The bridges will usually hold some walleye and at times, they can hold huge schools of walleye.  Bridges are popular options on lakes and rivers in deeper water and even shallower water.  Walleye love the rocky structures around the bridges.  You can find walleye in the slack water behind the bridge pilings and when the bite is aggressive, you can even find some walleye out in front of the pilings in the current when fishing a river.  Fish the bridges thoroughly until you find where the better bite will take place on any given day.