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09Aug91 UK: NEW TARMAC-BUILT M40 BRIDGES NEED £1M REPAIRS TO BEARINGS.

By Ben RoskrowMore than 220 bridge bearings on a new stretch of the M40 in Oxfordshire must be replaced at a cost of £1 million because they were damaged during construction.The Department of Transport discovered the problem, which affects 244 bearings on nine bridges on Tarmac's Banbury Three section, last August. But the much publicised early opening of the M40 went ahead in January without the repairs being carried out.Now the nine bridges, which take the M40 over roads, rivers and a canal, will have to be jacked up by 3 mm and the bearings removed and replaced while traffic continues touse the motorway. The operation would have been simpler and cheaper on a closed section.A spokeswoman for the Department of Transport said that it first became aware of the problem last summer through its agent on site Sir William Halcrow and Partners.'A detailed investigation began then, when just one bridge was thought to be affected. That investigation was still under way in January when the M40 was opened so there was no question of delaying the opening,' she said.But Shadow Transport Secretary John Prescott said he would be demanding an explanation from his opposite number Malcolm Rifkind.'I want to know if the opening of the M40 was rushed, thus imposing a bigger financial burden on the scheme and whether the taxpayer will have to foot the bill,' he said.'The M40 is controlled by a department obsessed by doing things quicker and cheaper rather than for the convenience of the road user.'The DTp is now considering a proposal from Tarmac to repair bearings without disruption to traffic. The work is expected to take three or four months.Liability is still being discussed but sources say the DTp is likely to claim the money from Tarmac.Each bearing will have to be removed and either replaced or re-polished. The bearings - which were supplied by the Glacier Metal Company - comprise a lower plate holding a Teflon disc in a socket. This acts on an upper plate which has a high quality steel surface. The efficiency and durability of the bearing depends on the quality of the stainless steel sliding plate.The 244 bearings were damaged during a gritblasting operation by a subcontractor.Tarmac, which would not comment on the repairs, completed the £52 million, 12.4 km section of the M40 at the end of last year. It was opened with six other sections of the road amid a fanfare of publicity in January, hailing the early completion of the Oxford to Birmingham road.The bridges affected have been designed to be jacked up if there is subsidence in the area. A transverse heavily reinforced jacking beam has been incorporated supporting the longitudinal beams.It is these longitudinal beams which rest on the damaged bearings. The contractor should be able to use the jacking beams to help the repairs.Insurance companies for the contractor have been informed.