The Idaho Stop – It’s Not Really Stopping

Q: Are you familiar with the Idaho Stop? It’s the law, in Idaho of course, that lets cyclists treat a stop sign like a yield sign. What do you think of that? It seems like there would be more crashes. Is it more dangerous than making cyclists stop?

A: Since 1982 Idaho has allowed cyclists to roll through stop signs after yielding to other traffic, and for over three decades it was just this odd little rule in one smallish state. That law became known as the Idaho Stop because, well, you could only legally do it in Idaho. Why are we talking about an Idaho law in a column on Washington traffic laws? First of all, Idaho is our neighbor, and also, the law is spreading. Delaware legalized the Idaho Stop in 2017, but called it the Delaware Stop. Last month Arkansas adopted the law; no word yet on whether they’re calling it the Arkansas Stop. Some cities and counties in Colorado allow it, and several other states in recent years have considered but not yet enacted the law.

Why would a state want to let cyclists blow through stop signs? First of all, to be accurate, the law doesn’t actually allow anyone to ignore the stop sign. Here’s what the Idaho law requires: “A person operating a bicycle  . . . approaching a stop sign shall slow down, and if required for safety, stop before entering the intersection. After slowing to a reasonable speed or stopping, the person shall yield the right-of-way to any vehicle in the intersection . . .” The Idaho Stop doesn’t change the right-of-way rules or give cyclists priority in the intersection; it just gives permission to continue through the intersection without coming to a full stop, if it’s safe to do so.

It may seem like this law gives an unfair privilege to bike riders compared to drivers, and that has been one of the big criticisms of the law, both from drivers and cyclists. There’s this “same road, same rules” philosophy that we try to apply to bikes and cars, and the Idaho Stop seems to violate it. As a sidenote, we already have different rules for different kinds of road users, from bikes to cars to commercial vehicles. This one just goes a little further than we may be accustomed to.

When it comes to traffic laws though, we shouldn’t be making decisions based on privilege or convenience; the primary motivator should be safety. Maybe it’s because until recently only one state had this law, but there isn’t much in the way of research when it comes to the Idaho Stop. I could only find one study, done by a researcher at UC Berkeley. In what might seem counterintuitive, the study found that the year after the law was passed cycling injuries decreased 14.5 percent, and that Idaho cities have about 30% less cycling injuries than comparable cities without the Idaho Stop law.

How does a law that lets cyclists roll through stop signs increase safety? Exposure. Intersections are a risky place for cyclists, so less time in an intersection is better. Entering the intersection with some momentum reduces the time that the bike rider is exposed to intersection traffic, decreasing exposure and risk. As a side benefit to drivers, the stop-as-yield law keeps cars moving more efficiently because when it’s their turn to yield they don’t have to wait for bike riders to mount their bikes after a stop and get moving.

Let’s talk about energy for a minute. Cycling is the most efficient mode of transportation out there (three times more efficient than walking and about 1000 times more efficient than driving), especially once the rider is at cruising speed. But getting up to speed takes a lot more effort. Riding at 13 mph, a reasonable average speed for commuting, takes 65 watts of power. Yep, that’s watts like what you see on a light bulb. Power is power – you could use your energy to ride a bike or power a common incandescent light bulb. But the average amount of power exerted to accelerate up to that speed is nearly double, at 120 watts. That stopping and starting takes energy, and time.

There is also an important difference between drivers and bike riders in their ability to assess traffic hazards when approaching an intersection. Cyclists approach at a slower speed, giving them more time to identify oncoming traffic, and by the time they reach the intersection, if they’re following the stop-as-yield rule, they’re travelling at roughly the speed of someone on a brisk jog. (We don’t require runners to stop before crossing the road, but they are prohibited from bolting into traffic – kind of like the Idaho Stop.) Cyclists also have less sight and hearing obstructions compared to someone in a vehicle. These differences mean that a bike rider may be able to assess the need to yield at an intersection without coming to a complete stop, so the stop-as-yield turns out to be less risky than it initially sounds.

Along with the positive data, there are some questions, like: Does yielding at a stop sign on a bike lead to the same behavior in a car? (The cynical part of me wants to point out that a significant minority of drivers already have adopted that behavior, even without the law.) How do we educate drivers to expect cyclists to roll through stop signs? (Again, lots of cyclists already do this behavior, so drivers are probably familiar with it.) Should we legalize a behavior just because lots of people already do it? Will it make more drivers mad? (It might, although in Idaho drivers seem to like it fine.) How we answer those questions influences how we feel about this law.

Regardless of your view on the Idaho Stop, right now in Washington the law is still “stop means stop”, and I’m not aware of any efforts to change that here. As I’ve said before, one of the best things you can do on the road is be predictable, and part of predictability is obeying the law.