A crack with a two-millimetre opening on one of the girders supporting the Champlain Bridge has forced the closure of one southbound lane for a month.

Teams discovered the crack in a 53-metre long horizontal concrete beam on the edge of the bridge Tuesday, during a routine inspection.

"Given the fact that it's at the centre of the beam — midspan  it is a critical crack," said Steve Tselios, senior engineer for the Jacques Cartier and Champlain Bridges Corporation.

The Jacques Cartier and Champlain Bridges Corporation said the discovery of the crack Tuesday afternoon led to the immediate closure of a South Shore-bound lane and an extensive examination of the damage.

Morning rush hour

Toward Montreal: Three lanes with buses integrated into regular traffic

Toward South Shore: Two lanes with no reserved bus lane

Evening rush hour

Toward Montreal: Two lanes 

Toward South Shore: Two lanes with one reserved bus lane

The analysts concluded that the crack compromised the safety of the girder and that the load on the bridge needed to be alleviated so that repair work could take place.

"We analyzed the situation to see what capacity this beam still has. It is beneficial to stay on the safe side, and as such keep the lane closed until we start the repairs," Tselios said.

Workers will fix the crack in the concrete, and reinforce the beam by adding carbon fibre.

Tselios said the repairs are complex, and it will take crews — working 24 hours a day, seven days a week — about one month to complete.

Officials insist the bridge is safe

The corporation said even though crews will be working for weeks to fix the crack, the bridge still remains safe for commuters.

Jean-Vincent Lacroix, spokesman for the Jacques Cartier and Champlain Bridges Corporation, said Wednesday that closing the lane was a precaution and that drivers should not be concerned.

“The Champlain Bridge is a safe bridge because we monitor it and we do a lot of safety inspections on a daily basis,” he said.

None of the girders next to the damaged one show signs of deterioration, according to a statement released by the bridge corporation.

Corrosion from road salts have been blamed in the past for the deterioration of some of the bridges' edge girders.

"We checked the adjacent beams, and [they're] in very good condition,"  said Tselios.

"We just want to be on the safe side for the public that uses it, that we do the repairs before we open the lane."

The Corporation asked that all people who commute between Montreal and the South Shore use public transportation, regardless of which bridge they normally use.

It said the evening rush hour bus lane's hours will be extended to improve circulation.

Evening rush hour buses leaving Montreal for the South Shore will also make use of the reserved bus lane on Marc-Cantin Street for better access to the Champlain Bridge and to avoid the traffic on the Bonaventure Expressway.

Coderre wants to see bridge reports

Montreal's new mayor Denis Coderre said he wants to know the current state of the bridge, and said he's tired of the Corporation's crisis management.

"If we are obliged to close one lane for one month, that’s fine - we’re not going to put anyone’s life in danger. But what I want is to for the [Bridge Corporation] to come clean about the real state of the bridge," Coderre said.

"I've always asked, as Member of Parliament and as mayor, what is the actual status of the bridge? What is at risk? What's the reality?"

Coderre said the Corporation should make public all its engineering reports on the current state of the bridge.