Soft ground

The station is located in central London between Tottenham Court Road and Liverpool Street Crossrail (CRL) Stations. Constructed in the geologically most complex area in the whole of CRL, an optimised geotechnical and SCL tunnel design was implemented, which resulted in significant time and cost benefits for the project. Using a dynamic 3D geological model in conjunction with SCL tunnelling represented a key element of the geotechnical risk management framework.

Beacon Hill Station is part of the 22.5 km initial segment of Sound Transit's Central Link Light Rail. It is located 49 m below the ground surface in complex glacial soils with multiple groundwater horizons. The project comprises deep mined station tunnels and two 1.5 km long running tunnels excavated using a tunnel boring machine. The mined station was excavated through compressible glacial soils with multiple groundwater horizons using conventional mining techniques. The access shafts and station headhouses were constructed using slurry walls and cut-and-cover techniques.

Green Park tube station is a LU station situated on the north side of Green Park in central London. The station serves as an interchange between the Piccadilly, Victoria and Jubilee lines. As part of Transport for London's (TfL) investment programme, LU is implementing capacity enhancement and step‐free access (SFA) works to various stations. Dr. Sauer & Partners was responsible for the design of the primary support, i.e. sprayed concrete lining (SCL) and for providing construction support services including supervision of the excavation works and installation of the primary lining.

Bond Street Station serves an interchange between the Jubilee Line, the Central Line and the future Crossrail Station. New tunnels including access and lift shafts, construction adits, binocular cross passage tunnels, large concourse and connection chambers, underpass and over-bridge tunnels cutting through existing platform tunnels, and an inclined escalator tunnel were constructed in very close proximity to existing London Underground structures.

Bond Street tube station is a major gateway to London's West End served by both the Central and Jubilee lines. As part of the LU tube upgrade plan, the station is undergoing a major upgrade to increase capacity, improve accessibility and create interchange with the new Crossrail station. The project provides two additional escalators from the interchange level to the Jubilee line, low-level interchange route between the Central and Jubilee lines, a new step-free entrance, ticket hall and new lifts. The majority of the tunnelling works will be mechanically excavated and lined with sprayed concrete.

The major upgrade to the LU Tottenham Court Road Station has been proposed to relieve congestion, achieve step-free access and modernise the station. The major elements of the station upgrade comprised a new enlarged sub-surface ticket hall, a fire-fighting access / emergency escape shaft linked to both Central and Northern lines, a triple escalator barrel, and concourses to the Northern and Central lines. In the latter concourse two new overbridges were included to lead to the platforms via new stairs and lifts. For the tunnelling works, a particularly challenging part was to design and construct the two SCL overbridges over the operational Central line.

Currently over 150,000 passengers use the station daily and with the completion of Crossrail in 2017, passenger numbers are expected to increase to over 200,000. The tunnels are of diameters between 4.0m and 11.0m and typically consist of a temporary sprayed concrete primary lining, a spray applied waterproofing membrane and a cast-in-place concrete secondary lining. Multiple transitions and interfaces to existing LU structures make for a challenging design and construction project under the busy streets of central London.

Contract C305 is the biggest design-bid-build construction contract of the Crossrail (CRL) project and includes the eastern running tunnels of CRL's central section with launch shafts and SCL launch adits for TBMs at Limmo Peninsula, SCL caverns and launch adits for TBMs at Stepney Green and 10 SCL cross passages between the running tunnels with lengths up to 30m. At the Limmo Peninsula site a 40m deep and 30m diameter SCL shaft was built. At the shaft bottom in Stepney Green, two 30m long and up to 10m wide SCL launch adits were constructed followed by two 14m high and up to 18m wide, SCL caverns with single sidedrift and double sidedrift cross sections.

Farringdon station is now one of London's major rail interchange stations, providing connections between three networks. During the construction of the Crossrail project, it also received four earth pressure balanced tunnel boring machines (TBMs): the two Drive X TBMs, running from Royal Oak to Farringdon and the two Drive Y TBMs, running from Limmo to Farringdon. The complete station layout will comprise two ticket halls, two platform tunnels, connecting cross passages, escape and ventilation adits, two escalator - inclines and two concourse tunnels constructed using mainly SCL tunnelling.