The Roman Roads of Ribchester
Construction of a Roman Road
Roman road construction was broadly similar right across the empire over hundreds of years, although the materials used would vary depending on what was available locally.
The main ridge, or agger, was formed from material from the two lateral ditches. This gives the road its distinctive profile which we can recognise today on many sections.
First, a broad ditch, the fossa, was dug. The base of the fossa was levelled and tamped down to form the pavimentum.
A foundation layer called the statument, consisting of layers of flat stones embedded in earth or clay, was laid on top of the pavimentum. This provided a firm foundation for the road as well as allowing drainage.
On top of the statument was a layer of sand or gravel called the rudus. This gave the road its resilience.
A top layer of gravel, the nucleus, formed the road's surface. This may have been bound with concrete, but not necessarily. In towns, the surface may have been paved, but that would not have been the case in the roads around Ribchester.
Note: Richard Mortimer of Cambridgeshire Archaeology has pointed out that the construction method described above applied to the Roman military roads, but there had been very successful and long-lived Iron Age societies before the Romans arrived, and these societies had roads and tracks of their own, many of which became 'Roman' roads. Even with the military roads, if there was no need to create the foundation they often wouldn't - a road over a good, hard gravel terrace would often only be de-turfed and ditched.