Cleddau Bridge (1970) Milford Haven, Wales
A mere ten days after the destruction of the Britannia Bridge, Cleddau Bridge, under construction across the Cleddau River, near the seaport of Milford Haven in Wales, collapsed. Proposed in various guises since 1943, permission for the bridge was granted in 1965 and construction began in 1969 on the seven span, 820 metre, box girder bridge linking the towns of Pembroke Dock and Neyland and in the process eliminating a 48 km road journey. The cost was £2.1 million and the bridge was due for completion by the spring of 1971.
On June 2nd, 1970 the north and south end spans had been erected and work was ongoing in erecting a second span at both ends. The second north span at 149 metres was built while supported midsection, but the south span had no such support, it having been judged unnecessary as it was considerably shorter at 77 metres. At 2.15 p.m. on that Tuesday a final section of that second south span was being lifted into place when the south structure buckled and, with a loud groan, collapsed amid a cloud of red dust.
The mangled iron narrowly missed the houses in the village of Pembroke Ferry, 30 metres below but killed four workmen and injured five. Construction was immediately halted. The collapse was attributed to the design of the bridge, in particular the failure of the pier support diaphragm to fulfil its function of lateral stability during erection. Immediate doubts arose about all box girder bridges and a subsequent inquiry outlined 27 recommendations in its report of 1973, establishing new standards for the design and construction of box girder bridges.
The Cleddau Bridge was eventually finished. Work recommenced in 1972 when the first of the new box units to replace those damaged were erected. The bridge, which carries the A477 road, the Wales Coast Path and Route 4 of the National Cycle Network, opened in 1975.