Request stops: timetabling and other questions

[70014IronDuke]

A few questions on request stops if I may, starting with timetabling (hence I put it into this sub-section).

If you have just one or two request stops in a service, I would assume the planners must assume 'the worst' - ie the train is timed to stop, and if it does not need to do so, then the minute or 90 seconds* saved by not stopping just becomes addtional recovery time.
* I guess that is the kind of net savings on most lines that have request stops in the timetable?

But what happens on lines that have multiple request stops, eg the Heart of Wales or Far North line? Is it the same 'worst case' scenario applied, or do the planners say, for example, well, between corssing points X and Y, we have four request stops. On most days, at worst, only two stops are needed, so we time the train for two stops - and if, on some freak days, the train has to stop at all four stations, it will just lose 3-4 minutes between X & Y? And no delay will be attributed to the driver?

And how do train crew view request stops? Do you just get used to them, or do they introduce extra concern? eg - for a driver - what if I don't see a passenger waiting at night? and for a guard - what if I forget a passenger needs to alight?

And what about some stations where only some services, eg outside the peaks, are request stops? Thanks for insights and thoughts.

 

[The Planner]

Normally a request stop is a stop with no dwell. You then add recovery time approaching the next booked stop and wait time if no stops occur prior to this.

 

[Wilts Wanderer]

I think the HOWL is the most difficult due to the chains of 7-8 request stops between each mandatory stop. Other than recovery time, the other way to do it is to advertise successive stops earlier and earlier against 'WTT' time, therefore as the train skips stops it does not end up running earlier than advertised by accident. The downside being when it does have to call at several stops in a row, it appears to run late, but in practice is just following working vice public timings and will recover it at the next mandatory stop.

 

[70014IronDuke]

Normally a request stop is a stop with no dwell.

So that means a minute or 75 secs or what? IS there a standard time? Or do you calculate one for each stop, depending on line speed and stock used?

You then add recovery time approaching the next booked stop and wait time if no stops occur prior to this.

So this means that, in a 'normal, worst-case" scenario - ie the train is required to stop at every stop for alighting or joining passengers, but no added complications - any train booked over a line with request stops should still be able to keep time. And the advantage of request stops is merely that the time saved can be used as recovery time for any unscheduled delays - otherwise, it's lost as waiting time?
Plus, I suppose, a little saving on fuel if the train doesnt have to stop and a bit on wear and tear.

 

[70014IronDuke]

I think the HOWL is the most difficult due to the chains of 7-8 request stops between each mandatory stop. Other than recovery time, the other way to do it is to advertise successive stops earlier and earlier against 'WTT' time, therefore as the train skips stops it does not end up running earlier than advertised by accident. The downside being when it does have to call at several stops in a row, it appears to run late, but in practice is just following working vice public timings and will recover it at the next mandatory stop.

Thanks, but am a bit confused. Are you saying "it is done this way, sometimes" or are you saying "it could be done this way" ?

 

[edwin_m]

I did some journey time modelling on the HoWL for a study a few years back, including comparing my predicted times with actual ones while travelling the route. Nobody could explain the logic behind the timetable, I got the impression it was set up "back in the mists of time" but as it seems to work they just leave it alone.

It appears the trains would run close to time if they called at every request stop with 30s dwell time. However if a train actually stops it's unlikely to be less than 45s (for a 153, 150 may be a bit better) so it will run slightly late if multiple request stops are observed. This is likely to be caught up during the rather long scheduled dwell time at the next passing station. I can't comment on practice on other routes.

 

[70014IronDuke]

I did some journey time modelling on the HoWL for a study a few years back, including comparing my predicted times with actual ones while travelling the route. Nobody could explain the logic behind the timetable, I got the impression it was set up "back in the mists of time" but as it seems to work they just leave it alone.
...

he he he - probably the right answer! Thks.

 

[The Planner]

So that means a minute or 75 secs or what? IS there a standard time? Or do you calculate one for each stop, depending on line speed and stock used?

It means exactly what it says, you time the train to stop with a 0 second dwell. That allows the train to slow down and accelerate if no one is there to pick up.

So this means that, in a 'normal, worst-case" scenario - ie the train is required to stop at every stop for alighting or joining passengers, but no added complications - any train booked over a line with request stops should still be able to keep time. And the advantage of request stops is merely that the time saved can be used as recovery time for any unscheduled delays - otherwise, it's lost as waiting time?
Plus, I suppose, a little saving on fuel if the train doesnt have to stop and a bit on wear and tear.

Basically yes.

 

[30907]

A look at a suitable service or two on RealTime trains (detailed version) will show how it's done.

 

[Wilts Wanderer]

Thanks, but am a bit confused. Are you saying "it is done this way, sometimes" or are you saying "it could be done this way" ?

It is done this way but either is acceptable. Or a combination of both. If the TOC decides to go with 30sec dwells (standard minimum for 15x stock) then it would use my method, as the train would run progressively earlier if it doesn't stop everywhere. If zero-dwell stops are used (which is permitted depending on the route) then the recovery time method would be used, as the train will only keep time if it doesnt stop everywhere. Depends on the route and the method the TOC feels is most appropriate. Equally if particular request stops are regularly / usually stopped at, then the TOC will consider making them mandatory (open) stops.

 

[70014IronDuke]

It means exactly what it says, you time the train to stop with a 0 second dwell. That allows the train to slow down and accelerate if no one is there to pick up.
...

Yes. I understand zero dwell time to mean 0 second stopping. Nought. As in nothing, two buzzes and away - if, that is, the conductor needs to buzz.
My question was referring to the extra time allowed for deceleration and subsequent acceleration - as opposed to just running past the station with no scheduled stop of any kind. Is there a standard timing for this, or is each station treated on its particular specifics?
I would imagine that on a secondary (tertiary?) line like the HoWL, or Cambrian up to Pwllehi, each request stop would be given a fixed time penalty, something like one minute or 75 seconds - but I don't know, hence my question.

 

[edwin_m]

The time penalty of slowing down and re-starting depends on rolling stock performance, gradient and line speed, so is train- and station-specific (included in what are known as Sectional Running Times, which aren't published but are deducible from the Working Timetable. Most of the HoWL is only 45mph so the penalty of stopping is small. For most request stops the train has to slow down anyway, so as to be able to stop at the platform if someone is seen waiting, so some of that time penalty will occur regardless of whether the stop is made. The speed the non-stopping train passes through probably also depends on sighting - for example Up trains at Avoncliff would have had to be dead slow when that was a request stop, because the aqueduct gives drivers a very poor view of the platform.

 

[The Planner]

The penalty will be a minimum of 30 seconds as that is the lowest change we can show. We can only use half and whole minutes in running times so we round appropriately.

 

[Parallel]

I've been on a train that has stopped at all stops between Pwllheli and Machynlleth apart from one, we arrived about 10 mins late into Dovey Junction despite trains being ready to pass us at Harlech and Tywyn. I think the timetable assumes we'd stop at some but not all on this line. The train was full and standing from Llandecwyn though (a large group of youth trekkers boarded) and it got busier as we went on so dwell times were longer.

 

[edwin_m]

The penalty will be a minimum of 30 seconds as that is the lowest change we can show. We can only use half and whole minutes in running times so we round appropriately.

Indeed so, but I think you also take account of the cumulative effect over several stops so the errors don't build up (for example if the actual penalty at each stop was 45s then you'd have alternating 30s and 1min).

 

[CheeseOnToast]

Cumulative rounding applies to running times as defined in the National Timetable Planning Rules para 6.4.10 available online.

Dwell time is defined in para 6.8 of the same document but interestingly doesn't mention request stops.

45s dwells are done exactly like that, alternating between 30s and 1 min dwells. Wessex TPR captures this against Class 450 minimum dwells with a footnote of

"An actual minimum dwell time of 45 seconds is required at all station stops. As timetable systems can only use multiples of 30 seconds, every second station stop must have a dwell time of at least 1 minute input into the
system."

 

[The Planner]

The actual noting of cumulative rounding is only a recent thing and was often ignored or misunderstood, the amount of SRTs I have seen over the years where each one has been treated as an individual is astounding and can cause problems.

 

[AY1975]

I know this is slightly off-topic, and could potentially warrant a separate thread, but I wonder if there could be a better solution than the current procedure for asking a train to call at a request stop.

At present, the railways still follow the time-honoured practice whereby passengers who wish to board must give a hand signal to the driver (as with buses), and those who wish to alight must inform the guard (who then presumably tells the driver either by word of mouth or by giving a single buzz on the buzzer as the train approaches the station).

That is OK in principle, except that the driver may not notice anyone waiting on the platform (especially at night if they are wearing dark clothing), and the train may be too crowded for a passenger to go and find the guard.

It might be better if trains that call at request stops had bell pushes. Some German and Czech DMUs have this (as do nearly all buses in the UK and elsewhere). In Germany, you hear a pre-recorded announcement saying that the next station is a request stop, and you must ring the bell now if you wish to alight there.

I have also seen some request stops in Germany and Switzerland where passengers who wish to board must press a button on the platform that switches a light on that can be seen by the driver. It is usually a plain white light at the end of the platform, next to the signal if there is one. Maybe we should do the same.

 

[Parallel]

I have a picture somewhere of the CIS at Dyffryn Ardudwy, it had the up train expected to depart 2 mins BEFORE the booked timetable time. I can only assume that the train had left Harlech early and being request stops with no dwell, the system just took the literal running time. (There is a chain of 6 request stops between Harlech and Barmouth)

On another occasion, I have chatted to a conductor on the line who said if he is on a train that starts running early, he’ll just stop it at a request stop even if nobody wants to board/leave.