Temporary traffic lights were installed near to the railway bridge in Devonshire Road, North Shore, yesterday.
The restriction will be in place for at least two weeks, with repair work to the bridge set to take a total of 15.
If the lights lead to traffic chaos, the council will revert back to its original plan of closing the major route to southbound traffic. That idea was shot down by nearby traders, who said it would harm business.
The authority had planned to divert traffic along Warbreck Hill Road – where double yellow lines were painted over the weekend – and onto Plymouth Road, Poulton Road, Westcliffe Drive, and Talbot Road.
Diversion signs dug into the ground by council workers –after plans for a diversion were scrapped – will be covered up to avoid confusion, the council also pledged, though businesses said they feared the signs were an indication the lights trial was only being used to appease upset traders.
Work to repair the bridge is being done as part of an £11.3m project across Blackpool. Supporting steel beams, which have corroded over time, will be replaced.
Temporary traffic lights were put up at the bridge briefly in April, sparking chaos.
They were taken down by rail contractors working on the electrification of the train line on the orders of the council.