The WCSCU project will deliver additional capacity and step free access to the Victoria line at London Underground's Walthamstow Central station. A new station box will provide a new station entrance, a new subsurface ticket hall and connecting routes to both Victoria line platforms via escalators, stairs and lifts. Four new tunnel structures will connect the new station box with the segmental cast iron lining of the Victoria line platform tunnels. The use of traditional timber headings was chosen as the preferred construction method during conceptual design primarily due to the length of the structures (i.e. approximately 2 m each).