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Re: Stations List

Posted: 05 May 2020, 22:22
by ANDY_JS
Sorry if I'm going off topic. I was wondering — does anyone know what the average journey time is across the entire Tube network for individual journeys between two stations? I'm guessing it's about 2.6 or 2.7 minutes but I haven't actually timed all the journeys. Not yet anyway. :D

I'd also be interested to know how many distinct individual journeys are possible using the 270 tube stations. Obviously it would depend on whether you count a journey between station A and station B twice going in each direction or just count it as one. (I think I'd count it as just one journey instead of two). I might have a go at working it out with all the spare time we've got at the moment.

Re: Stations List

Posted: 06 May 2020, 12:16
by xcooler123
The Working Timetables (WTT, which can be found on the TfL website) have the average off-peak times between stations, this is a useful starting point.

Re: Stations List

Posted: 06 May 2020, 20:19
by RJSRdg
In answer to your second question - a lot!

Discounting alternative routes between stations (e.g. Edgware Road-Tower Hill clockwise or anticlockwise, or using any of the myriad of routes across the middle), if we start at say Upminster, there are 269 other stations you can travel to. From Upminster Bridge, there are also 269 stations you can travel to, but we've already counted the journey between Upminster and Upminster Bridge, so there are 268 new destinations.

In total, the number of pairs of stations is 269+268+267+265+....+1

= 269(269+1)/2
= 36,315

Then as I say, you have to count alternative routes, and you would have to come up with some rules for those. I'd suggest the following:

1) Once your train stops at your destination station, that's it, you can't carry on, turn round and come back again (other than where the Met and Jubilee parallel each other, or the Picc and District, and one line runs non-stop). Likewise you can't pass through your start station again (so Southgate - Cockfosters via Terminal 4 is out).
2) Journeys must be carried out completely by Tube - walking between stations, buses, taxis, boats etc don't count, nor do other forms of rail.

Re: Stations List

Posted: 07 May 2020, 09:10
by michael_churchill
RJSRdg, I'm afraid your maths is wrong, it involves multiplication, not adding...

Say you can choose any of the 270 stations to start from, for each one you can then choose any of the other 269 to visit next. So far that's 270 x 269 = 72,630.
For each of those 72,630, you can then choose from 268 next. 270 x 269 x 268 = 19,464,840.
Carry on and you get 270 x 269 x 268 x 267 x ... x 4 x 3 x 2 x 1, known as "270 factorial" or "270!"
Google tells me that number has 541 digits and starts with a 6!

Anyway, I'm not sure that's what ANDY_JS was asking...

I think he meant, how many different journeys from A to B are there, which would be 72,630 or 36,315 if you consider B to A as the same.
Which is OK for simple journeys like Upminster to/from Upminster Bridge. But for Upminster to/from Chesham, how many routes can you take?

Re: Stations List

Posted: 07 May 2020, 18:08
by RJSRdg
michael_churchill wrote: 07 May 2020, 09:10 RJSRdg, I'm afraid your maths is wrong, it involves multiplication, not adding...

Say you can choose any of the 270 stations to start from, for each one you can then choose any of the other 269 to visit next. So far that's 270 x 269 = 72,630.
For each of those 72,630, you can then choose from 268 next. 270 x 269 x 268 = 19,464,840.
Carry on and you get 270 x 269 x 268 x 267 x ... x 4 x 3 x 2 x 1, known as "270 factorial" or "270!"
Google tells me that number has 541 digits and starts with a 6!

Anyway, I'm not sure that's what ANDY_JS was asking...

I think he meant, how many different journeys from A to B are there, which would be 72,630 or 36,315 if you consider B to A as the same.
Which is OK for simple journeys like Upminster to/from Upminster Bridge. But for Upminster to/from Chesham, how many routes can you take?
Michael - that's what I calculated - the number of "pairs" of stations you can travel between., and indeed got 36,315...

Your calculation of 270! is the number of different orders you can write 270 Tube stations in!

Re: Stations List

Posted: 08 May 2020, 15:41
by ANDY_JS
Thanks for the replies, although I haven't looked at them yet because I wanted to work out the answers without being influenced.

I'm getting the following: there are 314 possible different journeys between two tube stations in one direction, which means 626 journeys if you count both directions since you can only go in one direction for two journeys, namely between Hatton Cross and Heathrow Terminal 4, and between Heathrow Terminal 4 and Heathrow Terminals 2 and 3. This includes taking into account the journeys you can do on the Metropolitan Line on the various slow, semi-fast and fast services, and also the fact that sometimes you can arrive and leave at/from Turnham Green station on the Piccadilly Line.

Re: Stations List

Posted: 10 May 2020, 14:53
by RJSRdg
Ah, so you're talking about journeys between adjacent tube stations (I got just counted and got 309 but the map I was using didn't show the fast and semi-fast services on the Met, so I didn't count them).

Did you include Kennington - Kennington?