On bridges I would try match style tactics using a flat method feeder and a small bolie or 8mm pellet as bait.
You will catch bream and tench but the carp should put in a appearance. I would try fishing to the point of the last island on bridges as you drive down the road in the middle. casting close to the island.
Keep the bait going in for the first hour casting every few minutes and the carp should turn up, the splasing of the feeder will attract them. This is probably a better way of catching them than sitting behind a bank of rods waiting all day using traditional carp tactics.