The repair and strengthening of Burnton railway viaduct, UK

摘要

Burnton railway viaduct in Ayrshire, Scotland, carries the freight-only, single-track Waterside branch line from Dalrymple Junction to Chalmerston coal yard over the Purclewan Burn and the B742. The striking grade 'B' listed structure was constructed in 1889, is curved in plan and comprises 16 masonry arch spans. A permanent speed restriction of 5 miles/h had been imposed on the line and the structure was being constantly monitored in real time using accelerometers attached to the arch intrados and the vertical face of the spandrel walls. In 2001 the structure began to exhibit an increase in 'liveliness' during the passage of the trains. This movement was investigated by Railtrack engineering staff as a matter of urgency. As part of their commitment to maintain the safe and efficient operation of the railway, Railtrack (succeeded by Network Rail) commissioned John Mowlem Ltd (now Carillion JM Ltd), through its alliance contract, to investigate the problem and prepare a cost-effective solution in accordance with the line classification. In turn, Carillion appointed Scott Wilson Scotland Ltd (SWSL) as its designer. Initially, SWSL and Carillion undertook a joint investigation of the viaduct, which was quickly followed by an assessment of the structure. This confirmed that there was a need to undertake a comprehensive programme of strengthening and refurbishment. This paper describes the techniques adopted to stabilise the viaduct and the methods of construction.