Traffic restrictions have been imposed on all Britain's 42 box-girder bridges and they and another 61 still under construction are to undergo rigorous new safety tests.
Traffic restrictions have been imposed on all Britain's 42 box-girder bridges and they and another 61 still under construction are to undergo rigorous new safety tests. These measures, affecting the type of construction involved in the collapse of the Yarra bridge in Melbourne last year were announced in London on Wednesday (June 16) by the Department of the Environment.
The checks were originally ordered with a minimum of publicity to avoid public alarm. As well as the restrictions announced on Wednesday, the bridges must conform to interim rules recently issued by a technical committee set up by Britain's Environment Minister, Mr. Peter Walker. The committee was set up by Mr. Walker following the collapse of three box girder bridges. The first to go was in November 1969, over the Danube in Vienna. The bridge was virtually complete, but not open to traffic at the time of the collapse. Then in June 1970, a bridge under construction at Milford Haven in Wales, collapsed killing four workmen.
Then in October, last year,come the most spectacular collapse of all. The crash of the yarra River bridge under construction near Melbourne, the cost 35 lives. The Australians immediately set up a Royal Commission and in November, the British Minister announced his technical panel.
The restrictions affect two new British projects--one in Manchester and the other in Glasgow--which were due to be opened within the next two weeks. One of the projects includes two bridges on the approaches to the new Mersey Tunnel which were to be opened by the Queen on June 24. The other, the Erskine Bridge in Glasgow, was to have been opened by Princess Ann on July two. Now they won't be opened until the new checks have been made.
Box girder bridge design has considerably reduced bridge buildings costs. It replaces the traditional methods by welding, or bolting together, thin sheet steel boxes, spaced at intervals by bulkheads and stiffened with steel ribs. But under certain stresses these steel tubes have been known to buckle and bend like biscuit tins.