Drivers say they fear for their lives queuing up to get off the M6 at Leyland because of jams on both exit slip roads.
Frightened motorists have complained that problems with traffic lights onto Leyland Lane are causing tailbacks along the inside lane of the north and southbound carriageways.
Daryl Snape, who uses the motorway every day to get to and from work at Walton Summit, said: “Someone is going to get killed – it’s a tragedy waiting to happen.”
And another commuter, Chris Walmsley, added: “It’s terrifying. We’re like sitting ducks waiting to get off with huge trucks thundering past.”
County council engineers have been sent to the junction to assess the problems, which highways chiefs believe could be down to faulty traffic sensors in the new surface of the slip roads.
But they have warned it could take time to resolve the problem.
South Ribble councillor Claire Hamilton has written to MP Seema Kennedy in a bid to speed up the repair work and relieve the danger.
She said: “It needs immediate attention or I fear the problem will only get worse. It’s an accident waiting to happen.”
Martin Porter, principal network planning officer for Lancashire County Council, said: "The slip roads at this junction have recently been resurfaced by Highways England.
"We suspect the traffic sensors in the slip road, which are fixed into the surface and help to control the traffic lights, may not be operating properly following this work. We're discussing this with their engineers to resolve the issue.
"In the meantime, our signal engineers are monitoring the situation and adjusting times of traffic lights at the junction to try and reduce the queues. However, this is a complex process and may not result in an immediate improvement as the traffic lights at three very busy junctions close to the motorway exit have to work together."