Skanska’s civil engineering team has been awarded a £6.5 million contract by Network Rail to replace the existing Harthope Viaduct in South Lanarkshire.
The viaduct is situated on the West Coast Main Line near Beattock Summit and crosses the B7076 (formerly the A74). Its current six-span structure is to be replaced with a two-span continuous structure on the present alignment, together with a new piling system, specifically designed to cause minimal disturbance to the existing structure during the construction of the foundations for the new substructure.
The highly complex works will comprise of the construction of a new reinforced concrete pier on piled foundations in the third span of the existing viaduct and the construction of new reinforced concrete abutment walls on piled foundations within the first and sixth spans. The existing voids in the cellular south abutments are to be grouted.
The effective spans of the new superstructure will be approximately 49.5 metres and 34 metres and will be supported by fixed bearings at the south end and sliding bearings on the piers and north abutment.
Skanska will also make provision for the re-routing of signalling and telecommunications cabling before the slide-in of the new superstructure and for re-establishment of cabling upon its completion.
The demolition of the existing viaduct and the slide-in of the new viaduct (which will have been temporarily erected adjacent to the existing structure) will be carried out during a five-day possession of the West Coast Main Line at Easter 2006.
Although the new viaduct has been designed for future linespeeds of 125mph (PS), the track will be reinstalled to 95mph (P.S.) and 115mph (EPS) for both up and down lines.
Significant environmental measures are being put in place to ensure minimal disturbance to the local communities, wildlife and natural habitats as well as specific measures to preserve the nearby Evan Water.
“We are delighted to be continuing our successful working relationship with Network Rail,” said Bill Hocking, Managing Director of Skanska’s civil engineering operating unit. “Schemes such as this one really demonstrate our capabilities in complex, technical engineering projects and that our philosophy of integrated team working really does work.”
Skanska and Network Rail have previously worked together on several key schemes around the UK, most recently on the challenging refurbishment of three Victorian railway tunnels on the Folkestone-Dover line in Kent, which opened to rail traffic this month.
Work begins immediately and will continue until Summer 2006.