National Routeing Guide - Permitted Routes

Permitted Routes

Three types of routes are acceptable: direct trains, shortest route, or mapped routes. The first two are simple and outlined above. Almost the whole of the routeing guide is taken up with specifying the third for the entire country.

Principle

• The UK rail network has stations which are deemed routeing points. These are principal stations, or junctions, shown in green on the adjacent map. Groups of nearby stations are sometimes treated as a single routeing point (e.g. "Portsmouth Stations").
• All other stations are associated with one or more routeing points. When a station has more than one routeing point available, fares from each routeing point to the other station are compared, and only those where the fare is equal to or cheaper than the overall journey are deemed appropriate.

Journeys The rules can be summarised thus:

• Where both stations have a common routeing point, only the shortest route between them is valid.
• Otherwise, for every pair of routeing points the guide lists at least one map (or series of maps) that may be used to get from one point to the other. These maps in turn define which lines are valid between routeing points. Any route on these maps is valid so long as it does not involve doubling back (passing through the same station twice), unless there is a specific easement allowing doubling back, or the doubling back is done within a station group for the purposes of interchange.
• Some ticket types have specific route restrictions, e.g. 'not London', or prescriptions e.g. 'Reading'.

The guide allows many journeys which one might not expect. Travelling from Cardiff to Cambridge via Swansea, Shrewsbury, and Birmingham is acceptable, for instance, rather than simply via London. Generally there are a large number of permitted routes which are rarely used because they are inconvenient, but which are nevertheless legitimate. Some travellers have reported being charged extra for 'special' routes, however.