Theoretical times

[Root]

Whoa, two new topics in two hours!

I've seen lots of people posting on these forums about their "theoretical" times - based on TFL's JourneyPlanner. In some cases, their times are only a few minutes inside Neil & Geoff's record. You'd have to be very lucky to get a day with no delays.

What's the best theoretical time JourneyPlanner has given you? How confident are you that your time could beat the record?

I don't think it would even be worth trying an attempt if your theoretical time was much above 18 hours. Even half an hour can get eaten away by only a few bad connections - Olympia, Mill Hill East and Hainault all spring to mind. If you can get JourneyPlanner to give out a time under 18 hours, even considering it's inaccuracies, you may have a shot, but you'd still have to get lucky on the day.

What do you think?

[tubeguru]

I wouldn't touch JP with a barge pole.

[CrunchySaviour]

The thing with JP is that it will tell you how long you'll have to wait for a train in minutes. If you put a Zone One route in, my guess is that it would overestimate the time.

I've got an 18:23 route, which means little more than "I can probably get around the Tube in a day". It assumes... a 3 minute average change time with about 60 changes, I do believe.

What's the most reliable method of working out a theoretical time, short of actually going and doing it?

[tubeguru]

There isn't.

You can only produce average wait times based on the frequency of the service as outlined in the detaila for each line on the LU site.

Once a delay comes, the planning goes to buggery.

[hwolge]

I'd say there is a method that's pretty good. Get statistics for every line/station. Assume some statistical distribution (a normal distribution is good enogh) to match these. Do the same with runs(walks), buses and so on. Have a computer work it through. Get a distibutuion as a result.

I was amazed how close to reality it came out... (Had Earl's Court worked as expected, we'd would have hit our 60% mark - i.e. in 60% of all tries we would had been quicker, in 40% slower´). The overall average/standard deviation (with my partly guessed assumptions) was 18h17m+/-30m according to my calculations and I beleive them to be fairly accurate. This assumes "normal delays" (which we experienced a fair share of (West Harrow, Aldgate, Canons Park, Edgware Road, Finchley Central (for HB) - each at least 5 minutes more than expected). To be fair we also experienced a few "unexpected beneficial delays" (eg an H&C train that was 2 minutes late so we just made it instead of waiting another 6 minutes).

[jonny]

But Journey Planner, obviously, does only work if you have a perfect day but it does also overestimate some things. For example, Journey Planner will have you wait at Moor Park for 10 minutes for your Watford train when you know that you just run across the platform and you don't wait at all.

[hwolge]

You're right. When it comes to changes JP is quite pessimistic (obviously assumes slow pace walk). However, there is a definite risk that you miss the earlier Watford train. In my plan I had a 74% chance of making it...

[CrunchySaviour]

Christ.

So the Watford train usually leaves moments after the southbound train arrives at Moor Park?

Dodgy!

[nozzacook]

As a tool for roughing out a route JP works well but in the end once you have a polished route the only way to get a estimated time is with practice runs. This is when you find the bus froM Walthamstow to Leytonstone takes way longer than timetabled during midmorning to early afternoon JP will not take this into account.

[CrunchySaviour]

The bus from Leytonstone took ages on my attempt.

[Root]

As a tool for roughing out a route JP works well but in the end once you have a polished route the only way to get a estimated time is with practice runs. This is when you find the bus froM Walthamstow to Leytonstone takes way longer than timetabled during midmorning to early afternoon JP will not take this into account.

It's no more pessimistic than always. If you look at a timetable for a particular bus, from A to B might take ten minutes. JourneyPlanner will tell you it takes 20 minutes, because the buses are every ten minutes. On average, you're only going to have to wait five minutes, giving you a total time of 15.
The way JourneyPlanner works out bus journeys is retarded.

[hwolge]

If you look at a timetable for a particular bus, from A to B might take ten minutes. JourneyPlanner will tell you it takes 20 minutes, because the buses are every ten minutes. On average, you're only going to have to wait five minutes, giving you a total time of 15.
The way JourneyPlanner works out bus journeys is retarded.

UNLESS - I noted - when the bus time table (as PDF download) gives departure times as opposed to frequency. THEN JP gives the estimated journey time only (not including a worst case wait). Usually this applies to early mornings and late evenings.

[spoogie37]

I have just revised my theoretical route to take accout of the 90 second change at Moor Park (I had previously allowed ten minutes) and, to make the most of the time saving, I made some other revisions further on in the route. My theoretical time is now 18 hours 3 minutes.

As it stands the route doesn't include Regents Park as this is soon to close for refurbuishment - can someone remind me when and for how long please?

If I do the attempt for real it will be after T4 reopens but maybe I'll need to fit it in before RP reopens (though adding RP back in probably won't add too much to the time).

Thanks

[Root]

Regent's Park will be closed from the 5th of July 2006 to the 4th of June 2007. You'll still have to pass through the station though - you can't just alight at Baker Street when coming down the Bakerloo.

[spoogie37]

Regent's Park will be closed from the 5th of July 2006 to the 4th of June 2007. You'll still have to pass through the station though - you can't just alight at Baker Street when coming down the Bakerloo.

Thanks - I'm actually coming up the Bakerloo at this point, changing at Oxford Circus for Westbound Central Line. I guess I'll have to go on up to Baker Street and then Jubilee to Bond Street. Does mean the next train arrives at its destination at just the time the bus I need departs (ah well, maybe the bus will be a bit late ...)