The Anonymous Widower

Crossrail 2 October 2015 – Tunnels, Shafts And Head-Houses

Crossrail 2’s underground structures will be very similar to those of Crossrail.

Tunnels

The tunnels will be built in the same way to those of Crossrail, using tunnel boring machines or TBMs.

But I believe there will be slight differences.

• The tunnels of High Speed One, which Crossrail 2 has to cross at Dalston, are at a depth of 34 to 50 metres, so will we see Crossrail 2 bored across London below all the other foundations and infrastructure?
• Crossrail 2 will be built some years after Crossrail and tunnelling technology is improving by leaps and bounds.
• Because Crossrail 2 tunnels will be going through similar terrain to Crossrail, I wouldn’t be surprised to see a much faster process, simply because everything is easier, the second time around.
• Tunnel spoil will probably be taken away by rail, as only the Tottenham Hale site has access to water.

These tunnels under London are getting very much a routine task.

Shafts

There is a Crossrail 2 document entitled Crossrail 2 Shafts.

This is said about the need for shafts.

Shafts would connect the underground Crossrail 2 tunnels with the surface. During everyday operations, the motion of trains would push air out of the tunnels and pull air into them from the atmosphere. As the air pushed out is usually warmer than the air pulled in, the shafts would help to provide a more comfortable temperature for passengers and staff. During periods of disturbed service, when trains could be held in Crossrail 2’s tunnels for an extended period of time, the shaft’s ventilation system would deliver cooler air from the atmosphere to the tunnels and to stationary trains. In the unlikely event of a fire, the shafts would control smoke, provide access for the fire and rescue services and provide a safe evacuation route for passengers.

The document also describes what a shaft might look like.

Most of the shaft would be underground with an aboveground structure known as a ‘head-house’. This would provide access to the shaft itself, the equipment within it and the tunnels below. A head-house is ideally located directly above the shaft and tunnels, except in some cases where they can be located separately and connected by a short underground passage. A street-level entrance would provide access for the fire and rescue services, for the safe evacuation of passengers in an emergency as well as for maintenance. Direct access to the head-house is required for emergency and maintenance vehicles.

A typical head-house is also described.

At stations the head-house would typically be integrated with the overall station structure. At locations between stations the head-house would be separate. At this early stage of Crossrail 2 design, we expect a typical headhouse to occupy an area of around 25 metres by 25 metres and to be at least two storeys high – although the size of each head-house would be influenced by local factors including the depth of the tunnels and the height of surrounding buildings at each site. Further design work would be required to determine our requirements at each individual location.

As the Crossrail 2 scheme develops further, we would engage with the relevant local authority, interested stakeholders and local communities to inform the designs for each head-house.

But although the head-houses for the Channel Tunnel Rail Link were all very similar, it is true to say that there is nothing like a standard shaft and head house.

The Ventilation Shafts For Crossrail And The Channel Tunnel Rail Link

It is worthwhile looking at the shafts and head-house designs for Crossrail, which I described in The Ventilation Shafts For Crossrail.

Every one seems different, although I suspect that there lots of similarities in the equipment used.

But compare those with those of the Channel Tunnel Rail Link.

The only certainty about the shafts and head-houses of Crossrail 2, is that they will be smaller, more elegant and better designed.

October 29, 2015 - Posted by AnonW | Transport/Travel | Crossrail 2, Crossrail 2 October 2015, Trains, Tunnels