Uphill excavation of an escalator barrel between operational underground platforms.

A new underground triple escalator has been provided at Bank Station in London as part of a major capacity upgrade project. Unusually, the inclined escalator tunnel was excavated uphill rather than downhill due to restricted access. Using a sprayed-concrete lining and no pilot tunnel, it was a first in the UK for a triple escalator. The new escalator intercepted several existing structures which had to be backfilled and then broken out, some just 0.5 m from operational Tube lines. This paper sets out design considerations, construction sequence decisions and operational risk management, and discusses the existing assets' response to uphill tunnelling based on a comprehensive monitoring scheme. [ABSTRACT FROM AUTHOR]