Stopping service (not) in front of non-stop service

[arb]

Yesterday I travelled on the 1055 stopping service from Cambridge to Kings Cross (not all the way to Kings Cross!). Despite the train being ready to leave on time, we were held in Cambridge and left about 10 minutes late. This was because an incoming service from Kings Lynn, which then joins to another 4 carriages at Cambridge and runs non-stop to Kings Cross (schedued departure 1047), was late.

I hadn't ever considered this situation before, but after giving it a moment's thought, it of course made perfect sense to delay the stopper, because you wouldn't want to let it go on time and then have it holding up the direct service that should have been in front of it.

This got me wondering though - at what point in time would the stopper have been allowed to leave anyway, ahead of the direct serivce? Is there a standard rule for this situation that says if the direct service is more than (for example) 20 minutes late then the stopper gets to go anyway? Or would each situation considered entirely on its own merits?

On a similar vein, sometimes I've been on a late-running train from Kings Lynn that has been terminated in platform 5 or 6 at Cambridge instead of joining to a London-bound train - presumably to allow the direct London train to leave on time, and not be held up behind a subsequent stopper. Again, is there a standard rule of "more than so many minutes late means that the Lynn train will be terminated at Cambridge"? Or is it considered entirely on a case-by-case basis?

 

[MidnightFlyer]

This got me wondering though - at what point in time would the stopper have been allowed to leave anyway, ahead of the direct serivce? Is there a standard rule for this situation that says if the direct service is more than (for example) 20 minutes late then the stopper gets to go anyway? Or would each situation considered entirely on its own merits?

I suspect the latter - in the example here, once you are beyond the confines of Cambridge station then there's no opportunity (save the bi-di at Royston?) for it to overtake until Hitchin. Seven stops have to be made between Cambridge and Hitchin (exclusive) so that's about fifteen minutes at a guess that the stopper will lose over the fast. There's then the question of fitting both of them through Hitchin (in the case of the fast onto the Fast line) and over Welwyn Viaduct. Contrast that to an area where the fast and stopper run on a four-track railway with no such constraints and it's a different matter. What each Toc's policy for holding for connections is will also dictate what happens.

 

[arb]

Thanks for the answer, but I was curious specifically in the context of how the Kings Lynn/Cambridge/Kings Cross direct and stoppers interact with each other. Not in general across the whole network.

 

[Wilts Wanderer]

Most junction stations with local ops staff such as AOM will have their own set of rules concerning exactly these kind of instances. They will be agreed by all affected parties such as Control and signal boxes and cover things like maximum holds for connections, regulation rules (general and train specific) and rules concerning attachments / detachments.

For instance a 4-car Kings Lynn-KX might be dispatched without the attachment if it was coming in late off-peak, but if it is 1600 and the back working is a loading-critical departure from Kings Cross that won't cope with 4 cars then it might be held, and get stuck behind the stopper. Equally holding the departure might then force a series of step-ups at Kings Cross in order to maintain booked departures during the peak. It really is quite a complex decision tree and this is how ops staff and Control really earn their keep.

 

[LAX54]

At Colchester, if the Up Inter-City is 9 or more late, then the 1Nxx service from Clacton will run ahead from Colchester, will be put in the Maldon back at Witham for the 1Pxx to pass.

 

[Failed Unit]

They do it a lot at WGC. Although the stopper departs to clear the platform. It is held just south of the station for the semi-fast to go. Not sure how long they will hold it.

On the other hand the amount of times the late running XC services to Edinburgh are let out ahead of the on-time east coast services is amazing. I have missed many connections at Edinburgh as a result. On-time turns to 15 late as the east coast gets signal checked at Durham and Alnmouth as well as delays getting platforms at Darlington, Newcastle and Berwick

 

[bramling]

Yesterday I travelled on the 1055 stopping service from Cambridge to Kings Cross (not all the way to Kings Cross!). Despite the train being ready to leave on time, we were held in Cambridge and left about 10 minutes late. This was because an incoming service from Kings Lynn, which then joins to another 4 carriages at Cambridge and runs non-stop to Kings Cross (schedued departure 1047), was late.

I hadn't ever considered this situation before, but after giving it a moment's thought, it of course made perfect sense to delay the stopper, because you wouldn't want to let it go on time and then have it holding up the direct service that should have been in front of it.

This got me wondering though - at what point in time would the stopper have been allowed to leave anyway, ahead of the direct serivce? Is there a standard rule for this situation that says if the direct service is more than (for example) 20 minutes late then the stopper gets to go anyway? Or would each situation considered entirely on its own merits?

On a similar vein, sometimes I've been on a late-running train from Kings Lynn that has been terminated in platform 5 or 6 at Cambridge instead of joining to a London-bound train - presumably to allow the direct London train to leave on time, and not be held up behind a subsequent stopper. Again, is there a standard rule of "more than so many minutes late means that the Lynn train will be terminated at Cambridge"? Or is it considered entirely on a case-by-case basis?

A very regular situation with this particular service, and the same in the down direction too.

The signaller's decision will be influenced by the likely impact on both services, and whether there's platform availability at Cambridge to hold back the stopping service (less of an issue now there's the new island platform).

This exact issue will rear its ugly head when Thameslink's proposed service patterns arrive at Cambridge. Instead of 2 stopping trains per hour on the Cambridge branch there will be 4.

 

[arb]

For instance a 4-car Kings Lynn-KX might be dispatched without the attachment if it was coming in late off-peak, but if it is 1600 and the back working is a loading-critical departure from Kings Cross that won't cope with 4 cars then it might be held, and get stuck behind the stopper. Equally holding the departure might then force a series of step-ups at Kings Cross in order to maintain booked departures during the peak. It really is quite a complex decision tree and this is how ops staff and Control really earn their keep.

That's fascinating, thanks! I hadn't even got close to thinking about the knock-on effects on the trains coming back from KGX!

 

[arb]

This exact issue will rear its ugly head when Thameslink's proposed service patterns arrive at Cambridge. Instead of 2 stopping trains per hour on the Cambridge branch there will be 4.

So I'm trying to get my head round this ... if there are four stoppers an hour, let's assume that they leave Cambridge at xx00, xx15, xx30 and xx45. It was said elsewhere that it takes a stopper about 15 minutes longer than a direct train to reach Hitchin, which is the first place they can pass. So this means that the first direct train in the hour must be timetabled to leave just in front of the second stopper, let's say xx14, in order to not be held up by the first stopper?

But that means that any delay to the first stopper will have a knock-on effect on the first direct train, and there's nothing you can do about that, because you can't leave any more time between the trains?

But further, if the xx14 has come from Lynn and is itself delayed by a minute or two, then aren't you completely stuck? You either let the xx15 stopper out on time and delay the xx14 direct train even more. Or if you hold the xx15 stopper to let the xx14 out in front of it, then, by the above reasoning, the held xx15 stopper will cause delays to the next direct train?

Am I missing something? Or is this going to be an incredibly fragile timetable?

 

[317666]

Am I missing something? Or is this going to be an incredibly fragile timetable?

I would hazard a guess that two out of four will be semi-fast, calling only at Royston, Baldock and Letchworth, as is the case with one train per hour at the moment.

 

[arb]

I would hazard a guess that two out of four will be semi-fast, calling only at Royston, Baldock and Letchworth, as is the case with one train per hour at the moment.

Also (having just tried to understand the Great Northern/Thameslink timetable consulation documents), I *think* it's only the stoppers that are increasing from two to four per hour, and there will still only be two direct trains per hour. This would mean that in my example, you could hold the xx15 stopper for a little while because there isn't an xx29 direct - the next direct wouldn't be until xx44.

 

[bramling]

I would hazard a guess that two out of four will be semi-fast, calling only at Royston, Baldock and Letchworth, as is the case with one train per hour at the moment.

Yes that's correct, however 2tph all stations (1tph today) plus 2tph semi-fast (1tph today) will still be extremely fragile. This may well be a factor in the Thameslink proposal for the semi-fast service to omit Baldock, although this has caused nothing short of outcry locally.

A better service pattern would be:
2tph Thameslink - Cambridge (1x Finsbury Park, Stevenage, Hitchin, Letchworth, Royston, Meldreth, Shepreth, Foxton, Cambridge, 1x Finsbury Park, Stevenage, Hitchin, Letchworth, Baldock, Royston, Cambridge).
1tph Thameslink - Cambridge (Finsbury Park, Potters Bar, Hatfield then all stations to Cambridge).
1tph King's Cross - Royston (fast to Hitchin then Letchworth, Baldock, Ashwell and Royston).
1tph Thameslink - Peterborough (Finsbury Park, Potters Bar, Hatfield then all stations to Peterborough).

The benefit over the delusional Thameslink proposal is a reduction in the number of trains on the Cambridge branch, Meldreth Shepreth and Foxton get a fast service to London, Baldock retains 1tph fast to London, some busy destinations like Hitchin get an hourly non-stop London service, and Peterborough maintains its link to places like Welwyn and Hatfield plus gets 3tph to London instead of 2tph. The only risk is finding a way of reliably reversing 1tph at Royston.

 

[Ianno87]

Yes that's correct, however 2tph all stations (1tph today) plus 2tph semi-fast (1tph today) will still be extremely fragile. This may well be a factor in the Thameslink proposal for the semi-fast service to omit Baldock, although this has caused nothing short of outcry locally.

A better service pattern would be:
2tph Thameslink - Cambridge (1x Finsbury Park, Stevenage, Hitchin, Letchworth, Royston, Meldreth, Shepreth, Foxton, Cambridge, 1x Finsbury Park, Stevenage, Hitchin, Letchworth, Baldock, Royston, Cambridge).
1tph Thameslink - Cambridge (Finsbury Park, Potters Bar, Hatfield then all stations to Cambridge).
1tph King's Cross - Royston (fast to Hitchin then Letchworth, Baldock, Ashwell and Royston).
1tph Thameslink - Peterborough (Finsbury Park, Potters Bar, Hatfield then all stations to Peterborough).

The benefit over the delusional Thameslink proposal is a reduction in the number of trains on the Cambridge branch, Meldreth Shepreth and Foxton get a fast service to London, Baldock retains 1tph fast to London, some busy destinations like Hitchin get an hourly non-stop London service, and Peterborough maintains its link to places like Welwyn and Hatfield plus gets 3tph to London instead of 2tph. The only risk is finding a way of reliably reversing 1tph at Royston.

None of your Cambridge Thameslink services could be 12-car in your proposal (as they all call at the short village stations adjacent to level crossings). Which means that trains to Brighton etc have to be reduced to 8-car as well to make your plan work.

And good luck getting timetable space for regular turnbacks at Royston (as the King's Lynn fasts will still need to run in your proposal)

 

[bramling]

None of your Cambridge Thameslink services could be 12-car in your proposal (as they all call at the short village stations adjacent to level crossings). Which means that trains to Brighton etc have to be reduced to 8-car as well to make your plan work.

And good luck getting timetable space for regular turnbacks at Royston (as the King's Lynn fasts will still need to run in your proposal)

The first needn't be a problem, as worst-case scenario the two platforms currently being extended to 8 cars would have to have a further 80 metres added.

The second issue may well be thornier, however remember that 2tph turn at Royston in the peak hours today, and there are planned peak turnbacks at Royston in the Thameslink proposals (assuming they don't run empty from/to Cambridge). If it can be done in the peaks than 1tph in the off-peak should be manageable. Options to turn short at Letchworth and Baldock provide some resilience.

The ideal solution would be a centre siding somewhere on the country side of Royston. I'm sure it would be technically feasible as there's plenty of land available, but would come at a cost. If peak reversing does indeed happen at Royston then something may well need to be done anyway.

 

[Steve Harris]

I have noticed that this thread has become very similar to another one I have already posted in, namely http://www.railforums.co.uk/showpost.php?p=2827861&postcount=44

Also IIRC the Thameslink/Great Northern timetables will see a total recast when the GN services become true Thameslink services (ie. run through the core).

 

[61653 HTAFC]

It varies from place to place, but at Huddersfield the xx59 Leeds stopper is often held for a late-running xx55 York/Newcastle. If the express is over 12 late (based on my amateur observations) the stopper will leave on time but later held in the platform loop at Dewsbury.

 

[JamesRowden]

Another reason for holding the stopper is to maintain the connection between the fast service and the stopper at Cambridge.

 

[bramling]

Also IIRC the Thameslink/Great Northern timetables will see a total recast when the GN services become true Thameslink services (ie. run through the core).

The thing is, there's not actually much that can be done with the Cambridge line under current proposals, if they want to keep the non-stop services and maintain current journey times. When bored I did some scribbling about looking at various different options, but in reality there's only one or two ways of arranging things.

Getting rid of the 317s/321s will help a little as the newer trains will have better acceleration, but in overall terms this only buys a couple of minutes at best, and any benefits brought by this will be massively cancelled out by the upping from 4tph to 6tph overall.

 

[WelshBluebird]

This is quite common at Bristol Temple meads during disruption where the local stoppers will be held for the HSTs to London to get out in front.

 

[Parallel]

This is quite common at Bristol Temple meads during disruption where the local stoppers will be held for the HSTs to London to get out in front.

It doesn't just happen with the local stoppers though, also the Pompeys that only call at Bath before leaving the GWML. However, if this train loses its path, it can end up very delayed into Portsmouth and then leaves late back to Cardiff again.

I've been on a Warminster train that's been pulled over at the Bathampton loop before to let a Pompey and then a Paddington go in front. Problem is passengers weren't aware of this before leaving Bath and I felt bad for passengers travelling to Warminster especially because this train then got capped at Westbury due to the delay and then they had to wait about 55 minutes for the next train to Warminster (the next Pompey)... that was then 20 mins late!

Pulling over into the Bathampton loop doesn't happen often though. I wonder if it happens at the loop the other side near Oldfield Park for Bristol bound services. It's used occasionally for trains that have failed at Bath.

 

[Wilts Wanderer]

I don't believe Bath Goods down loop is cleared for passenger trains, only freight.