BBMV, an integrated joint venture comprising Balfour Beatty, Morgan Sindall and VINCI Construction constructed the station box for the Western Ticket Hall Tottenham Court Road Station, Contract 410 as part of the Crossrail project. Bachy Soletanche and Balfour Beatty Ground Engineering (BBGE), worked as part of the joint venture to construct the foundations for the new Western Ticket Hall.
Piling for the project comprised of a total of thirty-nine 1800mm diameter piles, up to 44 metres deep, to provide the foundations for both the Station Box and the future over-site development (OSD).
The team also installed a 1000mm thick, 221 metre long diaphragm wall for the station box. The wall is constructed in panels varying in length between 2800mm and 4400mm long. The reinforcement cage was also fitted with a number of “box out” units for later exposure and geothermal pipes for later connection to the heat exchanger system. The station itself will be divided into two sections, with the shallower ticketing hall having an 18 metre deep diaphragm wall, and the deeper train arrival area needing 41 metre deep walls.
Geothermal loops were installed in in 45 of the 63 diaphragm wall panels. This enabled Crossrail to maximise the use sustainable energy to provide geothermal heating and cooling capacity and helping the project reduce carbon emissions by 20%.
This was only the second time that a Geothermal system had been used on a Diaphragm wall in the U.K., and was designed to operate from +45 and +4 deg.C illustrating great innovation and sustainability by the client Crossrail.
Even with the geothermal pipe attached the concrete cover of 75mm was delivered and for Health & Safety reasons the pipe was installed on the outside face of the reinforcement cage. In this instance, to enable the high quality of the diaphragm walls to be confirmed, Crossrail requested that four to six sonic tubes were installed onto the reinforcement cages for later sonic testing of the panel.
The Tottenham Court Road Station project allowed us to demonstrate our commitment to pioneering piling and ground engineering work. Not only have we faced the challenge of installing diaphragm walling in an urban environment. The project team were duly proud that this project was delivered safely, on time and to budget. To achieve this in this location, next to the busiest shopping street in London, is testament to the skill of everyone involved.