Why does Seattle have so many #*$@!^& potholes?

Marc Lawrence was riding his Yamaha FZ1 motorcycle along Martin Luther King Jr. Way in south Seattle last fall when his front tire hit something in the road.

“I thought maybe something fell off a truck in front of me and hit my motorcycle," he said. Nope. It was a pothole. He wasn’t hurt, but the front end of bike was badly damaged. Now he’s asking the city to pay for his repair costs. That's not unusual: Last year Seattle received 179 claims of pothole damage. The city settled 92 of those, and there are 22 claims still open or pending. These pothole damage claims happen because Seattle’s roads are in bumpy shape. Seattle ranked 11th in the country for worst roads, according to nonprofit TRIP, with 40 percent in “poor condition,” meaning rutting and cracks and potholes.

Credit: Courtesy of Marc Lawrence

TRIP says these road conditions cost drivers here an extra $684 dollars each year on average. (Note that TRIP receives funding from the transportation industry, and this study used federal data that looked at all roads in Seattle, not just city-maintained roads.) That brings us to this week’s #SoundQ from listener Joy Canova: Why are there so many potholes in Seattle? Ben Hansen, a civil engineer and pothole expert with the Seattle's Department of Transportation, said it’s mostly because we have a “large backlog of streets that need to be re-paved.” Hansen said a brand-new road doesn’t get potholes because it doesn’t allow in rainwater. But as our roads age, they start to crack. That’s mostly due to the weight of large trucks and buses. According to one estimate, one large truck causes as much road damage as 9,600 cars.

Once the road cracks, the water seeps into the pavement, and down into the soil that supports the road. There it freezes and thaws and freezes and thaws and ... potholes! Seattle filled over 25,000 of them last year. And that's not just about safety. It’s also about politics. Seattle mayors have touted their "tough on pothole" policies for years. We don't just have road crews in Seattle: We've got “pothole rangers,” and we hold “pothole paloozas." Meanwhile, the decaying road infrastructure that gives rise to so many potholes never gets fixed. Part of it is money. It costs roughly $2 million to resurface a mile of two-lane street, and Hansen said deeper problems lurk further below the surface. "On Capitol Hill we've paved over brick and cobblestone streets, and that original pavement is still below that thin asphalt layer,” Hansen said. “We're really trying to bring our streets from the horse and carriage era, into the modern era.”

Credit: Courtesy of Baadal Nanjundaswamy