Portrack, Scotland?a major railway realignment

Abstract

Crossing the volatile River Nith at Portrack in Dumfriesshire has presented railway engineers with severe problems for over 150 years, at least one previous attempt having been destroyed in a flood. Despite ongoing maintenance and repairs, the existing 11 span wrought iron structure, which carries the increasingly important Glasgow and South West Scotland line over the river, needed urgent replacement to reduce long-term costs and improve the safety and efficiency of the route. Carillion Rail and Scott Wilson Scotland carefully evaluated a number of options before recommending a realignment of the railway, which involved the replacement of two viaducts. Working in an environmentally sensitive location, adjacent to a ‘live’ railway and to a tight deadline required a tremendous amount of planning, cooperation and ingenuity by all parties; even the local estate owner became the project's architectural advisor. The centre-piece of the scheme is a spectacular 90 m curved truss-girder crossing the river, which was erected using the world's largest mobile crane. The meticulous planning and teamwork paid off with the construction of the entire project being completed on time, within budget and without disruption to the railway.