Transports Québec spokesman Jacques Nadeau said a fire that began Monday at 11 p.m. in the scaffolding set up around a pillar near the north shore caused major damage to the steel structure under the bridge, which spans the Saguenay River.
Nadeau said the suspected cause of the fire was a heating system installed to dry the concrete pillar repair.
"That technique has been used hundreds of times in Quebec, and it usually works well," said Nadeau.
He said nobody was injured in the fire, and crews will be working around the clock to repair the damaged pillar.
Blaze causes delays
Because of the bridge closure, motorists must now take a two-hour detour to the Shipshaw area of Jonquière, however, emergency vehicles can still use the Dubuc Bridge during repairs.
The bridge is part of the busiest in the artery in the region, normally accommodating 46,000 vehicles a day.
Quebec Transport Minister Sylvain Gaudreault said his ministry will review the situation again on Thursday morning to determine whether the bridge can be reopened to vehicles.
"We have a plan of action, and we are in regular and close contact with the city," said Gaudreault.
Schools in Rives-du-Saguenay and Jonquière are closed as a result of the transportation delays, along with the Cégep de Chicoutimi.
Crossing by foot
On Wednesday morning, hundreds of people in Saguenay left their cars behind for the morning commute and walked to work across the Sainte-Anne Bridge, a pedestrian swing bridge that spans the river.
Claude Paradis was among the hundreds of people who trekked across the half-a-kilometre bridge this morning in –18 C weather.
"The way people were looking today, we have to be optimistic that the spirit is going to remain the same," said Paradis.
Saguenay’s public transit service (STS) has also set up a shuttle service on both sides of the Sainte-Anne Bridge to transport commuters to the bus terminal.
"I am very grateful to the people who must deal with a situation that is not easy," said Gaudreault.
STS says services will be free until further notice.