More than a fifth of drivers have ignored red X signs on smart motorways, a new study suggests.
Some 23% of motorists surveyed for the RAC admitted having driven under the lane closure signs.
The vast majority of this group said they disregarded red Xs “accidentally” but 3% of respondents admitted doing so “on purpose”.
Hundreds of miles of motorways across England have been converted into smart motorways, meaning the hard shoulder is used as either a permanent or part-time running lane.
Red Xs are used to indicate when a lane is closed, such as when a vehicle has broken down outside of the emergency lay-bys.
It is illegal to drive in a lane closed in this way and offenders can be handed a fixed penalty of up to £100 and three points.
The most serious cases are dealt with by more severe penalties or a court appearance.
Highways England, which manages the country’s motorways, has been working since 2016 to improve compliance with red X signs.
It has issued more than 160,000 warning letters to drivers who have either used sections of the hard shoulder when it was not designated as a running lane or failed to comply with a red X.
An amendment to legislation that will enable offenders to be punished after being caught by a remote or automated camera has not been completed.
Two-thirds (66%) of the 2,093 drivers surveyed by the RAC would support cameras being used to catch drivers in this way.
RAC spokesman Simon Williams said: “Red X signs are paramount in safety terms as any stricken driver who has not managed to reach an SOS area is at tremendous risk of being involved in a collision with vehicles that ignore them.
“Our research found drivers understand very clearly what red Xs mean, yet worryingly far too many appear to have driven under one, dramatically putting themselves at risk of encountering a stationary vehicle or a worker in their path and all the horrific consequences that could have.
“Highways England has been working hard to get the message across to drivers that they should not drive in lanes closed by red Xs, but there is still some way to go to ensure near total compliance.”