The Roman Empire built their roads as a way to protect their own interests and to help facilitate commerce throughout the empire. The earliest roads they built ran north and south to where troops were stationed. However as the Empire grew so did the network of roads.
How the Roads were Built
The roads were first proposed and then the cost was figured out. After the cost had been established private companies were allowed to bid on the project. Routes were then planned in a straight line following the topography of the land.
Once the route had been established work on the road began. A roadbed of 15 feet width-wise was cut into the ground about 2 or 3 feet deep along with drainage ditches along both sides. From there a foundation of rock and gravel was laid down and then compacted, from there a layer of sand was placed over top. Roads were then often metalled, which had nothing to do with any type of metal, but was instead topping the surface of the roads with a substance that can stand up against wear and tear and the weather.
Building Roads with Mountains in the Way
Although Romans usually built their roads to follow the contours of the land there were cases where that were simply not possible. Romans also occasionally cut into the hillsides to carve out a roadway. There were times when that too was impossible so Romans opted to go through the mountains. The Romans became expert tunnelers, a skill they later used in the building of their aqueducts.
Building Roads through Valleys
When roads had to cross deep valleys the Romans were able to apply their skills with arches and piers to create bridges that could cross them. These bridges required a very stable foundation so that they could support the weight of troops moving across them. To create these foundations the Romans dug down to the bedrock and then cemented the piers into the foundation.
Building Roads over Rivers
Romans used the same type of bridge over water as they did to cross valleys. In cases where the water wasn’t too deep a dam was built to divert water long enough for holes to be dug to and cement poured in to provide supports for the bridge. From there they could build their arches and then their bridges. In areas where the water was too deep it was necessary to use ferries.
