HS2 Colne Valley Viaduct construction updates

[stuving]

In the PWI video above they explain that there are temporary extra steel props each side of the piers, while the segments are being put into place, to deal with this problem.

The props (with jacks on them) are to prevent the cantilevers tipping over. The pier, and its lever arm longitudinally, are too small to provide a restoring moment if the balanced part-built cantilever starts to tip. It needs its mid-span ends (or at least one of them) fixed to something before the props are removed.

The post-tensioning tendons, some of which are put in with each new pair of sections, hold the sections' faces together. My understanding of that PWI video is that these can hold the bridge together with no help from the props.

== Doublepost prevention - post automatically merged: 27 Jun 2024 ==

Good point. Perhaps there’s a similar one visible in the overland section at the northwest end, or where it crosses Moorhall Rd?

There are three pier-mounted expansion joints, plus one on the northern abutment. There are also four piers that are "points of longitudinal fixity". The last expansion joint is 462 m from the final abutment; I think that is the one seen in the video.

 

[swt_passenger]

There are three pier-mounted expansion joints, plus one on the northern abutment. There are also four piers that are "points of longitudinal fixity". The last expansion joint is 462 m from the final abutment; I think that is the one seen in the video.

Thanks. Is that from an online resource such as the PWI lecture, that I can have a look at?

 

[stuving]

Than’s. Is that from an online resource such as the PWI lecture, that I can have a look at?

Yes, it's the one previously referred to, in post 157.

 

[swt_passenger]

Yes, it's the one previously referred to, in post 157.

Thanks again. I’ve taken a screen grab that sums up what you’ve said:

(If you can’t see the 8mage, it’s a presentation slide showing the 3.4 km overall length divided into four sections.)

 

[Snow1964]

New drone video, showing acoustic panels on sides of Colne Valley viaduct (opposite end to where Dominique is building it)

 

[vic-rijrode]

New drone video, showing acoustic panels on sides of Colne Valley viaduct (opposite end to where Dominique is building it)

To me, that viaduct looks beautiful and when the temporary road and work areas are restored, it will be a magnificent section of HS2.

 

[Nicholas Lewis]

New drone video, showing acoustic panels on sides of Colne Valley viaduct (opposite end to where Dominique is building it)

Great close up video. Looks to me the height of the walls will restrict views from the train

 

[Flying Phil]

To me, that viaduct looks beautiful and when the temporary road and work areas are restored, it will be a magnificent section of HS2.

Totally agree!

 

[Geogregor]

To me, that viaduct looks beautiful and when the temporary road and work areas are restored, it will be a magnificent section of HS2.

True.

Unfortunately it looks like passengers won't be able to see anything apart from the wall of sound barriers...

 

[swt_passenger]

In the earlier discussions of the barriers, (seems to get repeated every time someone notices), they were described as transparent, it’s all a bit weird.

 

[stuving]

In the earlier discussions of the barriers, (seems to get repeated every time someone notices), they were described as transparent, it’s all a bit weird.

In the PWI video (see post 157; around 12:00) the barriers are described as "partially transparent". Now the lower part is a separate concrete outer parapet, so that's always opaque. But I think the upper part is transparent in some places and not in others.

I have a vague memory that using transparent barriers for the main over-water sections was beneficial in reducing the structure's visual intrusiveness. I'd guess that the opaque bits are also as much to stop others seeing the trains, as to stop passengers seeing whatever its neighbours are up to.

 

[vic-rijrode]

True.

Unfortunately it looks like passengers won't be able to see anything apart from the wall of sound barriers...

Yes, those who pay the preseumably premium prices for travel on HS2 won't get the benefit of great views, but those on the A412 and local roads through the lakes will. It's pity that I used to travel that way daily but now live 300 miles away.

 

[Energy]

In the PWI video (see post 157; around 12:00) the barriers are described as "partially transparent". Now the lower part is a separate concrete outer parapet, so that's always opaque. But I think the upper part is transparent in some places and not in others.

Correct. Wherever possible it is hybrid barriers that have the lower half acoustic panels and transparent acrylic above 1.65m. The acoustic panels are a mineral wool/galvanised steel sandwich with the lower half intended to reduce noise from the track/wheels and full-height acoustic panels are only used where necessary. The view of the lower half is blocked from the outside by a continuous parapet.


Image Description: A computer-generated image of the view from the HS2 Colne Valley viaduct with the noise barriers shown.
[Source]

 

[Fazaar1889]

New drone video, showing acoustic panels on sides of Colne Valley viaduct (opposite end to where Dominique is building it)

That looks so cool imo. Definitely a futuristic timeless kind of vibe, similar to Westminster station.

 

[Snow1964]

Another new drone video, slightly further along the line, but also in Colne valley, around Breakspear Road. Looks like they need lot of fill to create an embankment between the new concrete bridges

 

[Snow1964]

New drone video of Colne Valley viaduct with Dominique now on dry land

 

[Fazaar1889]

Another drone shot. The barriers look alright

== Doublepost prevention - post automatically merged: 20 Jul 2024 ==

Construction nearing the end

 

[Flying Phil]

We drove along the A412 yesterday and went under that section of the viaduct, complete with its accoustic barriers. They have made it look a bit "bulkier" but it is still very graceful. Looking forward to seeing it completed and later having trains running.

 

[swt_passenger]

Latest video by Simonc.

Good progress by “Dominique”, there are now only 3 piers left visible between the front of the machine and the start of the embankment section towards Harvil Road and the Copthall tunnel. (4 if you add the pier under the end of the gantry.)

I think they could possibly finish installing viaduct sections during August?

I hope this is of interest:

 

[snowball]

Google Streetview has views from last month (June) on the A412 where the viaduct goes over it.

Google Maps

Find local businesses, view maps and get driving directions in Google Maps.

www.google.co.uk

 

[pokemonsuper9]

Google Streetview has views from last month (June) on the A412 where the viaduct goes over it.

Google Maps

Find local businesses, view maps and get driving directions in Google Maps.

www.google.co.uk

That says June 2023 not 2024.

 

[snowball]

You're

That says June 2023 not 2024.

Oops sorry. The viaduct has been essentially complete at that end for longer than I remembered.

Still good pics though, for anyone who hasn't seen them before.

 

[swt_passenger]

Another video update of the viaduct progress with Dominique, and the Copthall tunnel works. Loads of clearance under the overhead power lines, (which was discussed a few weeks ago).

 

[Snow1964]

Quite a lot of info on attached upcoming works in Hillingdon.

Mentions removal of the temporary jetties used for viaduct construction through to June 2025 (descriptions associated with locations map 1)

Dominique is expected to be dismantled in sections during September (descriptions associated with map 2)

https://assets.hs2.org.uk/wp-content/uploads/2024/07/Hillingdon-August-2024-Construction-look-ahead-Align-SCS-002.pdf

 

[Geogregor]

Some shots from a train:

P1870456 by Geogregor*, on Flickr


P1870457 by Geogregor*, on Flickr


P1870458 by Geogregor*, on Flickr

 

[TheHSRailFan]

Lovely Shots, Might try and get out to see it before it gets dismantled

 

[swt_passenger]

In the comments of the latest video from SimonC it is suggested there’ll be one more ‘jump’ to allow the launch girder to stand on the next pier, and that will happen early in the week after the bank holiday, 27th, then the last segment will go in on 5th Sep.

 

[snowball]

Are there any plans for Dominique to be used elsewhere?

 

[Nicholas Lewis]

Another video update of the viaduct progress with Dominique, and the Copthall tunnel works. Loads of clearance under the overhead power lines, (which was discussed a few weeks ago).

Great video again have to wonder why the next section needs to be cut and cover?

 

[swt_passenger]

Great video again have to wonder why the next section needs to be cut and cover?

There‘s an explanation of sorts on an HS2 web page I saw linked somewhere. A cutting to modern slope angle standards would have apparently meant vast quantities of spoil would have to be taken elsewhere. The cut and cover means it can be stored locally and replaced, with the landscape reinstated as it was. Sounds dubious, but that’s a quick summary.