SES Contracting has begun repairs to a tunnel that collapsed beneath homes in Liverpool.
The tunnel, at the site of the old Dingle station on the Liverpool Overhead Railway, collapsed in July 2012. Eleven properties were evacuated, and many residents have been unable to return since.
The complex repair project is expected to take at least three months. The first phase involves surveying and testing the tunnel from its entrance to the point where it collapsed.
Safe access will be secured before temporary portal supports are erected beneath the roof near the point of collapse.
After debris has been removed, two steel linings will be installed.
Steel panel formwork will be used to form a shutter for a mass infill of foamed concrete.
The steel linings will be left in position to allow access through the collapse area once it is declared safe.
Liverpool City Council announced in January that an agreement had been reached with six insurance companies that provided cover for the evacuated properties and for a car repairs business based in the tunnel.
It said the insurers had agreed to contribute to the structural repairs while making no admission of liability.
Councillor Paul Brant told NCE: “I’m incredibly proud of what we have done. We had no responsibility to do anything.
“Yet we paid for security measures at the site; helped rehouse residents; and invested a lot of officer time and energy to find a way forward.”
A spokesman for some of the insurers said in January that they “recognised” that these were unique circumstances and had sought to proactively resolve the problems for customers despite there being no cover under the policies in force following the initial collapse.