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Avonmouth Bridge tragedy: focus on windspeed


WIND SPEEDS at the time of the fatal collapse of a platform on the Avonmouth Bridge near Bristol two weeks ago exceeded the maximum safe limit specified by the contract, NCE has learnt this week.

Four men plunged 25m to their deaths from the under-slung platform beneath the bridge. It is thought that wind pushed the platform off its rails (NCE last week).

But NCE understands that a contractual clause restricted the use of the platforms in adverse weather. The contract clause states: 'Use of the gantries will be suspended when wind speed exceeds 12m/sec.' This equates to 43 km/h.

But Meteorological Office records for midday on 8 September, when the tragedy struck, show local winds were gusting south-west at up to 15m/sec or 57 km/h.

A suspended access expert working on site when the accident occurred suggested the platform, which was suspended from beam trolleys running along parallel I section rails under the bridge, had been inadequately tethered and was blown by powerful winds.

The platform was suspended either side of a 2m gap where rails were being replaced. One pair of beam trolleys ran off the exposed rail ends, up-ending the platform.

The wind loading safety breach is expected to focus attention on operating safety. Site workers had voiced concern over operating procedure 'in the recent past', said GMB Union regional industrial organiser John Phillips.

The contract stipulates operatives were to be fully trained and authorised by the supervising engineer; training courses, manuals and on site guidance were mandatory.

The contract also required completion of a checklist at the beginning and end of each shift to ensure the platforms were fully equipped and operational. Weekly, monthly and quarterly inspections were specified and the platforms had to be recertified annually.

Main contractor Costain and subcontractor Kvaerner Cleveland Bridge said they were unable to comment until investigations were complete.

Andrew Mylius

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