Ancient Roman Bridges and Arches

The Romans knew that crossing rivers was often the most difficult part of a journey by road. People might get wet or lose possessions when crossing, and if the river was particularly full there might be a long delay.

Fords could be built up where the river was wide and shallow. Large quantities of stone and rock would be dumped into the river to form a firm foundation. On top of this was laid a flagstone surface, like an underwater road.

Bridges were more effective where rivers were deeper or narrower. A narrow stream could be crossed by a single stone arch, which supported a humped road surface above.

Wider rivers had to be crossed by bridges with more than one arch. Each arch was supported midstream by an artificial tower built up from the riverbed.

First the engineers hammered a circle of wooden stakes into the riverbed to form a watertight compartment. The water was pumped out and workmen dug out the riverbed to remove loose mud and reveal a firm surface.

A stone tower, called a pier, was then built up to stand about 3 metres above the river surface. The tower was usually wider and stronger at and below the water surface so that it could withstand floods.

On important roads the bridge was completed by building a stone arch between each pier. On less important roads wooden beams connected the piers. The road surface was then built on top.

 

The Romans sometimes built large arches over roads. These had no practical purpose, but were ornamental structures built to mark boundaries or commemorate famous events.

At Richborough in Kent there was a vast arch over the road that led up from the docks to the fort. This was the main military port for Britain. All soldiers entering or leaving Britain had to march through this arch.

In Rome a series of triumphal arches were built over the sacred road. These stone arches were decorated with carvings of battles and campaigns won by the general who was being honoured in the triumph (see page 202).

 Photo shows :

The Roman bridge Pont Julien in southern France is a three arched bridge built in 3 BCE over the Calavon river on the Via Domitia, an important Roman road that connected Italy and Spain through the Roman province of Gallia Narbonensis.