What’s up with that? Grooves on I-205 will wear smooth

By Scott Hewitt, Columbian Arts & Features Reporter



Why is the Interstate 205 freeway segment from Mill Plain northbound to the Orchards exit in such a sorry state? It appears that an unsupervised apprentice was given the job of grinding down the surface of the freeway. When I travel on that section, my car suddenly pulls to the left or right because of all of the uneven ruts. This is a new modification that was made in the last few weeks, I believe. Someone is grinding down the surface and it is highly irregular rather than being smooth. I assume this is one step in a process?

Also, what are the evenly spaced short grooves in various freeways? They appear as long stretches of six grooves, three on each side of the lane, running many times for miles.

— Arlo Petersen, Salmon Creek

You’re right, Arlo, it is a step in a process. And you’re part of that process, according to Heidi Sause, a spokeswoman for the Washington State Department of Transportation. You’ve got to keep driving over those new, slightly wobbly grooves in the pavement in order to help wear them down.

“We’re right in the middle of a project to repair and replace deteriorating concrete on I-205,” Sause wrote in an email. “Our contractor is using a diamond-tipped grinder to smooth the pavement. The grinding process does leave fine grooves in the road surface that can feel a little different under the wheels of your car.”

This reporter went on a fact-finding odyssey to experience those grooves — that is, I drove up and down I-205 — and found them slightly jarring, but frankly no worse than the typically rumbly concrete sections of I-205 — which, according to WSDOT, are nearly 40 years old.

“Those grooves, while an inconvenience now, will wear down in time,” Sause said. “The grinding eliminates all those ruts in the pavement from heavy vehicle traffic, and will prevent water from pooling on the freeway during heavy rain. When the project is complete later this summer, drivers will see a smoother, safer road surface free of ruts.”

Take a look at the project website at www.wsdot.wa.gov/Projects/I205/SR14ToI5JunctionConcreteRehab

And those “evenly spaced short grooves” that you’ll notice on freeways here and there? They’re telltale signs of a concrete reinforcement technique called a dowel bar retrofit, Sause said. “Crews cut slots into aging panels, install steel dowel bars in the slots between the panels, refill the slots with concrete and grind the new concrete to be level with the existing roadway.

“The steel bars brace the concrete panels — engineers refer to this as ‘tying the panels together,'” Sause wrote. “This preservation technique keeps panels from knocking against each other and cracking under the wear and tear of time and traffic. It’s a fairly simple process and extends the life of the concrete, allowing us to get the most use out of each panel before replacement. Panels typically have a life of about 30 years.

“Dowel bar retrofit is a common preservation technique on the interstate system,” which largely dates back to the 1960s, Sause said. You can see the signs of dowel bar retrofit on most nearby interstate freeways, she said, including I-5, I-205 and I-90.

“As a general practice, WSDOT installs dowel bars when pouring new panels, or fresh sections of concrete.”