Q: Something that has not made sense to me since I started driving 49 years ago is the apparent discrepancy in the posted speed limit (for example 50 mph) and the cautionary speed signs entering sharp turns (say 35 mph). My understanding is that it is legal to fly unsafely around the 35 mph corner at 50 mph. Why does the legal speed limit not change when there are tight turns?
A: I think the fundamental issue here is an incomplete understanding of our speed laws. And please don’t take that as a criticism of you personally. I mean that collectively. So I guess you could say I’m criticizing all of us. I’ll explain what I mean in a moment, but first let’s consider some unintended outcomes if we did create regulatory speed zones for every curve that has a cautionary sign.
I’ll start with the obvious. It would mean more signs. You’d have a sign alerting drivers to a reduced speed limit ahead, a sign with the new speed limit and after the curve another sign with the previous speed limit. You might expect that I’m about to lament that more signs mean more tax money spent on posts and metal. That’s true, but from a traffic safety lens, that’s not what I’m concerned about.
There is such a thing as too many signs. Traffic signs should give drivers the information they need, but not overwhelm them. Sure, it’s only a couple more here, but those add up, and eventually, drivers pay less attention overall to important signs.
Then there’s the political aspect. I don’t mean partisan conflicts. I’m talking about the process that we go through to set speed limits. The Revised Code of Washington specifies maximum speed limits for various kinds of roads. Local jurisdictions can set different limits by conducting an engineering study and then having the responsibly political vote to approve the revised speed limit. One traffic engineer said they had over 600 locations with advisory speed limits in their county. That’s a lot of votes (and time) that both engineering departments and elected officials could spend on higher-priority issues.
Yes, practical and political issues could be overcome if there was a need to make a change. But I’ll argue that the law already kind of makes advisory signs the rule to follow. We tend to only think of speed restrictions as the numbers on the black and white speed limit signs, but that should be a secondary consideration for a driver choosing how fast to go. The law about speed begins by stating that “No person shall drive a vehicle on a highway at a speed greater than is reasonable and prudent under the conditions and having regard to the actual and potential hazards then existing.”
Traffic engineers calculate the threshold of instability for a curve, and then set the advisory speed below that threshold. The sign alerts drivers to a potential hazard, and if that driver continues to drive at the posted speed limit when that speed is in excess of what’s safe, that’s a violation of the law.
You might not see officers doing speed patrols in curves, but if you were to review citations issued after traffic crashes, you’d see many that list “Speed too fast for conditions” as the violation. As drivers, we should be reframing our concept of the speed limit to be something like, “Drive at a speed that’s safe, given all the influencing factors (like weather, road conditions, pedestrians and cyclists, curves, hills and other drivers) with an upper limit of what’s on the sign.
Doug Dahl writes a weekly traffic safety column for this newspaper. He is with the state Traffic Safety Commission.