Wednesday, November 4, 2015

The story behind Wednesday morning's rough commute into Seattle

By Mike Allende

The call came in just as our overnight maintenance crew was returning to their Corson Avenue base Wednesday morning, Nov. 4. Report of a loose expansion joint on southbound I-5 just north of the West Seattle Bridge. That was the start of what turned into a frustrating morning of traffic in Seattle.

Between 5 and 8:40 a.m., our crew worked as quickly as possible to make temporary repairs to an expansion joint that failed when a large anchor rod broke, causing a metal plate to flap up into the roadway. Fortunately, no vehicles were reported damaged but with two lanes blocked, traffic soon backed up significantly, leading to 2-hour travel times from Everett into Seattle.

WSDOT maintenance crews lift the damaged piece of an expansion joint on southbound I-5.

Sparks fly as crews work to repair the broken expansion joint on I-5.

While funding for highway maintenance has been stretched thin, keeping our highways safe for drivers is our highest priority. We work hard to prioritize fixes within our available budget and our maintenance staff takes great pride in their work. When we face issues like this, it's at best frustrating, especially emergency situations that affect our peak commute times with little warning.

Unfortunately, we have an aging infrastructure and sometimes these emergency situations happen. We've replaced some of the worst expansion joints on that stretch of I-5 in Seattle and are currently replacing expansion joints on three I-5 bridges in Snohomish County. The expansion joints on much of I-5 are at least 50 years old and funding has prevented a full replacement for all of them, so we pick those that are most likely to fail. Like anything that ages, they get fatigued and eventually break and that's what happened Wednesday.

Expansion joints are pieces of a bridge that expand and contract as traffic goes over them. But each time they flex, that puts pressure on them. Think of a paper clip. You can bend it back and forth over and over but eventually it will break. That's similar to what happened in this case. The anchor rod broke and the steel plate covering the expansion joint came loose.

Our maintenance staff inspects our expansion joints every month, looking for metal fatigue and tightening anchor rods. The bolt that broke Wednesday had just been inspected six days before. But like going to the doctor, you can get a clean bill of health and then a few days later end up sick. In that case, you might be in bed for a few days. In the case of the expansion joint, traffic backed up from south Seattle to Snohomish County.

Here's an example of the expansion joint bolt that broke on I-5. The bolt that broke was inspected last Thursday, Oct. 29.

Skilled maintenance crews work carefully to fix the broken expansion joint on I-5.

It was a rough morning for everyone involved and we appreciate drivers' patience as we worked to get the roadway fixed. We can't promise you that we'll never have another emergency roadway closure for maintenance, but we can promise that our crews will continue to work hard and do as much as we can within the resources we have to minimize these situations as much as possible.