Theoretical minimum time

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Nigel
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Posts: 640
Joined: 06 Jan 2008, 19:04
Location: Woodford

Theoretical minimum time

Post by Nigel »

I thought would start a new thread on this topic, picking up the comments from other recent posts.

In particular, I would like to compare and contrast the analysis Marc Gawley has posted today on his website:
http://www.thetubechallenge.com/

with the analysis I posted a couple of years ago based on one of my attempts in 2012:
http://www.tubeforum.co.uk/forum/index. ... pic#p63496

Marc defines 44 segments covering all 270 stations once and once only with a journey planner time of 9h 24min. In effect, I did the same thing by recording the time travelling on LU trains to new stations to be visited - I have a comparable time for this of 9h 49min. The 25 minute difference can be explained by mine just being defined by the order I happened to visit them (not necessarily optimal in defining such segments) and mine includes travelling to a new station from a previously visited one, which Marc's definition would exclude. Also, of course, mine is actual time on the day, Marc's is JP timings.

Secondly, Marc has a time for linking up the segments and backtracking - 2h 9m plus 2h equals 4h 9min. The equivalent for my analysis is the sum of travelling to previously visited stations (1h 18m), non-LU public transport (43m) and external runs (1h 2m) - total of 3h 3m. To this should probably be added some of the 25 min excess to allow for travelling from previously visited stations to new stations. So again broadly agreeing, but Marc is possibly being a little conservative.

Average wait time. Marc has 1h 45m. In practice, my attempt had 3h 8m. I know my attempt was not optimal in this regard - some late running caused missed connections resulting in a longer wait than anticipated, a scheduled delay early on (since I was aiming for a completion not a record), and my times were set when a less frequent Saturday service was running. I think Marc's estimate is not unreasonable, although possibly a little optimistic taking account of the less frequent services which have to be caught.

Finally - I had 43m being held stationary by delays of more than one minute while on an Underground train. Now some of this is just waiting to get back on timetable (and hence already in Marc's JP times), but over half was from being stuck due signalling problems or knock on congestion from such problems.

In conclusion, I think these two methods are in broad agreement. This is why I was confident in saying that I did not believe a 15h 6m time was achievable, but in theory one not much longer than that may be possible. But that depends on the timetables slotting together nicely for the difficult/infrequent sections, and (an even bigger proviso) the service running as scheduled throughout the entire day.
hopeful traveller
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Posts: 1397
Joined: 15 Jul 2011, 16:28

Re: Theoretical minimum time

Post by hopeful traveller »

Planning ahead, I don't think I've done analysis on the current 270 configuration, but I am currently doing analysis on what will become the 272 configuration when the Croxley Rail Link opens (see you on the opening day!). The way I'm working it out is slightly different to Marc's fantastic analysis (having done a GCSE in Statistics recently I want to leave advanced Stats for a couple of months before studying it at A Level). I've already worked out a draft CRL route, I now just need to timetable it (like that's going to happen within the next two and half years), but the idea of the waiting times will vary, plus I have no idea how long Moor Park :arrow: Watford Junction will take. At the moment we're looking at roundabout the 18 hour mark, although I'm sure that can be brought down over the next two years.

You bar chart is interesting, Marc: it does look like you got a "perfect three", but 6 4-minute waits shows you're quite unlucky - and therefore I think the "theory" time could be lower. If you expanded the dataset I think the mode would come down to maybe two or one. Also, as your attempt was done in 2011, this was before TFL decided to **** up Olympia, so, in theory, you could be waiting 13 hours for a train there (between the last morning and first evening train). Indeed, eight of the current top 10 on the leaderboard have had a "regular" service (the other two being occupied by none other than a certain Geoff Marshall). Indeed, on exhibition days, it's now 30, not 20 minutes, between trains (unless TFL are ******* around again, see Thursday!). Your bar chart has 34 changes, interestingly, thanks for giving us a tad of a clue to your route!! What, interestingly, is the unweighted mean, unweighted mean excluding outliers, and median? I'm not too sure that the mode is, at first glance, the best way to go about things. Also, the mode does have an impact on the weighted averages, which can render them slightly superficial.

Before Geoff spammed this board with "trains" everywhere, he would often hypothesise about the fastest time, and, to my mind, it was always a bit on the high side, for he would say something around the lines of 16:10. I have always thought, on the current configuration, that a sub-16 is possible (which would be the first sub-16 record time since 1968, which was a 15:00! :o :shock: ) Is a 15:18 too low in reality? I suppose not, but that just takes one late-running train to ping it back by 10 minutes.

Anyway, fantastic pieces, both of you!
1 FNC Completion (PB: 17:18:18 with G Bryant, A Chilcraft, I MacNaughton)
4 Zone Ones (PB: 03:00:35 with G Bryant)
15 R15s (PB: 01:55:48 with T Cooling and R Jackson)
11 All Lines (PB: 00:44:03)
Winner of the 2014 Formula 1 Side Competition
RJSRdg
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Joined: 16 Mar 2015, 00:35

Re: Theoretical minimum time

Post by RJSRdg »

I would say based on my own calculations that for someone fitter than me a sub-16 would indeed be possible, especially once TCR reopens on the Central Line....
272 stations in 18:30:32
The only person to have used a boat in a Random 15 Challenge!
palkanetoijala31

Re: Theoretical minimum time

Post by palkanetoijala31 »

RJSRdg wrote:I would say based on my own calculations that for someone fitter than me a sub-16 would indeed be possible, especially once TCR reopens on the Central Line....
although it makes it essential to go through tcr on northern a good route planner works around this and doesn't lose any time at all ok I must admit its a pain in the arse but in all my routes at moment I link it up with a certain connection.
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