Moorcock Viaduct, Cumbria, UK
Hytec waterproofing system plays important role in the refurbishment of scenic railway viaduct
The Moorcock Viaduct in Garsdale, Cumbria part of the Carlisle to Settle Railway Line, arguably the most scenic railway in England, has been waterproofed with the Hytec loose-laid waterproofing system from Stirling Lloyd.
- Moorcock Viaduct
Part of a structural refurbishment programme of this major tourist attraction, which recently celebrated its 125th anniversary, a new deck and waterproofing membrane were required on the masonry arch viaduct as the existing pitch system had failed. This had allowed water ingress and subsequent deterioration caused by the freeze thaw process and erosion of the mortar which has the effect of loosening the stone blocks in the arches.
The refurbishment also involved the re-alignment of the parapets and strengthening the arches with the use of pre-cast units. The viaduct would then be ‘tied’ together across its width and the new deck cast in-situ with fast setting concrete. To allow access to enable placement of the concrete one track had to remain open during the works.
As a consequence not only did this mean that the deck would have to be cast in two halves longitudinally but also that the waterproofing would have to be applied to green concrete, that would be less than 24 hours old in most cases. To accommodate these working restrictions clients - Railtrack (North West Region) opted for a loose laid system that had been assessed to Railtrack’s Code of Practice ‘Water proofing of Underline Bridge Decks RT/CE/S/041’ (PADS Reg. CAT. No. 028/970000).
The Application Part 2.
Of the competing systems Hytec, which is based on flexible polypropylene, was chosen due to the fact that the system offered costs savings, faster application times, higher performance characteristics and was more environmentally friendly than its PVC based rivals.
Working in two 12 hour shifts over two weekend possessions in November 2000, Hytec was applied to the 1,850m² deck by D & M Pitt (Waterproofing) Ltd., one of Stirling Lloyd’s trained Authorised Contractors.
Using hot air welding techniques the system was rapidly applied despite the cold temperatures and inclement weather experienced The new concrete deck had falls to the centre line of the bridge so the membrane was also laid into a precast drainage channel which had been installed to accommodate this.
The Hytec membrane was attached to the parapets of the viaduct using Hytec laminated metal profiles, part of the full range of accessories for the system supplied by Stirling Lloyd. The membrane on the deck of the viaduct was left loose-laid but was overlaid with the Hytec Geo 1000 protective matting - a non-woven, needle-punched polypropylene geotextile which is used to prevent damage to the membrane from the ballast application and mechanical damage caused by other trades.
Hytec is now performing successfully on this high profile project, one of England’s most famous stretches of railway. Hytec will not only enable Moorcock Viaduct to retain its status as a valuable working tourist attraction but is increasingly proving to be the Engineers preferred choice for the waterproofing of Underline Bridge Decks.