Friday, May 23, 2014

Skagit River Bridge – One year later

By Lynn Peterson

Today marks the one year anniversary of the Skagit River Bridge collapse. I was just finishing dinner when I received a call saying that a section of the Interstate 5 Skagit River Bridge had collapsed and several vehicles were in the water. I knew this was not a drill and that it would certainly be a critical test for my agency moving forward.

My first thought was how many people could be hurt? As first responders arrived on scene, the Governor and I flew out of Olympia by helicopter to survey the damage. Details were
After - The completed bridge
sparse. We knew that an oversized truck appeared to have hit a support beam of the steel-trussed bridge, which was later determined to cause the collapse. Thankfully, everyone who was on the bridge was found safe. Unfortunately, the state suffered a tragic loss after the bridge collapse when Trooper Sean O’Connell was killed while managing detour traffic. He made the ultimate sacrifice serving the citizens of Washington. 

The next three months, were a challenge for impacted Skagit families, communities and businesses as well as for this agency. And with just three months on the job, I along with many other people in our state, became keenly aware of the vulnerability of our transportation infrastructure.
A lot of questions arose from the impact of the Skagit River Bridge collapse. Questions about the safety of our bridges, commercial vehicles that carry goods long distances, and what more could be done to keep people moving.

There are nearly 3,700 bridges in our state inventory, and many were built long ago and are still in good shape. With the Skagit River Bridge, many people outside of the engineering world learned new terms, “Fracture Critical,” and “Functionally Obsolete.” Simply put, Fracture Critical means if that if key supports fail, the bridge is in danger of collapsing. Functionally Obsolete is a technical term to reflect that design standard have changed, and a modern bridge would be built differently. Neither term means that a bridge is unsafe. Our bridges are inspected at least every two years, to ensure they are able to meet the day-to-day demands of traffic. With our detailed records, we can make strategic decision for improvements and extend the life of these structures.

When the I-5 Skagit River Bridge was first constructed in 1955, freight cargo wasn’t nearly as large as it can be today. Since 2008, we’ve issued around 860,000 special vehicle permits for oversized and overweight loads. That number coupled with the 103 bridge impacts during the same time period show that freight haulers are generally very good about following the law by ensuring their load can safely travel underneath our structures. Still, the target is zero. We can’t drive the routes for each trucker, but we can provide drivers with good information so they can make good decisions. We sign our overhanging structures more aggressively than the national standard, provide easy to access permitting information and up-to-date restrictions for highways statewide.

Our team was able to quickly reopen the bridge to traffic in 27 days with a temporary span, followed by a permanent replacement in 66 days using a creative design-build method that minimized traffic impacts. This was an impressive achievement carried out by a creative team driven to reconnect our communities along this vital corridor and funded by our partners at the Federal Highway Administration.

Before Thanksgiving, we even raised the overheard clearance to 18 feet across all lanes. We’ve been asked about retrofitting the overhead height of other bridges, but we simply do not have the funding. With the little money we do have, we strategically use it (pdf) for preservation like painting projects that prevent corrosion of our steel structures, or bridge deck rehab projects that can extend the structure’s life 20 to 30 years to keep traffic moving.

There’s still one more chapter to be written for the Skagit River Bridge, and that will be included in the final report from the National Transportation Safety Board. With their information, we could learn what, if anything can be done to better protect our transportation infrastructure for generations to come.


Anonymous said...

Something I have been wondering about. The bridge, and I notice others on I-5 in that same area, were built in 1955, or so the markings on the abutments say. But the Interstate Highway project wasn't signed into law until 1956? What gives?

WSDOT said...

The current Interstate 5 Skagit River Bridge was built in 1955 as part of US 99. Much of US 99 was incorporated into the Eisenhower highway system and renamed.

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