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Exeter–London Permitted Routes

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Kilopylae

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A friend asked me to try and map the Permitted Routes from "Exeter St Davids to London" (Exeter Group to London Group) and this was the end product.

Want to go validly from Exeter St Davids to Cannon Street? Better take a detour via Warminster!
 

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Nunners

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Are the routes into Waterloo not then valid into Cannon Street via Waterloo East and London Bridge?
 

JB_B

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Are the routes into Waterloo not then valid into Cannon Street via Waterloo East and London Bridge?


Yes - I think that's right - the shortest route from Exeter St Davids to Cannon Street wholly by rail ( which leaves the SWML at Wimbledon to go via Peckham Rye ) is longer than the standard route using the walking link between Waterloo and Waterloo East - so both those routes are valid by the shortest route rule.

... Want to go validly from Exeter St Davids to Cannon Street? Better take a detour via Warminster!

The routes mentioned above both use the West of England line via Yeovil Junction ( which is also a mapped route on map LE ) - I don't think you need to go via Warminster.

A friend asked me to try and map the Permitted Routes from "Exeter St Davids to London" (Exeter Group to London Group) and this was the end product.

Want to go validly from Exeter St Davids to Cannon Street? Better take a detour via Warminster!

These are really impressive. For journeys like this just enumerating the permitted routes isn't a trivial task - combining them into a single human-readable diagram is tricker still. How long did it take you?
 
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Ianno87

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A friend asked me to try and map the Permitted Routes from "Exeter St Davids to London" (Exeter Group to London Group) and this was the end product.

Want to go validly from Exeter St Davids to Cannon Street? Better take a detour via Warminster!

How fantastic would it be to (somehow) create a map like that for any pair of stations automatically?!
 

infobleep

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A friend asked me to try and map the Permitted Routes from "Exeter St Davids to London" (Exeter Group to London Group) and this was the end product.

Want to go validly from Exeter St Davids to Cannon Street? Better take a detour via Warminster!
May I just say, speaking as a professional cartographer here, that is really good.
 

yorkie

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How fantastic would it be to (somehow) create a map like that for any pair of stations automatically?!
It would be impossible at that level of quality/detail.
I am aware of, and have access to, programs that do create maps, but not ones that look like this.
 

30907

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Superb! Just a couple of thoughts.

1. Two routing queries - which I haven't checked:
is Bath-Westbury-Chippenham specifically permitted despite the double-back from Trowbridge?
is Yeovil Jn-London via Westbury (and Salisbury?) also permitted

2. Presentation - you could de-emphasise the Virginia Water-Clapham Jn routing by putting "Twickenham/Richmond OR Hounslow" and reducing the number of individual routes that way by half.
(You could do similar with Weston SM, but I'm not sure that's so important.)
 

JB_B

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is Bath-Westbury-Chippenham specifically permitted despite the double-back from Trowbridge?

Trowbridge is a member of Westbury Routeing Point Group so that's not a problem.


is Yeovil Jn-London via Westbury (and Salisbury?) also permitted

You'd think it might be given the other valid options but no, as far as I can see that's not a mapped route for Exeter Group to London Group (and obviously it's way over shortest route).
 

Kilopylae

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Are the routes into Waterloo not then valid into Cannon Street via Waterloo East and London Bridge?
That's me showing my inexpert knowledge of London suburban lines — I've checked the LSE map and you're right that the routes via Clapham Junction are valid from Waterloo East to London Bridge and Cannon Street under the same principle that makes them valid from Waterloo East to Charing Cross.

Yes - I think that's right - the shortest route from Exeter St Davids to Cannon Street wholly by rail ( which leaves the SWML at Wimbledon to go via Peckham Rye ) is longer than the standard route using the walking link between Waterloo and Waterloo East - so both those routes are valid by the shortest route rule.
Tickets are issued from Exeter St Davids to London Terminals and so the shortest route rule can't be used to make a non-mapped route via Peckham Rye or Herne Hill Permitted.

The routes mentioned above both use the West of England line via Yeovil Junction ( which is also a mapped route on map LE ) - I don't think you need to go via Warminster.
Peckham Rye is a routeing point on map WC and the only map rule for Exeter Group to London Group that uses WC is WE+WC. WE and WC only overlap at Castle Cary and Westbury, and the only routes from Castle Cary/Westbury to London Group on WC are via Warminster routeing point, Salisbury, Basingstoke etc.

These are really impressive. For journeys like this just enumerating the permitted routes isn't a trivial task - combining them into a single human-readable diagram is tricker still. How long did it take you?
Working all the routes took about a week (in between real life!) iirc but it was a few months back. Making the diagram took about 15 hours using MS Paint over a few days.

Superb! Just a couple of thoughts.

1. Two routing queries - which I haven't checked:
is Bath-Westbury-Chippenham specifically permitted despite the double-back from Trowbridge?
is Yeovil Jn-London via Westbury (and Salisbury?) also permitted

2. Presentation - you could de-emphasise the Virginia Water-Clapham Jn routing by putting "Twickenham/Richmond OR Hounslow" and reducing the number of individual routes that way by half.
(You could do similar with Weston SM, but I'm not sure that's so important.)
1.1 The nuance here is that it doesn't require doubling back on the map, as map GW is drawn not to show the double-back. The routeing maps connect up the routeing points (and a few interchange points added to avoid irregularities) with straight lines. As you can trace the route on the map without doubling back, I would interpret it as a Permitted Route. Not like anyone would ever want to do it in real life anyway, though. Edit: as JB_B points out, the reason why it's drawn that way on the map is that Trowbridge is part of Westbury Station Group, so it's allowed under the group stations rule.

1.2 Not that I saw on the maps, could you let me know where to look?

2. I think I wanted the 'neatness' of having precisely one line for each route, but that's probably a shout for making it more human-readable.
 

30907

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Trowbridge is a member of Westbury Routeing Point Group so that's not a problem.

You'd think it might be given the other valid options but no, as far as I can see that's not a mapped route for Exeter Group to London Group (and obviously it's way over shortest route).
Thanks for clarifying. Interestingly, Paddington-Reading-Yeovil Jn via Castle Cary is 6m longer than Waterloo-Basingstoke-Yeovil, but only about 2m longer than from Paddington via Basingstoke (I wasn't serious about Salisbury-Westbury-Yeovil!).
 

JB_B

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... Tickets are issued from Exeter St Davids to London Terminals and so the shortest route rule can't be used to make a non-mapped route via Peckham Rye or Herne Hill Permitted. ...

I'm not sure that's quite right. The tickets are issued to London Terminals fares group. My understanding is that, in general, where tickets are issued to/from a (fares) group of stations they are valid on all permitted routes to/from any one of that fares group's members. The permitted routes include any mapped routes, shortest routes (+3 miles) and direct trains.

For example, tickets for journeys from Ledbury to Worcester Shrub Hill are issued to Worcester Stations (fares group). This isn't a mapped route but journey planners will offer tickets to Worcester Stations on indirect services (see: https://ojp.nationalrail.co.uk/service/timesandfares/LED/WOS/041120/1000/dep ) - since it's neither direct nor mapped that validity must rely on the shortest route rule.
 

Haywain

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For example, tickets for journeys from Ledbury to Worcester Shrub Hill are issued to Worcester Stations (fares group). This isn't a mapped route but journey planners will offer tickets to Worcester Stations on indirect services (see: https://ojp.nationalrail.co.uk/service/timesandfares/LED/WOS/041120/1000/dep ) - since it's neither direct nor mapped that validity must rely on the shortest route rule.
It can’t be a mapped route as Worcester Group is the appropriate routing point for Ledbury, and it’s difficult to see how a train from Ledbury to Worcester Foregate Street can be described as anything other than direct. Other journeys within the RP group are permitted anyway. If you want to prove something about how the routing guide works, I think you need a better example than the one you have chosen.
 

JB_B

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It can’t be a mapped route as Worcester Group is the appropriate routing point for Ledbury, and it’s difficult to see how a train from Ledbury to Worcester Foregate Street can be described as anything other than direct. Other journeys within the RP group are permitted anyway. If you want to prove something about how the routing guide works, I think you need a better example than the one you have chosen.

Sorry if the logic isn't clear. Just to recap: the OP implied that the shortest route rule doesn't apply to tickets issued to/from (fare) groups of stations - that's what I'm taking issue with.

I deliberately chose a non-mapped route where indirect journeys are valid ( the journey in question is Ledbury to Shrub Hill - so most journey require a change - the ticket is Ledbury to Worcester Stations ) - by exhaustion that leaves the shortest route rule. The point of the example is to show that shortest route rule does apply for tickets to/from fare groups.
 

Haywain

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Sorry if the logic isn't clear. Just to recap: the OP implied that the shortest route rule doesn't apply to tickets issued to/from (fare) groups of stations - that's what I'm taking issue with.

I deliberately chose a non-mapped route where indirect journeys are valid ( the journey in question is Ledbury to Shrub Hill - so most journey require a change - the ticket is Ledbury to Worcester Stations ) - by exhaustion that leaves the shortest route rule. The point of the example is to show that shortest route rule does apply for tickets to/from fare groups.
And I say it isn’t at all relevant because there is absolutely no alternative route.
 

JB_B

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And I say it isn’t at all relevant because there is absolutely no alternative route.


Ummm.. I can agree that it's certainly the only permitted route ( there are alternative routes but none of them permitted ).

Why is it a permitted route...?

Is it mapped? No.

Is it on a direct train? Not for the majority of journeys which require a change of train.

Conclusion: for those indirect journeys it's a permitted route because of the shortest route rule.
 

yorkie

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The shortest route from Exeter St Davids to London Bridge (from where you could continue to Cannon St) appears to be 177.04 miles.

The route via Salisbury, Wimbledon & Tulse Hill appears to be more than 3 miles longer than this, at 183.68 miles.
 

Class800

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Yeovil to Salisbury via Westbury is used as a diversionary route sometimes if the line is closed via Templecombe - tickets are valid that way when the diversion is operating
 

yorkie

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Yeovil to Salisbury via Westbury is used as a diversionary route sometimes if the line is closed via Templecombe - tickets are valid that way when the diversion is operating
If it's not a mapped route, or within 3 miles of the shortest route, it's valid under the direct trains rule, though this may not work for a longer journey involving a change of trains.
 

Haywain

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Ummm.. I can agree that it's certainly the only permitted route ( there are alternative routes but none of them permitted ).

Why is it a permitted route...?

Is it mapped? No.

Is it on a direct train? Not for the majority of journeys which require a change of train.

Conclusion: for those indirect journeys it's a permitted route because of the shortest route rule.
You are missing the point of my comment, which is that this is a very poor example. Yes, it is the shortest route and that is why it is permitted. It is not mapped because only one routeing point is involved. There are many direct trains to the routeing point and the connecting journey is between members of the routeing point (which are also members of a fares group) which are permitted regardless.
 

Kilopylae

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If it's not a mapped route, or within 3 miles of the shortest route, it's valid under the direct trains rule, though this may not work for a longer journey involving a change of trains.
Yorkie is completely right. They will often also add special easements in the case of planned diversions (consider easement 700914, "During engineering works between Exeter and Taunton from 28 September to 02October 2020, tickets priced on (00000) ANY PERMITTED, (00203) GWR SLEEPER &GWR, (00411) AP SLOUGH, (00700) NOT VIA LONDON, (00810) NOT VIA READING,(00820) GW ONLY and (00842) VIA TAUNTON will be valid on Great Western Trainsservices via Honiton, Yeovil and Castle Cary. This map easement will apply in bothdirections"). I would assume this is to make sure that journey planners work correctly.
 

yorkie

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Yorkie is completely right. They will often also add special easements in the case of planned diversions (consider easement 700914, "During engineering works between Exeter and Taunton from 28 September to 02October 2020, tickets priced on (00000) ANY PERMITTED, (00203) GWR SLEEPER &GWR, (00411) AP SLOUGH, (00700) NOT VIA LONDON, (00810) NOT VIA READING,(00820) GW ONLY and (00842) VIA TAUNTON will be valid on Great Western Trainsservices via Honiton, Yeovil and Castle Cary. This map easement will apply in bothdirections"). I would assume this is to make sure that journey planners work correctly.
Yes those route restrictions would otherwise trump the direct trains rule.

The more restrictive fares become in this regard, the more easements are required

Likewise if the Routeing Guide becomes more restrictive.
 

Kilopylae

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I don't really like the use of restrictive fares to limit routes like that, but that's a topic for a separate thread. Either way, diverted routes are kind of irrelevant anyway; during severe disruption, nobody has ever been turned away from an advertised diverted train (like a GWR to London running through Yeovil Junction) on the basis of a routeing technicality.
 
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