Last month, federal investigators ruled the collapse of an Interstate 5 bridge in Washington state was caused by an oversize truck hitting the bridge’s oversize support trusses. The bridge collapsed into the Skagit River on May 23, 2013, after a truck with oversize drilling equipment struck various sections of the steel-and-cement bridge. Two vehicles fell into a river, injuring 3 passengers, though there were no deaths.
According to the National Transportation Safety Board,the bridge had been struck repeatedly by oversize loads, and that state permits for trucks did not verify whether or not the truck would fit through bridges along the route.
In response to the accident, the board offered the following safety recommendations:
- More thorough evaluation for permitting oversize trucks
- More specific and detailed information about bridge clearance for each lane of traffic
- Policies prohibiting escort drivers from using cell phones and electronic devices
- Better signs for bridged warning about clearances
“Movement of oversized loads is a specialized operation that demands special precautions,” states the board’s acting chairman Christopher Hart. “What this investigation uncovered were multiple gaps in multiple systems and repeated occurrences of similar bridge strikes.”
According to the Federal Highway Administration, 67,000 out of 607,000 of bridges in America were structurally deficient in 2012. This translates to 11 percent of bridges across the nation. This percentage is a slight improvement since 2007, when 12 percent of bridges in America were labeled as structurally deficient. In 2007, an Interstate 35 bridge in Minneapolis collapsed, killing 13 people.
Just before the bridge collapsed, a 2010 Kentworth truck-tractor towing a 1997 Aspen flatbed trailer passed onto the bridge. The truck was towing and oversized load, which struck the overhead portal, as well as several braces on the bridges right side, NTSB reports. Two other vehicles were on the bridge when it fell, including a southbound 2010 Dodge Ram pickup towing a 2009 Jayco camper trailer, and a northbound 2013 Subaru XV Crosstrek.
The accident blocked a major north-south roadway, where an average of 71,000 vehicles passed the site of the accident everyday. The driver of the truck in question reported the truck to be 15 feet and 9 inches tall, though investigators found the truck 15 feet and 11 inches tall. Investigators also found the arched bridge;s lowest clearance on the right lane to be 14 feet and 5 inches tall. In 2012, the bridge had already been struck eight times by oversize loads before the accident.
“Everyone is pointing at everyone else,” said NTSB member Mark Rosekind.
The truck belonged to Mullen Trucking, a Canadian company, which received a $10 permit on the internet for the trip which claimed the trip to Washington state was fine, claiming “Route Ok: and that the agency “Does not guarantee height clearances.”
Investigators also report that a pole on an escort car driving ahead of the truck struck the bridge several times, and that the driver was distracted and using a cellphone. What’s more, the truck was following the car at only 400 feet, rather than the recommended 800 feet. This might have prevented the escort car driver from warning the truck driver.
The board reports the bridge has been rebuilt, with an 18 foot clearance across all four lanes.