Rishi Sunak has banned the construction of all new smart motorways, with 14 planned constructions being scrapped due to safety concerns.
Campaigners have praised the move, but called for the government to do more to ensure safety on the motorways.
In particular, they are calling for the government to return the hard shoulder to any motorway conversions.
Around 10 percent of England's motorway network is made up of smart motorways, which use traffic management methods such as variable speed limits and use the hard shoulder as a 'live running lane'.
Despite growing in number over recent years, smart motorways have been a cause of concern due to fatal incidents which occurred when vehicles stopped in live lanes were hit from behind.
In January 2022, the government paused the expansion of motorways where the hard shoulder was being used as a permanent traffic lane, to gather five years of data to assess its safety.
Sunak had previously vowed to ban smart motorways when running for Prime Minister last year.
Speaking of the recent ban, Mr Sunak said: "All drivers deserve to have confidence in the roads they use to get around the country.
"That’s why last year I pledged to stop the building of all new smart motorways, and today I’m making good on that promise.
"Many people across the country rely on driving to get to work, to take their children to school and go about their daily lives, and I want them to be able to do so with full confidence that the roads they drive on are safe."
Campaigner Claire Mercer, whose husband died in a collision on a smart motorway, welcomed the government's recent ban, but said more needed to be done to ensure safety.
Mercer said: "It’s great, it’s very good news.
"I’m particularly happy that it’s been confirmed that the routes that are in planning, in progress, have also been cancelled. I didn’t think they’d do that.
"So it’s good news, but obviously it’s the existing ones that are killing us. And I’m not settling for more emergency refuge areas.
"So it’s half the battle, but we’ve still got half the battle to go."
Echoing Mercer's words, AA president Edmund King said: "We have had enough coroners passing down their deadly and heart-breaking judgements where the lack of a hard shoulder has contributed to deaths.
"At last the government has listened and we are delighted to see the rollout of ‘smart’ motorways scrapped.
“We would also like to see the hard shoulder reinstated on existing stretches in due course."