01/19/2012 12:42 EST | Updated 03/20/2012 05:12 EDT

Mercier Bridge to stay partly closed Friday

Transport Quebec is warning commuters to expect delays again on Friday, as repairs continue for a third day on Montreal's Mercier Bridge.

Work crews blocked off one of the eastbound lanes on Wednesday after a motorist spotted a crack in a cement slab and reported the problem. Workers inspected the crack and installed a metal plate as a temporary fix, moving in on Thursday morning to repair it.

Those repairs were expected to take less than a day, but late Thursday, Transport Quebec announced it would resume work on Friday after the morning rush hour — warning motorists to expect delays for the drive home on Friday evening.

"The Ministère thanks the population for its understanding of the situation," the ministry said in a message from its website.

The partial closure comes less than a month after the South Shore-bound lanes of the Mercier were shut down completely for repairs.

A portion of the bridge was also abruptly closed in June after Transport Quebec found significant deterioration of some of the bridge’s steel gussets.

It was completely re-opened after those repairs in November.

The latest discovery raised questions about why this crack was not found then, but ministry official Claudia Goulet insisted the latest problem is a new one, likely caused by the recent cold snap.

"First of all [there's] the large fluctuation of the weather," said Goulet. "Secondly, there is a lot of traffic on the bridge."

"Absolute rubbish!" retorted McGill University professor emeritus Saeed Mirza, an expert in structural engineering.

"They should know that we have the cold with us all the time. What has happened is that we have had no maintenance — or very little maintenance over the years. The result is the defects have accumulated, and now we have to spend through the nose to fix these."

Mirza said government authorities should consider rebuilding the Mercier bridge, just as they are doing with the Champlain Bridge to the south.

A complete rebuild of the Mercier bridge is not on the provincial government's radar, and Goulet said the problems with the two bridges can't be compared.

"Champlain is made of concrete, and the Mercier Bridge is made of steel," Goulet said.

But Mirza says constant patchwork is not the answer.

"I think we'll keep doing this until something dangerous happens," he said.