HS2 Construction Updates -Long Itchington to Great Missenden / Chilterns North Portal

[Snow1964]

New you tube of the Waddeston to Thame valley area, drone view of construction showing various structures and part constructed trackbed

 

[PLY2AYS]

Another fantastic video. Glad you were able to make the most of the sunshine!
Is there a definitive list of expected completion dates for individual projects along HS2; I’ve perused the interactive map online, but haven’t delved too deeply to find expected completion dates for the infrastructure.
Is that a whole other level of accountability they wish to avoid in construction, or purely because it won’t be deemed officially completed until track sections are linked up and trialling/running rolling stock over it?

 

[Snow1964]

Another fantastic video. Glad you were able to make the most of the sunshine!
Is there a definitive list of expected completion dates for individual projects along HS2; I’ve perused the interactive map online, but haven’t delved too deeply to find expected completion dates for the infrastructure.
Is that a whole other level of accountability they wish to avoid in construction, or purely because it won’t be deemed officially completed until track sections are linked up and trialling/running rolling stock over it?

I don't think there is a public list of completion dates, and in practice some bits might be ahead, and others behind. The very wet weather will have affected progress.

I vaguely remember about 4 or 5 years ago was said about half the trackbed (including tunnels etc) should be ready during 2024. Even on these sections the landscaping and removal of temporary works will need to follow. But all construction movement could be along the completed base.

Reading the various reports, does seem about right, let's predict about 55% has track bed or completed tunnel by end of 2024. about 30% is still under construction. Of the remaining 15%, probably will split about 5-8% each of incomplete tunnels and viaducts. Possibly with around 1% not started were things in the way eg a road which is awaiting a new bridge etc. This is just an approx estimate at end of 2024, not anything official.

Suggests as move into 2025 around third of route will move onto landscaping etc (won't be whole completed trackbed, as about 10-15% will be completed bored tunnels). I would guess as 2025 and 2026 progress more mileage will be ready for railway construction (rather than trackbed construction).

 

[RPM]

New you tube of the Waddeston to Thame valley area

Thanks for sharing. This is very local to me but it is so much harder to make out what progress has been make from the ground. Really interesting.

 

[LNW-GW Joint]

Some project milestones were announced in 2022, mainly to do with the start/completion of tunneling sections.
With the exception of the Chiltern and Long Itchington tunnels, completed ahead of schedule, they have generally not been met.
There's time to catch up a bit, but the Colne Valley viaduct is running maybe 3-6 months late on its 2-year schedule (plus a year to fit out).

Annual spend was reduced by pausing work in some areas, and of course the Euston end and Phase 2 works have both been stopped.
Another important issue is the letting of the railway contracts (slab, track, overhead line and signalling), and none of them has been let yet bar one for switches and crossings - these are more than a year late on the 2022 schedule.
A schedule to construct the railway can't really be fixed until those contracts are let.
The main issue has been cost inflation, with most new contracts deemed "unaffordable" within the overall budget.
Not a happy position really.

The next DfT progress report is due around May, which may tell us more detail.
The winter has been mild but very wet. I imagine this has impacted progress in some areas (not the tunnelling, luckily).

 

[PLY2AYS]

Some great insights here:

Some project milestones were announced in 2022, mainly to do with the start/completion of tunneling sections.
With the exception of the Chiltern and Long Itchington tunnels, completed ahead of schedule, they have generally not been met.
There's time to catch up a bit, but the Colne Valley viaduct is running maybe 3-6 months late on its 2-year schedule (plus a year to fit out).

Annual spend was reduced by pausing work in some areas, and of course the Euston end and Phase 2 works have both been stopped.
Another important issue is the letting of the railway contracts (slab, track, overhead line and signalling), and none of them has been let yet bar one for switches and crossings - these are more than a year late on the 2022 schedule.
A schedule to construct the railway can't really be fixed until those contracts are let.
The main issue has been cost inflation, with most new contracts deemed "unaffordable" within the overall budget.
Not a happy position really.

The next DfT progress report is due around May, which may tell us more detail.
The winter has been mild but very wet. I imagine this has impacted progress in some areas (not the tunnelling, luckily).

I’m joining Chiltern Railways in the next few weeks from West end of GWR and obviously being SO much closer to some of the HS2 works is much more interesting now that it’s local!

Really appreciate the engagement and content posted on this thread, will be following comments and posts closely on here and subscribed on YT.

 

[masekwm]

Hi,

I've started following the works around Steeple Claydon, site looks a mess at the moment, but can see the area for the HS2 maintenance depot being developed now.

 

[Snow1964]

New drone HS2 construction, showing the piers of bridge (might be a viaduct) at Banbury Lane, near Lower Thorpe Mandeville, and some nearby earthworks

 

[swt_passenger]

In the video immediately above we can see a feature being built at about 15-20 seconds in, it’s a pattern of what looks to me like some sort of concrete ground reinforcement. I‘ve seen similar features in a number of videos, they’re often in a position where I’d expect them to end up hidden within future embankments, typically where there is going to be a transition from embankment to viaduct. Is my thinking correct, and are they effectively reinforcing the existing ground to support an embankment?

Many thanks if anyone can confirm.

 

[Snow1964]

In the video immediately above we can see a feature being built at about 15-20 seconds in, it’s a pattern of what looks to me like some sort of concrete ground reinforcement. I‘ve seen similar features in a number of videos, they’re often in a position where I’d expect them to end up hidden within future embankments, typically where there is going to be a transition from embankment to viaduct. Is my thinking correct, and are they effectively reinforcing the existing ground to support an embankment?

Many thanks if anyone can confirm.

Yes does look like a grid of piles, will probably be linked either with a slab (hence the tipping and making level), or a grid. Probably the subsoil isn't great so will stop the end of the embankment where it is tallest being piled on slippery or clay soil which might slump.

A new drone video showing construction of Thame Valley viaduct

New drone of HS2 construction of Newton Purcell - Finmere area (south of Brackley ). Lots of earthworks and start of some concrete bridges, no no sign yet of completed trackbed

New drone flyover of Wendover Dean and Little Dean viaducts

 

[bib]

A Wendover Dean viaduct slide is has been completed - 3000ton structure slid 270m

Quite a bit of info in the latest chiltern society video, seems like theres been a lot of issues around the wendover green tunnel

 

[Snow1964]

HS2 has published (12th August) a completion video and article on Wendover Dean viaduct

HS2 today revealed stunning new timelapse footage showing engineers carefully sliding a 3,700-tonne viaduct deck almost half a kilometre uphill into position near the town of Wendover in Buckinghamshire.

The deck of the Wendover Dean Viaduct – which stretches for 450m – was assembled in three stages, ranging from 90m to 180m, with each one pushed out from the north abutment before the next section was attached behind it.

This painstaking, eight-month long process meant that the weight of the deck increased with each push, up from an initial 590 tonnes at the start of work in January - to 3,700 tonnes by the time it reached the south abutment on Saturday

Will now be lowered 60cm (20cm on each pier in sequence, 3 times) into final position

With the steelwork now in position, engineers can begin the challenging job of lowering the deck 60cm onto the permanent bearings which will support the full weight of the structure.

The two-month long operation will see the steelwork above each pier carefully lowered by 20cm at a time, pier-by pier, until the whole 450m long deck settles into its final position.

New Timelapse: HS2 completes epic 8 month Wendover Dean Viaduct deck slide

View and embed a new timelapse video showing how engineers slid the 3,700 tonne deck of the Wendover Dean Viaduct carefully into position – up-hill over eight months between January and August 2024. Download new images showing progress on site near Wendover, Buckinghamshire.

mediacentre.hs2.org.uk

 

[LNW-GW Joint]

At last, something that looks recognisably like a railway in the landscape (along with the Colne Valley viaduct).
Still much to do at each end of the viaduct though.
Every completed structure makes the wider project seem more viable.
Plenty of UK content in the concrete and steel, too.

 

[masekwm]

Footage of the Green Tunnel North Portal at Wendover

 

[Snow1964]

Not sure if this is correct thread, the first viaduct on HS2 is now complete (including parapets).

A viaduct in Northamptonshire has officially become the first on the HS2 project to be completed as engineers working for the high speed rail project installed the last stretch of parapet along the sides.

The 163m long Highfurlong Brook Viaduct, near the village of Aston le Walls, is one of more than 50 being built as part of the new rail project, which is designed to improve journeys between London and the North, while freeing up space on the most crowded part of the existing West Coast Mainline for more freight and local services.

Consisting of seven spans, the viaduct crosses Highfurlong Brook’s floodplain at a height of around 9m. Each span is made up of four beams weighing up to 56 tonnes and were lifted into position last year to form the backbone of the structure.

Each of the beams – which are up to 25m long - were manufactured off site before being delivered over night to reduce disruption for local road users. The deck – which will support the track and electrical systems – was poured in situ earlier this year, with the parapets along each side manufactured off site and installed over the last four months.

The viaduct is one of around 500 bridging structures on the HS2 project which range from small road bridges and drainage culverts to massive viaducts like the record-breaking Colne Valley Viaduct which will become the longest in the UK when its deck is completed.

HS2 celebrates first completed viaduct

View and embed a new video explaining how the Highfurlong Brook Viaduct, near Aston le Walls, Northamptonshire, was built. Download the latest images of the 163m long viaduct.

mediacentre.hs2.org.uk

 

[Geogregor]

And video:

 

[Snow1964]

New drone video (not mine) of A41 Waddeston to Thame valley section of HS2. Nice to see a section with the cuttings with topsoil

 

[Snow1964]

New drone video, of the rebuilt East West rail where it crosses HS2, showing the area where the rail line crosses the bridge over the under construction HS2 line.

Not my video, but recently uploaded on you tube

 

[Snow1964]

HS2 has announced the first precast sections of Edgcote viaduct have just been installed. Photos on the link

HS2 has begun assembling the half-kilometre long Edgcote viaduct, which is set to become only the second in the UK to have all its major structural elements manufactured off-site helping to speed up construction, boost efficiency and reduce the number of lorry movements on local roads.

Set low into the landscape of West Northamptonshire, the 515m-long viaduct will carry the new railway across the floodplain of the River Cherwell, south of Chipping Warden.

The structure was redesigned last year, copying the approach used at HS2’s Thame Valley, near Aylesbury. This lighter weight design cuts the amount of concrete and steel in the viaduct, with the piers, beams, deck planks and parapet manufactured off site at a facility in Kent.

Edgcote and Thame Valley are amongst more than 50 major viaducts being built as part of the HS2 project, which is designed to free up space on the most crowded part of the existing West Coast Main Line and boost economic growth.

Instead of five beams per span, secured with concrete poured on site, the twin viaducts use just two larger ‘u’ shaped beams per span, secured directly to the neighbouring beams.

This innovation - inspired by viaducts on the Spanish high speed rail network - will reduce the number of lorry movement and speed up construction by removing the in-situ concrete work.

At between six and eight metres high, the viaduct will be supported by 20 pairs of pre-cast concrete piers. These must be carefully lifted into position with their steel reinforcing rods slotted into pre-prepared sleeves within the pile caps. The gaps are then sealed with grout.

Work begins on HS2’s half-kilometre long Edgcote viaduct

Northants viaduct becomes second HS2 viaduct to have every major element manufactured off-site, cutting its carbon footprint and simplifying construction. View and embed a new video explaining the design and start of construction at the site near Chipping Warden or download new photos.

mediacentre.hs2.org.uk

 

[Nottingham59]

HS2 has announced the first precast sections of Edgcote viaduct have just been installed.

Well at least that's two viaducts on HS2 with a commonality of design. One has to ask how many of the other 48 major viaducts on the route have different designs with all the costs (design, construction, maintenance) associated with that.

"The structure was redesigned last year, copying the approach used at HS2’s Thame Valley, near Aylesbury. This lighter weight design cuts the amount of concrete and steel in the viaduct, with the piers, beams, deck planks and parapet manufactured off site at a facility in Kent."

 

[bib]

A cool flyover of the route from Amersham to Long Itchington area, there was another one earlier this year in post#57

 

[Snow1964]

North of Brackley, but there isn't a thread that is open for HS2 construction in South Warwickshire.

New drone video from Wormleighton heading few miles north, doesn't appear to be much permanent earthworks, although a haul road crosses trace few times.

The construction of few minor bridges (lanes or farm access) can be seen

 

[Nottingham59]

North of Brackley, but there isn't a thread that is open for HS2 construction in South Warwickshire.

New drone video from Wormleighton heading few miles north, doesn't appear to be much permanent earthworks, although a haul road crosses trace few times.

The construction of few minor bridges (lanes or farm access) can be seen

Thanks for posting.

Does anybody know what is crossing the line of route at 1m36s? A long white structure with black holes in the sides.

And what about the bridge at 5m45s? Has that been built over an excavated cutting which was then filled in again? I can't work out why the structure is at that elevation.

 

[swt_passenger]

Thanks for posting.

Does anybody know what is crossing the line of route at 1m36s? A long white structure with black holes in the sides.

It’s an Oxford Canal feeder culvert at that location on the HS2 maps, not sure about the holes though, I think they might be black patches of a coating on the concrete segments.

 

[Snow1964]

HS2 has issued article with photo of the newly realigned A418 which passes over a new bridge over HS2.

Looking at photo looks like bridge is 20-25m span, which seems very wide for just 2 tracks, especially as there are side spans too.

The old road is now closed, so can be removed to create the HS2 cutting

HS2 opens second key Aylesbury road bridge

A418 reopens after week-long closure to complete its realignment over a new bridge across the HS2 route near Aylesbury Download new images of the bridge, which opened two months after a similar structure over the nearby A41

mediacentre.hs2.org.uk

 

[Nottingham59]

bridge is 20-25m span, which seems very wide for just 2 tracks,

Everything to do with HS2 seems to be over-specified.

 

[hwl]

Everything to do with HS2 seems to be over-specified.

It helps with aerodynamics and means that very shallow angles and be used for the cutting slopes which means they should be a lot more stable in the long term. On the latter point they are just effectively replicating proven motorway bridge geometry.

 

[Nottingham59]

On the latter point they are just effectively replicating proven motorway bridge geometry.

Very happy to be proved wrong, but I doubt that many new-build bridges over motorways are 103 metres long.

 

[swt_passenger]

It helps with aerodynamics and means that very shallow angles and be used for the cutting slopes which means they should be a lot more stable in the long term. On the latter point they are just effectively replicating proven motorway bridge geometry.

There are also noise barriers on both sides alongside the track through this particular cutting. But I’m sure that (as you say) it’s generally the overall cutting width that defines the length of overbridges. And I’m fairly sure the distance between tracks and bridge piers on any modern new build railway bridge will be wider than historically, to reduce the risk of collision, that will be a general standards change.

 

[Snow1964]

HS2 has produced a new newsletter covering construction Twyford to Greatworth section, with photos, updates, work happening soon.

(pdf document, multi-column text, not practical to quote)

https://assets.hs2.org.uk/wp-content/uploads/2024/11/T2G-Newsletter-Autumn-2024.pdf