What use is a turnback at Longsight? (Castlefield Corridor)

[FLIRTfan18]

Reading this month's Modern Railways' interview with the Network Rail North West and Central MD there's something that I just can't get my head around. He says that one of the reasons for congestion on the Castlefield corridor is the large amount of trains going through to the airport, caused by them not being able to turn around at Piccadilly. Therefore, they're thinking about a 'turnback' in the Longsight area. What I'm struggling to understand is why that would in any way ease the congestion because it's still sending trains back through the Castlefield corridor. Is anyone able to clarify please?

 

[LNW-GW Joint]

NR once said that sending ATW/TfW's North Wales service to the Airport actually improved the capacity at Piccadilly, rather than reversing in Mayfield siding.
In normal times TfW still turn peak services at Mayfield, enabling earlier departures to the west.
Longsight is also used on occasion.

 

[Ianno87]

A mix of:
-The TfW possibly not having to make a conflicting move to access the existing turnback siding, and

-Sending fewer trains to the Airport "unneccesarily" where demand doesn't really require it (but Airport itself is pretty congested), or

-Giving somewhere to turn a late running train back out if the way rather than send it late to the Airport (and late back)

 

[edwin_m]

Firstly it would remove the trains in question from Slade Lane, where the flat junction causes conflict which may delay trains heading towards the Corridor. If they can provide a centre turnback at Longsight then it would be even better because an Up train could go into it regardless of whether there was a Down train passing at the time. Even if they can't, the Up train waiting to go into a Down-side turnback would be waiting on the Up Slow, not in Platform 13, with the possibility for other trains to bypass it via the Up Fast.

 

[FLIRTfan18]

A mix of:
-The TfW possibly not having to make a conflicting move to access the existing turnback siding, and

-Sending fewer trains to the Airport "unneccesarily" where demand doesn't really require it (but Airport itself is pretty congested), or

-Giving somewhere to turn a late running train back out if the way rather than send it late to the Airport (and late back)

Firstly it would remove the trains in question from Slade Lane, where the flat junction causes conflict which may delay trains heading towards the Corridor. If they can provide a centre turnback at Longsight then it would be even better because an Up train could go into it regardless of whether there was a Down train passing at the time. Even if they can't, the Up train waiting to go into a Down-side turnback would be waiting on the Up Slow, not in Platform 13, with the possibility for other trains to bypass it via the Up Fast.

Good points
It's frustrating how the article doesn't explain itself at all further than what I said in the original post. Leaves the reader to fill in too many gaps in my opinion, because without quite a bit of background knowledge about what goes on at the Castlefield corridor it's really difficult to see why the turnback at Longsight that would obviously be a solution.

 

[4-SUB 4732]

The other reason for a Longsight Turnback perhaps is the ability to timetable in the terminating moves rather than just having it for perturbation?

And, when you leave Piccadilly P13, you can actually run bi-directional via the Down Slow to Longsight Down Side anyway. Perhaps this is what is meant?

 

[Cheshire Scot]

Terminating a train at Picc. P!3 whether planned or unplanned presumably requires a longer dwell than a simple call to enable the Conductor, perhaps assisted by station staff to ensure all passengers are off the train and therefore 'delays' the arrival of the next train i.e. it consumes capacity.

 

[edwin_m]

The other reason for a Longsight Turnback perhaps is the ability to timetable in the terminating moves rather than just having it for perturbation?

And, when you leave Piccadilly P13, you can actually run bi-directional via the Down Slow to Longsight Down Side anyway. Perhaps this is what is meant?

I imagine they will timetable in some terminating moves as you suggest. But I don't think wrong line on the Down Slow would be used routinely, because of the effect on Down trains.

 

[FLIRTfan18]

The other reason for a Longsight Turnback perhaps is the ability to timetable in the terminating moves rather than just having it for perturbation?

But how does timetabling to terminate a train at Piccadilly and then turning it around at Longsight (which I presume is what is being suggested here) rather than terminating it at the airport reduce congestion on Castlefield corridor? Because, as has been said by another poster above, terminating at Piccadilly just increases dwell times. I'm struggling to see where there's any massive benefit whereas the article seems to suggest the benefit is obvious (and therefore doesn't need explaining!)

I imagine they will timetable in some terminating moves as you suggest. But I don't think wrong line on the Down Slow would be used routinely, because of the effect on Down trains.

But terminating a train at Piccadilly instead of the airport doesn't take that train off the Castlefield corridor, and increases dwell time at Piccadilly which is right next to the corridor rather than at the airport which is well away

 

[edwin_m]

But how does timetabling to terminate a train at Piccadilly and then turning it around at Longsight (which I presume is what is being suggested here) rather than terminating it at the airport reduce congestion on Castlefield corridor? Because, as has been said by another poster above, terminating at Piccadilly just increases dwell times. I'm struggling to see where there's any massive benefit whereas the article seems to suggest the benefit is obvious (and therefore doesn't need explaining!)


But terminating a train at Piccadilly instead of the airport doesn't take that train off the Castlefield corridor

I've already suggested an answer to that. If it turns back at Longsight it doesn't need to go through the flat junction at Slade Lane which is one of the sources of conflict and congestion. A Down train delayed at Slade Lane will be late going into the Corridor.

 

[4-SUB 4732]

But how does timetabling to terminate a train at Piccadilly and then turning it around at Longsight (which I presume is what is being suggested here) rather than terminating it at the airport reduce congestion on Castlefield corridor? Because, as has been said by another poster above, terminating at Piccadilly just increases dwell times. I'm struggling to see where there's any massive benefit whereas the article seems to suggest the benefit is obvious (and therefore doesn't need explaining!)


But terminating a train at Piccadilly instead of the airport doesn't take that train off the Castlefield corridor, and increases dwell time at Piccadilly which is right next to the corridor rather than at the airport which is well away

There’s one thing people haven’t considered: flight the terminating train every 30 minutes in front of the Oxford Road terminator. That way, you buy yourself a solid 4-5 minutes to dump the train load off and move away?

 

[Ianno87]

But how does timetabling to terminate a train at Piccadilly and then turning it around at Longsight (which I presume is what is being suggested here) rather than terminating it at the airport reduce congestion on Castlefield corridor?

Presumably reduces the risk of a late journey to the airport returning late, so reducing lateness into the corridor in the first place.

 

[FLIRTfan18]

I've already suggested an answer to that. If it turns back at Longsight it doesn't need to go through the flat junction at Slade Lane which is one of the sources of conflict and congestion. A Down train delayed at Slade Lane will be late going into the Corridor.

Indeed, sorry. I think you're right, it would seem that is by far the biggest benefit. (I just wish Modern Railways could be clearerbin stating that )

 

[PHILIPE]

NR once said that sending ATW/TfW's North Wales service to the Airport actually improved the capacity at Piccadilly, rather than reversing in Mayfield siding.
In normal times TfW still turn peak services at Mayfield, enabling earlier departures to the west.
Longsight is also used on occasion.

TFW no longer turn back from the December Timetable and all go through to the Airport due to Network insisting to help the congestion on the Castlefield Corridor. However many are currently turning back at Mayfield due to crews not possessing the requisite route knowledge to the Airport and while they learn it..

 

[158756]

There’s one thing people haven’t considered: flight the terminating train every 30 minutes in front of the Oxford Road terminator. That way, you buy yourself a solid 4-5 minutes to dump the train load off and move away?

Which works as long as everything runs on time and in the right order, but as soon as it doesn't the trains start stacking up.

 

[4-SUB 4732]

Which works as long as everything runs on time and in the right order, but as soon as it doesn't the trains start stacking up.

That's an argument then for running no trains at all, surely? In case one goes wrong and delays the other?

 

[HST43257]

Why couldn’t the Oxford Road terminators go to a Longsight turnback? You can access more of the centre of Manchester that way, with no conflicting movement on departure across the lines at Oxford Road going back towards Liverpool

 

[4-SUB 4732]

Why couldn’t the Oxford Road terminators go to a Longsight turnback? You can access more of the centre of Manchester that way, with no conflicting movement on departure across the lines at Oxford Road going back towards Liverpool

I think that adds pressure to the whole thing.

 

[158756]

That's an argument then for running no trains at all, surely? In case one goes wrong and delays the other?

That's a bit extreme, but there are surely places to terminate trains more resilient to disruption than 13/14 at Piccadilly. If 15/16 were built yes, but as that isn't happening.

 

[daodao]

Why couldn’t the Oxford Road terminators go to a Longsight turnback? You can access more of the centre of Manchester that way, with no conflicting movement on departure across the lines at Oxford Road going back towards Liverpool

Piccadilly platforms 13 and 14 are some distance from the centre of Manchester; Oxford Road station is far more convenient, so extending stopping services from the CLC line east of Oxford Road is not particularly useful.

I don't see the purpose of turning services at Longsight. Surely the only claimed justification of running longer distance services via the Castlefield line (other than to Sheffield) is to go to Ringway Airport. If they are going to terminate at Piccadilly (and turn back at Longsight), they might as well be diverted to Victoria, as the main problems are on the Castlefield line itself.

I do not understand why Network Rail can't ban long-distance TOCs (TPE/TfW/EMR) from using the Castlefield corridor; this would solve the problems at a stroke. Northern Rail could run 1 semi-fast tph from Lime Street via the CLC line and Stockport to Sheffield to preserve a connection between Merseyside and South Yorkshire as there is no realistic alternative route, but otherwise the Castlefield line should be used solely from a passenger angle for local/regional services only.

 

[Greybeard33]

Another possible reason is lack of platform capacity at the Airport to allow longer trains. Platform double occupancy is only permitted at the Airport when both trains are 4-car or less.

Already one Northern 6-car morning peak service from Liverpool bypasses the Airport spur and terminates at Wilmslow instead, for want of a platform.

Why couldn’t the Oxford Road terminators go to a Longsight turnback? You can access more of the centre of Manchester that way, with no conflicting movement on departure across the lines at Oxford Road going back towards Liverpool

I think the CLC stoppers would have insufficient recovery time if they had to run the extra distance to Longsight. The Network Rail Congested Infrastructure report proposed a centre turnback at Oxford Road to avoid the conflicting movement on departure.

 

[Tomnick]

I do not understand why Network Rail can't ban long-distance TOCs (TPE/TfW/EMR) from using the Castlefield corridor; this would solve the problems at a stroke. Northern Rail could run 1 semi-fast tph from Lime Street via the CLC line and Stockport to Sheffield to preserve a connection between Merseyside and South Yorkshire as there is no realistic alternative route, but otherwise the Castlefield line should be used solely from a passenger angle for local/regional services only.

I don’t really understand what you’d achieve by “banning” the existing EMR service and replacing it with a service that’s not operated by a “long distance” TOC* but is otherwise nearly identical.

* - not that Northern doesn’t already have long-distance services...

 

[Bletchleyite]

NR once said that sending ATW/TfW's North Wales service to the Airport actually improved the capacity at Piccadilly, rather than reversing in Mayfield siding.

That'll be because there's no need to check everyone has got off before departing.

I don’t really understand what you’d achieve by “banning” the existing EMR service and replacing it with a service that’s not operated by a “long distance” TOC* but is otherwise nearly identical.

* - not that Northern doesn’t already have long-distance services...

One advantage would be "doors at thirds", though doing a shuffle to get EMR more 170s (or indeed 185s) would also do that.

 

[The Planner]

I do not understand why Network Rail can't ban long-distance TOCs (TPE/TfW/EMR) from using the Castlefield corridor; this would solve the problems at a stroke. Northern Rail could run 1 semi-fast tph from Lime Street via the CLC line and Stockport to Sheffield to preserve a connection between Merseyside and South Yorkshire as there is no realistic alternative route, but otherwise the Castlefield line should be used solely from a passenger angle for local/regional services only.

Not sure the Network Code allows us to do that. We can reject on performance, capacity and using the decision criteria but we would have to be absolutely water tight to get it past the inevitable dispute hearing especially when it could be argued a local service is just as much of a performance risk.

 

[Bletchleyite]

Piccadilly platforms 13 and 14 are some distance from the centre of Manchester; Oxford Road station is far more convenient, so extending stopping services from the CLC line east of Oxford Road is not particularly useful.

Umm...connections? Terminating at Oxford Road is really sub-optimal in that regard.

 

[4-SUB 4732]

Umm...connections? Terminating at Oxford Road is really sub-optimal in that regard.

But the reality is that only a small number of stations are not therefore served at Piccadilly: Hunts Cross, Flixton, Irlam? And even then, that’s only off-peak with some peak extra stops.

The main stations on the route still get their Piccadilly connections.

 

[edwin_m]

That's an argument then for running no trains at all, surely? In case one goes wrong and delays the other?

Normally if trains start getting delayed, sooner or later there's a gap in the timetable that allows them to recover. Because of the frequency of trains through Castlefield that's more difficult there. There are also many flat junctions, particularly west of the Corridor, so a train that's a couple of minutes late may miss its slot and conflict with several others as it passes over those junctions. Hence there's a risk of a minor delay "snowballing" into multiple delays to several other trains. So anything that avoids a couple of minutes delay to a train heading into Castlefield has got to be worth doing.

 

[4-SUB 4732]

Normally if trains start getting delayed, sooner or later there's a gap in the timetable that allows them to recover. Because of the frequency of trains through Castlefield that's more difficult there. There are also many flat junctions, particularly west of the Corridor, so a train that's a couple of minutes late may miss its slot and conflict with several others as it passes over those junctions. Hence there's a risk of a minor delay "snowballing" into multiple delays to several other trains. So anything that avoids a couple of minutes delay to a train heading into Castlefield has got to be worth doing.

If you assume a 30 minute repeating timetable, with a standard pattern, you’re looking at about 12tph each way as far as Oxford Road from the west. Thats an average of every 5 minutes, so by bunching some slightly you can create bigger gaps in all.

 

[edwin_m]

If you assume a 30 minute repeating timetable, with a standard pattern, you’re looking at about 12tph each way as far as Oxford Road from the west. Thats an average of every 5 minutes, so by bunching some slightly you can create bigger gaps in all.

Assuming you can manage a dwell time of about 3min at Piccadilly, and when that is breached work out how to handle the crowd surge as people try to board at the other end of the platform, which will inevitably make the subsequent dwell time far longer.

I come back to the crossings at the flat junctions. The timetable aims for services to and from the same route to pass each other on the junctions, though clearly it can't do that everywhere because there are so many. At the cluster of junctions west of Deansgate/Salford Central, if a train is 2min late it may well be in conflict at the diamond crossing with one in the other direction on the other route. Delaying the inbound train knocks on delay into the Corridor, delaying the outbound probably results in the one behind also being delayed, and could back up into the platforms at Deansgate or even Oxford Road.

 

[Ianno87]

Assuming you can manage a dwell time of about 3min at Piccadilly, and when that is breached work out how to handle the crowd surge as people try to board at the other end of the platform, which will inevitably make the subsequent dwell time far longer.

Boarding an empty train starting at Piccadilly will be quicker in dwell time terms than a train arriving from the Airport that passengers have to alight first.