Westminster Underground Station required a complete redesign to accommodate the Jubilee line extension, a much deeper underground line to the shallow District and Circle line already served by the station. This logistically challenging project also coincided with the construction of Portcullis House, the new parliamentary building, which our practice designed on the site above.

The new Westminster station reconciles the different line depths and axes as well as the supporting structure for Portcullis House, and the site’s proximity to Big Ben and the River Thames.

The station is entered from the colonnade of Portcullis House. The District and Circle Line has been lowered to accommodate two full storeys between platform level and street level. The upper storey contains the ticket hall, and the lower storey contains the platforms. All elements such as walls, escalators and ticket barriers follow either the diagonal grid of the railway, which cuts across the site at an angle of 45 degrees, or the orthogonal grid of the new building above.

Below lies the 30m deep escalator box to the Jubilee line platforms. Smooth, stainless steel escalators thread through the dramatic space, contrasting with the rough, tough concrete of the box wall and framed by a massive diagrid of beams and buttresses, which also form the foundations of Portcullis House.

The Jubilee railway tunnels themselves pass to one side of the box, one above the other, ensuring they are as far away as possible from the nearby foundations of the tower of Big Ben.