Description

Two short lengths of cable strands for the construction of the Queensferry Crossing with associated wedges (see 2015/001.2). The strands are 15.7 mm diameter comprising a king wire in the middle with six equivalent wires wound helically round it. These wires are 4.8 mm diameter and are made from high tensile steel. At 1860 megapascals tensile strength they are approximately five times stronger than plate steel. There are a variety of cable sizes on the Crossing, the largest being 471 mm (outside diameter of the sheath), containing 109 strands. The smallest cable has 48 strands. Total wire length on the project (if all joined together) is approximately 23,000 miles. The wires in each strand are wax coated and sheathed individually in high density polyethylene. Total number of cables is 288. The cable was manufactured in Switzerland and arrived on site in 1.9 m diameter coils and was cut to length on site.

The shorter length is 350 mm long and is fully sheathed in high density polyethylene.

The longer length is 500 mm long and is partially sheathed. Two semi-circular tapering conical high tensile steel wedges (collets) hold the cable in position through steel anchor plates (see 2017/015) at the correct tension at either end of the strand. The tension of the strand can be adjusted by relocating the wedges by the use of a winch to release and relocate the wedges to increase or reduce the tension.