’s Panorama programme cast fresh doubt on their safety.
Near-misses on the M25 London ring road went up by 20 times after the introduction of “smart running”, according to a freedom of information request, while one of the electronic warning signs was out of action for 336 days.
The investigation also revealed that 38 people have been killed on smart motorways in the past five years.
The day after the programme, a report by the all-party parliamentary group on roadside rescue and recovery, led by the ex-minister who signed off the expansion of smart motorways, branded them a “death trap”.
Former roads minister Mike Penning accused Highways England of “casually ignoring commitments” on safety.
The report criticised Highways England’s failure to implement a Stopped Vehicle Detection system, which uses radar to spot vehicles that have broken down.
In their report, the MPs said an admission by Jim O’Sullivan, Highways England chief executive, that radar technology could have saved lives was “a damning indictment of the agency’s on-the-hoof approach”.
Days after the emergence of fresh concerns about smart motorways, Shapps told the Commons that all new schemes would be on hold, including a £92m project in Kent.
Work to convert a 6.5 mile stretch of the M20 into a smart motorway between West Malling and Aylesford was due to be completed in March after two years of work which has disrupted journeys.
Chatham and Aylesford MP Tracey Crouch asked Shapps if he agreed that the new road system should not open because it does not have stopped vehicle detection systems or “appropriately spaced emergency refuges”.
He replied: “That stretch of the M20 and all other stretches which are currently being worked on will not be opened until we have the outcome of the stock take.”
Work will also cease on several major schemes that were due to finish this year, including stretches of the M20 in Kent, the M62 in Greater Manchester, the M23 near Gatwick Airport and the M6 near Coventry.
Philip Gomm, of motoring research charity the RAC Foundation, said: “On safety grounds this pause is unarguable.
“But it does mean that for users of the M20 – who have suffered delays not just because of this scheme but also the Brexit-related speed restrictions and lane closures – the inconvenience is set to go on.
“No-one underestimates the complexity of these schemes but it does underline the need to get the design right first time.”