Drivers are being warned to check signs at the Army and Navy flyover in Chelmsford as timings are readjusted ahead of Christmas.
A six-month trial of changes to the timings of traffic flow on the single-lane flyover will end on Monday, 5 December.
Changes to the trial timings will be staggered over the coming weeks to help drivers adjust safely.
Cllr Eddie Johnson, Essex County Council Cabinet Member for Highways and Transport, said: “Over the past six months we have explored ways of adjusting the timings to help traffic flow in central Chelmsford and further afield.
“The trial has given us useful insights into the positive and negative effects switching the traffic flow can have.
“I would advise drivers to take extra care as they approach the flyover over the coming weeks and only use it when they are certain from the electronic signs that it is open in their direction.”