Construction of Westminster Station, London

The most complex and technically demanding station on the jubilee Line Exte nsion Project, with the deepest basement in London, was constructed within the political heart of the country and under one of London's oldest undergr ound railway stations. Various civil engineering techniques such as tunnell ing, piling, diaphragm walling and top-down construction were used to const ruct the station escalator hall and foundations to a prestigious new parlia mentary building. Buildings surrounding the worksite, together with the Dis trict and Circle Line station passing diagonally through it, severely restr icted construction access and working space. Major challenges to the constr uction team included movement control of adjacent structures such as St Ste phen's ClockTower (Big Ben) and a major trunk sewer, and rebuilding the exi sting station while maintaining an uninterrupted flow of passengers and tra ins through the station. This paper describes the construction of the new W estminster Station (excluding tunnel works), which was part of Contract 102 of the jubilee Line Extension Project: Green Park to Waterloo Tunnels, Wes tminster and Waterloo Stations.