Is that a pothole or sinkhole on this northern Quebec highway? Man jumps in to sort it out

Alphonse Coonishish says he's a lucky man after his vehicle hit what he thought was a large pothole in the middle of the night in northern Quebec, on the James Bay Highway.

"I hit something, I couldn't see anything. There was no sign or anything," said Coonishish.

He was travelling south with his wife Margaret last Wednesday around midnight at kilometre 150. Given the late hour, the couple decided not to stop.

On their way back to their home in Chisasibi, Que., a few days later, they pulled over to see what they had actually hit.

"It wasn't a pothole. It was a sinkhole," said Coonishish. "I'm a lucky guy."

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Coonishish, who stands sixfeet tall, posed for a chest-deep photo in the hole and shared it on social media as soon as he could to warn other drivers.

"A lot of people thought it was Photoshopped," said Coonishish. "But it's real."

The Socit de dveloppement de la Baie James (SDBJ), which owns and maintains the James Bay Highway on behalf of the Quebec Transport Ministry and Hydro Quebec, says the sinkhole was caused by a corrugated metal culvert that failed. It was at the end of its lifespan.

"I have about 150 culverts that are in critical state," said Raymond Thibault, the chief executive officer of the SDBJ. "[It's] caused by the rust inside the culvert or the joints. The material above it falls into the culvert which causes a sinkhole."

By the time Coonishish and his wife saw the sinkhole on their way back North on Friday there were flags and signs warning drivers of the hazard. Thibault says the hole has been fixed for now but the culvert urgently needs to be replaced.

"In the meantime we have installed warning signs and filled the hole to give us time to do a complete repair," he said.

Culverts have a lifespan of 40 to 50 years, according to Thibault.The highway was built in the early 1970s to make way for hydroelectric development. About 330 culverts need replacing.

Thibault said the culvert in question is to be replaced this summer as part of a $265-millionrepair project to close to half the surface of the highway between now and 2021.

The work slated for this year includes $60 million to replace more than 60 culverts and repave more than 118 kilometres, including the section between kilometres 88 and 200. Eleven bridges will also be repaired and repaved, and guardrails replaced between kilometres 120 and 200.

Thibault says the corrugated metal culverts are being replaced with steel reinforced concrete ones, which have a lifespan of about 75 years.