The simple diagram on the right shows the expected pattern of deformation of the LUL running tunnels due to new construction work to one side (green area). Typically the new construction work will involve either removing soil, as suggested by the pattern of movement in the illustration, or piling. In either case there will be a change in stress in the soil around the tunnel causing a change in deformation of the tunnel lining.

The photograph (below left) shows the instruments installed to monitor the changes in deformation.
The photograph (below right) shows a close-up of the CMCS logger. The metal box for the logger is purpose built to fit inside the well of the lining segments.