Design and construction of Fisher Street crossover cavern on Crossrail contract C300/C410, London

The Fisher Street crossover cavern formed a significant part of the £750 m Crossrail contract C300/C410 “Western Running Tunnels and Station Caverns” which was delivered by BFK Joint Venture between January 2011 and October 2015.

The project works comprised the construction of two 6.2 m diameter 6.4 km long tunnel drives between Royal Oak and Farringdon and the construction of sprayed concrete lining (SCL) tunnels for Bond Street and Tottenham Court Road Station, together with an SCL crossover cavern between the running tunnels at Fisher Street (see Figure 1).

Donaldson Associates (DAL) was appointed as BFK's SCL designers for these works, with their Austrian partner IGT Geotechnik und Tunnelbau Consulting Engineers providing a number of key site supervisory staff. DAL's scope of work comprised a Due Diligence Review (DDR) of the Client's SCL primary lining design, which formed part of the permanent works, and the design of “Toolbox items” and any other necessary measures required wherever an unacceptable risk of instability during excavation was identified ^[1] . To supplement this, a 24/7 team of Senior SCL Engineers and SCL Shift Superintendents from DAL and IGT were embedded into the BFK engineering team.