The government has more than tripled the likelihood of serious accidents occurring on the motorways by increasing capacity “on the cheap”, according to the MP of a constituent killed by an HGV.

In a House of Commons debate last week, Sarah Champion said that after “much kicking and screaming”, National Highways had released data showing that the rates of fatal accidents involving stationary vehicles on all-lanes running motorways was more than three times higher than roads with safety features but maintaining the use of the hard shoulder – so-called “controlled motorways”.

Champion’s constituent Jason Mercer was killed on a smart motorway in South Yorkshire in 2019 when he was struck by a lorry.

She said: “The comparison is truly shocking. The rate of incidents involving stopped vehicles in which someone was killed or seriously injured on controlled motorways was 0.06 per 100 million vehicle miles travelled. For all-lane-running motorways it was a staggering 0.19 per 100 million vehicle miles travelled.

“In the name of increasing capacity on the cheap, National Highways has more than tripled the likelihood of serious incidents involving stationary vehicles.”

Champion added: “How much evidence do the government need? How many more people have to die? How many more families will be left to grieve for their loved ones?

“We cannot continue to gamble with the lives of motorists.”

Transport Minister Richard Holden said the government had agreed to take forward all of the recommendations in a transport committee report and had paused all new smart motorway schemes yet to start construction until more safety data was available: “That pause continues and the data continues to be gathered,” he said.

National Highways (NH) told that the rollout had been paused until five years of safety and economic data was available for schemes opened before 2020.

It also said that the impact of measures it had introduced as a result of a 2020 action plan was not reflected in the latest data.

However, an NH spokesman added: “The latest data shows that, overall, in terms of serious or fatal casualties, smart motorways are our safest roads.”

The Parliamentary debate came as swathes of the smart motorway network in England were hit by a software failure.

The problem froze signs and signals and deactivated the stopped vehicle detection system for two hours on Wednesday (22 February).

The NH spokesman said: “It’s right that road users expect high performance standards and when outages occur we have well-rehearsed procedures to deal with issues that arise.

“We took immediate steps to ensure the safety of road users, including increased patrols and CCTV monitoring.

We will now carry out a full investigation into why this happened and apply any lessons learned. We apologise for any inconvenience caused.

“We are committing £105m over the next two years to build further resilience into the operational technology to make journeys even safer and more reliable.”