So if you use the maps system. I.e for a london to bristol.. I could either go london paddington to bristol,london waterloo to sailsbury and up that way to bristol.. Is this how the system works.
Yes. For London Group - Bristol Group, the maps are:
London Group Bristol Group LA LA+WX WC WR WR+WX
Map LA allows
Paddington - Hayes - Slough - Reading - Westbury - Chippenham - Bath - Bristol.
That's relatively straightforward. A map combination, such as
LA+
WX is more complex. The instructions require us to start from, say, London on one map, change to the other somewhere, then end in Bristol on that map.
First, look for the points where the two maps coincide. These are Clapham Junction, Reading, Westbury, Bath, Bristol, Newport, Cardiff and Bridgend. There will be other possible points - nothing in the guide says that the change from one map to the other must be at a routeing point - but let's keep it simple for the moment. We can eliminate Newport, Cardiff and Bridgend because they would need doubling back.
By my calulations, we can now find these permitted routes:
- [LA] Paddington - Kensington O - Clapham Jn. [WX] Clapham Jn - Salisbury - Westbury - Bath - Bristol.
- [WX] (Waterloo or Victoria) - Clapham Jn. [LA] Clapham Jn - - Kensington O - Slough - Reading - Westbury - Chippenham - Bath - Bristol.
- [LA] Paddington - Slough - Reading. [WX] Reading - Staines - (Hounslow or Richmond) - Clapham Jn - Salisbury - Westbury - Bath - Bristol.
- [WX] (Waterloo or Victoria) - Clapham Jn - (Hounslow or Richmond) - Staines - Reading. [LA] Reading - Westbury - Chippenham - Bath - Bristol.
- [LA] Paddington - Slough - Reading - Westbury. [WX] Westbury - Bath - Bristol.
- [WX] (Waterloo or Victoria) - Clapham Jn - Salisbury - Westbury. [LA] Westbury - Chippenham - Bath - Bristol.
- [LA] Paddington - Slough - Reading - Westbury - Chippenham - Bath. [WX] Bath - Bristol.
- [WX] (Waterloo or Victoria) - Clapham Jn - Salisbury - Westbury - Chippenham - Bath. [LA] Bath - Bristol.
There are rather a lot of permitted routes between London and Bristol!