In order to facilitate navigation and maintenance, every classified road in Britain is allocated a road number. Each number is prefixed with a single letter indicating the road class. Additionally, A-roads with motorway restrictions are suffixed with the designation "(M)".
Almost all road numbers as unique, and most designate a virtually continuous route between centres. However, because there is no definitive road number listing, not every number is guaranteed to be absolutely unique. In addition, as the road network has developed, many lengths of road which have the same number have become disconnected from each other.
Unclassified roads are sometimes allocated a road number prefixed with the letter C, although this information is not recorded consistently across the country and therefore is not exposed in MAST.
Road number recording in STATS19
The main road is defined as the road which has priority. For roundabouts and signal controlled junctions, the main road is the one with the highest class of all the roads entering the junction. If roads are of equal class then the road with the lowest number is deemed to be the main road.
Road number filtering in MAST
Any MAST report can be filtered by road number. While it is possible to filter by road number using the Crash Location Route dimension, the easiest method is to use the Filter by Road Number Action Link at the top of the Edit Report page.
This link allows users to type the desired road numbers, including the class prefix and suffix as appropriate. A list of all corresponding road numbers appears, from which a number can be selected. It is possible to create filters based on multiple road numbers, and numbers can be added to or removed from the filter at any time.
Road number filters can be combined in any way with other filters.