New York State’s main gateway to Canada, the Thousand Islands Bridge, now has a smoother ride thanks to a six-month redecking project on the crossing over the American channel of the St. Lawrence River.
Cianbro Corporation of Pittsfield, ME, put the finishing touches on the $6.4-million project, which was completed at the end of October 2000.
The project included the removal and installation of 120 10-ton (9 t) suspension span deck panels and 300 stringers. It is the first time the Thousand Islands Bridge’s 1,500-ft. (455 m) deck surface has been replaced since the bridge was built in 1938.
The American span, which connects the mainland United States to Wellesley Island, has a suspension bridge of 800 ft. (242 m) with an under clearance of 150 ft. (45 m) above the river. The total distance from abutment to abutment is 4,500 ft. (1,364 m)
The Thousand Islands Bridge System covers a distance of 8.5 mi. (13.6 km) extending from Collins Landing in New York to Ivy Lea in Ontario, Canada. Cianbro is rehabilitating existing traffic guide rails and lighting systems for the entire United States portion of the bridge system.
A new 3,000-ft. (909 m) maintenance and inspection service walkway on the approach spans will save the Thousand Islands Bridge Authority money and time when it comes time to repaint.
“Each year a portion of the bridge gets new paint,” explained Cianbro’s Project Engineer Mark Zagrobelny. “With the installation of the service walkway, they can paint the bridge without restricting traffic.”
Zagrobelny said the hardest challenge his crews had to overcome was the limited hours they could actually work on the bridge deck surface. Cianbro crews worked around the clock with 25 workers on the job at a time.
“It looked like a NASCAR pit crew,” said Ed White, Cianbro’s field engineer on the project. “We had a twelve and a half hour window to demolish, remove and replace each 25-ft. by 13-ft. deck panel. One crew would go in to do their job and as soon as they were finished, the next crew would move in.”
The Thousand Island Bridge Authority closed one lane of traffic Sunday evening through Friday morning between 6 p.m. and 6:30 a.m. During prime traffic hours, the crews retreated below the decking surface to complete the work needed underneath.
“We replaced about two to three pre-cast concrete panels in a night,” said White.
White said Jefferson Concrete made the pre-cast panels. The company also was responsible for removing and disposing of the old concrete.
Once the new deck panels were in place, crews would move in to replace stringers between the floor beams while another crew would apply the sheer studs.
The 21,000-lb. (9,450 kg) concrete panels were hoisted up on the bridge deck by a gantry crane, which Cianbro had custom-made just for this job.
“There was a space restriction on the bridge. There was not a crane available that would fit,” explained Zagrobelny. Cianbro hired ORAH Construction Technologies Inc. to create the special gantry device.
Another challenge facing Cianbro’s crews daily was to have the section of deck, which they had pulled up and replaced overnight to be ready for traffic at 6:00 a.m.
“We would begin pouring rapid set five star concrete between the replaced panels between one and two in the morning,” said White.
“Anything that backs up traffic on that bridge is a big deal,” said Zagrobelny. “The rapid set concrete can handle up to 3,500 psi in two hours when regular concrete usually takes four to five days to dry.”
The rapid-set concrete would arrive at the work site via a mobile mix truck out of Brockville, Ontario. This specialized mixer has three bins. Each bin contains one of the dry ingredients needed to make the fast setting concrete. Once at the site, the materials are mixed in the right proportion to create the desired type of concrete.
This method of on-site concrete mixing can lead to considerable savings on the job because you only need to mix what you need thus eliminating raw material waste.
One device, which helped move the project along and kept the workers safe, was the installation of a Safespan platform underneath the bridge deck surface.
Located in Tonawanda in western New York, Safespan Platforms Systems Inc. installed a multi-span shielding system, which included a working platform. The system is suspended under the bridge deck by cables which run the length of the bridge.
“It was like walking on a modified trampoline,” said White. “I hate heights but this was just like being on the ground.”
The Safespan platform has a full safety fence railing, which allows workers to work faster and more comfortably because they do not have to be tied off.
“During the day, when both lanes on the bridge were open, we would have crews on the Safespan platform underneath replacing the center stringers,” said White. “The Safespan platform definitely sped up production.”
The Safespan platform also keeps construction debris from falling into the river or on to people boating below.
“It’s a lot more comforting for the crew to know that should they fall, it’s only a 10-ft. drop instead of 150 ft. into the river,” Zagrobelny said.
More than 250,000 commercial vehicles and a little more than a million passenger cars cross over the Thousand Islands Bridge system each year.
“The new bridge surface weighs less but it is just as strong,” said Zagrobelny. “It’s lighter because each new concrete deck panel weighs 6,000 lbs. less than the old deck panels. There is also less steel in the deck structure itself.”
Cianbro replaced the bridge’s approach spans in 1984.
The company specializes in heavy industrial construction. The Cianchette brothers Carl, Ken, Ival and Alto founded the company in 1949. Its annual sales are about $200 million.
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