HS2 construction updates

[Ethan1852]

Current TBM Status As of 1st November 2021

TBM Name	Tunnelling Status	Launch date*^1	Distance Tunnelled*^2	Distance Remaining*^2	Days Since Launch
Florence	Tunnelling	13 May 2021	2021 Meters	13.97 Km	174 Days
Cecilia	Tunnelling	1 July 2021	1384 Meters	14.61 Km	125 Days

*^1 Might not be 100% correct. Based on HS2 Press releases.
*^2 Information from https://www.hs2.org.uk/in-your-area/map/#16/51.6130/-0.5241/filter=hs2-stations,hs2-network. Correct as of 1st November 2021.

 

[Yindee8191]

Progress on demolishing the old Heathrow Express shed at Old Oak Common (shot from the window of a speeding IET just now, hence the blurriness).

 

[Horizon22]

Yep here’s another photo from me - slightly less blurry due to it being a 345 but not great!

 

[Yindee8191]

Yep here’s another photo from me - slightly less blurry due to it being a 345 but not great!

Looks almost gone now! Perhaps when I’m next in London I’ll go and try to have a look round the site.

 

[city dweller]

Curzon Street

 

[kevin_roche]

There is an article today on IanVisits about the start of construction of the Station Box at Old Oak common.

HS2 starts construction of the Old Oak Common station box

Construction work has started on the large subterranean concrete box that will eventually house the HS2 platforms at the new Old Oak Common station.

www.ianvisits.co.uk

Construction work has started on the large subterranean concrete box that will eventually house the HS2 platforms at the new Old Oak Common station.


Work to construct the 850m-long station box at HS2’s Old Oak Common station began as the concrete frame and substructure specialist, Expanded, started on site. The station box is a reinforced concrete structure that will form the frame and base for the HS2 station building. When completed, the station box will be 850m long – the length of eight football pitches.

 

[LNW-GW Joint]

TBM progress updates from HS2 Ltd on the Chiltern tunneling continue to be erratic.
The positions have been updated for November 22 (a 3-week gap from the previous update).
In Your Area Map - High Speed 2 (hs2.org.uk)

Florence was at 2256m, Cecilia at 1609m.
At close to 11m per day, this continues their slow decrease in progress rates over 3 months or so (they both initially had spells of over 16m/day).

 

[GRALISTAIR]

HS2 Launches First Midlands Giant Tunnelling Machine

Today [2 December] HS2 launched its first tunnel boring machine (TBM) in the Midlands The 2,000 tonne TBM has started on its journey to dig a one-mile tunnel under Long Itchington Wood in Warwickshire, preserving the precious habitats above The TBM is named ‘Dorothy’ after Dorothy Hodgkin...

mediacentre.hs2.org.uk

Meanwhile another TBM starts

 

[civ-eng-jim]

Looking like 4 years of tunneling at this rate.

TBM progress updates from HS2 Ltd on the Chiltern tunneling continue to be erratic.
The positions have been updated for November 22 (a 3-week gap from the previous update).
In Your Area Map - High Speed 2 (hs2.org.uk)

Florence was at 2256m, Cecilia at 1609m.
At close to 11m per day, this continues their slow decrease in progress rates over 3 months or so (they both initially had spells of over 16m/day).

At this rate it'll be 4 years of tunneling to complete.

 

[CarltonA]

Sometimes I can hear a slight roaring noise in the early hours. Would it be possible to hear a TBM as it scrapes it's way along? I live a couple of miles to the south of the Chalfonts. I'm fairly sure it's not the M40.

 

[civ-eng-jim]

Sometimes I can hear a slight roaring noise in the early hours. Would it be possible to hear a TBM as it scrapes it's way along? I live a couple of miles to the south of the Chalfonts. I'm fairly sure it's not the M40.

Probably rats

 

[TheHSRailFan]

A photo from HS2 themselves of TBM Dorothy. I guess since it's 1 mile they are not in a rush to get both going.

Source along with 2 other images:

https://twitter.com/HS2ltd/status/1466455851162550281

 

[Ethan1852]

Current TBM Status As of 2nd December 2021

TBM Name	Tunnelling Status	Launch date*^1	Distance Tunnelled*^2	Distance Remaining*^2	Days Since Launch
Florence	Tunnelling	13th May 2021	2256 Meters	13.80 Km	204 Days
Cecilia	Tunnelling	1st July 2021	1609 Meters	14.45 Km	155 Days
Dorothy	Tunnelling	2nd December 2021	Unknown	1.6 Km	0 Days

*^1 Might not be 100% correct. Based on HS2 Press releases.
*^2 Information from https://www.hs2.org.uk/in-your-area/map/#16/51.6130/-0.5241/filter=hs2-stations,hs2-network. Correct as of 2nd December 2021.

 

[civ-eng-jim]

Both? Is this not where the same TBM will be partially dismantled on completion of the first bite and transported back to do the second bore?

 

[GRALISTAIR]

Both? Is this not where the same TBM will be partially dismantled on completion of the first bite and transported back to do the second bore?

When I read and reread - YES- that is exactly what it says. Glad the TBM is getting two bites of the cherry so to speak.

 

[TheHSRailFan]

Both? Is this not where the same TBM will be partially dismantled on completion of the first bite and transported back to do the second bore?

When I read and reread - YES- that is exactly what it says. Glad the TBM is getting two bites of the cherry so to speak.

Intresting, I was given the idea of 2 TBM but I guess that's something.

 

[snowball]

Intresting, I was given the idea of 2 TBM but I guess that's something.

No point in using two TBMs when the tunnel is only one-tenth the length of the Chiltern tunnels.

 

[Pete_uk]

View attachment 106408

A photo from HS2 themselves of TBM Dorothy. I guess since it's 1 mile they are not in a rush to get both going.

Source along with 2 other images:

https://twitter.com/HS2ltd/status/1466455851162550281

That looks quite close to the surface

 

[hwl]

Is this not where the same TBM will be partially dismantled on completion of the first bite and transported back to do the second bore?

Yes the head will be taken back to the starting point by road, the tail will be pulled back through the first completed tunnel to the starting point.

 

[Kingston Dan]

Yes the head will be taken back to the starting point by road, the tail will be pulled back through the first completed tunnel to the starting point.

Why not do all of it through the completed tunnel?

 

[civ-eng-jim]

Why not do all of it through the completed tunnel?

The cutting head has a bigger external diameter than the internal diameter of the concrete rings that get placed behind it as it advances forward.

When I read and reread - YES- that is exactly what it says. Glad the TBM is getting two bites of the cherry so to speak.

Should have read "Bore" - Not "bite" - Well done for deciphering my cryptic code.

 

[Bald Rick]

Why not do all of it through the completed tunnel?

For the same reason circular manhole covers never fall in their manhole...

 

[Dave_Cardboard]

Sometimes I can hear a slight roaring noise in the early hours. Would it be possible to hear a TBM as it scrapes it's way along? I live a couple of miles to the south of the Chalfonts. I'm fairly sure it's not the M40.

I doubt it is the TBM's per se - maybe it's something from the West Hyde site which is presumably operating 24 hours a day to support the tunnelling works. Or even Heathrow - I can often hear that from nearly 5 miles away in Uxbridge depending on wind direction and cloud cover.

In a presentation given to Hillingdon residents close to HS2 tunnelling (link below) they state that noise/vibration from TBM passage should "only experienced for a few days" for properties only a few tens of metres above the tunnels. Thusly, I think it's not unreasonable to conclude it would be surprising if you could hear TBM's miles away.

Tunnelling works in Hillingdon - HS2

www.hs2.org.uk

That looks quite close to the surface

They are big machines and perhaps the scale is deceptive. If I grab the image, cut out a dude in a orange outfit and stack them up, I'd guestimate the TBM crown is about 8-10m below ground level.

In case anyone is not aware, tree roots do not burrow down into the ground as deeply as one might think, though it varies a bit depending on species. They tend to be near the surface where the water, nutrients and air is thanks to all the little critters churning the soil, dead leaves, etc. There are pictures and articles on the subject if one Googles.

More interestingly to me, one reads that there needs to be a certain about (mass) of material above the TBM ingress/egress points to resist the "up thrust" from them disturbing anything above. Or the ground needs to be treated (e.g. grouted) to stiffen it up a bit (or a bit of both.)

 

[Bald Rick]

I doubt it is the TBM's per se - maybe it's something from the West Hyde site which is presumably operating 24 hours a day to support the tunnelling works. Or even Heathrow - I can often hear that from nearly 5 miles away in Uxbridge depending on wind direction and cloud cover.

agreed - it won’t be the TBMs. A couple of miles south of the Chalfonts is close to the M40 and directly under the westerly departure flight path from Heathrow for flights to anywhere in Scandinavia / north east Europe / Russia / China / the Far East, accepting that won’t be happening in the early hours. doubt it’s west hyde, but it might be if there’s an easterly wind.

They are big machines and perhaps the scale is deceptive. If I grab the image, cut out a dude in a orange outfit and stack them up, I'd guestimate the TBM crown is about 8-10m below ground level.

yep TBMs typically need 8-10m cover.

More interestingly to me, one reads that there needs to be a certain about (mass) of material above the TBM ingress/egress points to resist the "up thrust" from them disturbing anything above. Or the ground needs to be treated (e.g. grouted) to stiffen it up a bit (or a bit of both.)

yes, lots of examples of grouting ahead of TBMs running shallow.

 

[The Ham]

In case anyone is not aware, tree roots do not burrow down into the ground as deeply as one might think, though it varies a bit depending on species. They tend to be near the surface where the water, nutrients and air is thanks to all the little critters churning the soil, dead leaves, etc. There are pictures and articles on the subject if one Googles

It does depend on the tree, those with tap roots do go down quite a bit further (however still not overly deep) than those which only spread out (which are typically about 1m to 1.5m down and about as wide as the canopy of the tree - again it depends on the type of tree).

If you ever see an uprooted tree there's not a lot of material which comes up with the roots and few roots of significant size. In fact it's perfectly possible for a tree to grow in a tree pit which has root guard material limiting the roots to what would typically look quite small.

Also of note piling up soil over tree roots can cause them harm as the extra weight isn't good for them, which is why "no dig" road construction isn't possible as the weight of the road would cause the tree(s) potentially significant harm. If roads are crossing a tree root protection zone they have to be built onto "bridges" for that reason.

 

[ABB125]

For the same reason circular manhole covers never fall in their manhole...

I believe that nowadays it's a "personhole".



Presumably if a TBM comes across some tree roots, it simply munches away at them as if they're not there?

 

[najaB]

Presumably if a TBM comes across some tree roots, it simply munches away at them as if they're not there?

In my experience, rock is harder than tree roots. Though one has to wonder why a TBM was being used to bore a tunnel so close to the surface that there are roots in the way.

 

[Kingston Dan]

The cutting head has a bigger external diameter than the internal diameter of the concrete rings that get placed behind it as it advances forward.


Should have read "Bore" - Not "bite" - Well done for deciphering my cryptic code.

Ah gotcha!

 

[CarltonA]

I doubt it is the TBM's per se - maybe it's something from the West Hyde site which is presumably operating 24 hours a day to support the tunnelling works. Or even Heathrow - I can often hear that from nearly 5 miles away in Uxbridge depending on wind direction and cloud cover.

In a presentation given to Hillingdon residents close to HS2 tunnelling (link below) they state that noise/vibration from TBM passage should "only experienced for a few days" for properties only a few tens of metres above the tunnels. Thusly, I think it's not unreasonable to conclude it would be surprising if you could hear TBM's miles away.

Agree it's unlikely to be the machine itself. The noise has been only occurring since the summer so not likely to be the airport which is not allowed to operate at those hours anyway. I'll investigate further, I thought the noise was coming from the north but maybe it's from another direction.

 

[edwin_m]

Agree it's unlikely to be the machine itself. The noise has been only occurring since the summer so not likely to be the airport which is not allowed to operate at those hours anyway. I'll investigate further, I thought the noise was coming from the north but maybe it's from another direction.

There's quite a lot going on south of the tunnel - including a factory to make the concrete segments, and a whole lot of other work relating to the viaduct. At a guess, there could be some kind of giant concrete mixer turning to keep the concrete fresh?