(CNN) A man stood on a freeway overpass near Detroit early Tuesday, threatening to jump. So 13 tractor-trailers lined up underneath, ready to break his fall.

Troopers closed off both directions of Interstate 696 and asked for the truckers' help, hoping to protect the man in case he fell or jumped, said Lt. Mike Shaw of the Michigan State Police.

Asking truckers to help in such cases is not unusual, Shaw said, but "most of the time these events are (resolved) pretty fast, so we only get one semi."

This time it took about three hours to get the man, whom police declined to identify, down from the bridge, he said.

It was 911 calls that alerted police to the man around 1 a.m. Tuesday on the overpass in Huntington Woods, just outside Detroit, Shaw said.

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