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HS2 construction updates

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si404

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Ploughman said:
Maybe they had surplus cones etc in the yard, might as well use them as no one else is.:D:D
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They all looked new - so perhaps they bulk ordered them for the years ahead and don't yet have enough sites to spread them out.
 
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city dweller

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jyte said:
Presumably that's an embankment they're building there? Curzon street will be elevated, right?
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The quote below is from a user on a different forum but seems quite accurate.

To me it looks like processing demolition materials. I read elsewhere (on the Euston site, https://s3-eu-west-2.amazonaws.com/commonplace-customer-assets/hs2ineuston/RPE managing demo materials FINAL.pdf,) that they crush the demolition material on site down to uniform size, stockpile for a few weeks to let it "settle," send off some samples for testing to ensure it's suitable (and possibly "clean" enough) so they can re-use it on site for piling mats, void fill and so forth.

Sites that might have "contaminated" land might need material to be cleaned - for example there was a lot of that done in East London for the clearing and construction of the Olympic Park (on former industrial land) and one wouldn't be surprised if similar is occurring at Old Oak Common & Curzon Street which have had railway depots for well over 100 years (think about all the ash, oil, lubricants, asbestos, etc. leaching into the soil.)
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Dave_Cardboard

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Same chap as above has posted another drone flight video over HS2 works site. POV appears to be to the North of Long Ichington Wood looking southish:

 
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jyte

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Dave_Cardboard said:
Same chap as above has posted another drone flight video over HS2 works site. POV appears to be to the North of Long Ichington Wood looking southish:

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The file name for that video is '2020-05-14 - DJI_0179.MOV' apparently, which suggests it was filmed about 3-4 weeks ago now. Still, It's a great channel to keep an eye on. Nice to see 'progress'.
 
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JamesT

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yoyothehobo

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JamesT said:
Not sure I've seen this referenced on here yet, but it looks like HS2 have had the case against them dismissed that was challenging the Euston tunnel layout - https://www.ianvisits.co.uk/blog/2020/06/05/hs2-wins-court-case-over-euston-tunnels-design/
Though the latest update from the complainant is that she intends to appeal - https://www.crowdjustice.com/case/hs2accountability/
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Nothing like throwing good money after bad.

Considering the engineering that can be done in the UK and worldwide with regards to tunneling and retaining walls and the amount of geotechnical and structural design that goes into these sort of projects and how all design is done, going down the avenue of "it is affecting her human rights" seems incredibly bizarre.
 
ABB125

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yoyothehobo said:
Nothing like throwing good money after bad.

Considering the engineering that can be done in the UK and worldwide with regards to tunneling and retaining walls and the amount of geotechnical and structural design that goes into these sort of projects and how all design is done, going down the avenue of "it is affecting her human rights" seems incredibly bizarre.
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Looking at the plans, my first thought would be, rather than build the tunnel directly under the wall, why not just move it a few metres to the side? Why does it have to go directly underneath the wall?
 
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Ianno87

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ABB125 said:
Looking at the plans, my first thought would be, rather than build the tunnel directly under the wall, why not just move it a few metres to the side? Why does it have to go directly underneath the wall?
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I suspect the alignment into the platforms at Euston (which have to be in a particular orientation, 400m long and then get a throat track layotu in) really could be that tightly determining on where the tunnel has to fall.
 
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Dave_Cardboard

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RSA BOB said:
I see from the photo,s that there are two TBM,s will they be used side by side or is one for another site.
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It seems that modern "long" tunnels (railway or otherwise) are all "twin bore with cross passages and emergency escape and ventilation shafts (to surface)" so the Chiltern Tunnel will indeed require two TBM's "side by side." Though it seems to me that on similar schemes (Crossrail for example,) they don't set them both off at the same time. One is launched, then a few weeks later the second one starts. I would presume that helps with any ground settlement above the line of route and possibly "helps" that the leading machine can feed back information on conditions it encounters to the following one.

For shorter twin bore tunnels, they might use a single TBM to drill one tunnel, then "back out" the support train, shuttle the cutter head back to the starting point, then use the same machine to drill the second bore. IIRC Long Itchington Wood tunnel and possible Bromford (Birmingham) are due to be constructed thusly. It's pretty easy to see why this would be the case for program and cost reasons - you can do that within the timescale of the project, whereas using a single TBM to drill the longer Chiltern tunnels would add years to the programme.

It's interesting to note the various different permutations being used for tunnelling HS2. To date, it seems Chilterns is two TBM's boring South to North in one drive (the longest, so probably starting soonest,) Northolt Tunnels (Ruislip to Old Oak) are using four TBM's starting at both ends and meeting in the middle, Euston is two TBM's boring West to East and the shorter Bromford and Long Itchington Wood tunnels each get one TBM to drill both bores. Plus there is supposed to be a "logistics" tunnel from the Old Oak stations box to the former Willesden EuroTunnel freight terminal to facilitate muck away via rail on the WCML, so presumably that'll need a TBM too. And up near where I live at Harvil Road West of London, they already used a couple of "tiddlers" to build some new tunnels for some utility diversions in the area (gas and water IIRC, though rumour has it that there is a pipeline in that area conveying jet fuel to Heathrow.)
 
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Bald Rick

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Dave_Cardboard said:
It seems that modern "long" tunnels (railway or otherwise) are all "twin bore with cross passages and emergency escape and ventilation shafts (to surface)" so the Chiltern Tunnel will indeed require two TBM's "side by side." Though it seems to me that on similar schemes (Crossrail for example,) they don't set them both off at the same time. One is launched, then a few weeks later the second one starts. I would presume that helps with any ground settlement above the line of route and possibly "helps" that the leading machine can feed back information on conditions it encounters to the following one.
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Twin bore with cross passages is simply cheaper. It produces less spoil and needs less concrete than a double bore tunnel. The logistics of getting rid of the spoil are usually the key constraint on tunnelling speed. The quantities are enormous.

TBMs are indeed started a couple of months apart, and it does help with settlement and the first machine gives advance warning of ground conditions - although on this latter point pilot drilling is often carried out from the TBM in addition to all the ground investigations done from ground level beforehand. But the main reason they are set off a couple of months apart is that that’s how they come off the production line at Herrenknecht (other TBM manufacturers are available), and a specialist team comes over to assemble and commission them. The same team does both, but they can only do one at a time. This also helps with the back up logistics for spoil and segments; it means that for the first couple of months the logistics are on ‘half power’ which makes it easier to shakedown any issues.
 
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