The Step-Free Access (SFA) project’s main goal is to provide step-free access from street level to all operational platforms via the ticket hall and between platforms for interchange purposes.
Gall Zeidler Consultants provided design and computer modeling services for a shaft and tunnel stub to be constructed using Sprayed Concrete Lining / New Austrian Tunneling Method (SCL / NATM). These structures serve as an elevator shaft and the elevator lobby, respectively.
The shaft and tunnel stub will be constructed entirely in London Clay. The initial shaft and tunnel stub support consists of a reinforced shotcrete lining. Excavation followed the principles of SCL / NATM. A PVC membrane-based waterproofing system as well as shotcrete and cast-in-place concrete linings were installed for permanent support.
London, United Kingdom
2008 – 2009
Shaft and Tunnel Stub
Tunnel Stub – 15.0 feet (4.6 meters)
Oval Shaft Diameter 29.9 / 31.5 high (9.1 / 9.6 meters) Axis Length – 91.0 feet (27.7 meters) Depth
Tunnel Stub – 28.5 feet (8.7 meters) Width, 42 feet (12.8 meters) Heigh
Man-Placed Fill, London Clay; Groundwater Table Approximately 9 – 12 feet (3 – 4 meters) Below Surface
Approximately US $30 Million
London Underground Ltd. (LUL)