"We will not open up a single bridge and road in Windsor until it meets Ontario standards and is signed off by the chief engineer," Transportation Minister Glen Murray said Wednesday as the panel's report was released.
Some of the concrete girders used to build one of Canada's largest infrastructure projects don't meet federal code, the panel said. Tack welding was used, which increases the risk of corrosion.
Based on the information received, "the girders do not meet the requirements of the applicable regulations, codes and standards," their report said.
Given the "various violations in the design and construction requirements and the uncertainties in the construction of these girders," the panel "cannot unequivocally opine that the girders are safe and durable."
"In fact, there is evidence that safety and durability of the girders have been compromised."
The panel, which included several engineers and a lawyer, concluded that it's not sure whether the girders can be made safe and durable now that they've been installed.
It offered two options: either replace the deficient girders, or monitor them to see if they show signs of cracking or corrosion and fix them if necessary.
Murray said he was going with the second option, even though he promised in July that "the girders in question will be removed unless the safety and durability can be assured and any compliance concerns are addressed."
Ontario's chief engineer reviewed the two options and concluded most of the girders could be salvaged, he said.
"The chief engineer of Ontario has set the standards and found a pathway to ensure that those engineering standards that we have to meet can be met," he said.
The minister dismissed opposition accusations that he went with a less expensive option.
"We did not consider costs" in deciding not to scrap the girders that have already been installed, Murray said.
"There was not a politician or an accountant involved in this decision," he said. "This was purely an engineering and safety standards decision, as it should be."
The chance that taxpayers will be on the hook for the extra costs to monitor the girders and do the remedial work is "minimal to almost zero," Murray said.
Although installation of the girders has been on hold since late July, he said the parkway should be open to motorists late next year.
"There might be a small delay, but I'm told it won't be a major one," he said.
Windsor Essex Mobility Group, which installed the girders, said it disagrees with the report's content and conclusions, but will work with the government to get the project going again.
"We value the public's trust above all else and given the importance of this project in connecting Canada to the United States, they deserve to know that critical infrastructure can withstand even the most extraordinary events," it said in a statement.
WEMG said the firms involved in the project would never compromise safety.
"These girders will become the gold standard in safety and durability under even the most extreme circumstances," it added.
One of the consortium's contractors, Freyssinet Canada Ltd., fabricated the girders in Ontario.
The report said some of the girders were manufactured before the plant obtained certification from the Canadian Standards Association, which was responsible for quality control. Most were installed in two tunnels.
The firm used tack welding when assembling the reinforced steel cages for the girders without the required prior approval by the ministry.
Infrastructure Ontario and the Ministry of Transportation discovered that tack welding was used during a meeting with WEMG and Freyssinet in December 2012. Murray says he wasn't aware of the problem until May.
The Liberals stopped the installation in July, but the New Democrats said they should have acted months earlier.
"I think what the people of Windsor are wondering is are they going to be safe, is the solution going to be one they can rely on and know that their safety is being taken care of," said NDP Leader Andrea Horwath.
"But what I think this shows is that the minister and his team in the ministry really let this thing get away without doing their due diligence up front."
The government also closed a bridge in south Windsor at the end of August based on information found during the review. Murray says it will remain closed.
The Herb Gray Parkway is an 11-kilometre corridor that includes 11 tunnel sections covering 1.8 kilometres of freeway, a six-lane below-grade freeway from Highway 401 and a four-lane at-grade road extension from Highway 3.
— With files from Keith Leslie.