Work is due to take place next week to repair a fault to a set of traffic signals on Accrington Road near Whalley.
The fault developed at the end of last week on the lights at the junction of the A671 Accrington Road, the main road between Whalley and Padiham, and the B6246 Accrington Road which connects Whalley to the main road.
The traffic signals have been switched off and temporary lights, along with a temporary 40mph speed limit, have been put in place until repairs can be completed.
Martin Porter, principal network planning officer, said: "We're sorry for the inconvenience to people's journeys due to the fault which has developed on these traffic lights.
"Work is due to start on Tuesday to replace the faulty cable. The roads will remain open, however the work will involve digging a trench across the main road (A671 Accrington Road) and we'd ask people to be cautious on their approach to the junction as the traffic management will vary as the work progresses.
"We expect that, as long as no further issues are encountered during the work, it will take no longer than a week."