Elmer Espinosa and his road repair crew were working on a Houston highway around 2 a.m. Monday when they heard a disembodied cry for help coming from the side of the road.

Mr. Espinosa, 47, and the other workers paused, looking around to see where the voice was coming from. The men began searching, brushing aside the knee-high growth on the roadside, as the voice called out to them, “I am here, I am here.”

After several minutes, Mr. Espinosa, using the light from his cellphone, spotted an uncovered manhole. When he looked inside the manhole, which was just under three feet in diameter, the upturned face of a man came into view, peering up at him from about a dozen feet down.