|Table of contents|
2 Main trunk routes in Scotland
3 Two-digit "A" roads
4 Other "A" roads
5 "B" roads
7 Ancient roads
8 See Also
Main trunk routes in England
Main trunk routes from London have single digit numbers, starting with the A1 which heads due north. The numbering continues sequentially in a clockwise direction, thus:
Main trunk routes in Scotland
Similarly, in Scotland, main trunk routes radiating from Edinburgh have single digit numbers, thus:
Two-digit "A" roads
These radials are supplemented by two-digit codes which are routes that are slightly less important (but may still be classified as trunk routes). These routes are not all centred on London, but as far as possible follow the general principle that their number locates them radially clockwise from the associated single digit route. For example, the A10 (London to Cambridge) is the first main route clockwise from the A1, the A11 (London to Norwich) is the next, and so forth. Some of the more important ones are:
Therefore the motorways are designated "M" roads and are numbered to match the existing main radials which the motorways in general follow. One exception is the M5 whose closest A-road equivalent is the A38. The numbering of two digit motorways is based on a zone system formed by the 1-digit motorways, not on the zone system formed by the 1-digit A-roads. The other exception is the M6 Toll a recently opened toll motorway which bypasses the busiest section of the M6 around Birmingham.
Some ancient routes, such as Roman roads, travel for great distances and have a single modern number for the majority of their length (e.g. the A5 for the Roman road Watling Street). Others, such as the pre-Roman Icknield Way and the Roman Fosse Way are nowadays rather patchy and where a modern road exists, are numbered according to the local scheme.