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Mission accomplished. Crews installed a giant 75-tonne “super beam” over the Nov. 29- Dec. 2 weekend after a huge crack was discovered in an underlying girder on Montreal’s problem-plagued Champlain Bridge.
It was the first time such a support girder was needed but the Crown corporation managing Montreal bridges, Les Ponts Jacques Cartier et Champlain Incorporée (PJCCI), was prepared for the eventuality.
Bridge remedial work has been going on for years and of 350 Champlain girders, more than 60 damaged ones have been reinforced, leaving almost 30 still being closely monitored.
The crack, discovered Nov. 12, was in one of 13 girders of particular concern.
On Nov. 22 a decision was made to shore up this outside girder as quickly as possible because of the Champlain’s importance as a transportation link.
The Champlain — one of Canada’s busiest bridges — is also a prime transit commuter route and carries most commercial trucks to Montreal’s south shore suburbs and the United States.
The 75-tonne super beam — at 56 metres the length of a bridge section — and three metres tall, was hauled up the bridge the night of Nov. 29.
It had previously been assembled from five pieces on neighbouring Nuns’ Island. Lanes were closed and two 160-foot tonne cranes were positioned on either side, on platforms, to distribute their weight.
The beam, on standby in an east side yard since 2009, was designed by Vancouver-based bridge consulting firm Buckland & Taylor and fabricated in Montreal.
The Champlain has been undergoing almost constant remediation because of the 51-year-old structure’s degradation, mainly caused by winter road salt.
The cracked girder’s reinforcement actually consists of two stages. The weekend work was the first — and temporary — phase.
The next — and that will come in the spring — is a modular steel truss that will connect underneath the damaged girder to permanently support it.
Some 50 people took part in the weekend operation, estimated to have cost $2 million.
And while it was a first for PJCCI, officials were confident the job would go like clockwork.
Having studied conceptual drawings, “we were prepared for this,” engineering director Juan Echague said.
“We also studied all the logistics which now seems to be very easy,” he added. “But there was a lot of thinking about the logistics of transportation and erection of this.”
On the afternoon of Nov. 29, engineers assessed whether the bridge could support the two cranes and made sure the weather was right.
Echague said that while the work was novel and high profile because of the Champlain’s importance, it wasn’t all that complex.
“In other words the erection manoeuvre is simple but the elements are impressive,” he said. He said similar operations in, for example, mine shafts, would not be “as heavy” but require “more complicated” crane movements.
The super beam was attached to the underlying cracked concrete beam via plates and cable at seven points through the bridge deck, stressing everything together.
By 7 a.m. on Nov. 30 the bridge reopened to one lane of traffic in each direction as crews continued to do the fastening.
By rush hour on the morning of Dec. 2 the bridge was back to handling full commuter traffic.
The Champlain’s lanes are 3.5 metres wide but the super beam takes up 1.3 metres of the right lane so lanes must be narrowed around it.
But the beam, to the untrained eye protruding almost absurdly as motorists circle around it, will be removed come spring when the permanent truss is attached, opening all six lanes to traffic.
Until, that is, an entirely new replacement bridge is built. Also on that weekend the federal government announced the speed-up of development of that bridge, now to be opened in 2018 instead of 2021.
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