Fifty drivers a day are being caught speeding on the M65 between Burnley and Colne.
Police have reported that since the speed limit and enforcement cameras were reactivated after Christmas, the number of offences has risen from a handful each day to 50.
Lancashire County Council is currently carrying out work to upgrade the safety barriers on the hard shoulder and is warning drivers that breaking the average speed limit could have potentially serious consequences.
County Coun. John Fillis, Cabinet member for highways and transport, said: “It’s a real concern that so many drivers appear to be ignoring the 50mph average speed limit which is in place for workers’ safety.
“The work to replace the barriers on the hard shoulder between junction 10 and 14 is due to continue until the end of March.
“The speed limit was removed over the Christmas break but it’s now back in place. Unfortunately, the police have reported that since the New Year the number of people being caught by the average speed cameras has gone up considerably.
“Both traffic lanes are now completely open and the only barriers are on the hard shoulder, but it’s vital that we keep speeds low to protect the workers.
“I’d urge people to observe the speed limit, by breaking it they are putting at risk the lives of people who are simply doing their job.
“Offenders will be detected by the average speed cameras and may be fined and have points endorsed on their licence as a result, or be asked to attend a speed awareness course.”
Lancashire Constabulary’s assistant chief constable Tim Jacques, chairman of the Lancashire Partnership for Road Safety executive board, added: “We hope people take note of this important message. We would rather prevent speeding in the first place and keep workers – and motorists – safe than prosecute them.”
Work began in July 2015 to replace safety barriers on the hard shoulder of the M65 which, inspections have shown, are nearing the end of their life. Improvements to drainage and repairs to the road surface and fencing are being carried out at the same time.