Limits of capacity?

[Senex]

In the franchising process the DfT lays down the sort of timetable it expects bidders to bid for, and ove the years this has involved getting more and more trains on to an infrastructure that has seen minimal provision of additional facilities. Debate in these forums has shewn very clearly how the Trans-Pennine route appears to be at its limits of capacity, with relatively small perturbations being able to upset the timetable quite dramatically, and debate has also questioned the wisdom of running more and more small trains rather than fewer and longer trains at somewhat greater intervals, given the limits of the infrastructure. My question is how far running a system at near-maximum capacity is now affecting performance on other main lines too.
Yesterday I made a return trip from York to London. Both trains were, as usual, late, even though there were no technical problems and as far as I could see the only TSR in force was an 80 on the up line at Bawtry. The 0738 from York was an HST, booked to arrive in King's Cross at 0737 (public) or 0735 (WTT). This train appears to be allowed 8 extra minutes on top of the point-to-point times, as 4 minutes for engineering, 3 minutes for pathing, and 1 minute for performance, and then there are th 2 extra minutes between the WTT and the PTT arrivals in King's Cross — a total of 10 minutes. Despite all this, it was 3¼ minutes late on the public time. The train was very severely slowed before Doncaster station, brought to a near-stand outside Grantham, and the same again outside Peterborough, all apparently on account of late-running other services. Then came very severe signals at Knebworth and then following a local service making the killer stop at Welwyn North as far as Digswell. Still not the end: dead slow outside Finsbury Park and a crawl right up to the buffers at the terminus, and these delays too seemed to be down to other trains running late. Indeed, there seemed to be delays from conflicts at almost ever possible location except Hambleton North Jn and Newark Crossing! (As for Hambleton, I watched a 75-mph Leeds-Hull train leave York just in front of an on-time 125-mph XC service, which went out on single yellow and had to follow the DMU to Hambleton ...)
Northbound I was on the 17:30 from King's Cross, this time electric and with 4 minutes engineering allowance, 1½ minutes pathing allowances, and 1 minute for performance, 6½ minutes in all. Yet we were 5 minutes late into York. This time it was down to catching moderate siganls at Huntingdon, but then after a lengthy slow approach being brought to a stand for 2 minutes at Fletton followed by a slow approach to Peterborough. A normal run followed as far as Chaloners Whin, where it was signals again to a near-stand at Holgate Bridge, apparently to allow a DMU to leave the station as we of course were by then approaching out of path.
All the delays on both services seemed to be down to congestion on the line caused by other services running by a small amount out of the planned paths. Just as on the Trans-Pennine route, it seems that small amounts of lateness cannot be absorbed. Are there simply too many trains for the network to operate reliably, given that in this country we cannot match Japanese standards? If we want so many (and more!) trains, do we need urgent investment in more facilities at strategic locations? Or do we just struggle on trying to get a quart out of a pint jug?

 

[Spartacus]

I Are there simply too many trains for the network to operate reliably, given that in this country we cannot match Japanese standards? If we want so many (and more!) trains, do we need urgent investment in more facilities at strategic locations? Or do we just struggle on trying to get a quart out of a pint jug?

Yes.

The ECML's harder to fix than Transpennine though as far fewer long distance services could be extended due to platform constraints. The less said about trying to squeeze even more on before long the better. The trouble is that a big terminus like Kings Cross is pretty hard to extend or rebuild for a number of reasons.

 

[55018ballymoss]

In short, yes.

All of the allowances in the timetable for pathing, performance and the difference between working and public times increase to mitigate risk of late running, but as demonstrated by your example, the snowball effect of a small delay somewhere, quickly escalates and the allowances are not enough.
It could be said that the allowances are pointless as they do not help with regulation of the late running trains by signallers, as even some services you would consider local come with a class 1 headcode today and have the same priority as much longer distance services, and if these services are on time then they can be sent in front of a late running longer distance service.
It might be argued that the only purpose of the allowances is to try and limit the amount each franchisee has to spend on delay/repay arrangements!

 

[Hadders]

The issues around Knebworth, Welwyn and Finsbury Park are probably due to the Thameslink shambles.

 

[The Planner]

In short, yes.

All of the allowances in the timetable for pathing, performance and the difference between working and public times increase to mitigate risk of late running, but as demonstrated by your example, the snowball effect of a small delay somewhere, quickly escalates and the allowances are not enough.
It could be said that the allowances are pointless as they do not help with regulation of the late running trains by signallers, as even some services you would consider local come with a class 1 headcode today and have the same priority as much longer distance services, and if these services are on time then they can be sent in front of a late running longer distance service.
It might be argued that the only purpose of the allowances is to try and limit the amount each franchisee has to spend on delay/repay arrangements!

Pathing time isn't there to mitigate against late running, it is there to keep the train at the planning headway or junction margin etc. Performance time is requested by a TOC, and not by NR and is an odd allowance full stop. PTT vs WTT is TOC requested too, not prescribed by NR.

 

[tbtc]

In the franchising process the DfT lays down the sort of timetable it expects bidders to bid for, and ove the years this has involved getting more and more trains on to an infrastructure that has seen minimal provision of additional facilities. Debate in these forums has shewn very clearly how the Trans-Pennine route appears to be at its limits of capacity, with relatively small perturbations being able to upset the timetable quite dramatically, and debate has also questioned the wisdom of running more and more small trains rather than fewer and longer trains at somewhat greater intervals, given the limits of the infrastructure. My question is how far running a system at near-maximum capacity is now affecting performance on other main lines too

I don't think that there are any/many lines with too many trains - the problem that we have is the desire to have through services from everywhere to everywhere else.

Six an hour on the Trans-Pennine line doesn't look too many for the infrastructure - the current stopping pattern looks better than the previous "five fast, one stopper" (when Northern ran on the line).

BUT combining the Trans-Pennine service with the total of nine services an hour between Piccadilly and Manchester Airport, adding in the various other complications it imports (flat junctions on the way to Liverpool/ Newcastle, a little single track section at Malton etc) means there's not a lot required to upset things.

I agree with the "running fewer but longer" argument - no debate required - but I think that the obsession with maintaining through services over a hundred miles long makes delays inevitable.

As an example, the Thameslink services that will have affected the southern end of the ECML that you discuss were previously confined to one line north of the Thames and two lines south of aforementioned river. I appreciate the need to increase the frequency through the Thameslink core but the large number of termini (is it now seven separate routes south of London and three to the north?) seem to guarantee a mess.

My solution (tot he England-wide problem) would be to cut some of the through services or at least limit the number of branches (e.g. if you want twenty four an hour through the Thameslink core then focus on keeping most of them on the Croydon - Gatwick corridor).