Structures

Ouse Bridge, York

The bridge replaced a previous stone structure on the same site which stood for 6 centuries. It has 3 arches. It took 10 years to build.

Arch bridges are one of the oldest types of bridges and have great
natural strength. Instead of pushing straight down, the weight of an
arch bridge is carried outward along the curve of the arch to the
supports at each end. These supports, called the abutments, carry the
load and keep the ends of the bridge from spreading out.

When supporting its own weight and the weight of crossing traffic, every
part of the arch is under compression. For this reason, arch bridges
must be made of materials that are strong under compression.
The Romans used stones. Today materials like steel and pre-stressed
concrete have made it possible to build longer and more elegant arches,
typically, modern arch bridges span between 50 and 300 metres.

An arch can cover a wider span than an unsupported beam bridge. To cover a wider distance it is only necessary to add more arches. Ouse bridge has 2 arches of equal span and one narrower one.

Arch bridges are always under compression