The federal agency that oversees the Champlain Bridge was so concerned about the state of the structure that it worked out an emergency plan in 2009, and that plan is going to be used in the months to come to repair the serious damage spotted in the past two weeks.

In the next few weeks a 'super girder' -- built in 2009 and sitting in a depot ever since -- will be used to patch the weakened girder and strengthen the bridge until a permanent repair is made in the spring.

The Bridge Corporation announced late Thursday night that it needed to close a second lane on the southbound side of the bridge because the damage first spotted last week was more extensive than previously thought.

Those two lanes will stay closed until mid-December, and one of the lanes on the opposite side of the Bridge will become a counterflow lane -- at least for Friday's commute home. Officials will meet next week to decide if the two and two configuration will stay in place, or if something else will be done.

On Friday morning bridge officials revealed that the original crack in the girder had grown substantially in the past week, and they found new damage.

"On Tuesday of this week we found a new crack. It's sure sign the girder is under stress. It's not good to find fissures in a girder," said Glen Carlin, the general manage of the Jacques-Cartier and Champlain Bridge Corporation.

With the extra damage limiting the number of open lanes, the federal agency has decided that trucks heading to the South Shore will now have to stay in the left-hand lane.

Traffic will also have to stay below the 50 km/h limit, something which will be strictly monitored by police.

"We will be doing inspections twice per day, and it will not be possible to have bus lanes," said Carlin.

Repairs planned in 2009

Several years ago when it was evident the Champlain Bridge was going to need extensive repairs and be replaced, the bridge authority came up with a plan for a super-girder -- a 75-tonne piece of steel that could be laid atop a weakened edge girder, and be lashed to the concrete beneath.

The five girder sections were built and stored in a depot, just waiting for an emergency such as what has cropped up this week.

"Next week we will take this giant girder and we will place it on top of the girder that is weakened," said Carlin.

When crews are ready to put the girder into place the bridge agency will have to close four out of six lanes for 48 hours.

"We don't know when we will do this work. In an ideal world we'll do it on a weekend. If we see the girder continuing to weaken, we will do the work immediately," said Carlin.

Once the girder is in place and attached to the bridge, something that should happen by mid-December, all three southbound lanes will reopen but drivers will need to kink around the new, massive structure on the outside edge of the span.

Permanent fix in 2014

The massive girder lying on top of the bridge deck is just a temporary solution.

A permanent repair will be needed for the Champlain to survive the decade until its replacement is built.

Carlin said that in the spring, when the weather is better, work crews will return to build a support below the bridge deck.

"Our next step will be to install a modular truss below the weakened girder. Once the trellis is in place the 'super girder' can be removed... and the truss will fully support the weakened section," said Carlin

Premier Pauline Marois said she hoped a permanent fix for the decaying bridge would be in place sooner rather than later, but was glad that federal officials had a plan already in place.

"We hope we will have a solution to this bridge rapidly because this is very important to the citizens of Montreal and the South Shore," she said.

Plans to build a replacement for the Champlain Bridge are still in the design phase, although the federal government recently announced it would accelerate what it could.