HS2 Old Oak Common

[najaB]

Don't know, not too long, but wasn't that an emergency replacement not a planned job?

It was very much a planned job: https://scotlandsrailway.com/projects/ravenscraig

 

[zwk500]

It was very much a planned job: https://scotlandsrailway.com/projects/ravenscraig

Oh, silly me I got it confused with the Lamington viaduct that got washed out some years ago

 

[kevin_roche]

If they are replacing the GW bridge due to a widening of Old Oak Common Lane then that will be a lengthy blockade wont it?

The first part of the works is described here...

Notice of Upcoming Bridge Works - HS2

Notice of Upcoming Bridge Works High Speed Two (HS2) is the new high speed railway for Britain. Old Oak Common Lane will be widened and lowered in a few years. We previously wrote to you about the preparation works that are needed for this to happen. This update is to advise of the change in […]

www.hs2.org.uk

To support the bridge replacements and demolition, we will be piling along the east side area of Old Oak Common Lane from Monday 17 April to Friday 27 May (excluding bank holidays).
The working times will be Monday to Friday, 8am to 6pm and Saturdays, 8am to 1pm.

 

[Meerkat]

Looking at the plans above again it looks like the GWR bridge is really a long curving tunnel - I'm guessing it can't be built in one lift-in piece.
Just lifting out the old Wycombe line bridge is going to take a week of closure!

 

[najaB]

Looking at the plans above again it looks like the GWR bridge is really a long curving tunnel - I'm guessing it can't be built in one lift-in piece.

If that's what will require the shortest closure and be cheapest overall, then that's exactly what will happen. Engineers can literally move the Earth if you give them enough incentive!

 

[zwk500]

Looking at the plans above again it looks like the GWR bridge is really a long curving tunnel - I'm guessing it can't be built in one lift-in piece.
Just lifting out the old Wycombe line bridge is going to take a week of closure!

Looks to me like a fairly simple concrete box-girder structure. No reason it can't be craned in reasonably quickly. The bigger issue appears to be the tripling of the void required for the road. (Image from Proposed_Bridge_Sections_-_1C4C0C~1.PDF) on the planning website. That extra space will take time to dig out, so I would expect the closure length of road and rail to be mainly for the excavation.

Slight differences in the structure, but general principle viewable here:

.

 

[Meerkat]

Looks to me like a fairly simple concrete box-girder structure. No reason it can't be craned in reasonably quickly.

Not in one piece though! I assume they would use a lot of beams/slab and lift them in one by one.
The length (not span) means you can't do that short cut where they put big piles/pillars in either side before closure, then use them to support the new bridge abutments.

 

[zwk500]

Not in one piece though! I assume they would use a lot of beams/slab and lift them in one by one.

Indeed. It looks from the plans like it'll be made of lots of sections of pre-formed concrete blocks and beams that a crane or two will assemble sequentially.

The length (not span) means you can't do that short cut where they put big piles/pillars in either side before closure, then use them to support the new bridge abutments.

I think the active railway on top may also be an issue...

As a side note it's good to see that they are dropping the road, presumably if it's deep enough for a coach it'll also be deep enough for double decker buses? It's also funny to see that the Architect's default car model is a Volvo, I wonder if they used to use Saabs?

 

[najaB]

That extra space will take time to dig out, so I would expect the closure length of road and rail to be mainly for the excavation.

That's maybe what, a couple of days max to dig out. The video linked on the page above shows what can be done in a couple of days (skip to 1:23 for the bridge installation):

 

[zwk500]

That's maybe what, a couple of days max to dig out. The video linked on the page above shows what can be done in a couple of days (skip to 1:23 for the bridge installation):

There's a lot more material than in that video to dig out though - the existing ground line is marked on the part I posted, the depth is at least doubled and the width nearly tripled, across an 8 track width. Also it depends where they can move the dirt to - you can only dig out dirt if you've got the storage or disposal ready for it.
That being said I'd be surprised if it couldn't be done over a Christmas blockade at worst. Might even fit an Easter Block.

 

[najaB]

There's a lot more material than in that video to dig out though - the existing ground line is marked on the part I posted, the depth is at least doubled and the width nearly tripled, across an 8 track width. Also it depends where they can move the dirt to - you can only dig out dirt if you've got the storage or disposal ready for it.

All I'm hearing is "more room for more diggers".

 

[zwk500]

All I'm hearing is "more room for more diggers".

It's quite a dramatic change - every bit as transformative as Cow Lane Bridge in Reading, if not more so. That was a seriously impressive job as well.

 

[reddragon]

All I'm hearing is "more room for more diggers".

Or connection to conveyor belt?

 

[PG]

As a side note it's good to see that they are dropping the road, presumably if it's deep enough for a coach it'll also be deep enough for double decker buses? It's also funny to see that the Architect's default car model is a Volvo, I wonder if they used to use Saabs?

4.98 metres will comfortably fit a double decker bus with room to spare so no worries there. Why do you think they may have previously used Saabs?

 

[zwk500]

4.98 metres will comfortably fit a double decker bus with room to spare so no worries there. Why do you think they may have previously used Saabs?

Architects had a reputation for preferring Saabs as their actual cars.

 

[PG]

Architects had a reputation for preferring Saabs as their actual cars.

Ah right, thanks. I note the pedestrians appear to be both females wearing trousers with the one nearest the road seeking to reintroduce flares! Also the cyclist seems to have substituted a straight pole in place of the handlebars the bicycle was supplied with.

 

[kevin_roche]

For those interested in the GWML track layout at OOC, there's a planning application at OPDC that includes the (latest) iteration of the track layout including provision for links to the Chiltern line. It shows 4 platform faces on the GWML Relief lines with 3 turnback sidings to the West.

There was a recent talk given to the PWI in which a track diagram for the GWML at OOC was presented. Here is a screenshot I took at the time. It only shows a single line link to the Chiltern line but an earlier slide in the presentation mentions a proposal for a two-platform station on the Chiltern line.




In case you would like to see the presentation. It is available on YouTube

 

[Dave_Cardboard]

IIRC that same talk (and it's accompanying slides) also showed the sequencing of the works. Basically, they build out the new section of bridge/tunnel at the northern end, the slue the GWML relief tracks onto it, followed by some more slues of the Mains, knock down and rebuild the southern end, then slue the lines back and/or fettle them to their final alignments. This is all happening in concert with the GWML new station build. I don't recall when the dig down of the roadway beneath occurs and whether they are going to keep traffic lane open whilst they do so.

There has already been a lot of work done for diverting the utilities buried on Old Oak Common Lane - a whole bunch of new small tunnels to accomodate them have been (IIRC) "pipe jacked" under the lines.

The PWI slide deck is here... https://www.thepwi.org/wp-content/u...n-Station-HS2_Chris-Ford-Rakesh-Athukattu.pdf

 

[kevin_roche]

IIRC that same talk (and it's accompanying slides) also showed the sequencing of the works. Basically, they build out the new section of bridge/tunnel at the northern end, the slue the GWML relief tracks onto it, followed by some more slues of the Mains, knock down and rebuild the southern end, then slue the lines back and/or fettle them to their final alignments. This is all happening in concert with the GWML new station build. I don't recall when the dig down of the roadway beneath occurs and whether they are going to keep traffic lane open whilst they do so.

There has already been a lot of work done for diverting the utilities buried on Old Oak Common Lane - a whole bunch of new small tunnels to accomodate them have been (IIRC) "pipe jacked" under the lines.

The PWI slide deck is here... https://www.thepwi.org/wp-content/u...n-Station-HS2_Chris-Ford-Rakesh-Athukattu.pdf

Edit: The slide deck has the handover dates on page 17 Section D (Bridge) Apr 2025 and Section N (Underbridges) Feb 2028, Part 3 OOCL bridges April 2028.

 

[Meerkat]

I'm a bit confused because looking at various diagrams the bridges (OOC Lane and Central Line) get done in three goes (off line to the north, space created by slueing the reliefs, space created by slueing the mains) but there are only two big blockades, one of which would be to get it to finished state??
And the narration said there are two big blockades because they have little confidence in the ETCS signal engineers - takes months to set up conventional interlocking but years to set up the same for ECTS as an overlay.......I thought ECTS was the simpler, better, future!!

Couple of promising asides from the Q&A
The DfT specifically funded the extra bridging for the Wycombe lines so must be fairly keen on a future Chilterns station (hopefully too late to pull that!)
They are building a business case (and have a quote IIRC) for electrifying the Poplar lines (Acton to NLL link) for getting the 345s from a West Ealing - Reading shuttle to the Crossrail depot via the NLL to Stratford and then back through the central tunnel section during blockades. With a separate, less ambitious, business case for electrifying just the nearer 600m so they can turn a couple more relief line trains per hour.

 

[zwk500]

And the narration said there are two big blockades because they have little confidence in the ETCS signal engineers - takes months to set up conventional interlocking but years to set up the same for ECTS as an overlay.......I thought ECTS was the simpler, better, future!!

ETCS on it's own is simpler, ETCS Overlaid on conventional signals is much harder because you have to make sure everything is moving together as it's meant to.

 

[The Planner]

There will be more than two blockades...

 

[brad465]

Is the intention to have all GWR services call at OOC when complete? I suspect HEx services won't, either because it defeats the purpose of that service, or because it will cease to exist by 2028 on grounds of being redundant, but happy to be corrected.

 

[Benjwri]

Is the intention to have all GWR services call at OOC when complete? I suspect HEx services won't, either because it defeats the purpose of that service, or because it will cease to exist by 2028 on grounds of being redundant, but happy to be corrected.

Because of the setup of the station and pathing, if HEx still exists, which it probably will, it will have to call at OOC, which will create all kinds of issues with contactless etc

 

[swt_passenger]

Is the intention to have all GWR services call at OOC when complete? I suspect HEx services won't, either because it defeats the purpose of that service, or because it will cease to exist by 2028 on grounds of being redundant, but happy to be corrected.

Yes, this been stated often in official documents, such as the last Network Rail Western route study. Also has been regularly pointed out in these forums over recent years, it’s exactly why the GW side will have eight platforms, two for each of the four through lines

 

[cuemaster]

Any chance Paddington could become the temporary london HS2 terminus or take some trains while Euston gets sorted....with a short 1km tunnel from OOC to the surface...presumably one issue woud be platform capacity at Paddington as well as the cost of constucting the additional tunnel.. i'm sure there are other things too...

 

[The Planner]

Any chance Paddington could become the temporary london HS2 terminus or take some trains while Euston gets sorted....with a short 1km tunnel from OOC to the surface...presumably one issue woud be platform capacity at Paddington as well as the cost of constucting the additional tunnel.. i'm sure there are other things too...

None.

 

[cuemaster]

Thanks! if you don't ask, you'll never know...

 

[zwk500]

Thanks! if you don't ask, you'll never know...

If you have a look at how deep the OOC box is on the HS2 publicity you'll see the problems with trying to link into Paddington before you even consider the capacity issues.

 

[LNW-GW Joint]

Not to mention the Elizabeth and Bakerloo line tunnels already there, plus H&C sub-surface and the canal alongside.
Paddington is on quite a sharp bend from Royal Oak too, making 400m platforms hard to fit in.
An underground station would probably compromise the whole trainshed structure as well, leading to the same sort of construction problems as at Euston.
The initial search for a London terminus concluded that Euston was the only viable site of the (23?) possibles analysed.