How to Build an Arch Bridge. An arch bridge is the oldest and strongest type of bridge; some of these bridges have survived from ancient Roman times. Most of these bridges are not built of stone anymore, but of structural steel members bolted together, possibly in combination with one of the other types of bridge design. Here are the details of how to build an arch bridge.
Design your bridge with the placement of the arch and roadway in mind. The type of arch most people think of is under the roadway, however some arch bridges are built so the roadway goes through the arch and is suspended from it. This would be a combination of an arch and suspension bridge.
Excavate and prepare the banks for the building process. This might include excavating to bedrock for placement of the ends, or abutments, of the arch, or placing concrete anchors to bear the weight of the arch and its load.
Construct the arch up from both banks. The arch will be completely unstable until both ends meet, so depending on the type of material, you can support your arch temporarily by using cables anchored into the banks or building a scaffolding to support it's weight. Build the arch with a material that is good under compression, since that's the type of load on an arch bridge.
Measure the bridge progression carefully. If the arch building is not kept to reasonable tolerances over a long length, the two sides might not meet in the middle, creating rather large and very expensive pieces of useless concrete or steel.
Connect the two ends of the arch bridge at the top and slowly remove the temporary bracing.
Build up the roadway from the bottom of the arch, or suspend it from the arch depending on which type of design you chose.
Pave your new arch bridge and enjoy your new roadway.
Building a bridge is a long, complicated and dangerous process. A building company experienced in the bridge-building process should do this type of work.