Why do no-passing zones lack conformity in Washington?

Q: Are there rules for where no-passing zones have to be placed? Is it just totally at the discretion of traffic engineers or are there regulations to follow? I ask because I find it rather odd that not all intersections are worthy of a no-passing zone.

A: If it turns out that the determination for no-passing zones was “just totally to the discretion of traffic engineers” would that be a bad thing? I’m wondering, who else would you prefer to make that decision?

Generally, I’m a fan of letting the pros do what they’re good at. I think I understand what you’re getting at though. It’s a question of consistency. You want some reassurance that a no-passing zone in Whatcom County will be similar to one in Walla Walla County. Is there some rulebook that the engineers, no matter where in the country they’re located, have to follow?

The answer is yes, absolutely, and no, not really.

First, the yes part. The Manual on Uniform Traffic Control Devices is the national standard for all traffic devices installed on any public roadway. No matter what city, county or state you’re in, the manual sets the rules for signs, lights and roadway markings. If a city wants to put up a no-passing zone sign, the manual has the standards for what the sign looks like, how big it should be, the required retro-reflectivity and what the minimum passing sight distance is for no-passing zone markings, depending on the posted speed limit.

The manual explains how to mark a no-passing zone, but it leaves out a lot of details about where they should go. It addresses locations with limited sight distance, but we also have plenty of no-passing zones that aren’t based on how far you can see, such as roads that cross railroad tracks, in high-traffic urban areas, on bridges and at intersections.

In some of those locations, establishing a no-passing zone is up to the traffic engineer. The Revised Code of Washington gives authority to state and local officials to establish no-passing zones when driving to the left of the center of the road would be “especially hazardous.” In addition, the Washington Administrative Code states, “The decision to use a particular device at a particular location should be made on the basis of either an engineering study or the application of engineering judgment.”

Washington law does specify a few locations where no-passing zones always exist, including within 100 feet of an intersection. (When driving, 100 feet is tiny; at 35 mph, you can cover it in two seconds. Any passing done on approach to an intersection should be completed well before the 100-oot range.) But most intersections are not marked as no-passing zones, either with signs or solid center lines. The Washington DOT Traffic Manual points out that “state law does not imply a need to mark no-passing zones for such situations.”

If intersections aren’t marked as no-passing zones, how can a driver know the rules? Short of coming across this article, they’d have to have been taught it. This is a great example of the importance of driver training. Anyone up for continuing education for drivers? I think I’ll save that for another discussion.

Doug Dahl writes the weekly The Wise Drive for this newspaper. He is with the state Traffic Safety Commission.