MONTREAL - A massive supergirder required to brace the cracked Champlain Bridge has been put in place Saturday, as the bridge is slowly re-opening to traffic after a 10-hour delay.

Officials said the bridge began to slowly re-open at 5 p.m. Originally, they had hoped to partially open the bridge as of 7 a.m.

Crews began the impressive task of installing the mammoth piece of reinforced concrete starting at 2 a.m. Saturday. They fell 10 hours behind schedule in part because part the concrete median had to be torn down so the trucks carrying the giant beam could load it onto the bridge.

“With the forecast, with the cold, it was really tough to remove that and we lost some time during that step,” said Jean-Vincent Lacroix of the Jacques-Cartier and Champlain Bridge Corporation, explaining that about a dozen engineers were on hand since Friday.

“They were monitoring the span while we were doing the work, so they were really looking at all the vibration on the bridge during the operation because you have to remember there were two major cranes of 160 tonnes.”

The 75-tonne girder was put in place early Saturday afternoon, and then strengthening work began, securing it into place with steel plates and cables.

The $2 million operation was made necessary when a crack was detected on a concrete edge girder in early November.

Drivers take note: though the bridge was set to re-open to traffic at 5 p.m. Saturday, it will remain down to one lane in each direction until 5 a.m. Monday.

Officials expect that by the morning commute on Monday the operation will be finished and the bridge will re-open with three lanes toward Montreal and two toward the South Shore.

Trucks heading south will have to continue using the left-hand lane, unlike the standard traffic configuration.

The third lane toward the South Shore will re-open in December, after crews alter the lane markings to let drivers squeeze through the bottleneck created by the superbeam.

Transportation officials recommended drivers look to other bridges to cross the St. Lawrence

Enormous undertaking

Crews used a pair of massive, 160-tonne cranes to lift and install a 75-tonne steel beam that is longer than a section of the bridge deck.

This beam was lowered into place above a weakened concrete edge girder and then firmly attached to the bridge, bracing the structure from above, much like a splint prevents a broken bone from moving.

The beam projects into the right-most lane of the southbound section of the bridge.

It will be closely monitored for any new emergencies, said Peter Taylor of Buckland & Taylor bridge designers.

“We're doing our best to accumulate information. We have frequent inspections and we're able to measure quantitatively the deterioration so that we can assure safety for the bridge users,” he said, adding, “But we do not have all the answers.”

Temporary solution

The massive supergirder is just a temporary solution for the troubled Champlain Bridge.

In the spring when winter weather is long gone, crews will get to work on a long-term solution to supporting the bridge deck.

“It's got to be planned properly,” said Taylor. “It's got to be done right and let's be realistic, doing that sort of thing in Montreal in January is extremely difficult. Likely it will be after the worst of the winter is over.”

That will entail building a lattice-style steel support truss that will stretch from one support pillar to the next, directly underneath the weakened concrete girder.

Once the supporting truss is in place, the supergirder will be removed, and kept in case other pieces of the bridge deck fail.

The Bridge Corporation has had the supergirder waiting in storage since 2009, and recently decided to order several more in case of more cracks.

The Champlain Bridge is due to be replaced by 2021.