Q: I recently drove from Blaine to Kelso and back on a weekend. Other than downtown Seattle, the average speed on I-5 was 80 mph in both lanes, and there were vehicles passing me by. Twice, a motorcycle blasted through weaving between cars at over 100 mph. I’ve not experienced this kind of freeway driving in Washington before. Is this commonplace now?

A: What does it say about our driving culture that the part of your question I find hardest to believe isn’t the 100 mph motorcycles; it’s that you drove almost the entire I-5 corridor in Washington and only had slow traffic in downtown Seattle. My experience has typically been traffic jams starting near Olympia and continuing to Smokey Point.

Speed is a problem, no doubt. But is it always as bad as you described? I’m not discounting your experience, but with a data set of one, it’s hard to know if that’s an outlier or the norm. Fortunately, we have more sources. A recent speed observation survey by the state Traffic Safety Commission at over 200 locations found that about three-quarters of drivers speed, at least a little bit. Of the drivers who were speeding, just over half were within 5 mph of the speed limit. About 6% were 16 or more mph over the speed limit. But none of those locations were on a freeway.

The Department of Transportation’s traffic count database includes vehicle speeds from many of its stations. To get an idea of typical I-5 speeds I picked a location that generally has an open flow of traffic and looked at data for the month of June. Of the nearly one million cars tracked, 44% were at or below the 70-mph speed limit. A third were no more than 5 mph above the speed limit. Less than 1% exceeded 85 mph. But that still works out to around 300 cars a day at excessively high rates of speed. On a long drive like yours, you’re bound to see some of them.

When we’re dealing with close to six million drivers in the state, a small percentage of high-risk drivers is still a lot. Speed increases both the likelihood and the severity of a crash. And I’ll argue that it’s not just the drivers going 15 mph over the speed limit who are creating unnecessary risk. The relationship between speed and crashes is a power function; for every 1% increase in speed, there is a 4% increase in traffic fatalities. In Washington, about one-third of all traffic deaths include speed as a factor.

We’re also collectively driving 3.5 billion more miles per year than we did 10 years ago, while the available lane miles have slightly decreased. To offer a poor analogy, if I lived on 100 acres, I could play Nickelback as loud as I wanted, but since I live in a neighborhood I have to consider the musical tastes and sleep schedules of my neighbors.

But the consequences of loud music and risky driving aren’t equivalent. I’m stating the obvious; speeding and other dangerous driving puts more people at risk when there are more people on the road. So how about this: let’s expand our understanding of our neighborhood to include the roads we share with other drivers. And from that perspective, safe drivers make good neighbors.

Doug Dahl writes a weekly column for this newspaper. He is with the state Traffic Safety Commission.