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The world’s iconic unending job—the painting of Scotland’s legendary Forth Bridge—is about to end.
The 10-year-long, £130 million project ($207 million US) is set to be completed in December—months ahead of schedule—liberating the span from the acres of scaffolding that has enclosed it for the last decade.
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Aloysious A Gruntpuddock / Creative Commons |
| Scaffolding was a fixture on the Forth Bridge for years before this photo was taken in 2007. |
At that point, contractors and officials say, cliché buffs will need to find a new expression for “like painting the Forth Bridge"—an old saw that refers to a task that takes so long to complete that it needs redoing as soon as it is done.
‘Job Done’
“For the first time in the bridge’s history, there will be no painters required on the bridge,” Colin Hardie, Balfour Beatty’s construction superintendent, told The Scotsman, of Edinburgh. “Job done."
Balfour Beatty Civil Engineering gained the painting contract in 2002 after an earlier contractor left the project due to financial problems. That initial £40m ($63.7 million US) refurbishment package, which had begun in 1998, involved steelwork repairs, some surface coating, access improvements and an upgrade of the floodlighting.
Both projects followed a 1996 structural and maintenance assessment of the bridge requested by the UK’s Health & Safety Executive.
Network Rail, which maintains the 121-year-old crossing between North and South Queensferry, said the work would end the "modern myth" that painting the bridge would never be finished, The Scotsman reported.
"Over the last decade, the bridge has been restored to its original condition, and its new paint will preserve the steelwork for decades to come,” David Simpson, route managing director for Network Rail, told the newspaper.
Coatings Tested Offshore
The bridge’s new three-coat system, designed to last 20 years, is comprised of a zinc-based primer (35 microns); a glass flake epoxy intermediate barrier coat (400 microns); and a polyurethane gloss top coat (35 microns) in “Forth Bridge Red.”
Before applying the 56,532 gallons of coating, crews abrasive-blast-cleaned the structure’s 4.2 million square feet of surface area to bare metal. The coating system has been tested on North Sea oil rigs, bridge officials said.
The painting project involved more than 200 workers.
Engineering Marvel
Construction of the 1.5-mile Forth Railway Bridge, the world’s first major steel bridge, began in 1883 and was formally completed March 4, 1890, when HRH Edward Prince of Wales tapped into place a “golden” rivet.
More than 4,000 workers worked on the bridge, with its gigantic girder spans of 521 meters (1710 feet); 57 workers perished during the project.
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www.forthbridges.co.uk |
| Civil engineer Benjamin Baker, who helped design the Forth Bridge, showed its revolutionary structure with a “human cantilever” model using his assistant Kaichi Watanabe representing the live load. The pull in his supporters’ arms indicates the tension in the ties, and the push in the lower struts the compression in the tubes, bridge officials say. |
The bridge uses the balanced cantilever principle. The main crossing comprises tubular struts and lattice-girder ties in three double-cantilevers, each connected by 105-meter (345-foot) “suspended” girder spans resting on the cantilever ends and secured by man-sized pins, according to a history at www.forthbridges.org.uk. The outside double-cantilever shoreward ends carry weights of about 1,000 tons to counter-balance half the weight of the suspended span and live load.
The bridge, a vital artery in Network Rail’s East Coast railway system, carries up to 200 train journeys each day. Earlier this year, the structure was nominated as a Unesco world heritage site.
‘Treasure’ Touch-Ups
Of course, no painting job is ever really finished. The most exposed sections of the bridge still will require regular touchups, officials say.
Still, the current achievement should help quiet the chatter about an “endless paint job,” the contractor says.
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www.forthbridges.co.uk |
| The Forth Bridge is the world’s oldest steel bridge, with 54,000 tons of steel, 6.5 million rivets and 45 acres of surface area. |
Marshall Scott, of Balfour Beatty, told The Guardian newspaper that the restoration would serve as a testament to the skills and expertise of those who built the "much-treasured structure.”
“The now-fully-restored Forth Bridge will continue to operate for many decades to come,” said Scott, “and it will provide the world-renowned image that Scotland can be rightfully proud of."
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