Road Rules – Unmarked intersections

Q: There are some intersections, usually in neighborhoods, that don’t have any traffic control: no stop signs or yield signs. How are you supposed to handle those? Who yields to whom? And how do the road engineers decide when to use stop signs, yield signs, or no signs?

A: What if, instead of limiting uncontrolled intersections (ones without signs or signals) to neighborhoods, we pulled out the signs and lights at intersections all over our cities? What would happen? Mayhem? Anarchy? You might be surprised.

Hans Monderman is probably the most famous traffic engineer of our lifetime; the Taylor Swift of road design, if you will. And his celebrity status (to use the term in its loosest sense) came not from what he added to traffic design, but what he took away from it.

In his work in the Netherlands, Monderman was the first person to reduce crashes by making roads less safe (or more accurately, the roads appear less safe). He addressed problem intersections by removing stop signs and signals, speed limit signs, speed bumps, railings, pavement markings; all the things we rely on to keep us safe as we drive. Contrary to what you might expect, it was enormously successful both in safety and efficiency. Crashes fell while the throughput of cars climbed.

You might argue that Monderman’s ideas are fine in a country that ranks in the top five for happiness, but it would never work in America. Of all places to prove you wrong, how about West Palm Beach, Florida? When the city applied Monderman’s methods to some intersections, they had less crashes and shorter commute times.

The reason it works is hinted at in your question: who yields to whom? When a bit of ambiguity hovers over an intersection, drivers tend to approach more cautiously. Remove traffic control devices and drivers have to take on more responsibility. We can’t just follow the signs and assume it’ll all work out. Speeds naturally decrease without the need of signs telling drivers to slow down, and drivers pay more attention because they’re unsure of what might happen. It turns out that slow, cautious drivers end up getting through intersections quicker. As the special ops folks are known to say, “slow is smooth, and smooth is fast.”

Traffic control devices provide guidance and let us know the rules. But they can’t force drivers to obey. Build an intersection with long red lights and more drivers will race through on a yellow. Build a road with multiple 12-foot-wide lanes and generous shoulders, and then post a 25-mph speed limit, and compliance will be dismal. People tend to travel at speeds that feel comfortable, regardless of the posted speed limit, even if that comfort is misplaced.

That’s a long way and rather round-about way of getting to your question: If you don’t know who should yield, it might be you, so approach cautiously. But you want a real answer. According to the Washington Driver Guide, at uncontrolled intersections “drivers must yield to vehicles in the intersection and to those coming from the right.” It works sort of like a four-way stop without the requirement to stop if there’s no one to yield to.

As to how road engineers decide when to put up a stop or yield sign, or just leave them out, our state law gives them authority to “place and maintain official traffic control devices when and as required” and “as he/she may deem necessary.” Traffic signs go up when the law requires them, or an engineer does the math and decides it’s the right thing for that location.

(Doug Dahl is the Target Zero Manager and Communications Lead for the

Washington Traffic Safety Commission.)