It was constructed between 1887 and 1890, and listed as a Grade B listed building in 2004.[1]
In 2005, the viaduct was strengthened during an eight-day closure of the railway.[2][3] 120 tonnes (118.1 long tons; 132.3 short tons) of steel and 600 cubic metres (21,000 cu ft) of high strength concrete were used to add a reinforced concrete slab underneath the track, in order to improve the load-carrying capacity to Network Rail's standards.[3] The work was worth around £5 million, and engineered by Corus and carried out by Mowlem.[4][5] 20,000 man-hours were worked during the period of closure, which coincided with a "possession" of the Forth Bridge.[2][3]
Design
The viaduct is a skew arch - note that the truss girders are not continuous
It has four main steel girder spans, supported by three sandstone piers.[6] As well as the four steel spans, there is a stone arch at each end of the viaduct.[1] The steel spans are 33.4 metres (110 ft) long, and are at a skew of 70°[1] The spans consist of twin truss girders sitting on the piers, and on top of the truss cross-girders supporting steel deck plates, with a ballasted track.[1]
The viaduct carries the line crossing the Forth Bridge, from Edinburgh to Aberdeen and the north of Scotland, and carries a significant volume of both passenger and freight rail traffic, which previously included transporting coal to Longannet Power Station[1] prior to its closure in 2016. As of 2006[update] there were up to 200 train movements a day and loads of 27 million tonnes annually.[3]
It spans the B981 public road and the former branch railway to North Queensferry and Rosyth.[6] It runs close to and nearly parallel to the A90 road, but the viaduct has a slight curve to the east.[7]
