Erskine Bridge, over the Clyde estuary, is a multispan road bridge with the dual two-lane carriageways, footpaths and cycle tracks carried on a continuous high yield steel box girder of trapezoidal cross-section. The main span, of 350m (1000 ft), is stayed by single cables over centre towers above the main Piers and anchored in the median. The bridge is notable for the economy of material: steelwork in the superstructure weighs only 298 kg/m2 (61 lb/ft2) of deck area and steelwork plus mastic road surfacing 393 kg/m2 (80 lblft2). The cost of the bridge has been correspondingly attractive: £124 per m2 (£11.5 per ft2) of deck area.
O.A. Kerensky, W. Henderson and W.C. Brown