Fire and water – the London Crossrail experience

The idea for an East-West rail link across London has its origins in the Regents Canal & Railway Company of the late 19^th Century. The concept of the link went through several other evolutionary developments over the following 90 years including the post second world war Abercrombie Plan, leading up to the more recent 1974 London Rail Study where “Crossrail” was finally born. Had the scheme been built at any of these previous times we would probably be looking at a very different product to the one now showing its face to the world today, which uses the latest materials and technology to meet the demanding performance requirements imposed on the project. With a combination of a design life of 120 years and some exacting performance demands for the structures, for example the requirement to withstand the extremes of a 1200°C fire and resist 40m head of external water pressure, the project has developed solutions based upon previous project experience and robust engineering to satisfy requirements that could be argued to require conflicting solutions for the materials in terms of their permeability at the very least.