Skanska has secured a project to repair three major rail tunnels for Network Rail.
The £6.2 million scheme encompasses the repair of Martello, Shakespeare and Abbotscliffe Tunnels, all situated within the chalk cliffs of coastal Kent, located between Folkestone East and Dover Priory stations.
Works will include the repairing of the tunnels structure, after high levels of water ingress suffered over many years, which has led to degradation of the tunnels’ lining, which is comprised of spalling brickwork, open joints and hollowness. Network Rail has explained that if no work is taken now, the progressive defects will impact on the serviceability of the lining and ultimately affect structural performance.
Specifically, patch repairs and water control will form a core component of the works, together with haunch and crown waterproofing, with associated concrete re-lining. Rock anchors will also be installed, as will new permanent monitoring systems.
In the Shakespeare and Abbotscliffe Tunnels, there are sections of fractured side wall and instances of extreme water ingress known as the Lydden Sprout. Cracks in the brick lining have manifested in the area of the Lydden Sprout for some time and attempts have been made to stabilise the tunnel in a small area by installing centring steel. Skanska will repair all sections of sidewall and of the Lydden Sprout, together with the creation of a new drainage system and waterproof membranes.
Work is being undertaken in a line closure scheduled to last a total of four months. Network Rail will be taking advantage of the closure to also renew over 5km of track in the Shakespeare and Abbotscliffe tunnels, which will help improve the performance of this stretch of line for passengers.