Some low clearances are highlighted for caution
OLYMPIA – Washington state’s transportation department has known since the 1970s that the Interstate 5 bridge that recently collapsed after being clipped by a truck hauling an oversize load had been struck repeatedly before by similar big rigs.
Just last fall, a tall vehicle crossing the Skagit River bridge hit the overhead structure, ripping a 3-inch gash in the steel and deforming three components.
Even knowing that history, state officials didn’t take precautions as they often do to prevent truckers from hitting overhead structures, raising questions about whether the state could have done more to prevent the collapse from happening.
The Associated Press found that the DOT regularly puts detailed warnings on its trucking permits when routes are projected to encounter potential areas of low clearance. But the Skagit bridge – along the crucial I-5 corridor between Seattle and Vancouver, B.C. – was never added to that group.
Federal transportation investigators believe an oversize load struck the bridge last month, causing a portion of it to collapse into the river and taking two vehicles with it. Nobody was seriously injured, but the failure has continued to disrupt transportation and renewed attention on the condition of the nation’s infrastructure.
DOT spokesman Travis Phelps said the agency puts out the caution notifications on some areas that have had clearance problems in the past – but not every clearance height is noted. The state didn’t consider the Skagit bridge to be particularly problematic.
“We don’t put every bridge that’s been struck onto a permit,” he said.
In the DOT permit to allow the oversized load across the bridge, the state determined that the route was OK for a load that stood 15 feet 9 inches tall, even though the outer edges of the bridge had a clearance of less than 15 feet.
DOT did add a qualification that the agency does not guarantee the height clearances, and Phelps said it is the company’s responsibility to ensure that the load safely passes across. The state also provides separate information to companies about bridge heights.
The permit, however, was much different than another approval given just two days earlier to the same company. In that request, Mullen Trucking sought to bring a large boiler along Interstate 90, with a maximum height of just 14 feet.
At 10 points on the route path, the DOT issued a “CAUTION” notice, detailing the height of the overhead clearance and asking the driver to take a different route, if the load was within two inches of that level. None of those overhead heights were a problem on that specific permit because they were at least seven inches higher than the load.