Tunnelling under London

London is full of tunnels. The latest additions are for Crossrail and I was really pleased to be invited to see them for myself. We walked from Limmo Penninsula to the Tunnel Boring Machine ("Elizabeth") headed west. 

Crossrail is Europe's biggest construction project right now. It will be a 73 mile long railway linking Essex with Berkshire with 24 trains an hour running underneath central London in 26 miles of newly dug tunnel. Different to our current infrastructure, these deep level tunnels are much larger than on the Underground’s tube lines, for example they are some 60% larger than the Victoria line. 

Crossrail’s long history can be traced back to a stillborn project in the 1880s. The idea re-emerged towards the end of World War II. After that it was very much "off" and "on" from mid-1970s. It features in the 1974 Rail Study, and again in a British Rail discussion paper in 1980. A Bill to build Crossrail was rejected in 1994. Subsequent studies and reviews continued to outline the benefits which would accrue to London if it were to be built. 

The London East-West Study by the SRA in 2000 reconfirmed the need for an East-West cross-London railway. After much discussion over the funding model, the current Crossrail project emerged. Finally after all these years, trains will be running through the new tunnels in 2018. 

The scale of the Crossrail works is incredible. Eight tunnel boring machines are working their way under London. These 1000 ton machines are at work day and night - indeed you can see their progress at http://www.crossrail.co.uk/route/near-you# 

After our safety briefing we were taken down in a lift at the vertical shaft and then walked some considerable distance to where TBM 'Elizabeth' was working. As the TBMs tunnel further their power supply is lengthened and their spoil extraction arrangements increased. It is warm and dry underground. But the progress is fast: 100m a week. 

I stood in a mostly finished 7.1m wide tunnel, some 40m deep underground which for the last billion years or so has been solid earth. As I reflected on this with a construction worker I asked him how long ago this particular place was solid London clay. 

"Tuesday" he said...... 

Back on the surface we saw the consequences of the work. Spoil from the tunnels is removed and shipped away by rail or water for re-use. A new nature reserve at Wallasea Island in Essex in a joint RSPB project is the main beneficiary. 

And no matter how glossy the brochures or snazzy the videos are about Crossrail in the near future - the current reality is that heavy industrial machines and serious labour are digging under London and shifting the spoil onto trains and into ships. 

Digging will be complete in 2014 and then follows the complex task of fitting out, laying the tracks and building a railway......