How much recovery time is reasonable?

[SuspectUsual]

i totally get that the timetable needs a degree of resilience, so that a delay doesn’t ripple through the network and cause havoc.

But how much is reasonable? I’m currently on the late running 832 Hebden Bridge to Chester (some aggro at Bradford apparently) which left Leeds 21 late but is - apparently - on course to arrive in Chester on time. Currently -10 at Eccles. Is being able to catch up 21 minutes in a 160 minute run (13%) reasonable, or an excessively padded timetable that diminishes the customer offer when things don’t go wrong?

Are TOCs moving layover time at terminals into padding of the timetable?

And obviously under the traditional performance measure of timekeeping measured only at final destination it distorts the customer perception of punctually for those going to intermediate stations. At least that should be resolved with measurement at every stop.

 

[Ianno87]

What you describe is not "padding". It is time added to the schedule to weave a new service through an increasingly busy timetable.

 

[hexagon789]

i totally get that the timetable needs a degree of resilience, so that a delay doesn’t ripple through the network and cause havoc.

But how much is reasonable? I’m currently on the late running 832 Hebden Bridge to Chester (some aggro at Bradford apparently) which left Leeds 21 late but is - apparently - on course to arrive in Chester on time. Currently -10 at Eccles. Is being able to catch up 21 minutes in a 160 minute run (13%) reasonable, or an excessively padded timetable that diminishes the customer offer when things don’t go wrong?

Are TOCs moving layover time at terminals into padding of the timetable?

And obviously under the traditional performance measure of timekeeping measured only at final destination it distorts the customer perception of punctually for those going to intermediate stations. At least that should be resolved with measurement at every stop.

I seem to recall reading somewhere that BR introduced a standard padding of two minutes for every 50 miles with a minimum of 2 minutes on shorter routes.

 

[The Planner]

What Ian said, its not padding, it is time added to keep you away from other trains to remain compliant with the planning rules. If your trains ends up out of path then you are going to either lose more time or actually make it back up, especially if you are timed to wait at a junction.

What Hexagon is suggesting is likely to be engineering allowance, and that rule certainly doesn't apply now.

 

[ForTheLoveOf]

Looking into your service in particular, whilst it's true that it isn't a "bare-bones" run like some trains are (without any allowances for anything), I think the timetable balances performance vs time in a reasonable fashion. The exact timetabled breakdown is available here (archived for posterity).

There's only one station stop which has more time in there than would be strictly necessary - and that's Bradford Interchange, where the train reverses. All other station stops are tight affairs, especially considering that, for example, Manchester Victoria will presumably involve a full crew change? (there may be another en-route)

So then there's just the other three types of allowances - engineering, pathing and performance.

The first is a necessity in any timetable, because on a route as long as Leeds to Chester there will almost always be a couple of temporary speed restrictions (TSRs - especially in warm weather like today) meaning that the train can't achieve the run as quickly as in perfect conditions.

There are 5 minutes of engineering allowance throughout the run - to be honest, that's probably a bit more than will be necessary to allow for TSRs on a run of that length on most days. I would have thought 2 or 3 minutes would suffice, but then again I'm not a timetable planner!

The last type of allowance, performance, is also necessary on most runs that don't run along entirely flat terrain. The kind of train used on the run can be quite variable, and Leeds to Chester involves some fairly decent ascents between Bradford and Manchester!

If, for example, a 75mph Pacer or a Sprinter (153/155) finds its way into the mix then this could hinder adherance to the timetable quite a lot, given the run is based on the train running with a 90mph Class 158 Super Sprinter. Given this, I'm surprised to see there's no allowance at all on this run - presumably this is made up somewhat by the slightly excessive engineering allowance.

So then to come to the most controversial type of allowance - pathing. This is the truest kind of 'slack' in a timetable. But again, it's a necessity on today's congested railway network. There are 12 minutes of pathing time on this particular run. To be honest, again that's on the high side of what I'd expect to see on a run of this length, but there are several points at which the train goes through veritable bottlenecks, such as at Manchester Victoria.

The difficulty is that if one particular station stop takes longer than usual, e.g. because there's more passengers than usual or there's a wheelchair bound passenger who needs the ramp taking out, then this could mean a lot of trains get held up and people start missing connections, and it all goes to pot! Unfortunately this is an area that can only be solved by planning the timetable carefully and reducing the number of conflicting movements, e.g. by adding flyovers. Unfortunately the former often means that you have unattractive journey times or irregular service patterns, and the latter is ruinously expensive.

So overall it's clear there's no easy solution to it all. Yes, you could just schedule everything with a timetable that is based on the quickest possible run in perfect conditions, but then this would mean that a lot of people would become delayed very easily, and a lot of official connections would become unreliable. Not to mention the effect on the oft-quoted timeliness statistics. So I think there's certainly a balance to be struck. I agree that on this particular run the amount of allowances in the timetable is a bit excessive, but if it means that you can actually rely on it arriving at each station when they say it will, I'm happy with that, really.

 

[hexagon789]

What Hexagon is suggesting is likely to be engineering allowance, and that rule certainly doesn't apply now.

It may well be that, I just recall reading that in some cases they omitted it from some of the fastest InterCity workings, found that didn't work and added ended up adding it in.

 

[cambsy]

The 3 hr 59 min London-Edinburgh Scottish Pullmans, were famously given just one minute recovery on London-York section, northbound only, with a timing of 1hr 41 mins, I did it couple of times in under 100 mins, was very hard to keep to, Rail track at the time were prepared to tighten everything up, keep virtually free of TSR’s and leave just one minute of recovery, now days Network rail wouldn’t entertain such a timing, network is too busy etc, I’m not sure how often the 101 minute timing was kept, but it gave some exciting performances from drivers trying to keep to it, lets just say, some times the speeds were somewhat over the 125mph official max speed.

 

[hexagon789]

The 3 hr 59 min London-Edinburgh Scottish Pullmans, were famously given just one minute recovery on London-York section, northbound only, with a timing of 1hr 41 mins, I did it couple of times in under 100 mins, was very hard to keep to, Rail track at the time were prepared to tighten everything up, keep virtually free of TSR’s and leave just one minute of recovery, now days Network rail wouldn’t entertain such a timing, network is too busy etc, I’m not sure how often the 101 minute timing was kept, but it gave some exciting performances from drivers trying to keep to it, lets just say, some times the speeds were somewhat over the 125mph official max speed.

30% on time performance I was told.

 

[Mogster]

My morning service (2K81) has 18 minutes timetabled from arriving at Salford Crescent to leaving Manchester Piccadilly. It’s a 2 mile journey...

As the OP says resilience is one thing but ridiculous timetable padding to prevent compo payouts is another. That’s the way it appears anyway.

 

[ForTheLoveOf]

My morning service (2K81) has 18 minutes timetabled from arriving at Salford Crescent to leaving Manchester Piccadilly. It’s a 2 mile journey...

As the OP says resilience is one thing but ridiculous timetable padding to prevent compo payouts is another. That’s the way it appears anyway.

The only thing that is "padding" that journey on top of the minimum running time that the scheduled class of traction is able to achieve, is the 5 minute dwell at Manchester Oxford Road. Most through trains are scheduled to have 1 minute here. However, this does seem a bit of an oddity. There's nothing that I can see in the timetable which overtakes it at Oxford Road. Neither is there anything blocking the booked platform at Piccadilly, which is 13. Perhaps someone can elaborate?

But just to confirm, there is no pathing or any other kind of allowance that I can see.

 

[Ianno87]

The only thing that is "padding" that journey on top of the minimum running time that the scheduled class of traction is able to achieve, is the 5 minute dwell at Manchester Oxford Road. Most through trains are scheduled to have 1 minute here. However, this does seem a bit of an oddity. There's nothing that I can see in the timetable which overtakes it at Oxford Road. Neither is there anything blocking the booked platform at Piccadilly, which is 13. Perhaps someone can elaborate?

But just to confirm, there is no pathing or any other kind of allowance that I can see.

The extended dwell is more than likely for pathing in that case - i.e. it has a specific timing at a junction further along, and thus needs to wait somewhere. So might as well be at a station, and Oxford Road is better to fester at than Piccadilly due to having more than one platform per direction. Also helps guard against inadvertent early dispatch from Piccadilly.

 

[edwin_m]

The last type of allowance, performance, is also necessary on most runs that don't run along entirely flat terrain. The kind of train used on the run can be quite variable, and Leeds to Chester involves some fairly decent ascents between Bradford and Manchester!

If, for example, a 75mph Pacer or a Sprinter (153/155) finds its way into the mix then this could hinder adherance to the timetable quite a lot, given the run is based on the train running with a 90mph Class 158 Super Sprinter. Given this, I'm surprised to see there's no allowance at all on this run - presumably this is made up somewhat by the slightly excessive engineering allowance.

So then to come to the most controversial type of allowance - pathing. This is the truest kind of 'slack' in a timetable. But again, it's a necessity on today's congested railway network. There are 12 minutes of pathing time on this particular run. To be honest, again that's on the high side of what I'd expect to see on a run of this length, but there are several points at which the train goes through veritable bottlenecks, such as at Manchester Victoria.

The difficulty is that if one particular station stop takes longer than usual, e.g. because there's more passengers than usual or there's a wheelchair bound passenger who needs the ramp taking out, then this could mean a lot of trains get held up and people start missing connections, and it all goes to pot! Unfortunately this is an area that can only be solved by planning the timetable carefully and reducing the number of conflicting movements, e.g. by adding flyovers. Unfortunately the former often means that you have unattractive journey times or irregular service patterns, and the latter is ruinously expensive.

Performance allowance is effectively just there to make the statistics look good. It is usually extra time added before final destination, and with very few exceptions it is at the TOC's discretion not imposed by Network Rail. If a train may routinely be formed from different types of unit then it will be timed for the slowest one.

Pathing is added when the timetable doesn't join up. A train may get a path as far as the approach to a certain junction, but the next available path over the junction itself is several minutes later. In this situation a pathing allowance is added. The Leeds-Chester has been added to the timetable recently, probably without moving too many other trains around, so is likely to get a lot of pathing allowance so it can fit round everything else. At some future time there will be a major re-cast of the timetable, most likely when Northern gets all its new units into service, which might allow a bit of optimisation and removal of some of this time.

 

[ForTheLoveOf]

Performance allowance is effectively just there to make the statistics look good.

In the case of TOCs like Northern who have a massive assortment of different types that might turn out to work a service, isn't the performance allowance there to allow for variations in performance depending on the stock used, especially on "challenging" terrain?

 

[edwin_m]

In the case of TOCs like Northern who have a massive assortment of different types that might turn out to work a service, isn't the performance allowance there to allow for variations in performance depending on the stock used, especially on "challenging" terrain?

These trains will probably be timed for 150. 156s have the same timings as 150 so are never timed separately, Pacers are a bit quicker and EMUs will be a lot quicker. I don't know about 769s in practice but I think they were claimed to match 150 timings in diesel mode.

158s might be slower on a journey with many stops, mostly because of slow door operation, but they are unlikely to escape onto that type of service. 153s are a bit slower than 150s so if a service has a possibility of being operated by one then it will be timed for 153.

 

[Ianno87]

Performance allowance is effectively just there to make the statistics look good. It is usually extra time added before final destination

It can often be added approaching key pinch-points, where Right Time presentation is critical for robust operation of the timetable.

Examples being approaching and leaving the Thameslink core from all directions, and approaching the two-track section at Welwyn.

 

[tpjm]

The only thing that is "padding" that journey on top of the minimum running time that the scheduled class of traction is able to achieve, is the 5 minute dwell at Manchester Oxford Road. Most through trains are scheduled to have 1 minute here. However, this does seem a bit of an oddity. There's nothing that I can see in the timetable which overtakes it at Oxford Road. Neither is there anything blocking the booked platform at Piccadilly, which is 13. Perhaps someone can elaborate?

From experience I would suggest it being due to a crew change - usually just the guard at MCO.

 

[800002]

i totally get that the timetable needs a degree of resilience, so that a delay doesn’t ripple through the network and cause havoc.

But how much is reasonable? I’m currently on the late running 832 Hebden Bridge to Chester (some aggro at Bradford apparently) which left Leeds 21 late but is - apparently - on course to arrive in Chester on time. Currently -10 at Eccles. Is being able to catch up 21 minutes in a 160 minute run (13%) reasonable, or an excessively padded timetable that diminishes the customer offer when things don’t go wrong?

Are TOCs moving layover time at terminals into padding of the timetable?

And obviously under the traditional performance measure of timekeeping measured only at final destination it distorts the customer perception of punctually for those going to intermediate stations. At least that should be resolved with measurement at every stop.

Looking into your service in particular, whilst it's true that it isn't a "bare-bones" run like some trains are (without any allowances for anything), I think the timetable balances performance vs time in a reasonable fashion. The exact timetabled breakdown is available here (archived for posterity).

There's only one station stop which has more time in there than would be strictly necessary - and that's Bradford Interchange, where the train reverses. All other station stops are tight affairs, especially considering that, for example, Manchester Victoria will presumably involve a full crew change? (there may be another en-route)

So then there's just the other three types of allowances - engineering, pathing and performance.

The first is a necessity in any timetable, because on a route as long as Leeds to Chester there will almost always be a couple of temporary speed restrictions (TSRs - especially in warm weather like today) meaning that the train can't achieve the run as quickly as in perfect conditions.

There are 5 minutes of engineering allowance throughout the run - to be honest, that's probably a bit more than will be necessary to allow for TSRs on a run of that length on most days. I would have thought 2 or 3 minutes would suffice, but then again I'm not a timetable planner!

The last type of allowance, performance, is also necessary on most runs that don't run along entirely flat terrain. The kind of train used on the run can be quite variable, and Leeds to Chester involves some fairly decent ascents between Bradford and Manchester!

If, for example, a 75mph Pacer or a Sprinter (153/155) finds its way into the mix then this could hinder adherance to the timetable quite a lot, given the run is based on the train running with a 90mph Class 158 Super Sprinter. Given this, I'm surprised to see there's no allowance at all on this run - presumably this is made up somewhat by the slightly excessive engineering allowance.

So then to come to the most controversial type of allowance - pathing. This is the truest kind of 'slack' in a timetable. But again, it's a necessity on today's congested railway network. There are 12 minutes of pathing time on this particular run. To be honest, again that's on the high side of what I'd expect to see on a run of this length, but there are several points at which the train goes through veritable bottlenecks, such as at Manchester Victoria.

The difficulty is that if one particular station stop takes longer than usual, e.g. because there's more passengers than usual or there's a wheelchair bound passenger who needs the ramp taking out, then this could mean a lot of trains get held up and people start missing connections, and it all goes to pot! Unfortunately this is an area that can only be solved by planning the timetable carefully and reducing the number of conflicting movements, e.g. by adding flyovers. Unfortunately the former often means that you have unattractive journey times or irregular service patterns, and the latter is ruinously expensive.

So overall it's clear there's no easy solution to it all. Yes, you could just schedule everything with a timetable that is based on the quickest possible run in perfect conditions, but then this would mean that a lot of people would become delayed very easily, and a lot of official connections would become unreliable. Not to mention the effect on the oft-quoted timeliness statistics. So I think there's certainly a balance to be struck. I agree that on this particular run the amount of allowances in the timetable is a bit excessive, but if it means that you can actually rely on it arriving at each station when they say it will, I'm happy with that, really.

It's interesting, to me, to compare the actual running time to the planned running time.
I've used Open Train Times:-
Actual running, Sat 29th June
http://www.opentraintimes.com/schedule/Y61042/2019-06-29

Against the Blank WTT schedule, showing allowances more clearly.
http://www.opentraintimes.com/schedule/Y61042/2019-07-06


Firstly, all the engineering time [in square brackets] is as per the Train Planning Rules. Although it does seem most of it simply didn't aid the recovery of the service. Most of it used.
That could be for a number of reasons - it has to be in the schedule though (and can be different amounts for different traction at the same point). I won't go into those reasons here and now.

Pathing time - added to maintain headway and junction margins:

The half minute pathing from Bramley to New Pudsey:- Evidently was used. A 4 minute stop - stop time in the WTT was maintained in real running.

The half minute pathing between Milner Royd Jn and Sowerby Bridge:- Evidently was used, plus an additional half minute - presumably required for headway into Sowerby Bridge. A minute and a half planned run taking two minutes.

The half minite pathing between Sowerby Bridge and Mytholmroyd:- Evidently was used. A Five minute stop to stop time in the WTT was matched in actual running.

The minute pathing time between Salford Central and Ordsall Lane Jn:- Evidently was used. A two minute pass to pass time in the WTT was matched in actual running.


The five and ahalf minutes pathing time between Earlstown and Winwick Jn:- Was only partly used. Eight and a half minutes planed - Five minites taken. A recovery of three and ahalf minutes.

The minute pathing time between Frodsham and Helsby:- Evidently was used. A four minute stop to pass time time in the WTT was matched in the running.

The two minutes pathing time between helsby and Mickle Trafford:- was not used atall. Neigher was the two minutes engineering, meaning a Four minute recovery.

Enginering time:-
Vitriol Works to Thorpes Bridge Jn:- 2 minutes. On face value, one and a half minutes was used.

Earlestown to Winwick Jn:- 1 minute. I would suggest this was used -although it is unclear. A 'clean run' including the 1 engineering minute should take three and ahalf minutes. It took five.

It appears that the vast majority of time recovered was due to good running and reduced station dwell times.
The eight minutes planned at Bradford Interchange being done in the minimum three minutes certainly played it's part.

My opinion would also be that the Sectional Running Times are a bit slack. Either that, the the diagrammed unit on the day was quicker than the unit planned for.