1
Determine what type of bridge you need for the situation. The common types are arch, suspension, truss, cable-stayed and beam types. If you're crossing a short span, you probably only need to build a beam or a small truss bridge. If you're crossing a deep ravine, an arch bridge might be the best choice. A bridge to span an ocean bay requires the very expensive suspension bridge.
2
Identify an ideal place to build the bridge. A lot of legwork goes into determining the ideal site to build anything, and when you're talking about something as expensive as a bridge, engineers are even more careful. The engineering team will send out surveyors, people who use electronic measuring devices to make a map of the general area. From this map, they will make calculations and determine the length and placement of the bridge.
3
Design the bridge. The engineer will take into account the potential traffic load of the bridge and use ASTM steel design manuals, computer programs and drafters to aid in the bridge designing process. The materials chosen should also take into consideration the inspection and upkeep costs after the bridge is built.
