Alexandra Suspension Bridge

In January 2004 Glasgow Engineering were invited to assist with the rebuild of the Alexandra Suspension Bridge over the first basin, Glasgow Engineering were required to re-manufacture the lead lined cable chairs, suspension rods, cable clamps and turn buckles 

When originally built in 1904 the structure was said to be the best of its kind in the Commonwealth. While being light, it is exceptionally strong, and is so splendidly braced that it vibrates only very slightly. It is of graceful proportions that are appropriate to the surroundings.

The total length is 220 feet, the clear span between the centers of the steel towers being 150 feet. The bridge structure is formed of steel frames, hung by steel rods from the main cables, and carrying a wood decking, with a galvanized steel lattice guard at each side, giving a path way 3 feet wide. There are two main cables, taking the whole of the weight. These are made of plough steel wire, of the highest quality, and are 1 3/4 in diameter. Anchored at each end to the solid rock, they are passed over steel towers 32 feet high, between which they depend in graceful curves.

At regular intervals, clips are placed, gripping the cables and affording a connection for the suspension rods, to which are attached the steel bridge frames. Two co-terminus steel angle beams run the full length of the bridge, at the lower angles of the frames, and form with the lattice guards, a strong and rigid longitudinal frame. The steel towers, which carry the cables, rest upon massive concrete abutments, and are fitted at the summit with cast iron lead-lined chairs, or seats, for the cables. In order to give lateral stability, diagonal land ties are fixed, passing from anchor bolts in the rocks to brackets on the bridge beams. The design is by David St John, the city surveyor, who supervised the work of construction and erection by the contractors, the Salisbury Foundry Company. The cost of the original structure was about £450.