Design and construction of Westminster station on the Jubilee Line Extension

Creating Westminster station on the Jubilee Line Extension involved constru ction of the deepest box excavation in London and complete renewal of an op erational Underground station with only minor disruptions to service. The t ask was further complicated by the need to provide foundations for a New Pa rliamentary Building above the station, which required lowering the Distric t and Circle Line tracks by 300 mm. The control of ground movements was als o of paramount importance since one of the world's most famous landmarks-Bi g Ben clock tower-is within 30 m of the 39 m deep station.