| slammer111 | 07-01-2010 01:02 PM |
Not sure if they're doing it now, but there is new construction technology that lets you build and replace sections of bridge super quickly, and without expansion joints!
The article below makes the overnight sectional replacements on the Lions Gate back in 2000 look like nothing. :eek: http://www2.canada.com/ottawacitizen...d-6547ffcb3154 Quote:
A fast fix for a fast world
Maria Cook, The Ottawa Citizen
Published: Friday, August 10, 2007
Replacing an overpass on a city's busiest artery usually means months of delays and huge costs to the economy. But Saturday night, as Maria Cook explains, the Queensway's Island Park bridges will be replaced in a mere 15 hours - a sign of things to come for a society that doesn't like to wait.
Two weeks ago, Gilles Emond, a muscular 33-year-old with a buzz cut, was in New York City moving a power plant. Last year, he was on remote Sakhalin Island off the coast of Russia transporting pieces of an oil refinery. Today, he and his red-jumpsuited crew and their giant Tonka toys are in Ottawa to lift the Island Park Drive bridges - each weighing the equivalent of a fully-loaded Boeing 747 - and replace them with new ones.
"It's just as scary to do the small stuff as it is to do the big stuff," says Mr. Emond. "Everything is a challenge."
Some bridges, like the Golden Gate Bridge in San Francisco, are monumental works of art and engineering. Others are humble, non-descript highway overpasses.
The Island Park bridges along the Queensway belong to the latter category.
The concrete deck and steel girder structures weigh about 650 tonnes each. They carry four lanes of traffic each, east- and westbound. About 150,000 vehicles pass over them each day, most at more than 100 km/h, going ka-chunk over the expansion joints, the gaps between highway and bridge that allow the bridge to expand and contract as the temperature changes.
Forty-eight years old and punished by ice, salt, transport trucks and ever-increasing volumes of traffic, the bridges are deteriorating and need to be replaced.
Typically, that means months of lane closures and detours, jackhammering and orange cones, frustration and delay.
Tonight, however, this ordinary overpass becomes extraordinary.
For the first time in Canada, a new highway bridge will be installed overnight using so-called rapid-replacement technology.
This technique uses powerful but highly manoeuverable heavy-lift equipment to remove an existing bridge and replace it, in hours, with a new one that has been built in advance nearby.
In 2006-07, the Ontario government will repair 83 bridges and build five new bridges, including the $8.6-million Island Park project.
Bold, millimetre perfect and testosterone-driven, you might say, this technique is considered to be a better way to build a bridge. Proponents say it is faster, cheaper and produces a better-quality bridge. By dramatically reducing traffic disruption, it makes a strong statement that human time is valuable.
Mammoet, the Dutch engineering company that salvaged the sunken Russian submarine Kursk in 2001, is supplying the heavy-lifting equipment known as self-propelled modular transporters (SPMTs.)
With many bridges across the country nearing the end of their 50-year lifespan, and with public concern running high over recent bridge collapses in Laval, Que. and Minnesota, rapid replacement is expected to be the way of the future. The Ontario Ministry of Transportation, or MTO, plans to use the heavy lift transporters to replace bridges at Clyde Avenue next summer and at Carling Avenue eastbound and westbound and Kirkwood Avenue starting in 2010. The Merivale Road bridges will also be rehabilitated but in the conventional way because they cannot be lifted out.
MTO officials chose the Queensway bridges over Island Park Drive for the first rapid replacement because of their ideal setting. Over the past four months, the new diamond-shaped bridges have been built adjacent to the Queensway in Hampton Park.
"Having this wide-open space to build new bridges, it's perfect," says Frank Vanderlaan, senior project engineer with MTO.
The football field-sized meadow has become a gravel-strewn construction site, surrounded by a fence, and home to big machines and workers in hard hats.
The new grey concrete bridge decks, completed three weeks ago, sit on primer-red columns called a high-load shoring system, which is basically an oversized scaffold on jacks. Motorists have been watching them take shape as they drive by on the highway.
The heavy-lifting equipment arrived last week on 30 tractor trailers from jobs in Louisiana, Seattle and New York City.
The red steel transporters look like a cross between a flat-bed trailer and a centipede.
"They're like the best toy I've ever had," says Mr. Emond, a New Brunswick native who now lives in Kitchener. "It's like a remote-controlled car but for grownups. It's a big, square, remote-controlled bridge-builder. You put stuff on it, off you go."
During a 15-hour period - from 8 p.m. tonight to 11 a.m. tomorrow - the remote-controlled transporters will pick up the existing eastbound and westbound bridges, one by one, and place them in the Hampton Park work yard. Then, they will pick up the new bridges, drive back and slide them into the highway.
"You have to use all your senses," says Mr. Emond. "You have to respect what you're doing because there's many things that can go wrong."
l
Just beyond the epicentre of tonight's action, bleachers have been set up for transportation ministry officials and media. Sitting among them will be Quazi Islam, head of the structural section of the MTO's eastern region.
Mr. Islam is the engineer who championed this new technology and pushed for Ontario to be the first province to try it.
"People have a comfort zone," he says. "They don't want to do something different. They think: Will it come down? Will it sit properly? Will it open on time? What is the risk? What if it doesn't go through? People like myself get nightmares over this."
But Ontario certainly has a need to find ways to replace its aging bridges without bringing the province to a halt. There are about 2,800 bridges under provincial jurisdiction in Ontario. The average age is 37 years, and most were built to last 50. Built in 1959, the Island Park bridges were also designed to last 50 years. They were patched in 1983. In 2005, the ministry decided to replace them.
Why? "Extensive testing and inspection of the bridges has shown a need to replace these structures due to concrete spalling (pieces falling off) and corrosion of the reinforcing steel," says an MTO report.
Rapid bridge replacement had been happening in Europe for about 20 years. It recently started in the United States after a team of American bridge engineers toured Europe and Japan in 2004 and were impressed by the savings of time and money.
"I was convinced this was something I should take forward," says Mr. Islam.
Last summer, the ministry's Mr. Vanderlaan was among 100 transportation officials who attended a conference in Florida to learn about the use of transporters for bridge construction. They watched the installation of the final span of a bridge in Volusia County, Florida, which was the first time in the United States that the technology was used to replace a bridge over an interstate highway.
Abd El Halim, professor and chairman of the civil and environmental engineering department at Carleton University, says interest in the rapid replacement of bridges took on new urgency after the terrorist attacks of Sept. 11, 2001, the massive blackout in the northeast United States and Canada in 2003 and Hurricane Katrina in 2005.
"All this opens eyes of policy makers in Canada and the United States that we need to deal with the aftermath. We need to develop protection for critical infrastructure."
He notes that $120 billion in annual trade between Canada and the United States crosses the Windsor-Detroit border. "If that bridge, God forbid, closed for any good or bad reason, it's not only financial loss, but our means of life - medicine, equipment, food."
The conventional way to replace a bridge is to close lanes of traffic and work in sections, jackhammering or sawcutting the existing bridge. But the public is fed up with the usual way. Who's got the time?
"We have limited time for closing, mostly in the night-time and weekends, because the travelling public doesn't expect that we close the highway," explains Mr. Islam.
"They don't want any delay. When people sit in their cars they really get edgy and agitated. They have to be at a certain place at a certain time. Ottawa doesn't have too many alternative routes."
Normally, the work would have been spread over two years, taking almost two six month construction seasons (mid-April to mid-October) to complete. Instead, the highway will be closed only 15 hours, most of it in the middle of the night. In addition to eliminating long-term congestion, the provincial government estimates it is saving about $2.4 million on road detours and equipment for lane closures. With five locations in Ottawa slated for rapid replacement, the ministry says it is saving $12 million overall. The average cost of replacing a highway bridge is about $1.5 million, but could be significantly more or less depending on the size and type of bridge.
It's hard to compare the cost of rapid replacement versus conventional techniques, say ministry officials.
But, in addition to the traffic detour savings, Ontario is saving millions in indirect costs for travellers and the economy. These costs include wear and tear on vehicles, fuel consumption, increased accident rates, lost productivity, pollution and greenhouse gases that contribute to climate change. On a personal level, congestion affects quality of life and robs people of time that could be spent with families and friends, or on the job.
Ontario doesn't calculate these costs but Mr. Islam says they are immense. To take one example, from 2000 to 2004, there were 10,906 collisions in Ontario in highway construction zones, involving 38 fatalities and 3,106 injuries.
In 2005, a market researcher estimated that Ottawa's economy lost at least $2.5 million when a bomb threat shut down the Queensway for more than three hours. The researcher determined that, for every idle hour a car spends on the highway, $125 is lost in wages, gasoline consumption and car maintenance.
According to the United States government, in 2003, Americans lost 3.7 billion hours and 2.3 billion gallons of fuel sitting in traffic jams.
"Most travellers clearly do attach significant value to their travel time," said a U.S. government report. "Otherwise traffic congestion would not generate so much public concern and irritation."
"The magnitude of this benefit is hard to measure, which is why many governments find it difficult to justify the use of rapid bridge replacement technology," says Glen Aitken, vice president of sales at Mammoet's office in Cambridge, Ont.
Consequently, despite the apparent benefits, rapid replacement technology hasn't been an easy sell, Mr. Aitken says. "We have approached most of the provinces and states in North America. It often takes years to get governments to change their ways."
He says Mammoet's portion of the Island Park bridges project is less than 10 per cent of the $8.6-million overall cost.
"Adding our services into the picture could potentially increase the total construction cost by five or 10 per cent," he says. "When we get involved in a project, it is usually because our methods will result in cos savings elsewhere in the project, which justifies the additional investment to use our technology."
The Canadian Construction Association welcomes the innovation. Spokesman Jeff Morrison says Canada has about $22 billion worth of deferred highway renewal and expansion. "We would encourage governments who tend to be more risk-averse to use some of these technologies." Ontario decided to "take the risk" because it is regarded as a leader in highway and bridge engineering in Canada, says Mr. Islam. "I do not see any downside. I'm very positive and excited that this will be the first step we are taking for the future of Ontario and bridge building."
l
Not only is the new Island Park overpass being replaced using up-to-date techniques, the bridge itself is a vast improvement over the structure it replaces.
For starters, you may hear less of that ka-chunk as you pass over it. The new bridge will be attached to the highway with something called a semi-integral abutment, which means there's no expansion joints to drive over.
More importantly, eliminating expansion joints makes for a longer-lasting bridge. Expansion joints are the Achilles heel of bridges because water and salt leak through and erode the structure.
Many of the country's bridges were built in the 1950s and '60s when designers didn't fully understand the impact of concrete degradation on structures, says Jacques Marchand, a professor at Laval University and an expert witness at the commission investigating the deadly Laval bridge collapse last year.
Road salt is a big culprit.
"After 30 years of experience, we have a better understanding of concrete."
Canada has a lot of bridges built between the 1950s and 1970s that are nearing the end of their lives. Bridges built during that period were constructed to last 50 years. The current Canadian bridge design code says bridges should last 75 years.
Zoubir Lounis, head of the concrete structure group at the National Research Council, says government agencies need to stop looking at the immediate costs of building a bridge and take into account the costs of delays to users and long-term environmental costs.
NRC researchers are looking at how to design a bridge that will last 100 years with minimum maintenance with the use of low-permeable concrete and corrosion-resistant steel. They cost more but the bridges will last longer. "It's also green, when you build for 100 years."
l
As many as 100 workers will be involved in tonight's big move. It's a bit like planning for a royal wedding or a rocket launch. "There's a big choreography going on," says MTO contracts control officer Felipe Mendoza.
The one thing that could stop the show is a lightning storm, because lightning tends to hit high metal objects out in the open. The forecast for today is sunny. For tomorrow, scattered showers.
The 12-member Mammoet crew will be the stars. Most are Canadians, but some have come from the Netherlands, Houston and Atlanta to lend a hand. Their uniforms are emblazoned with a cute stylized mammoth (Mammoet means mammoth in Dutch). The company's motto is 'work hard, have fun.' These guys work with incredible precision, speed and skill but with an air of apparent nonchalance.
They must lift out the old bridges and position the new ones safely and precisely on their foundations. They will have about six hours to do it - and with one-millimetre precision.
The rest of the time will be spent removing, attaching and adjusting the structures.
"Working at night in the dark is a challenge," says Mr. Emond. "The clearances are really minimal. We're talking about a few inches of clearance on either side."
Many things can go wrong, says Mammoet engineer Barend Schuring - from a blown hydraulic hose on a trailer to discovering the bridge is too wide to fit the gap. "People can misunderstand each other or give a wrong signal," says Mr. Schuring. "There could be a soft spot in the ground; we could sink away with our trailer. The bridge could be heavier than calculated." The worst-case scenario is that the bridge doesn't fit.
Mr. Turner attended a rapid replacement in Louisiana last year where the bridge ended up being an inch higher than the freeway.
"They had to lift the bridge up, take jackhammers to the bearing seats; they had to remove the bearing pads. It took them an extra five hours to jackhammer it all out. Something as obvious as that, but nobody had ever checked the depth of the bridge."
Before Island Park's new bridges were built, surveyors took measurements - three times - of the space between the abutment the bridges sit on and the road surface it will meet. They wanted to make sure they will be the right thickness to line up with the road and exactly the right length.
"They triple-checked to make sure all the dimensions were able to accommodate the new bridges," says MTO area construction engineer Ken Polson. "We're going to be bang on."
Even so, the old bridges will be left on the stands for about a week.
"This is kind of a one-shot deal," says Mr. Turner. "You have to have a backup plan. Let's say one of the bridges falls apart. You can't have the Queensway closed for a month."
| http://a123.g.akamai.net/f/123/12465...001/name-1.jpg |
