The Anonymous Widower

Could We Bore A Double-Track Railway With A Tunnel Boring Machine?

There is one inevitability about construction projects.

As buildings get taller, foundations get deeper, structures get heavier, machines like cranes get bigger and more able to lift heavy loads.

I remember how in the 1970s, a project manager was eulogising about how the latest floating cranes that could lift 4,000 tonnes wee revolutionising the construction of oil platforms in the North Sea.

Crossrail may be a railway under London, where people think the tunnels are massive.

This page on the Crossrail web site describes the tunnels.

A network of new rail tunnels have been built by eight giant tunnel boring machines, to carry Crossrail’s trains eastbound and westbound. Each tunnel is 21 kilometres/13 miles long, 6.2 metres in diameter and up to 40 metres below ground.

But they are not the largest tunnels under London.

The Thames Tunnel, built by the Brunels, opened in 1843.

• It is eleven metres wide.
• It is six metres high.
• It carries the double track railway of the East London Line, which runs Class 378 trains, which are very much a typical British loading gauge.

There is also the Thames Tideway Tunnel, which is being dug to be a 7.2 wide circular tunnel.

And then there’s Bertha!

This description is from Wikipedia.

Bertha was a 57.5-foot-diameter (17.5 m) tunnel boring machine built specifically for the Washington State Department of Transportation’s (WSDOT) Alaskan Way Viaduct replacement tunnel project in Seattle.[1] It was made by Hitachi Zosen Sakai Works in Osaka, Japan, and the machine’s assembly was completed in Seattle in June 2013. Tunnel boring began on July 30, 2013, with the machine originally scheduled to complete the tunnel in December 2015.

It looks like London’s tunnels should be considered small.

Cross section areas of various tunnels are.

• Thames Tuideway Tunnel – 40.7 square metres.
• Thames Tunnel – 66 square metres
• Seattle Tunnel – 240 square metres.
• 8 metre circular tunnel – 50.3 square metres
• 10 metre circular tunnel – 78.6 square metres
• 12 metre circular tunnel – 113 square metres

The Seattle Tunnel shows what is possible today.

I am led to the obvious conclusion.

It would be possible to build a tunnel to take a full-size double-track UK railway using a tunnel boring machine.

Whether you would want to is another matter, as two single tunnels may be more affordable and better operationally.

September 5, 2019 - Posted by AnonW | Transport/Travel | Crossrail, Thames Tideway Tunnel, Thames Tunnel, Tunnel Boring Machine, Tunnels