Roads are organised into a strict hierarchy. At the top is the motorway network for fast long distance travel and at the bottom small residential cul-de-sacs where vehicles might share the road space with local people on foot. Between these extremes there are at least three national categories (A, B & C).
A driver’s road atlas gives a feel of the road hierarchy in any location. It is easier to reduce traffic flows in a road that is lower down the hierarchy.
The same road network can also be understood as a series of junctions and the roads (known as links) between the junctions.