Midland Mainline (South) capacity issues

[DanDaDriver]

Wasn’t there also talk of some new freight terminal at Cricklewood North? Or did I imagine that?

Not the reinstated aggregate sidings on the down.

 

[Aictos]

Luton has 5 platforms and trains turning back will generally use Platform 2 which is between the Up and Down Slow lines, thus leaving the through lines clear, though again platforms 1 to 3 are now all bidirectionally signalled so the signaller can work round a train using another platform if necessary.

However we have to bear in mind that from the London end of Luton, trains can only turnback in Platforms 2/3 as you cannot get to Platform 1 from London while from the Bedford end of Luton, trains can turnback using Platforms 1 to 3.

So to give a example if a train has failed in Platform 3 heading to Bedford and you've got a train awaiting it's next working in Platform 2 then you're pretty much buggered as there's no way of getting any other trains though on the slow lines with the only option using the Fasts between Harpenden Junction and Leagrave Junction bearing in mind you also have the EMT services as well to think about.

What might have been helpful would be if Platform 1 was accessible from London so Platforms 1 to 3 were fully bi directional from London or from Bedford as well as replacing WH585 which I believe is a shunt signal with a full MAS signal which would allow EMT services to turnback in Platform 4 during engineering works and disruption.

 

[twpsaesneg]

However we have to bear in mind that from the London end of Luton, trains can only turnback in Platforms 2/3 as you cannot get to Platform 1 from London while from the Bedford end of Luton, trains can turnback using Platforms 1 to 3.

So to give a example if a train has failed in Platform 3 heading to Bedford and you've got a train awaiting it's next working in Platform 2 then you're pretty much buggered as there's no way of getting any other trains though on the slow lines with the only option using the Fasts between Harpenden Junction and Leagrave Junction bearing in mind you also have the EMT services as well to think about.

What might have been helpful would be if Platform 1 was accessible from London so Platforms 1 to 3 were fully bi directional from London or from Bedford as well as replacing WH585 which I believe is a shunt signal with a full MAS signal which would allow EMT services to turnback in Platform 4 during engineering works and disruption.

True - this would be useful functionality. A Facing crossover South of St Albans to allow turnbacks directly in Platform 1 would probably be helpful too, but the reverse curves don't make that particularly easy.

 

[mr_jrt]

Where would the “LO” service go to the south? Given that the TL core is full and St Pancras is full, and Belsize tunnels are 4 track.

Well, the easy option is to just terminate at West Hampstead, where passengers can interchange to Thameslink to continue south, or head down the road to the Jubilee or the existing LO route between Stratford & Willesden (would be nice if the Met stop was moved there from Finchley Road too!). In time there's a likelihood you will also have the option of running down the Dudding Hill line to OOC Lane and on to Richmond instead, but as you would miss out on West Hampstead, I can't see that being too popular. Perhaps St Albans to West Hampstead, then reverse and run to Richmond?

The more "ambitious" option for me is another one of my pet concepts of a new tunnel from the Finchley Road area alongside the current MML tunnel portals to the Goblin somewhere around Tottenham North curve tunnel #2, potentially severing the current rail link there by removing Carlton Rd junction. That new tunnel you can then make as much or as little out of as desired, i.e. optionally adding underground platforms at Gospel Oak and Belsize Park LUL, or indeed, somewhere new. That doesn't get you any better interchanges beyond West Hampstead heading south, but it gives services a useful connectivity function by giving the Goblin an outlet, though admittedly the bigger benefit would be to freight by giving it a path from the Goblin that didn't need to interact with the Thameslink tracks at all unless heading north of wherever the Hendon lines end up finishing. I believe something similar popped up in Boris's ill-fated R25 materials?

But anyway. Let's focus on the MML aspects. With a base assumption that you could run a frequent segregated LO service between St. Albans and West Hampstead, and Thameslink could run fast between St. Albans and West Hampstead, would that free up sufficient capacity whilst still being acceptable for the good people of Radlett, Elstree & Borehamwood, Mill Hill Broadway, Hendon, Brent Cross, & Cricklewood having to change onto Thameslink services at West Hampstead, given that there could end up being more frequent Thameslink services if capacity were able to increase?

Additionally, could there be a case for opening new local stations served by the LO lines, i.e. midway between Cricklewood and West Hampstead, a Northern Line interchange at Colindeep Lane, Grahame Park, somewhere between Scratchwood and Apex Corner, Napsbury? ...or would these stations make the service too slow? Could that be mitigated by an additional Thameslink stop at, say, Mill Hill? Obviously there is still the issue of Kentish Town, but at least there are four platforms there, so stopping Thameslinks could be overtaken.

 

[Bald Rick]

But anyway. Let's focus on the MML aspects. With a base assumption that you could run a frequent segregated LO service between St. Albans and West Hampstead, and Thameslink could run fast between St. Albans and West Hampstead, would that free up sufficient capacity whilst still being acceptable for the good people of Radlett, Elstree & Borehamwood, Mill Hill Broadway, Hendon, Brent Cross, & Cricklewood having to change onto Thameslink services at West Hampstead, given that there could end up being more frequent Thameslink services if capacity were able to increase?

I think the 9m people per year who use the intermediate stations, a significant majority of whom travel direct to central London, would have something to say about losing their direct services and being forced to change.

Or to put it another way: you would need to spend several billion on new infrastructure to make the service significantly slower and worse for a notable proportion of people who use it.

 

[Aictos]

How difficult is it to replace a Shunt Signal with a Full MAS signal?

 

[mr_jrt]

Fair enough, thanks for indulging me. Personally I don't understand the problem with changing trains though, as long as the change is quick. Surely its the overall journey time that matters, and for many of those smaller intermediate stations I thought they only get relatively few flighted services per hour in order to provide non-stopping paths for the services from further out that are already full. Plucking nearly-arbitrary numbers out of the air for the point of illustration, if you could provide a evenly spaced 8tph (or higher) local LO service feeding into a 12tph fast TL service at West Hampstead with a minimal interchange time penalty, then surely that's going to give you comparable average journey times over the hour to the existing bunched 6tph or so direct service they currently get? And even if they're slightly worse, if you were to gain an extra set of paths on the TL lines that could be used for more fast 12-car services, is the net benefit not worthwhile?

Without something dramatic like this then I don't see how else you can provide more capacity on the Thameslink lines once the trains are all 12-cars long. Even if you disregarded the canal tunnels and ran the full core service up the MML, you simply can't increase frequency to the minor stations unless you plan on stopping every single service at them, so you will have to either cut their services to squeeze more down the lines (abet without providing an alternative local service), sacrifice even more capacity on the fast lines to bypass them, or settle for the capacity you've got and just price people off the railways.

 

[Bald Rick]

How difficult is it to replace a Shunt Signal with a Full MAS signal?

It depends, but usually not too difficult. It does need changes to the interlocking and control system. The issue is if it changes the arrangements for other signals and then they need moving.

 

[Bald Rick]

Fair enough, thanks for indulging me. Personally I don't understand the problem with changing trains though, as long as the change is quick. Surely its the overall journey time that matters, and for many of those smaller intermediate stations I thought they only get relatively few flighted services per hour in order to provide non-stopping paths for the services from further out that are already full. Plucking nearly-arbitrary numbers out of the air for the point of illustration, if you could provide a evenly spaced 8tph (or higher) local LO service feeding into a 12tph fast TL service at West Hampstead with a minimal interchange time penalty, then surely that's going to give you comparable average journey times over the hour to the existing bunched 6tph or so direct service they currently get? And even if they're slightly worse, if you were to gain an extra set of paths on the TL lines that could be used for more fast 12-car services, is the net benefit not worthwhile?

Without something dramatic like this then I don't see how else you can provide more capacity on the Thameslink lines once the trains are all 12-cars long. Even if you disregarded the canal tunnels and ran the full core service up the MML, you simply can't increase frequency to the minor stations unless you plan on stopping every single service at them, so you will have to either cut their services to squeeze more down the lines (abet without providing an alternative local service), sacrifice even more capacity on the fast lines to bypass them, or settle for the capacity you've got and just price people off the railways.

The trains aren’t flighted on the slows, at least not in the up. Radlett, Elstree and Mill Hill have 8tph in the peak, spaced either 7/8 mins or 6/9 minutes apart. It’s effectively evenly spaced now and turn up and go. Hendon and Cricklewood have 4tph at 15 minute intervals.

Generally, there isn’t a capacity problem on the trains to the stations between West Hampstead and Radlett. The issue is the fast trains, but the 700s are far, far better than their predecessors in terms of capacity, and crowding is less of an issue than it was. They are still full and standing. In the peak, but rarely crush loaded, and even rarer are the occasions when you can’t board because of crowding (it basically doesn’t happen now). With the old trains being unable to board was a regular occurrence; at least once a week in my case.

 

[John Webb]

True - this would be useful functionality. A Facing crossover South of St Albans to allow turnbacks directly in Platform 1 would probably be helpful too, but the reverse curves don't make that particularly easy.

Before electrification, St Albans had facing crossover 4 (installed 1973) south of the station to allow exactly that move. There was also a trailing crossover 17 south of the station (of much earlier installation) which allowed trains to terminate on platform 2 and turn back to London with a ground-mounted 3-aspect colour light signal. But either of these ways of turning back meant that a line was blocked until the train left - hence the central turnback siding between the two slow lines installed as part of the electrification to minimise these blocks on the running lines.

 

[ChiefPlanner]

Before electrification, St Albans had facing crossover 4 (installed 1973) south of the station to allow exactly that move. There was also a trailing crossover 17 south of the station (of much earlier installation) which allowed trains to terminate on platform 2 and turn back to London with a ground-mounted 3-aspect colour light signal. But either of these ways of turning back meant that a line was blocked until the train left - hence the central turnback siding between the two slow lines installed as part of the electrification to minimise these blocks on the running lines.

The SAC center turnback is again a great example of the extreme care taken in the 1977 resignalling and remodelling of the layout done under BR , very carefully worked out as mentioned before , and one that has coped really well with the massive increase of passenger business since then -....

My only gripe is that , despite every effort on my part - the turnback siding is not track circuited , so the signallers at West Hampstead have to use a magnetic disc to show there is a train in the siding......

 

[Bald Rick]

Before electrification, St Albans had facing crossover 4 (installed 1973) south of the station to allow exactly that move. There was also a trailing crossover 17 south of the station (of much earlier installation) which allowed trains to terminate on platform 2 and turn back to London with a ground-mounted 3-aspect colour light signal. But either of these ways of turning back meant that a line was blocked until the train left - hence the central turnback siding between the two slow lines installed as part of the electrification to minimise these blocks on the running lines.

What was the through linespeed when they were in, about 40mph?

 

[DanDaDriver]

The SAC center turnback is again a great example of the extreme care taken in the 1977 resignalling and remodelling of the layout done under BR , very carefully worked out as mentioned before , and one that has coped really well with the massive increase of passenger business since then -....

My only gripe is that , despite every effort on my part - the turnback siding is not track circuited , so the signallers at West Hampstead have to use a magnetic disc to show there is a train in the siding......

Out of interest, are they moving to EMCC in the distant future?

 

[Aictos]

The SAC center turnback is again a great example of the extreme care taken in the 1977 resignalling and remodelling of the layout done under BR , very carefully worked out as mentioned before , and one that has coped really well with the massive increase of passenger business since then -....

My only gripe is that , despite every effort on my part - the turnback siding is not track circuited , so the signallers at West Hampstead have to use a magnetic disc to show there is a train in the siding......

What needs to be done to track circuit a siding?

 

[John Webb]

What was the through linespeed when they were in, about 40mph?

I don't know for certain, but probably 10 mph and 'Approach Controlled' for the facing crossover 4 from down slow to up slow. Crossover 17 was only ever used from a standing start.
The 1970 diagram as modified in 1973 and after the box closed in December 1979:

Note the unnumbered fixed stop signal at the left-hand end of the up slow platform to stop drivers proceeding any further 'wrong direction'.

 

[Aictos]

I don't know for certain, but probably 10 mph and 'Approach Controlled' for the facing crossover 4 from down slow to up slow. Crossover 17 was only ever used from a standing start.
The 1970 diagram as modified in 1973 and after the box closed in December 1979:

Note the unnumbered fixed stop signal at the left-hand end of the up slow platform to stop drivers proceeding any further 'wrong direction'.

That's quite interesting, certainly will be looking at a trip to St Albans this year at some point.

 

[Bald Rick]

I don't know for certain, but probably 10 mph and 'Approach Controlled' for the facing crossover 4 from down slow to up slow. Crossover 17 was only ever used from a standing start.
The 1970 diagram as modified in 1973 and after the box closed in December 1979:

Note the unnumbered fixed stop signal at the left-hand end of the up slow platform to stop drivers proceeding any further 'wrong direction'.

Sorry John, I didn’t explain myself. I was wondering what the linespeed was on the slow lines in the area of the crossovers. Given that it is only 65mph through the platforms now, and 80 on the London side, with lots of cant, I can’t imagne it would have been more than 40mph in order to get the geometry for the crossovers.

I agree the crossovers would have been 10mph, perhaps 15. I wouldn’t have fancied being the St Albans South bobby if they had been 40mph; would have needed arms like Popeye!

 

[edwin_m]

What needs to be done to track circuit a siding?

You'd install a track circuit...

I think the interlocking would also change to give a main aspect into the siding if the line was clear to the stops. This would allow trains to enter it slightly faster, being assured there wasn't a train in there already. However it would probably trigger a buffer stop risk assessment and installation of a friction stop if there isn't one there now.

 

[43055]

Out of interest, are they moving to EMCC in the distant future?

Possibly. As far as I am aware Kettering to Bedford is definitely going to the EMCC and a rumour that everything south is going to Three Bridges.

 

[ChiefPlanner]

You'd install a track circuit...

I think the interlocking would also change to give a main aspect into the siding if the line was clear to the stops. This would allow trains to enter it slightly faster, being assured there wasn't a train in there already. However it would probably trigger a buffer stop risk assessment and installation of a friction stop if there isn't one there now.

It is a very tight siding - (the 8 car 700's just about fit) , access only (and rightly so) , with a shunt signal and a slow speed. Just be useful to have detection in there , as the s/er sets up the return trip once the outward set is berthed on the up slow.

 

[ChiefPlanner]

Possibly. As far as I am aware Kettering to Bedford is definitely going to the EMCC and a rumour that everything south is going to Three Bridges.

That was my understanding the last time I enquired.

 

[John Webb]

You'd install a track circuit...

I think the interlocking would also change to give a main aspect into the siding if the line was clear to the stops. This would allow trains to enter it slightly faster, being assured there wasn't a train in there already. However it would probably trigger a buffer stop risk assessment and installation of a friction stop if there isn't one there now.

Current access is via a subsidiary signal and there seems to be a limit of circa 5mph both entering and leaving the turnback siding at St Albans. It can only hold 8-coach trains, by the way. I can't recall what buffer stop is currently fitted.

 

[adamedwards]

5mp limit explains why each morning I see the 08:22 crawl out of the siding and then speed up when it gets to the road bridge, as I assume the rear car is off the siding.

 

[mr_jrt]

The trains aren’t flighted on the slows, at least not in the up. Radlett, Elstree and Mill Hill have 8tph in the peak, spaced either 7/8 mins or 6/9 minutes apart. It’s effectively evenly spaced now and turn up and go. Hendon and Cricklewood have 4tph at 15 minute intervals.

Generally, there isn’t a capacity problem on the trains to the stations between West Hampstead and Radlett. The issue is the fast trains, but the 700s are far, far better than their predecessors in terms of capacity, and crowding is less of an issue than it was. They are still full and standing. In the peak, but rarely crush loaded, and even rarer are the occasions when you can’t board because of crowding (it basically doesn’t happen now). With the old trains being unable to board was a regular occurrence; at least once a week in my case.

Ah, ok. I'm basing my knowledge of overcrowding primarily on what I've read these last few years - I've not commuted on TL for about 10 years (back before FCC!), but it was standing from Elstree then on my train to Kings Cross TL...which presumably also means it must've been an 8-car service. Figures things would be better now.

I took a quick look at 7am-8am at Elstree and it seemed a little weighted, but still a lot better than I thought it would be - I take your point. I couldn't think how so many fast services could be passing the minor stations whilst still giving them a good service and then I remembered how many TLs run on the fasts, so effectively it's kinda like what I was proposing, but the fast lines are taking the hit rather than using the freight lines.

I would still like to see more local stations opened up along the line, though. Brent Cross is a given, Colindeep Lane for Northern Line interchange would be useful, abet expensive, Grahame Park would be very popular, and if these were all to use them (which I still think they should), the Hendon lines extended up into new terminal platforms west of Mill Hill Broadway's platforms to tie things together nicely.

So the next question becomes: if you could shift the Thameslink services off the fast lines, is there suppressed demand for more LDHS services? Obviously platform capacity at St. Pancras becomes a major issue if you were to run more, but let's work on the simple (ambitious) assumption you could add a couple more platforms and lengthen all 6 to remove all constraints there. If you could get the services there, would they be needed? ...and (largely rhetorical!) does that change pre and post HS2? I seem to recall they're not exactly long trains either, so would lengthening make more sense first?

 

[VT 390]

does that change pre and post HS2?

There should still be demand for MML services after HS2 as Leicester will not benifit from HS2 and both Derby and Nottingham will have to travel to the East Midlands Hub so there will not be much difference in journey time.

 

[Kettledrum]

There should still be demand for MML services after HS2 as Leicester will not benifit from HS2 and both Derby and Nottingham will have to travel to the East Midlands Hub so there will not be much difference in journey time.

There's also a lot of traffic between Leicester and Nottingham and Derby which will continue after HS2

 

[Bald Rick]

From my observations, the EMT services are probably the lightest loaded of all LDHS services into London. Off peak is often deserted.

 

[Aictos]

From my observations, the EMT services are probably the lightest loaded of all LDHS services into London. Off peak is often deserted.

Could they fill them up by stopping more off peak at St Albans and Luton?

 

[Bald Rick]

Could they fill them up by stopping more off peak at St Albans and Luton?

Not St Albans, as they would then be overfull; people wedged on the luggage racks etc.

Reintroducing the Bedford and Luton calls will be the way to do it.

 

[Aictos]

Not St Albans, as they would then be overfull; people wedged on the luggage racks etc.

Reintroducing the Bedford and Luton calls will be the way to do it.

I bow to your greater knowledge, besides St Albans still has the fast TL services to use.

So what services would stop at which station? Nottinghams already stop at Luton Parkway and Bedford, Corbys already stop at Luton and Bedford so could Sheffields stop at Luton and Bedford?