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Stirling Lloyd's Hytec Solution for Whalley Viaduct
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Hytec, Stirling Lloyd’s loose laid waterproofing system has proved to be the solution to the protection of the deck of the historic Whalley Viaduct which carries the Ribble Valley Railway Line over the River Calder in Central Lancashire.
Hailed as a major success of Victorian engineering when it was first built over 150 years ago, the viaduct comprises of 48 hand made brick arches. However time had taken its toll on the structure. Failure of the original pitch waterproofing had resulted in the ingress of water causing extensive damage to the bricks and mortar throughout the viaduct.
Railtrack, owners of the viaduct, decided that a new waterproofing membrane should be applied during track renewal works. Despite the track being closed, time was of the essence for the refurbishment and so as well as providing an effective waterproofing membrane the chosen system had to be capable of meeting Railtrack’s ambitious programme which allocated a total of nine days for the whole refurbishment with the waterproofing of the 6,000m² deck being allocated two 36 hour possessions.
Of the systems available Railtrack chose the Hytec system, a flexible, durable polypropylene sheet membrane. The loose laid Hytec was specified in accordance with the recommendations of the Railtrack Code of Practice, RT/CE/C/001 (now RT/CE/S/041), for areas where no discreet deck exists for the application of a tightly bonded option.
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Hytec not only offered the rapid application required but also a high level of puncture resistance, important as in several locations only a minimal ballast depth below the rails was available. The system also has exceptional resistance to chemical attack and resists environmental stress cracking, ensuring long service further enhanced by its retained flexibility and impact resistance down to -40°C.
The Nuttall-Railtrack North West Alliance awarded the contract for the application of the system to D & M Pitt (Waterproofing) Ltd, one of Stirling Lloyd’s Authorised Contractors for the Hytec system. To enhance the speed of application Stirling Lloyd specially manufactured sheets to the specific width of 4.5 metres to fit the bridge, which minimised the amount of on-site welding. In addition the large sheets were mechanically handled into place on the deck. These adaptations ensured D & M Pitt were easily able to meet the required programme and apply 3,000m² during each of the two 36 hour weekend work windows.
In fact John Pitt, MD of D & M Pitt (Waterproofing) Ltd. commented "Though not the largest project we have carried out but in over 30 years in the industry I cannot remember such a large waterproofing scheme to be carried out in such a short time."
Tony Frescini of Railtrack (North West Region) echoed these thoughts and commented: "Stirling Lloyd was the only company able to provide a bespoke solution, with the Hytec allowing the contract to be complete in the nine day time span. Quality, reliability and cost efficiency were vital elements in the specification process and the Hytec FPP fulfilled all these criteria."
The refurbishment of the Whalley Viaduct is now complete, and with the help of Stirling Lloyd, this lasting monument to previous generations of Rail Engineers, is set to prolong its role of serving the Rail Traveling public for many more years to come.
[ Stirling Lloyd Press Release PR03-05 : 02/2003 ]
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