Alltask win on UK's longest tunnel project
02/01/2005
Chalk falls will be a thing of the past in the Strood-Higham tunnel in Kent when it re-opens in January 2005, thanks to a tough new cement lining which is now in place.
The £35 million project is the longest tunnel relining to be undertaken on Britain’s railways in recent times spanning over 3.5km of tunnel and track. To restore the tunnel linings, the design incorporates steel support arches and concrete lining to reinforce both sections of tunnel which are currently unlined with the provision of refuges and shaft stabilisation.
Alltask was approached by the Main Contractor in Spring 2004 to offer a design and build access solution for the demolition of temporary steel tunnel support beams installed some years earlier as a measure to stop potential chalk falls. Alltask’s access solution was accepted and work began in July. The access had to be capable of withstanding the loads imposed during the demolition as well as the rotational thrust loads imposed by drilling operations for the installation of the new cement lining. At the same time a strict criteria had to be met to allow the rail mounted concrete re-mixers to pass below the structure to enable the programme of works to be maintained.
Additional work includes the installation of a new drainage system to protect the line from rising water levels from the Thames and Medway Rivers, a complete renewal of the tracks, temporary signalling, telecommunications and renewal of 33V HV cable to complete the restoration and ensure the tunnels are a viable working asset in the future.
The Victorian tunnel has been closed for nearly a year whilst the work takes place. Bus services are replacing trains between Strood and Higham. Rail disruptions had been frequent due to chalk falls from the unlined sections of the double-track tunnel, originally constructed as a canal tunnel in 1830 to link the Medway and Thames.
The works confirms Alltask’s ability to offer a comprehensive design solution to customer’s requirements, and endorses the resolution of Alltask to become Link-up registered as an approved supplier to Network Rail in 1998. Being a Link-up registered/qualified supplier credits Alltask with a recognised standard throughout the UK rail industry.
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