A major research project investigating the effect of tunnelling on existing tunnels has been
completed at Imperial College London. This subject is always of great concern during the
planning and execution of underground tunnelling works in the urban environment. Many cities
already have extensive existing tunnel networks and so it is necessary to construct new tunnels at
a level beneath them. The associated deformations that take place during tunnelling have to be
carefully assessed and their impact on the existing tunnels estimated. Of particular concern is the
serviceability of tunnels used for underground trains where the kinematic envelope must not be
impinged upon. The new Crossrail transport line under construction in London passes beneath
numerous tunnels including a number of those forming part of the London Underground network