A truss arch bridge

Bridge

A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...

combines the elements of the truss bridge

Truss bridge

A truss bridge is a bridge composed of connected elements which may be stressed from tension, compression, or sometimes both in response to dynamic loads. Truss bridges are one of the oldest types of modern bridges...

 and the arch bridge

Arch bridge

An arch bridge is a bridge with abutments at each end shaped as a curved arch. Arch bridges work by transferring the weight of the bridge and its loads partially into a horizontal thrust restrained by the abutments at either side...

. The actual resolution of force

Force

In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...

s will depend upon the design. If no horizontal thrusting forces are generated this becomes an arch-shaped truss, essentially a bent beam — see moon bridge

Moon bridge

A moon bridge is a highly arched pedestrian bridge, which in its wooden form may require the walker to initially climb and also when descending. This type is associated with gardens in China and Japan...

 for an example. If horizontal thrust is generated but the apex

Apex (geometry)

In geometry, an apex is the vertex which is in some sense the highest of the figure to which it belongs.*In an isosceles triangle, the apex is the vertex where the two sides of equal length meet, opposite the unequal third side....

 of the arch is a pin joint, this is termed a three-hinged arch - see The Iron Bridge

The Iron Bridge

The Iron Bridge crosses the River Severn at the Ironbridge Gorge, by the village of Ironbridge, in Shropshire, England. It was the first arch bridge in the world to be made out of cast iron, a material which was previously far too expensive to use for large structures...

 for an example.