(Bloomberg) -- Auto manufacturers and suppliers would see their operations disrupted within days if protests against vaccine rules continue to stop traffic at border crossings between the U.S. and Canada, according to the chairman of a major parts supplier.

“Basically if there’s a shutdown of transportation routes, the auto industry comes to a screeching halt in about two days,” Robert Wildeboer, executive chairman of Martinrea International Inc., said Tuesday on BNN Bloomberg Television. 

Protesters halted traffic Monday night at the Ambassador Bridge that connects Windsor, Ontario to Detroit, the busiest border link for goods moving between Canada and the U.S. and a crucial artery for the auto supply chain. Traffic to Canada was still blocked as of Tuesday morning, though it was moving again on lanes headed to the U.S. 

The slowdowns are a problem for Martinrea, which is based in the Vaughan, Ontario, but has locations in the U.S. and around the world. “We have 38 trucks cross at the Detroit border per day and 16 in Sarnia,” Wildeboer said. On Sunday, protesters on tractors and trucks blocked off the Blue Water Bridge that connects Sarnia to Port Huron, Michigan. 

He called on Prime Minister Justin Trudeau to back down on new rules that require truckers to be vaccinated against Covid-19 to enter the country. The vaccine mandate is one of the causes of the protests that have paralyzed downtown Ottawa for more than 10 days. 

“A closure of the bridge would be catastrophic for the Canadian economy,” Brian Kingston, president and chief executive officer of the Canadian Vehicle Manufacturers’ Association, said by phone. “It’s responsible for approximately 25% of our goods trade, it is far and away the most important border crossing between Canada and the U.S.”

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