Ok today April 5th & Montreal Gazette sports another story about the Champlain Bridge,by Andy Riga again...It seems there is suddennly a lot of interest in just a short 'span'...............hahahaha 3rd story in a week and a half-Hey maybe there's a musical in it yet.....lol
MONTREAL - The design left engineer Hugh Pratley scratching his head. But the lower price tag put a smile on the faces of federal officials.
The resulting decision - to use a highly unusual, neverbefore-tried design for a new Montreal-South Shore bridge in the late 1950s - was supposed to save a few million dollars.
Fifty years later, that span - the Champlain Bridge, total cost to build: $35 million - is crumbling at an alarming rate. A recent study concluded sections could collapse, a risk that would be compounded in a major earthquake.
Canada's busiest bridge, the Champlain is crossed by 164,000 vehicles daily, as well as 40,000 bus passengers.
Within weeks, Ottawa and Quebec will get a report on whether to tear the Champlain down and build a new one. Cost: more than $1 billion.
In May 1958, civil engineer Hugh Pratley was supervising construction of several Nova Scotia bridges when his father - famed bridge builder P.L. Pratley - took ill. Pratley rushed back to Montreal. His father had cancer; within weeks, he was dead.
The younger Pratley took over his father's job - consulting engineer on the Champlain Bridge. British-born Montrealer P.L. Pratley - the man behind Montreal's Jacques Cartier and Vancouver's Lions Gate bridges - had been hired in 1957 by the National Harbours Board to oversee the construction of the Champlain, which would cut traffic on other bridges and speed the Montreal-to-Sherbrooke drive.
When Hugh Pratley took over, the first tenders were being prepared.
"We had two designs available with the tender documents - one in steel and one in reinforced concrete," Pratley, 84, recalled recently. "Then, this strange thing was proposed by a contractor - to build it with pre-stressed concrete, which was way too adventuresome, nothing like it had been built like this in Canada," he said. Imported from France, the concept had never been used on such a long bridge.
The design, involving girders permanently connected to one another, is the reason the Champlain can't easily be fixed, unlike the Jacques Cartier and Mercier bridges.
Pratley tried unsuccessfully to dissuade officials from using the "futuristic" design. "We had a lot to say but we didn't have much power to guide anybody," he said.
"The design was done entirely by the contractors' engineers. We did review them to see that they met Canadian standards but the principles of the design - we didn't have the right to change that because that's how they were trying to save money."
The Harbours Board, a federal agency, "wanted to make their decisions based solely on cost, not on engineering advice," Pratley said.
A consortium said it could build two major sections of the bridge - from Nuns' Island to the Seaway and from the South Shore to the Seaway (for a total of 2.6 kilometres) - using the newfangled system. They said it would cost $8.3 million.
Other companies submitted bids for $10.3 million for a steel structure over the same length. The $8.3-million bid - the lowest of 28 submitted - was chosen. "Being government, they wanted to take the cheapest (bid), but it didn't end up being the cheapest one, not by a long shot," said Pratley, who was involved in repairs and inspections on the bridge until about 1990.
In the end, cost overruns caused the price of those two sections to soar. The consortium "had all sorts of claims. They bid low, obviously, and they did everything they could think of to make extra claims, and eventually they got over $10.3 million" - what it would have cost for a steel structure.
The unusual design ended up being used on about fourfifths of the bridge's length.
"The (Champlain) was designed rapidly and constructed with a view to efficiency, economy and speed of construction," notes a recent study by engineering firm Delcan. "The deterioration of the bridge . is progressing at an exponential rate and therefore the risks to the bridge are increasing as time passes by."
Pratley says it would have saved headaches and money had Ottawa opted for a completely steel bridge. Only the sections over the St. Lawrence Seaway - 764 metres long - are in steel. Those sections, completely renovated in the early 1990s, are "in good condition and there are no serious concerns with regard to (its) basic integrity," the Delcan study said.
Road salt is devouring the bridge. It wasn't supposed to be this way.
During planning, the Harbours Board insisted salt would never be used on the bridge, Pratley said. At the time, ashes from coal furnaces were used for traction on slippery roads.
No spouts were installed on the sides of the bridge to keep the snow melt and salt away from the concrete structure.
Original drainage was rudimentary - holes on the side of the roadbed. That meant water and salt flowed down and draped under the exterior girders, and cascaded down piers that support the bridge. The corrosive effect of the salt, coupled with the freeze-thaw cycle, caused significant deterioration in the steel reinforcement in girders and piers. Drainage was only added in the 1990s, after much damage was done.
It would be "a bit extreme" ?to avoid the Champlain Bridge out of fear it could collapse, according to Pratley. But studies raising questions about a possible collapse are worrisome. "I'm sure they're watching it very carefully but these things can happen by surprise, too."
At his age, Pratley rarely leaves Montreal Island. He last crossed the St. Lawrence last summer, driven over the Victoria Bridge.
Completed in 1859, that bridge is made of steel, supported by solid limestone piers showing no signs of deterioration.
CHAMPLAIN BRIDGE'S TROUBLED DESIGN
Concrete girders: Seven pre-stressed girders were placed parallel to one another. Concrete was poured between the projecting flanges of the girders to create a slab.
Steel cables: High-strength steel cables were pulled between the girders and concrete slab. That permanently bonded the seven girders together.
Damage: Salt and water have severely damaged the outside girders along the length of the bridge. Many high-strength steel cables that were supposed to be providing internal strength have broken.
Repairs: One way the bridge has been reinforced is through "external pre-stressing," which strengthens corrosion-damaged girders. Concrete brackets are built at either end of the section of beam to be reinforced. A steel tube is installed, connecting the concrete brackets near the girder ends. High-strength steel wires are passed through the tube and secured at both ends.
FIXES HAMPERED BY WAY IT WAS BUILT
To save money, the Champlain Bridge was built using a unique design, one apparently never used again. The concrete part of the bridge is made up of 50 spans. A span is a section of a bridge between two piers.
On the Champlain, each span is made up of seven pre-stressed concrete beams known as girders. Their internal strength comes from steel. The girders were built in a yard on Nuns' Island and then carried by crane to the piers. For each span, seven girders were placed parallel to one another. Concrete was poured between them.
Then, high-strength steel cables were pulled laterally through the girders and concrete using hydraulic jacks. This action converted all seven girders into a single, totally integrated "grillage."
Over the years, external girders near the bridge's outside edge have been severely damaged by the corrosion of steel reinforcement caused by the salt and snow melt runoff from the bridge.
Because the girders were integrated into a single entity, it's impossible to replace crumbling sections. If the bridge deck had not been laced together laterally, "one could easily stop traffic for a weekend, remove a girder and replace it with a new girder in concrete or steel," said Saeed Mirza, a McGill University civil engineer who has studied the Champlain.
Instead, to replace high-strength steel in girders lost due to corrosion, repairs have involved adding "external pre-stressing." But that can only be done for so long, since the concrete anchor blocks for the external pre-stressing are fastened to sections of the bridge that are crumbling.
Normally, when building concrete bridges, pre-stressed girders are installed parallel to one another on piers but they are not connected together laterally, Mirza said. A reinforced concrete deck is cast in place on top of the girders which, along with a layer of asphalt, supports traffic. In such a design, it is possible to replace deteriorated girders, as well as the bridge's deck.
QUESTIONS ABOUT SAFETY
A study by engineering firm Delcan contains troubling conclusions:
"The possibility (of) a partial or complete collapse of one span ... cannot be ruled out." If one external girder fails, "it could cause a progressive collapse of an entire span."
"The bridge was not designed to sustain significant seismic loading and ... analyses have shown that it has no capacity to do so. In its current condition, this bridge can be expected to collapse partially or altogether in a significant seismic event." This despite the fact that the Champlain is designated a "lifeline bridge," meaning it is supposed to be able to resist the largest earthquake Montreal could get within 475 years.
Authorities have "emergency support standby structures ... near the bridge site in the event of the anticipated loss of an edge girder. This is a very unusual step and speaks to a lack of confidence in these edge girders."
Officials insist the bridge is safe and is being closely monitored.
Saeed Mirza, a McGill engineering professor who has studied the bridge, said there is little risk the failure of one girder could be catastrophic and cause a chain reaction, bringing down an entire section. "Such a failure is not probable" because girders are bonded together, so "if one of the girders fails, the load would be transferred to the interior girders which are not as deteriorated as the exterior girders."
If "two or three girders fail, then of course we have a serious problem. Even if they don't fall into the river, the bridge would be rendered non-functional."
Earthquakes are Mirza's big concern. "A major earthquake - 8 or higher on the Richter scale - could pose a high level of risk to the survival of the bridge, which was not originally designed to resist significant seismic loads."
In view of the bridge's poor condition, Mirza said: "I have serious doubts about the survival of the Champlain during a major earthquake." But "if there is no large earthquake, then it could last for another 10 to 15 years," he said.
"In view of the extensive deterioration ... it would be prudent to construct a new bridge without any further delay," Mirza said. "The risk involved under such conditions is too high to make the safety of Champlain users a political football."
NEXT: REPAIR OR DEMOLISH AND BUILD ANEW?
It may be 15 years before a Champlain relacement could be ready.
Ottawa and Quebec will soon get a study on the bridge's future.
That report, known as a pre-feasibility study, is considering three options:
1) fix the current structure, an option that seems out of the question because it would cause traffic chaos and be extremely expensive; 2) build a tunnel, which would be pricier than a bridge; and 3) build a new bridge.
A recent engineering study by Delcan said it is virtually impossible to extend the span's life over the long term.
Normally, before a new bridge is built, a feasibility study and environmental assessment would be done. They could take years. Construction itself would take several more years.
Many issues aren't settled:
Who pays? Ottawa owns the Champlain but Quebec wants it to carry trains run by a provincial transit agency.
Will it carry a train? A 2007 plan for a $1-billion light-rail transit system on the ice bridge next to the Champlain fell through. But authorities say a train is still needed to cut traffic on bridges. Today, buses go against traffic in a reserved lane on the bridge.
Will it be a public-private partnership? One study suggested a PPP bridge would be costlier but more likely to be on time and on budget.
Will there be tolls? Maybe, Ottawa says. Users will pay tolls to use the Highway 25 bridge opening in May. The fee: $2.40 per rush-hour passage.
1958 Construction starts
1962 Champlain opens
1964 Links open to Atwater, La Vérendrye Blvd.
1967 Bonaventure opens
1982 Reserved bus lane
1990 25-cent toll abolished
2009 Start of 10-year, $212million repair job. Study on bridge's future starts.
2011 $158 million more added to repair bill. Due: study on bridge's future.
2019 Study says repairs extend life to 2019 and, "it is hoped, for a limited period somewhat beyond."
Number of cars daily:
In 1963 7,300 cars
In 1968 33,400
In 1989 109,700
In 2010 164,000
SOURCE: Federal Bridge Corp