As many as 10% of drivers would ignore red X no-go lane signs on motorways, according to an AA/Populus survey.
The "trespass" rate is even higher for some motorists, with 12% of drivers in south east England and 14% of those in London prepared to enter closed-off lanes.
Of those ignoring the signs, some would continue in the closed lane until they saw an incident and some would stay in the lane until they encountered another red X sign. Words: PA
The survey, of 19,887 AA members, was conducted in the light of the decision to do away with the hard shoulder on some sections of motorway to allow for congestion-easing all-lane running.
The survey also found that the loss of the hard shoulder meant 56% would carry on driving with a flat tyre until they reached an emergency refuge area or the next motorway exit.
With spacing between emergency refuge areas extended from 800 metres on the M42 hard-shoulder-running pilot scheme to a new standard of up to 2,500 metres, cars could be limping along for up to 1.5 miles in fast traffic, the AA said.
It added that Government road casualty statistics revealed that, although there were fewer motorway accidents involving back-seat passengers, those passengers were more likely to be killed.
"Drivers who ignore the red X are not only putting themselves and the lives of other motorists around them at risk but are also risking prosecution."
He went on: "The AA applauds the Government's move to increase motorway capacity - but it can't be done on the cheap by skimping on safety features.
"There should be no doubt in drivers' and their passengers' minds as to what they should do when a car breaks down on a motorway without a hard shoulder."
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