The 40-year-old Saint John Harbour Bridge is showing "considerable signs of distress," according to a leaked document obtained by the CBC.

Bridge engineers have concluded "the safety of the bridge is compromised if remedial work is not undertaken right away," the leaked memo says.

That finding reinforces questions about the New Brunswick bridge's safety that were raised a few of weeks ago by Steven Chase, the city's deputy mayor.

Chase was echoing statements in a letter written by engineers who had inspected the four-lane bridge.

Ken Anthony, general manager of the Harbour Bridge Authority, said the report comes as no surprise and shows why there is a 10-year plan to repair the bridge.

Repairs could cost $30M

"There are certain parts on it that need to be replaced," Anthony said. "That's what we're in the process of doing now.

"That doesn't mean that it's not safe to go across. It just means that if we don't do this work now, in 10 years it may not be safe to go across."

The anticipated cost of the repairs is more than $30 million.

The memo mentioned that crumbling concrete has fallen onto the Harbour Passage walking trail. The bridge authority's chairman said that problem is being fixed.

Anthony said the work being done is typical for a 40-year-old structure. He said investments are being made so the bridge's life is extended for an additional 40 to 75 years.

Another specific concern is the present barriers on the bridge, which are degrading and are deemed unsafe.

Peter Buckland, the bridge engineer and author of the report, said that's because safety standards have changed, not because the barriers are ready to fall off.

"The barriers themselves, they look a little rough, but they haven't deteriorated all that much. But the rules have changed," he said.

"So they haven't exactly become unsafe, but the bar has been raised."

Both Buckland and Anthony said if any part of the bridge was found to be structurally unsafe, they would shut the bridge down.

The letter was written to be shown to officials in Ottawa as the Bridge Authority made a case to suspend paying down the debt owed to the federal government.

The letter outlined the cost, and immediacy, of repairs that are needed.