Proposed changes to stretches of the M1 motorway could put drivers' lives at risk, according to campaigners.
The RAC along with the Association of British Drivers (ABD) takes particular issue with the idea of replacing the hard shoulder between junctions 28 and 35A with an extra lane in an effort to cut congestion on the motorway.
The lack of a continuous hard shoulder, combined with many vehicles' lack of a spare wheel, is a potential recipe for danger.
Another option currently being assessed by the Highways Agency for the stretch of the M1 is a reduction in speed limit to 60mph to cut emissions pollution.
But it is the proposal to remove the hard shoulder that motoring groups have the most concern over.
With no hard shoulder to pull on to, a punctured tyre could easily become shredded, leading to a greater risk of danger in the event of abreakdown .
RAC technical director David Bizley said: "The RAC has raised concerns with the Highways Agency about the added risk arising from increased distance between emergency refuge areas, and we are disappointed so far at the absence of action to address them.
"Dynamic hard shoulder running has proved to be very successful in terms of reducing congestion and has a good safety record. Indeed, so far, these sections of motorway have proven to be significantly safer than a conventional three-lane motorway with a hard shoulder.
"However, we believe the greater distance between emergency refuge areas creates an unnecessary risk to the safety of any motorist breaking down in lane one on an all-lane running section."
Adding to the debate, ABD spokesman Hugh Bladon said: "At motorway speeds, drivers need to be able to pull over as soon as possible in the event of a puncture to prevent the tyre shredding and possibly losing control of the car.
"The lack of a hard shoulder on the modern so-called 'Smart Motorways' means drivers have no alternative but to continue to the next 'refuge'.
"A can of foam will not inflate a shredded tyre, leaving the driver stranded."
Copyright Press Association 2014