MONTREAL -- The latest on this story: Ile-aux-Tourtes bridge closure 'only responsible decision,' says Quebec transport minister

The Ile-aux-Tourtes bridge, one of two main connections linking the western tip of Montreal with everything across the river, including Ontario, has been closed suddenly after engineers found it was structurally unsound.

The decision was made with no warning and was carried out immediately, with Quebec's transport minister announcing it on Twitter on Thursday afternoon, and an official news release going out more than an hour later.

"Engineers decided to close the bridge for the safety of users," Minister François Bonnardel tweeted at around 3 p.m.

"The teams of [Transport Quebec] are on site. Mitigation measures will be announced shortly. I am following the situation closely," he wrote.

The closure of the two-kilometre structure will cause major traffic headaches and has led the province to make commuter rail in the area free indefinitely, among other measures.

During normal times, with fewer people working from home, the bridge is traversed by roughly 83,000 cars every day.

REBAR TOO DAMAGED FOR SAFETY

In a news release, the Ministry of Transport said that "reinforcing rods" in the bridge, or rebar in English, were too damaged to ensure the bridge would be safe.

"As part of the work in progress, the Ministry observed damage to reinforcing rods," it wrote.

"Since the structure could have been weakened by this damage, complete closure is considered the only responsible option to ensure the safety of road users."

While some speculated the earthquake this week may have worsened the bridge's structure, that's not the case, said a spokesperson for Transport. 

“There's no relation between these two events," said spokesperson Gilles Bayer.

“This bridge is already under maintenance, long-term maintenance, [going back] months, years," he said.

The teams working on it "found something" and, after checking to see if the problem was widespread, decided it was.

As of about 3:30 p.m., the bridge hadn't been closed yet, and people were still crossing. A spokesperson for Bonnardel tweeted that the process has begun but will take time.

"The procedure to close the bridge is underway," wrote Florence Plourde.

"This process may take a while. To achieve the closure in a safe manner, various steps must be taken beforehand, including the closing of entrances or exits."

She also wrote that Bonnardel and the junior transport minister, Chantal Rouleau, will hold a press conference Friday morning to explain the situation in more detail.

TOLLS SUSPENDED ON HIGHWAY 30, TRANSIT MADE FREE

With traffic limited to highways 20 and 30, the province has suspended tolls on the 30, effective as of 4:30 p.m. Thursday, it said.

"In order to offer road users an alternative route and simplify travel on the network, the Ministry will exceptionally withdraw the toll on Highway 30 until the bridge reopens," it said.

The free admission applies to cars, trucks and all other traffic.

There will also be free service on the commuter Vaudreuil-Hudson line, in collaboration with EXO, as of Thursday at 4 p.m. That will remain in effect this weekend and then on all following weekdays until the bridge reopens.

The Ministry said it's aware the move will create major traffic problems and asked for people's cooperation by taking transit as much as possible and working from home.

DON'T CUT THROUGH STE-ANNE'S: MAYOR

The mayor of the small town that's located on a main alternate route has a warning for drivers: don't try to cut through.

Ste-Anne-de-Bellevue Mayor Paola Hawa says it won't save time for drivers to try to get to the metropolis, or out of it, on the eastern side of the bridge, where Highway 20 connects to Highway 40 near her town.

“For Ste-Anne's that means an incredible amount of traffic. People will try to cut through our city to get to the 20 because that is the last bridge off the island," she said.

Ste-Anne-de-Bellevue got a taste of what that's like last week, when a lane was closed on Ile-Aux-Tourtes, she said.

"Our little city was paralyzed from 3 p.m. to 9 o’clock at night,” she said.

"I’m hoping people understand that St-Anne’s is not a viable shortcut. For people who lived through last Thursday, you know you will be stuck for hours in narrow little streets, one-way streets, no way to go forward or back, so you will be stuck for hours.”

NEW BRIDGE CONSTRUCTION WAS DELAYED

There were already plans to rebuild the bridge, which was built in 1965 and has long been a concern. 

The CAQ government announced quietly in December 2018 that the bridge would be rebuilt sometime before 2030.

At the time, emergency repair work had already been ongoing for about a year, often taking one of three lanes out of commission. An inspection in December 2017 had found a serious risk of falling concrete.

About a year later, the repairs had already cost the government around $100 million, according to Rick Leckner, CJAD's traffic reporter, at the time.

The plans were to build a much wider bridge, with six lanes, a dedicated public-transit reserved lane, and a pedestrian walkway. Construction was forecast to begin in 2020, but it hasn't started yet.

In the meantime, the province said Thursday, "repair work on the apron began in 2016, and is expected to continue until 2025."

This is a developing story that will be updated.