New drainage systems are being installed on two Grade II listed viaducts as part of a £17 million investment on the West Coast Main Line. Dating from the 1840s, the structures’ original drainage had failed, causing track quality issues and numerous brickwork defects which are undergoing repair.
An 11-day blockade is needed to take the track off the viaduct and install pre-cast concrete ballast retention units which will collect water and discharge it into down pipes. An additional benefit of this solution is the relieving on lateral loadings into the parapets, the cause of longitudinal fracturing of the arch barrels.
Although clearly undesirable on such a strategically important route, the 11-day closure minimises the disruption caused by the works overall by driving efficiency improvements. Had they been done piecemeal, six months’ worth of weekend possessions would have been needed; around £500,000 of cost benefits are also generated.
As well as waterproofing the viaducts, two bridge reconstructions, remedial works to an overbridge and a considerable amount of routine maintenance has been progressed during the blockade.