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HS2 construction updates
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BRX
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Does this mean the tunnel segment trains from Grain should start running quite soon?
TheHSRailFan
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Surprised this has not been shown here so why not...
the Colne Valley Viaduct being constructed over the A412 (North Orbital Road) which the progress has shown quite a bit. a few people have shown the progress on Twitter so credit goes to them.
Credit: @RailNutter on Twitter
the Colne Valley Viaduct being constructed over the A412 (North Orbital Road) which the progress has shown quite a bit. a few people have shown the progress on Twitter so credit goes to them.
Credit: @RailNutter on Twitter
Such an impressive piece of machinery.
Presumably a similar setup will be used to build the series of viaducts over the M42/M6 Toll complex to the east of Birmingham?
Would it still be possible to do this over a very busy live motorway, slightly different to the A412 I imagine.
I recall there being an explainer on the HS2 website for the Water Orton viaducts which was similar to the Colne Valley one with the segments cantilevering, but looks to have disappeared from the page now:
https://www.hs2.org.uk/building-hs2/viaducts-and-bridges/water-orton-viaducts/
BananaRepublic
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The span across the A412 is now almost completed with the next span progressing out on the other side of the pier on the eastern side of the road.
The Launching Girder will soon be moving forward to the next pier base.
This photo is already 5 days out of date....
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LNW-GW Joint
Veteran Member
HS2 Ld has a piece on the arrival of the Chiltern TBMs at the Chalfont St Giles ventilation shaft, at the 4-mile (6.4km) mark.
mediacentre.hs2.org.uk
TBM Shushila, launched last week at the West Ruislip portal, is also now visible on the In Your Area progress map.
www.hs2.org.uk
HS2 Chiltern tunnel – ‘Florence’ and ‘Cecilia’ reach 4 mile point at Chalfont St Giles
HS2’s first Tunnel Boring Machines (TBMs) excavating HS2’s longest tunnels have completed the first 4 miles of their drive – from the Chiltern tunnel’s south portal to the second ventilation shaft at Chalfont St Giles Download latest photos of the Chiltern tunnel and Chalfont St Giles vent shaft
TBM Shushila, launched last week at the West Ruislip portal, is also now visible on the In Your Area progress map.
In your area map - HS2
Search our interactive In Your Area Map to find information about current or planned HS2 construction works taking place across the route.
www.hs2.org.uk
BananaRepublic
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HS2 Ld has a piece on the arrival of the Chiltern TBMs at the Chalfont St Giles ventilation shaft, at the 4-mile (6.4km) mark.
HS2 Chiltern tunnel – ‘Florence’ and ‘Cecilia’ reach 4 mile point at Chalfont St Giles
HS2’s first Tunnel Boring Machines (TBMs) excavating HS2’s longest tunnels have completed the first 4 miles of their drive – from the Chiltern tunnel’s south portal to the second ventilation shaft at Chalfont St Giles Download latest photos of the Chiltern tunnel and Chalfont St Giles vent shaft
Surely that press release must have been put out, more than a week too late?
The first TBM, Florence, was reported being a further 200 metres beyond the Chalfont St. Giles ventilation shaft, 5 days ago, having covered that distance in 8 days. That’s makes it nearly 2 weeks from setting off again.
They had both reached the shaft over 2 weeks ago, from other reports and HS2’s own progress reports.
No doubt the HS2 Ltd PR and information budget must be substantial, but their track record on output has been very sporadic, often late.
Their interactive progress map is updated at irregular intervals, sometimes up to a month behind. It even had the position of TBM Dorothy, mysteriously in the Chilterns last week!
kevin_roche
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Thet is an interesting diagram of the above and below-ground construction. I was wondering if the ventilation sucks air out of the tunnel does it all go in at the portals or do other shafts blow air in. Does the ventilation only operate when trains are stationary or there is a fire or will it be continuous?
I was under the impression the ventilation was mostly passive. The trains moving through will push air in front of them which can escape through the shaft ahead, and air will be sucked down behind. Then the fans are used to extract smoke etc. if there’s a problem.
LNW-GW Joint
Veteran Member
Apparently the number of vent shafts is determined by the separation of trains in the tunnels (ie signalling headway), and their speed.
So the 18tph timetable and 400km/h design of HS2 means 5 vent shafts for the 16km Chiltern tunnels, at roughly 3km intervals.
Another oddity is that the Northolt tunnel diameter is slightly smaller than the Chiltern ones, presumably because of the lower speed in the London tunnels.
So the 18tph timetable and 400km/h design of HS2 means 5 vent shafts for the 16km Chiltern tunnels, at roughly 3km intervals.
Another oddity is that the Northolt tunnel diameter is slightly smaller than the Chiltern ones, presumably because of the lower speed in the London tunnels.
edwin_m
Veteran Member
It's usual to arrange the signalling so there can only ever be one train between any two ventilation shafts. Hence if a train catches fire the smoke can be removed before it reaches another train, so only one train needs to be evacuated urgently.
When moving normally the trains will be widely spaced due to the high travel speed and long braking distances, but if for some reason a train has to stop, the one behind must be stopped further behind so there is a ventilation shaft in between. This somewhat increase the minimum achievable headway and incidentally means that moving block signalling wouldn't offer much capacity benefit.
When moving normally the trains will be widely spaced due to the high travel speed and long braking distances, but if for some reason a train has to stop, the one behind must be stopped further behind so there is a ventilation shaft in between. This somewhat increase the minimum achievable headway and incidentally means that moving block signalling wouldn't offer much capacity benefit.
kevin_roche
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Interestingly they do something like that on the Elizabeth line with moving block signalling. Two trains are allowed in each ventilation section.
Fazaar1889
Member
Thought this was cool. From the official HS2 Twitter account. What will they do about that small gap?
Ploughman
Established Member
At a guess, I would suggest some Hydraulic jacks and pull to close the gap.
As long as the next pier along is not too far open.
As long as the next pier along is not too far open.
Fire the person who was holding the measuring tape!
In seriousness, I'm pretty sure that's an expansion gap so it'll be filled with a flexible gap filler.
Surely the structure isn't that strong to tension loads?
It will have post-tensioning cables surely?
From a previous post, don't they have a very thin segment they slide in to fill the gap?
Yes, there will be post-tensioning cables, but they're unlikely to be strong enough to drag the whole viaduct section by tens of centimetres.
From what I read elsewhere (can’t remember the source) the gap is filled by casting in situ.
swt_passenger
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It has to be I think, because the normal segments are cast against their matching predecessor segment. They have a slightly stepped face that interlocks against the previous section. (The first photo in post #1445 shows it clearly.)
I think the final slightly narrower segment can only be accurately cast against one side or the other in the factory, but not both. Then the last narrow gap can’t have a piece lowered in, because the face interlocking would prevent its being moved vertically.
edwin_m
Veteran Member
The half-spans are balanced with the ones on the opposite side of the pier, so there is in theory very little force on the last joint where they are linked with the next one. All the other joints have to bear the forces arising from the weight of the segments further out towards the midpoint.
themiller
Member
Don’t they just jack the new isolated section on its pier to close the gap?
Yes, definitely it is. There are photos on Twitter etc showing the mould in place
A reminder that this thread is for posters to provide HS2 Construction Updates.
If anyone wants to discuss anything else they are welcome to start a new thread elsewhere.
To discuss the concept of Open access Operators on HS2 please see this thread:
If anyone wants to discuss anything else they are welcome to start a new thread elsewhere.
To discuss the concept of Open access Operators on HS2 please see this thread:
Could Open Access Operators operate on HS2?
Could open-access operators run on the HS2 lines? Similar to Lumo (London to Edinborough) or Italo in Italy? I think it could become a viable alternative to cheap domestic flights.
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LNW-GW Joint
Veteran Member
TBM Shushila, boring the west bore of the Northolt tunnel from West Ruislip, has posted its first progress report.
Since launch on October 6 it has travelled a modest 25m in 12 days. (to Oct 18).
A slow start is to be expected as the project beds in.
www.hs2.org.uk
The Chiltern TBMs continue to make good progress.
PS The October 19 update shows rates for TBMs Florence (at 6758m) and Cecilia (6520m) of over 30m/day, higher than any previous rate.
HS2 Ltd has also announced the start of excavation of the two longest cuttings, near Brackley (4.1km) and at Calvert (3.4km), the latter including the East-West Railway passing overhead.
mediacentre.hs2.org.uk
Since launch on October 6 it has travelled a modest 25m in 12 days. (to Oct 18).
A slow start is to be expected as the project beds in.
In your area map - HS2
Search our interactive In Your Area Map to find information about current or planned HS2 construction works taking place across the route.
www.hs2.org.uk
The Chiltern TBMs continue to make good progress.
PS The October 19 update shows rates for TBMs Florence (at 6758m) and Cecilia (6520m) of over 30m/day, higher than any previous rate.
HS2 Ltd has also announced the start of excavation of the two longest cuttings, near Brackley (4.1km) and at Calvert (3.4km), the latter including the East-West Railway passing overhead.
HS2 begins enormous dig in Bucks/Oxon for two of the route’s longest cuttings
1.9 million cubic metres of rock and earth to be excavated to create the two cuttings – enough to fill the Royal Albert Hall more than twenty times. Download new photos showing early works on HS2’s longest cutting – the 2.5 mile Barton Hartshorn to Mixbury cutting near Brackley – and the 2.1...
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12LDA28C
Established Member
Has the 'Aylesbury spur' from EWR at Claydon LNE Junction been reinstated after being quietly postponed indefinitely? I've seen some plans for HS2 works north of Quainton which clearly show a 90mph railway being installed north of Quainton at the section where HS2 and EWR (Aylesbury spur) run parallel to each other. I believe HS2 contractors are preparing groundworks for both lines, no doubt this work on the Aylesbury spur was budgeted and planned for as part of HS2 construction.
swt_passenger
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This is all discussed in the EWR construction thread somewhere. There’s no conclusive answer, there are definitely photos showing the earthworks progressing. I think you need to differentiate between the track itself for the curve, and EWR passenger services over the curve. It’s the latter that seems up in the air…
It’s about here and onwards:
East-West Rail (EWR): Oxford-Bletchley construction progress
If Modern Railways are correct in explaining the track from the landfill to EWR is not guaranteed, (known as the Aylesbury link, but really an offline replacement of the original chord), and the revised layout in the IMD presentation, (post #323), is correct in explaining that the south to east...
www.railforums.co.uk
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The Planner
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As far as I understand it, and based off some of the latest signalling plans, the connection isnt being put in to start with, just provision ( blue on the signalling diagram)
Looking at a drone video of the area back in May both EWR and HS2 routes at Calvert are a moonscape. HS2 are bringing aggerate from the railhead near the Greatmoor Efw and are busy building the EWR over HS2 bridge.
Here is the video on Youtube
Here is the video on Youtube
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