M25 Bell Common tunnel refurbishment: faster, leaner, safer

The 500 m long cut-and-cover Bell Common tunnel was opened in 1984 as part of the M25 London orbital motorway. This paper describes a recent £90 million refurbishment to bring the tunnel up to European directive standards, including the replacement of all mechanical, electrical, operational and communication systems and the installation of passive fire protection. The project drew on lessons from a similar refurbishment of the nearby M25 Holmesdale tunnel, which was completed by the same team in 2007. Using the same principles of lean construction, the Bell Common project finished ahead of programme, below target cost and with minimal disruption to the 85 million vehicles which passed through the tunnel during the works.