Tacoma Narrows crane mishap blamed on human error

Investigators looking for clues into Monday’s crane accident on the Tacoma Narrows Bridge have determined that the cause of the accident was the turning of the crane’s boom after its outriggers had been retracted, which is not a standard procedure for this operation, according to a statement released yesterday by the Washington State Department of Transportation.

The event occurred while a working crew was demobilizing after a night construction operation. In the process of turning the boom, the 30-ton crane toppled over on its side, resulting in a six-and-one-half-hour closure of the bridge.

Following the incident, engineers examined the bridge and found no damage to its key structural components. Damage to the bridge deck itself was minimal and included a few small indents created in the asphalt.

Most of the damage was limited to the pedestrian railing, which was struck by the crane’s falling boom. A 32-foot section of railing was damaged beyond repair and was removed from the bridge. Temporary cable pedestrian railing has been installed and will remain in place until WSDOT crews can fabricate and install new permanent railing. That process is expected to take one month.

“We know this incident caused major inconveniences to thousands of motorists who rely on the bridge every day,” said Secretary of Transportation Doug MacDonald. “We thank them for their patience and understanding as we worked through the recovery process. We also thank the Washington State Patrol and Washington State Ferries for their efforts to keep people moving. We deeply regret the disruption the bridge closure had on the traveling public.”