Management of Obstructions and Adverse Ground Conditions During SCL Tunnelling Works at Bond Street and Tottenham Court Road Stations for Crossrail Contract C300/410

An inherent aspect of any tunnelling project is ground risk: how it is identified, quantified and managed throughout the various stages of a project. As far as reasonably practical, early identification of these risks, such as adverse ground conditions or potential obstructions is crucial. If early identification is not possible, having plans and procedures in place for dealing with potential ground risk scenarios as they occur during the construction works is critical to ensure the safety of the workforce.

A number of experiences of potential ground risk were encountered during the sprayed concrete lining (SCL) works on Crossrail contract C300/410 which was constructed by a joint venture of BAM Ferrovial Kier (BFK). The C300/410 works comprised of over 2.5 km of SCL tunnels for Bond Street (BOS) and Tottenham Court Road (TCR) Stations and the Fisher Street crossover as well as two 6.2 km TBM tunnel drives between Royal Oak and Farringdon. BFK appointed Donaldson Associates (DAL) as their SCL designers for the works. BFK with DAL were responsible for excavation stability up to the point of ring closure.