London Bridge reconstruction works

[mr_jrt]

When I raised similar concerns it was pointed out to me that given Thameslink will have only two platforms through the core and ATO, what would be the benefit of having more of them at London Bridge unless you wanted to increase dwell times for interchange...

 

[Class377/5]

When I raised similar concerns it was pointed out to me that given Thameslink will have only two platforms through the core and ATO, what would be the benefit of having more of them at London Bridge unless you wanted to increase dwell times for interchange...

London Bridge Thameslink trains will have a higher dwell time there due to more passengers expected to be boarding/leaving the train.

 

[GW43125]

I just have visions of one TL train taking a minute longer than usual dwell time, then all the ones behind it stacking up. I recall when TL still ran through LBG waiting foe a northbound TL train and being able to see the train I was after third in a queue of trains with one on every block. Seems like very little margin for error.

 

[IrishDave]

I just have visions of one TL train taking a minute longer than usual dwell time, then all the ones behind it stacking up. I recall when TL still ran through LBG waiting foe a northbound TL train and being able to see the train I was after third in a queue of trains with one on every block. Seems like very little margin for error.

That's not necessarily specific to London Bridge, though, is it? Blackfriars, City Thameslink, Farringdon and St Pancras will also only have two through platforms each for Thameslink trains, so that kind of problem could happen at those stations too. Would there any be benefit to having more than two platforms for Thameslink trains at London Bridge, when the other stations in the core don't?

(Of course, one could argue that Blackfriars and St Pancras could have had more through platforms added when they were recently rebuilt - but that isn't likely to happen now.)

 

[GW43125]

That's not necessarily specific to London Bridge, though, is it? Blackfriars, City Thameslink, Farringdon and St Pancras will also only have two through platforms each for Thameslink trains, so that kind of problem could happen at those stations too. Would there any be benefit to having more than two platforms for Thameslink trains at London Bridge, when the other stations in the core don't?

(Of course, one could argue that Blackfriars and St Pancras could have had more through platforms added when they were recently rebuilt - but that isn't likely to happen now.)

Though in the core the speed is a lot lower and consequentially the blocks are a lot closer together, meaning that you can get them closer to each other.

 

[Dr_Paul]

Of course, one could argue that Blackfriars and St Pancras could have had more through platforms added when they were recently rebuilt...

That's what I thought, especially with St Pancras, where I thought that a better arrangement would have been to have the junction between the existing line and the new one up towards Finsbury Park to the south of a four-platform station, rather than to the north of a two-platform station.

As for Blackfriars, was there any suggestion to reinstate the old upstream bridge and thereby have another couple of through platforms?

 

[mr_jrt]

I'm with you on St. Pancras - stupid cost cutting as I believe the original design had 4 platforms and the junctions as you stated. Blackfriars should've had the old bridge used to create 4 through platforms, and Farringdon should've had Smithfield sidings knocked though to the old Farringdon Street station site to give four platforms there under what is now the western ticket hall. But we are where we are.

Here's the old posts (200 posts back on this thread!) for reference: http://www.railforums.co.uk/showpost.php?p=2690132&postcount=1009

 

[ijmad]

The intervals at London Bridge for Thameslink trains on 4 & 5 will be 2.5 minutes, 5 minutes, 2.5 minutes, 5 minutes etc., to 'slot in' the 8tph from Elephant and Castle running every 5 minutes.

So for those trains that have another 2.5 minutes behind them, the maximum dwell time will be the same as in the core. Plus there's not going to be a lot of flexibility for trains to be delayed given the amount of services running through that area over a flat junction.

I guess they'll be depending on ATO to keep things in sequence, which should provide some advantages over traditional signalling.

 

[ComUtoR]

Though in the core the speed is a lot lower and consequentially the blocks are a lot closer together, meaning that you can get them closer to each other.

It's faster through the core than through London Bridge. There are also midpoint signals at London Bridge (same as the core) and additional signals have been added, inducing the horrible ones approaching Waterloo East. I could [redacted] don't have nice things to say about the person who put those signals in.

 

[carriageline]

It's faster through the core than through London Bridge. There are also midpoint signals at London Bridge (same as the core) and additional signals have been added, inducing the horrible ones approaching Waterloo East. I could [redacted] don't have nice things to say about the person who put those signals in.

What'a nasty about the signals mate? Would be really handy to know from a signallers point of view! PM if preferred


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[carriageline]

I've looked at the new layout, and although a lot of it does seem to ease congestion, one thing I can't help but notice is that TL are once again only allocated one platform in each direction-now 4&5.

Surely this must be a right spanner in the works when it all goes Pete Tong, and being sandwiched between opposite-direction lines, do we know if there are any plans to make 3&6 BiDi to allow TL to have some measure of flexibility? If not, it'd seem rather short-sighted to me if they want to run their 20-something trains per hour.

Anyone got any ideas?

There is flexibility to run into 3/6. Whether it's going to be used much is another matter, I would assume it's going to be quite a job stopping problem before it is used. It certainly won't be used as a regulating point unfortunately, if a train/platform is having issues in ANY of the platforms or lines, then someone paid more than me needs to devise contingency plans for when trains run on adjacent lines.


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[Ianno87]

I'm with you on St. Pancras - stupid cost cutting as I believe the original design had 4 platforms and the junctions as you stated. Blackfriars should've had the old bridge used to create 4 through platforms, and Farringdon should've had Smithfield sidings knocked though to the old Farringdon Street station site to give four platforms there under what is now the western ticket hall. But we are where we are.

Here's the old posts (200 posts back on this thread!) for reference: http://www.railforums.co.uk/showpost.php?p=2690132&postcount=1009

At St Pancras, the size of the station box was (I believe) covered in the Bill for CTRL works, as was the Canal Tunnels, as this was the only sensible time be be able to physically build the platforms. This, in effect, required the government to stump up the first £200m or so of commitment to Thameslink funding, just for the two platforms. I'm sure HM Treasury would've been much less keen on providing the funding for 4 platforms, given the lack of commitment to the rest of the scheme. So, if 4 platforms had been insisted on, we wouldn't have a Thameslink Programme at all, in all likelihood.

 

[Ianno87]

There is flexibility to run into 3/6. Whether it's going to be used much is another matter, I would assume it's going to be quite a job stopping problem before it is used. It certainly won't be used as a regulating point unfortunately, if a train/platform is having issues in ANY of the platforms or lines, then someone paid more than me needs to devise contingency plans for when trains run on adjacent lines.


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Running in to 3/6 would involve messing up the (actually more frequent) Cannon St/Charing Cross services in the process - only likely to be done in extremis (e.g. failed train) or for planned platform posessions.

 

[Ianno87]

The intervals at London Bridge for Thameslink trains on 4 & 5 will be 2.5 minutes, 5 minutes, 2.5 minutes, 5 minutes etc., to 'slot in' the 8tph from Elephant and Castle running every 5 minutes.

So for those trains that have another 2.5 minutes behind them, the maximum dwell time will be the same as in the core. Plus there's not going to be a lot of flexibility for trains to be delayed given the amount of services running through that area over a flat junction.

I guess they'll be depending on ATO to keep things in sequence, which should provide some advantages over traditional signalling.

Not quite at London Bridge itself, as 1.5 minutes is the minimum peak dwell time, with 1.5/2 minute platform re-occupations alternately. So it'll be at least 3 minutes between consecutuve trains (trains losing/gaining the time required to even out to 2.5 minute intervals on the run from London Bridge to Blackfriars Jn, also neatly giving some performance recovery before entering the core)

 

[Barn]

I've looked at the new layout, and although a lot of it does seem to ease congestion, one thing I can't help but notice is that TL are once again only allocated one platform in each direction-now 4&5.

I'm surprised that 4&5 (which will serve a plethora of different stopping patterns) appear to be narrower than 8&9, which serve trains headed towards Waterloo East and Charing Cross.

I would have thought that both islands would have big 'AM peak spill outs' of passengers travelling to London Bridge, but passengers departing from 4&5 might be more likely to need to wait around on the platform for their particular service.

Will passengers somehow be encouraged to remain on the concourse for longer when arriving for Thameslink services?

 

[Class377/5]

I just have visions of one TL train taking a minute longer than usual dwell time, then all the ones behind it stacking up. I recall when TL still ran through LBG waiting foe a northbound TL train and being able to see the train I was after third in a queue of trains with one on every block. Seems like very little margin for error.

There a problem world of difference between the old set up at London Bridge where TL had to weave inbetween Southeastern services and having their own platforms like in 2018.

As for stacking up due to a minutes delay, the signalling in the Core is not planned to be at its maximum ever in booked. The planned 24tph service is not the full capabilities of Thameslink which is actually 32tph.

Now the Victoria line achieve this with far smaller platforms than Thameslink (Farringdon aside) meaning those waiting for less regular service have more space. The Thameslink Programme was designed to last with passenger numbers for the next 50 years and stations were modelled accordingly.

 

[Bald Rick]

I'm with you on St. Pancras - stupid cost cutting as I believe the original design had 4 platforms and the junctions as you stated. Blackfriars should've had the old bridge used to create 4 through platforms, and Farringdon should've had Smithfield sidings knocked though to the old Farringdon Street station site to give four platforms there under what is now the western ticket hall. But we are where we are.

Here's the old posts (200 posts back on this thread!) for reference: http://www.railforums.co.uk/showpost.php?p=2690132&postcount=1009

For the umpteenth time - 4 platforms was not in the original spec at St P, for the rather significant reason that it would not actually be possible without billions of extra expense.

 

[TheDavibob]

I'm surprised that 4&5 (which will serve a plethora of different stopping patterns) appear to be narrower than 8&9, which serve trains headed towards Waterloo East and Charing Cross.

I would have thought that both islands would have big 'AM peak spill outs' of passengers travelling to London Bridge, but passengers departing from 4&5 might be more likely to need to wait around on the platform for their particular service.

Will passengers somehow be encouraged to remain on the concourse for longer when arriving for Thameslink services?

Are the up/down platforms the same width? I feel like having a wider southbound than northbound platform would make sense (since anybody heading through the core would be more happy to just catch the first train and change later).

 

[hwl]

I'm surprised that 4&5 (which will serve a plethora of different stopping patterns) appear to be narrower than 8&9, which serve trains headed towards Waterloo East and Charing Cross.

I would have thought that both islands would have big 'AM peak spill outs' of passengers travelling to London Bridge, but passengers departing from 4&5 might be more likely to need to wait around on the platform for their particular service.

Will passengers somehow be encouraged to remain on the concourse for longer when arriving for Thameslink services?

There is a lot more space behind the hoarding on the P4/5 island than in front so you'll be surprised. Also remember that the current track alignment along P5 at the western end is much further North than the final arrangement when it becomes up Blackfriars, this has also precluded the construction of the final circa 35m at the western end form being constructed till after the Cannon Street services revert to going through P1 and P2 in few months time.

 

[Barn]

Are the up/down platforms the same width? I feel like having a wider southbound than northbound platform would make sense (since anybody heading through the core would be more happy to just catch the first train and change later).

They're on each side of a single island platform together, so the up and down Thameslink passengers mingle with each other (unlike the Charing Cross platforms which have a large "double-up" island and a separate large "double-down" platform).

There is a lot more space behind the hoarding on the P4/5 island than in front so you'll be surprised.

Yes, hopefully it's an optical illusion. I'm still a bit nervous though, especially as those platforms will be a major drop-off / pick-up point for people travelling to London Bridge itself, and not just passing through. For example, on the Redhill line, passengers who previously would have used the terminating platforms to board at London Bridge will now all head to platform 4.

 

[TheDavibob]

They're on each side of a single island platform together, so the up and down Thameslink passengers mingle with each other (unlike the Charing Cross platforms which have a large "double-up" island and a separate large "double-down" platform).

Of course it would be - no idea why I was thinking otherwise. Cheers

 

[mr_jrt]

For the umpteenth time - 4 platforms was not in the original spec at St P, for the rather significant reason that it would not actually be possible without billions of extra expense.

I'm genuinely intrigued where you're getting that figure of billions from. The new platforms are built largely under the new shed extension (and south under the old coal drops and parcels deck which were demolished), so there would have been no structural issues from them, certainly no more than the two platforms we did get. Information on the precise alignment of the tunnel under the main station are difficult to find, but the general consensus seems to be that the tunnel largely follows under or alongside Midland Road's old alignment with a slight difference of bearing with the modern alignment so that it remains straight but roughly aligns with the canal crossings further north, which means the curve roughly finishes behind the British Library, and indeed, the platforms were built where they were as that's the southernmost bit of straight track.

With that in mind then, building an additional tunnel west of the current one, merging under Midland Road, should have been fairly easy (and thus relatively cheap). The complicating factor is the listed main station. Given the new tunnels wouldn't need to run under much, if indeed any of that, I don't see the problem that would lead to billions in additional costs. It was my understanding the new station was built by digging down around the operational railway and excavating a box, which was then covered over the new St Pancras elevation built atop it. Digging out a larger space shouldn't have been particularly challenging given the open space to the west of the station at that time.

...now by all means make the argument they weren't necessary, but that's certainly not the same as arbitrarily inflating costs to make your case.

 

[Bald Rick]

I'm genuinely intrigued where you're getting that figure of billions from. The new platforms are built largely under the new shed extension (and south under the old coal drops and parcels deck which were demolished), so there would have been no structural issues from them, certainly no more than the two platforms we did get. Information on the precise alignment of the tunnel under the main station are difficult to find, but the general consensus seems to be that the tunnel largely follows under or alongside Midland Road's old alignment with a slight difference of bearing with the modern alignment so that it remains straight but roughly aligns with the canal crossings further north, which means the curve roughly finishes behind the British Library, and indeed, the platforms were built where they were as that's the southernmost bit of straight track.

With that in mind then, building an additional tunnel west of the current one, merging under Midland Road, should have been fairly easy (and thus relatively cheap). The complicating factor is the listed main station. Given the new tunnels wouldn't need to run under much, if indeed any of that, I don't see the problem that would lead to billions in additional costs. It was my understanding the new station was built by digging down around the operational railway and excavating a box, which was then covered over the new St Pancras elevation built atop it. Digging out a larger space shouldn't have been particularly challenging given the open space to the west of the station at that time.

...now by all means make the argument they weren't necessary, but that's certainly not the same as arbitrarily inflating costs to make your case.

I've done this at least twice before, but here goes:

The curve from the south is too tight for pointwork to have a linespeed high enough to maintain a 75 second headway. Indeed it's too tight for any pointwork AIUI.

Therefore, to get the necessary divergence / convergence for the platforms, the point work needs to be on the straight section, ie the toes of the points would be about 1/3 of the way along the existing platforms.

Allowing for the points themselves, and to get the necessary track separation for the platforms - with escalators etc - puts another 100 metres or so on. More so in the southbound direction, as you would want a 100metre overlap clear of the platform starter signal before the conflicting point of the converging junction. Therefore the south end of a four platform station would be, at best, where the north end of the two platform station is today, ie at least 250metres further north.

Now look to the north of the existing platforms. The northbound tracks turn sharply upwards. And there are the junctions for the Canal tunnels immediately off the platform ends. Let's assume that putting new platforms on that gradient is acceptable (it isn't), then the junction for the ECML is at least 250metres north of where it is today. And that is the problem, as the alignment of the tunnels as built is such that they can only just twist and turn to the right place to make the junction on the ECML (I can vouch for this having walked them).

Therefore with the junction at the St Pancras end being 250m further north, the tunnels couldn't reach the junction on the ECML, so that would also have to move north. Unfortunately Copenhagen tunnel is in the way so the Canal tunnels would have to be bored to a point north of that, popping up somewhere on Holloway bank or near Finsbury Park. By this point, the ECML tracks are paired by direction, not use, so there would need to be two portals, one either side of the ECML. Note the residential properties neighbouring the railway at this point. Also note the Piccadilly line is just about under the ECML along here and would also have to be avoided, somehow.

Compared to what was built that results in an at least an extra 2 miles of single tunnel, an extra portal, plus rather a lot of property acquisition and demolition. Easily half a billion, probably more.

Turning to St Pancras, the current platforms are partly built outside the footprint of the station building and are partly under the taxi rank. additional platforms would have to have gone to the west - there being a culverted river / sewer to the east. That would have required cut and cover tunnelling under Midland Road and the demolition of many properties on the west side of same. Given that a 4 platform low level station is 250m further north, it would be well outside the footprint of the main station and would require the excavation of St Pancras church gardens, and probably demolition of the church itself. There would also need to be a head house for the secondary escape at the north end, somewhere near the Regents Canal. All told, this is a 4 platform sub-surface station well outside the footprint of an existing station. That is easily another billion, probably more.

And the end result that most passengers would notice is they have to walk at least an extra 250metres to get to where they want to get to.

 

[telstarbox]

Well we've had enough of experts

 

[ScotGG]

I'm sure its been answered and sorry if so, but as Cannon Street post 2018 sees a peak time cut in capacity of about 2tph from what it was in 2014, have they finalised what services are going?

Or is a future SE consultation deciding that alongside the Thameslink one which diverts some former SE routes onto it eg via Charlton?

 

[mr_jrt]

Well we've had enough of experts

C'mon, that's not fair.

He's provided a very good answer that more than satisfies my query. I was aware it had cropped up before, but I'm fairly certain I've never had such a good explanation. You can see how much more useful than "it will cost a billion more" it is.

...and now everybody does, for posterity.

 

[Barn]

I'm sure its been answered and sorry if so, but as Cannon Street post 2018 sees a peak time cut in capacity of about 2tph from what it was in 2014, have they finalised what services are going?

Or is a future SE consultation deciding that alongside the Thameslink one which diverts some former SE routes onto it eg via Charlton?

It's a bit of a guess, but it seems likely that the Greenwich / North Kent line will see:

• 4tph to Cannon Street via Greenwich (stopper)
• 2tph to Thameslink Core (semi-fast Dartford - Chalton, stopper on Greenwich line, keeping Greenwich line stations at 6tph)
• 2tph to Charing Cross via Blackheath (stopper, giving North Kent line stations at least 6tph)

This would allow the 2tph Cannon Street reduction to come from the Greenwich service.

 

[Class377/5]

C'mon, that's not fair.

He's provided a very good answer that more than satisfies my query. I was aware it had cropped up before, but I'm fairly certain I've never had such a good explanation. You can see how much more useful than "it will cost a billion more" it is.

...and now everybody does, for posterity.

Until we start a new page and everyone forgets

 

[Roast Veg]

Will Waterloo East go to 2 up 2 down from the current alternating arrangement as per new London Bridge platforms? That is, will platforms B and C switch directions if they haven't already?

 

[carriageline]

Will Waterloo East go to 2 up 2 down from the current alternating arrangement as per new London Bridge platforms? That is, will platforms B and C switch directions if they haven't already?

I'm not sure what your asking, but there are no signalling or pway changes at Waterloo east planned whatsoever. What we have got
Is what is staying now.

2 up 2 down island platforms wouldn't work


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