Corus design grants historic viaduct new lease of life
08 Aug 2006
Coinciding with the longest planned maintenance closure of the Forth Bridge in its history, Network Rail had just eight days to undertake strengthening work to the 115 year-old Jamestown viaduct, using a bespoke and rarely documented solution, developed by Corus Infrastructure Services for Mowlem Civil Engineering.
Constructed between 1883 and 1890, the Jamestown Viaduct to the south of the Fife town of Inverkeithing, needed upgrading to meet the modern standards demanded by the increasing frequency and size of 21st century trains. Corus’ outline design for strengthening the 115-year old listed structure was chosen by Mowlem and Network Rail following a design competition.
The challenging Network Rail design brief asked for the external appearance of the viaduct to remain largely unaltered and specified critical work should be carried out during the eight day closure.
In close partnership with Mowlem, Network Rail and Historic Scotland, Corus developed an innovative design based on the introduction of a reinforced concrete slab to act with existing trusses and cross girders – one of the few instances in which this has been used on a railway structure.
To achieve this, steel diaphragm panels were installed in the apertures between the cross girders to transfer shear between the slab and the tops of the trusses. Trials carried out in advance verified the feasibility of welding to the existing 19th Century deck plates to function as a permanent formwork for the slab. The connection between the new deck slab and structure is provided through 8600 stud connectors.
Clive Roberts, Professional Head of Bridge Design at Corus, comments:
‘This project called on Corus’ technical expertise to develop a unique solution and deliver it within an extremely tight timeframe. This was only made possible by the close working relationship and positive attitude adopted by the entire supply chain.’
The project involved some 20,000 man hours and required Mowlem to coordinate a complex supply chain involving engineers, plant operators, tradesmen and technicians from all over Scotland. The successful completion of the project means the bridge will now be able to cope with 27 million tonnes of rail traffic per year – significantly lengthening the life of this historic structure.