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Embarrassed by the weather?

Painting the Forth Rail Bridge has been abandoned for at least a year. Neither client nor contractor will say why. David Hayward seeks the answer.

THE WEATHER can usually be relied upon to remind civil engineers just how hard their job is. But when it hinders the world's largest outside painting project - one that has continued for a century - is anyone really surprised?

However, it is still acutely embarrassing for both client and contractor that the latest Forth Rail Bridge painting contract was abandoned earlier this month.

Railtrack and contractor Rigblast are saying very little bar a bland joint statement indicating that the £40M project was taking too long. The decision to terminate the four-year contract half way through, they insist, was mutual.

But off the record a different tale seems to emerge. On the one hand, sources close to the contractor this week hinted that it pulled off the job after atrocious weather conditions resulted in four times the expected downtime.

On the other, unattributable comments from within Railtrack circles suggest that Rigblast could have - and should have - been working quicker.

The truth lies probably somewhere in the middle. Both sides underestimated the size of the task. Grit blasting back to base metal without losing any of the toxic debris to the atmosphere was a tough brief. Repainting every millimetre of the 350,000m 2of steelwork in the 2.5km crossing with three coats of epoxy paint was a long job. Mutually agreeing to complete this task, working continuously for over four years, was, in hindsight, totally unrealistic.

Railtrack still insists the painting system was the right choice. A sprayed zinc phosphate primer, followed by a glass flake epoxy mid coat protected with a polyurethane gloss finish, was the result of research and trials by Rigblast.

And both sides would agree that having to literally touch every part of the 112m high structure, and the tight environmental specification meant that the 4,000t of scaffolding, now being ignominiously removed, had been essential.

Sections of bridge were sequentially cocooned within dozens of individually enclosed work platforms erected ladderlike up main beams.

Yet the contractor is understood to blame the onerous sliding scale of wind speeds, above which an increasing number of critical path operations had to stop. When the anemometer reached 80km/h everyone had to abandon the bridge.

Rigblast is also thought to be claiming that, despite studying a decade of weather records, over the last two years there was four times more lost time than predicted. Given the temperature and humidity sensitivity of applying epoxy glass flake coatings, the programme could not be accelerated.

However, Railtrack might note that, under the New Engineering Contract, bad weather delays, proven to be above the accepted norm, could easily be claimed for. The client could also point to delays unrelated to bad weather - fires in work shelters and brief strikes.

But, speculation apart, the fact is last month's mid contract review revealed that less than 30% of the contract was complete and both sides were unhappy with the nine month delay. Despite the NEC's weather clause, 'delicate' compensation talks will continue for months, and a new contractor will not be chosen for a year.

Railtrack argues that getting it right is more important than completing on time and hopes new tenderers will come up with innovative ways to overcome the structure's challenges. Seasonal, rather than full time painting, it says, is now 'possible' when work restarts next spring.

But the original December 2001 completion date will slip by at least two years, possibly three. In the meantime lessons will be learnt. The bridge's legend of continuous painting hides the fact that the painters of the past only actually worked a third of the year, concentrating on just the easily accessible areas. The paint technology may have changed, but the weather certainly hasn't.

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