A tower rising 50 stories. A one-pound tape measure attached to the waist of a construction worker. An unsuspecting man stepping from a vehicle at the foot of the building.

The three elements converged on Monday morning in a freakish accident, when a 58-year-old man died in Jersey City after being struck in the head by the tape measure after it fell some 400 feet.

The accident led to the suspension of work on one of the largest development projects in the city.

Looming above the Grove Street PATH station, the building at 70 Christopher Columbus Drive is near completion, and the man who died, Gary Anderson, had arrived at Marin Boulevard and Christopher Columbus Drive shortly before 9 a.m. to make a delivery of wallboard.

Mr. Anderson had just parked his truck and was not wearing a safety helmet when he stepped from the vehicle, said Carly Baldwin, a spokeswoman for the Jersey City Department of Public Safety.