Fisher Street Crossover – Construction of the Secondary Lining
Summary
The Crossrail route will run for more than 100 km from Reading and Heathrow in the west, through new twin-bore 21 km tunnels under central London, to Shenfield and Abbey Wood in the east. Crossrail has the requirement for crossovers, one of which was provided at Fisher Street – a small site between Tottenham Court Road and Farringdon Stations. The crossover will allow trains to switch between eastbound and westbound running tunnels, for maintenance or emergency reasons.
The Fisher Street site is located next to the Holborn London Underground (LU) Station in Central London, and was part of the Crossrail contract C300 – Western Running Tunnels (Royal Oak to Farringdon), awarded to the joint venture of Bam Nuttall, Ferrovial Agroman, and Kier Construction (BFK), in December 2010.
The underground environment in this area is rich in important LU assets. The Piccadilly Line bores are the deepest tunnels in the area followed by those of the Central Line. The Crossrail running tunnels are constructed between the Central Line tunnels and the disused Kingsway Tram Tunnel (KTT). The KTT was initially used for compensation grouting works through a grout shaft, however, it was later decided to use it to overcome the logistics challenges of a small footprint site in central London, resulting in an area for concrete deliveries and materials storage.
Opened in 1906, this tram cut-and-cover tunnel once took passengers from Holborn to Waterloo Bridge, providing a link between the north and south London tram networks. KTT and its double deck trams were abandoned in 1952, however this unique piece of London’s transport history is still fascinating audiences in films, including The Escapist and The Avengers, where it serves as the entrance to a secret underground base.
This paper intends to present the construction of a secondary lining at Fisher Street site, highlighting the main challenges of the project and the solutions developed by the engineering team.