November 6, 2009
FEATURE | General and trade contracting
Whirlpool Rapids Bridge gets historic facelift
US$2 million metal contract will see replacement of rivets, steel
NIAGARA FALLS, Ont.
The Whirlpool Rapids Bridge across the Niagara River has been carrying traffic between the two countries since 1897 so it’s not surprising the old steel arch needs refurbishing from time to time.
The bridge is currently undergoing the second of a two-stage painting project with a large steel repair component. The 330-metre span comprises two decks. The upper is limited to rail traffic, while the lower is reserved for vehicles.
The first stage involved the railway deck, says Ron Koert, Construction Manager, with the Niagara Falls Bridge Commission. Stage two involves the lower bridge, the vehicular deck and the arch to the skewbacks—the sloped abutments that support the arch—and replacing the catwalk system .“The steel is sandblasted to the bare metal and then given a visual inspection,” he says. “Any problems are repaired and the bridge is then repainted. With the original rivets you can’t tell what sort of shape they’re in until they’re sandblasted clean of rust and corrosion.”
Niagara Falls-based Bradshaw Iron, which specializes in custom metal work, has the US$2-million metal contract .
“Last September we removed the catwalk which was so old that the stringers were just wooden planks—we’d guess it’s about 60 years old,” says Jason Bradshaw, company president.
The new catwalk, manufactured by Bradshaw’s company, will be installed next spring. They are also replacing the access stairs on the main columns with galvanized ladders.
Bradshaw’s work depends on the schedule of the painting contractor, who has broken the job into quadrants.
The painter sandblasts the bridge in a fully contained environment, surrounded by plastic sheeting. An elaborate venting system provides air to the workers and filters out any debris that would otherwise escape.
“Some of the old paint on the bridge is red lead paint, which obviously can’t be released to the environment,” says Bradshaw. “At the same time, you need a climate-controlled environment to paint the bridge. If it’s too humid, you can’t paint.”
The real grunt work for Bradshaw involves the period between sandblasting and painting. “If we find problems with the rivets or the connecting steel, we have to pop out the old rivets using a pneumatic rivet-buster nicknamed a helldog,” he says. “It’s hard, physical work because some of those rivets are up to five inches long.
“When they were driven in they might have gone through 10 different layers of plate steel with 10 different holes, all of them slightly off-centre. The rivets were practically molten when they went through. We’d normally use a torch on something like that, but in a contained environment the engineers don’t want you to bring in the heat.”
The last resort is to drill the centres out of the rivets and either way, it’s a dirty job, says Bradshaw.
“You get 100 years of crud coming off between the layers of steel and you’re sweating your ass off while getting covered in rust dust,” says Bradshaw who with his crew of six are tied off on safety lines during the work but are always reminded of the Whirlpool Rapids raging below them.
“Whenever you get close to the water, the roaring sound is incredible,” he says.
Whenever structural steel on the bridge requires a full replacement, the contract requires Bradshaw to fashion new steel that looks like the original metal.
“Today you can buy an I-beam, but in the old days there were no steel mills producing them,” he says.
“They made it out of plates and angles all riveted together. We provide steel that gives it the same visual appearance, although we now use hex-head bolts instead of the original button-head rivets.”
Bradshaw also inspected the bridge’s road bearings, which connect the bridge to the road and slide back and forth to accommodate bridge expansion.
“When we pulled off the angle brackets, the paint looked as fresh as it did in 1897 and the bearings looked like they hadn’t been touched since they were brand new,” he says. “Some things are just built to last.”
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