WASHINGTON — A series of safeguards failed to prevent an oversize truck from hitting a low-clearance bridge on Interstate 5 in Washington state last year, leading to the collapse of one of its spans, federal safety investigators concluded Tuesday.
The National Transportation Safety Board faulted a Canadian trucking company for failing to account for the low-clearance bridge over the Skagit River at Mount Vernon, Wash., in its route planning for shipments of unusual size.
A driver in an escort vehicle ahead of the truck who was supposed to detect restrictive clearances was using a hands-free cellphone at the time of the accident, the board found.
“As we can see from this accident, any element that reduces a driver’s attention can have harmful results,” said NTSB Acting Chairman Christopher Hart.
The board, which has no enforcement power and only makes recommendations, said that states should prohibit escort vehicle drivers from using cellphones except in emergencies or to warn the driver of the oversize truck of safety problems.
It also faulted Washington state for not providing low-clearance warning signs ahead of the bridge. Protection of bridge infrastructure was too vital a concern for states to leave risk assessment in the hands of companies shipping oversize loads, the board concluded.
It also recommended adding roadway clearance data to navigation systems on commercial motor vehicles. The current method for detecting clearance problems is to use a pole mounted to an escort vehicle driving ahead of the loaded truck.
Deborah Bruce, NTSB project manager for highway safety, called the device “primitive.”
Washington Transportation Secretary Lynn Peterson said her department would work with state lawmakers and freight shippers to address the board’s recommendations.
“We all aim to provide the safest conditions possible for the traveling public,” she said.
While no one was injured or killed in the May 23, 2013, bridge collapse, it closed one of the Pacific Northwest’s most critical highways for nearly a month, inhibiting the movement of goods and costing local businesses.
It’s cost nearly $13 million to replace the damaged span and retrofit the undamaged portion to accommodate taller trucks.
The Skagit Bridge, built in 1955, had an 18-foot clearance in its two center lanes, but the curved design of the steel supports provided only a 15-foot, 6-inch clearance at the right edge of the roadway, about five inches shorter than the container that struck the bridge.
The country’s economy depends on movement of oversize loads on roads and bridges built decades ago, Hart noted.
“This is not a Washington state problem, it’s a national problem,” he said.
The NTSB issued its recommendations on the same day the House of Representatives was scheduled to vote on a temporary fix for the federal Highway Trust Fund, which is quickly nearing insolvency. The measure passed the House by a vote of 367-55. A similar bill has been approved by a Senate committee, but has not been voted on in the full Senate.
The U.S. Department of Transportation warned earlier this month that in the absence of congressional action, it would begin rationing payments to states for road and bridge projects beginning on Aug. 1.The House bill would not address the need for a permanent solution.
The Congressional Budget Office projects a $129 billion shortfall in the highway fund by fiscal year 2024.
Last summer, Reps. Rick Larsen of Washington and Nick Rahall of West Virginia, both Democrats on the House Transportation and Infrastructure Committee, co-sponsored a bill to establish a federal program to help states repair or replace bridges before they fail.
“Local, state and federal governments need to keep working together to share information and make investments that will prevent our infrastructure from crumbling beneath us,” Larsen said Tuesday.