Secret station at Heathrow

[dave1]

Found this Heathrow I don't remember reading anywhere that this was built, but it's not secret anymore.

[Nortube]

Well at least the tunnel didn't collapse like the last one that was built

[dave1]

Feb 23, 2016 9:07:11 GMT Nortube said:

Well at least the tunnel didn't collapse like the last one that was built

That collapse was in an area where they used NATM method,I am sure they built some of the Jubilee extension with that method. They have built this unused station or whatever you want to call it for the future.

[Nortube]

I think a lot of the Jubilee line was built using the NATM method, but I'm not sure how much.

I know the London Bridge area track tunnels were built that way because I saw it during construction. The Northern line diversion between the new SB platform and the step plate junction was built that way, but north of the SB platform it was constructed using rings in the conventional way.

My first site visit was when the tunnel was being constructed (after the Heathrow collapse) and they were about halfway through the construction of the ring tunnel, going north from the newly constructed platform tunnel. I was told that they were using rings rather than NATM as a precaution until the reason for the Heathrow collapse was known. This may have been the reason, but it didn't seem possible that they could suddenly change tunnelling methods (and get the supply of rings etc.) at such short notice, so I just assumed that rings were used on the new section between north of the platform and where it merged with the old SB tunnel because it was a more convenient way to continue from the SB tunnel as there was no step plate junction there. Also, I seem to recall that they were still carrying on with the NATM work on the Jubilee side at the time of the visit.

[dave1]

Feb 23, 2016 18:16:40 GMT Nortube said:

I think a lot of the Jubilee line was built using the NATM method, but I'm not sure how much.

I know the London Bridge area track tunnels were built that way because I saw it during construction. The Northern line diversion between the new SB platform and the step plate junction was built that way, but north of the SB platform it was constructed using rings in the conventional way.

My first site visit was when the tunnel was being constructed (after the Heathrow collapse) and they were about halfway through the construction of the ring tunnel, going north from the newly constructed platform tunnel. I was told that they were using rings rather than NATM as a precaution until the reason for the Heathrow collapse was known. This may have been the reason, but it didn't seem possible that they could suddenly change tunnelling methods (and get the supply of rings etc.) at such short notice, so I just assumed that rings were used on the new section between north of the platform and where it merged with the old SB tunnel because it was a more convenient way to continue from the SB tunnel as there was no step plate junction there. Also, I seem to recall that they were still carrying on with the NATM work on the Jubilee side at the time of the visit.

That's interesting about London bridge I did not know that they used the same method there. I suspect that because of the river they used conventional segments. I understand at various places there are monitoring systems in place, I went on a visit to Aldwych years ago and there was some sort of detection/monitor in place and the person who took us around (civils) said that at various places around the system there were similar equipment.

[Nortube]

From Richard Griffiths ( at www.squarewheels.org.uk/ )

The JLE running tunnels were mostly constructed using traditional Tunnel Boring Machine technology and rings of concrete segments, mainly from major working sites at Old Jamaica Road and Durands Wharf.

I believe NATM was used in the stations and crossovers.