All four stoplights at the intersection of US Route 41 and Old Elm in north suburban Lake Forest will be flashing red come Monday.
A temporary traffic control box will be in place until the repairs are complete, according to a statement from the Illinois Department of Transportation.
The repairs come after a vehicle hit the traffic signal cabinet at the intersection, IDOT said.
The intersection, which is interconnected with the Union Pacific Railroad, will continue flashing until testing is finished with the railroad. There are no road closures and railroad gates are functioning normally, IDOT said.
