HS2 Colne Valley Viaduct construction updates

[stuu]

Post-tensioned is the correct term

 

[snowball]

Yes, it’s explained in the text of HS2’s web page about the viaduct. But I think this is called post-stressed construction?

Haven't read the page but I think the phrase is post-tensioned, or in long form, pre-stressed post-tensioned.

Oops - stuu said it first.

 

[davews]

Planning a walk past there on the London Loop to take a look. Do I take it the towpath and London Loop are still open as normal or are there any diversions or closures? Last time I walked there, four years ago, there was little more than a bit of signage from HS2 Ltd.

 

[DelW]

Yes, it’s explained in the text of HS2’s web page about the viaduct. But I think this is called post-stressed construction? No pictures or videos show the cables though.

The cables will go through some of the ducts which are visible in the last photo of post #84. They will probably be added and stressed as each segment is added to each span.
At one time it was the norm to grout up the ducts after stressing, but unless that's done very carefully to ensure that there are no voids left, corrosion can still occur which is then very difficult and expensive to deal with. I think the current philosophy is to leave ducts ungrouted so that tendons (cables) can be replaced during the lifetime of the bridge if necessary.

 

[LNW-GW Joint]

HS2 Ltd has a piece on the completion of the first of 11 piers in the system of lakes on the route of HS2, under the Colne Valley Viaduct.
Elsewhere in the piece it says 300 of 1000 deck segments have been placed by the "Dominic" girder, so that means the viaduct is 30% completed after one year.
Much advance work will have also been done, including the new pier.
While it's hard to tell, progress overall seems less than planned, for a 2-year viaduct construction period (plus another year to finish off).

HS2 reveals first giant lake piers for record-breaking Colne Valley Viaduct

On first anniversary of the start of deck construction for the UK’s longest railway bridge, HS2 reveals first enormous lake piers that will carry the 2 mile (3.4km) viaduct across a series of waterways on the outskirts of London. In pictures - highlights from the first year of deck construction...

mediacentre.hs2.org.uk

One year after the launch of HS2’s giant ‘bridge-building machine’, progress on the UK’s longest railway bridge has taken another major step forward with the completion of the first piers that will carry the viaduct over a series of lakes just outside London.
The Colne Valley Viaduct – which is being built near Hillingdon - will carry high speed trains more than two miles (3.4km) across the Grand Union Canal, River Colne, local roads and a series of lakes between the end of the London tunnels and the start of the Chiltern tunnels.

 

[Bald Rick]

Elsewhere in the piece it says 300 of 1000 deck segments have been placed by the "Dominic" girder, so that means the viaduct is 30% completed after one year.
Much advance work will have also been done, including the new pier.
While it's hard to tell, progress overall seems less than planned, for a 2-year viaduct construction period (plus another year to finish off).

almost 9 months to the day I was down there and only a handful had been done. So I’d say progress has definitely ramped up significantly, and is continuing at the higher pace.

 

[cuemaster]

A month since i last visited the viaduct and the final segment additions over the haul road is complete..noting the 2 supporting piers in the middle of this seemingly extra large span and different pier type and on-going work.I was wondering if this is something to do with the 4 expansion joints along the viaduct..?

The haul road will divert back next accross the river Colne as the viaduct begins to curve at some point accross the waterways.



Dominique launching girder at the beginning of a span that will cross the river Colne to join up with piers that have been constructed in the water..

 

[LNW-GW Joint]

Great pictures of a spectacular project...

 

[Flying Phil]

Thanks for these updates - the amount of cantilever on that last section looks scary!
I remember the "Box Girder" failures during construction back in the 1970's(?) which resulted in the new Tinsley viaduct through Sheffield being restricted to two lanes (each way) whilst it was internally reinforced....and it is still only two lanes.

 

[snowball]

Thanks for these updates - the amount of cantilever on that last section looks scary!
I remember the "Box Girder" failures during construction back in the 1970's(?) which resulted in the new Tinsley viaduct through Sheffield being restricted to two lanes (each way) whilst it was internally reinforced....and it is still only two lanes.

I've lost count as it has had several rounds of strengthening, and several road configurations at different times, including having a lane closed and having all lanes open but the the hard shoulder closed in places. However I think it's currently three lanes and hard shoulder both ways, and has been for several years.

At one time it was kept down to two lanes even though the latest round of strengthening had been completed, because the traffic was flowing well, owing to the large proportion that turned off at the approach at each end. I think it was restored to three lanes in conjunction with the widening of both approaches to four lanes.

 

[cuemaster]

Thanks for these updates - the amount of cantilever on that last section looks scary!
I remember the "Box Girder" failures during construction back in the 1970's(?) which resulted in the new Tinsley viaduct through Sheffield being restricted to two lanes (each way) whilst it was internally reinforced....and it is still only two lanes.

Thanks - yes the next span accross the river looks as if it will be much longer than normal..

 

[Flying Phil]

I've lost count as it has had several rounds of strengthening, and several road configurations at different times, including having a lane closed and having all lanes open but the the hard shoulder closed in places. However I think it's currently three lanes and hard shoulder both ways, and has been for several years.

At one time it was kept down to two lanes even though the latest round of strengthening had been completed, because the traffic was flowing well, owing to the large proportion that turned off at the approach at each end. I think it was restored to three lanes in conjunction with the widening of both approaches to four lanes.

Thanks Snowball - I believe we still have a local 60mph "For air quality" reasons through Sheffield....
But the Colne valley viaduct is going to be spectacular when finished.

 

[Geogregor]

It is looking better and better with every segment added. It will be quite impressive structure:

 

[Nicholas Lewis]

It is looking better and better with every segment added. It will be quite impressive structure:

Im not an HS2 fan (there were higher priorities elsewhere) anyhow the design of this and the way it blends into its surroundings will earn it accolades like Victorian structures did. Oh and the wildlife will have about five years to fully recovery before any train service appears!!

 

[Flying Phil]

I took a diversion to go along the A412 last week and it is difficult to get a clear view of the structure - so much for it dominating the landscape!..... However what can be seen is certainly impressive.

PS passenger took the pics.

 

[zwk500]

PS passenger took the pics.

That passenger is leaning very far over the drivers side!

 

[Flying Phil]

That passenger is leaning very far over the drivers side!

true!

 

[CyrusWuff]

That passenger is leaning very far over the drivers side!

Could be a left-hand drive car, of course.

 

[zwk500]

Could be a left-hand drive car, of course.

Would be a funny left hand drive car to have the steering wheel on the right and the glove box on the left...

 

[bib]

Not sure there's anything new here but a good overview

 

[Mag_seven]

Another reminder that this thread is for posters to provide HS2 Colne Valley Viaduct Construction Updates.

if anyone wants to discuss anything else then please start a new thread elsewhere.

 

[Fazaar1889]

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500th segment of the 1000 for Colne Valley Viaduct has been installed

 

[LNW-GW Joint]

500th segment of the 1000 for Colne Valley Viaduct has been installed

Not quite - the concrete factory has produced the 500th segment.
It will be some time before it is installed in the viaduct structure by "Dominique".
But it does represent half way for the factory production.

 

[Nicholas Lewis]

Not quite - the concrete factory has produced the 500th segment.
It will be some time before it is installed in the viaduct structure by "Dominique".
But it does represent half way for the factory production.

How many of the 500 are installed?

 

[Fazaar1889]

Not quite - the concrete factory has produced the 500th segment.

Oh whoops sorry, I just came home after a long day at work and saw 500. My mistake

 

[LNW-GW Joint]

How many of the 500 are installed?

It's a while since I saw a viaduct progress report with numbers.
I think it might be about half of that - ie 25% of the viaduct installed.
There's quite a long curing period for the segments after construction I think, before they can be installed.

 

[swt_passenger]

It's a while since I saw a viaduct progress report with numbers.
I think it might be about half of that - ie 25% of the viaduct installed.
There's quite a long curing period for the segments after construction I think, before they can be installed.

30% of 1000 segments were installed by late May, according to your own post #95

 

[LNW-GW Joint]

30% of 1000 segments were installed by late May, according to your own post #95

Ah!

 

[cuemaster]

Some interesting developments i noticed when i trekked out to the Colne Valley site in West London is part of the side screens started to be erected at the beginning of the viaduct. Another change is concrete has been added to the formwork to create the safety barriers(?) for the trains. And the viaduct has now crossed over the river Colne. Quite some progress since the construction started last summer, due for completion around 2025.

 

[pokemonsuper9]

Video contains a couple short interviews about the process of the construction, as well as a look at the site.