Road Rules: Speed limits for alleys

Question: I see cars going what looks like at least 25 mph in the alley behind where I work. That seems too fast to me. Is there a speed limit for alleys? And if there is, why isn’t it posted?

Answer: Everything has its limits. The maximum speed for the Saturn V rocket was 25,000 mph. The maximum speed of a Bugatti Chiron (the fastest production road car) is 305 mph. The Mitsubishi Mirage (the cheapest car available in the U.S. in 2023) tops out at 105 mph. Maybe you think I’m not taking your question seriously, but it’s quite the opposite.

The Revised Code of Washington has a set of default speed limits for various types of roads. City streets are 25 mph, county roads are 50 mph and state highways are 60 mph. That’s the starting point, but you’ve driven on roads with other speed limits. If the default limit isn’t appropriate for the design of the road, local authorities can specify other limits.

Our state law doesn’t have a default speed limit for alleys; you’ll find that in your local municipal code. Or maybe not. I came across several municipal codes that didn’t have an alley speed limit listed, at least not one that I could find. All of the ones I did find have a limit of 15 mph. I’ll also note that even though 15 mph seems to be the standard speed limit for alleys, the National Association of City Transportation Officials recommends a 10 mph speed limit for alleys.

Without a local alley speed limit law, does it default to the state law of 25 mph? The law I referenced actually opens with a broader requirement: “No person shall drive a vehicle on a highway at a speed greater than is reasonable and prudent,” and goes on to say that “speed shall be so controlled as may be necessary to avoid colliding with any person, vehicle or other conveyance.” Also, it requires drivers to “drive at an appropriate reduced speed when traveling upon any narrow roadway.” No matter what road you’re on, the maximum speed is one that’s reasonable and safe.

The “reasonable” part is important. You can’t make the argument that not crashing while racing down an alley (or any other road) is proof that you were driving safely. The standard is based on what a reasonable person would consider safe. An alley is commonly only 12 feet wide; the width of one lane on an interstate highway. What’s a reasonable speed for a road where there’s not enough room to pass an oncoming car, and very little cushion when encountering a person on foot or bike? I’d argue that it has to be slower than a street with sidewalks and two lanes.

Why don’t alleys have posted speed limits? I couldn’t find a clear answer, but it’s probably because of their purpose; providing access to the rear side of properties. They’re not intended for through traffic. I checked the Manual for Uniform Traffic Control Devices (MUTCD) for any rules about signs in alleys, and I found only two: A one-way alley must have a sign, and signs are required at train and light rail crossings.

We have a system that sets a cap for how fast we can legally travel, and we drive vehicles that are capable of exceeding that, so we have a responsibility to choose speeds that are safe, no matter what the limits are, whether that’s the limits of your vehicle or a default speed limit in the law. Not that you’d take a Saturn V through town.

Doug Dahl is a manager with the Washington Traffic Safety Commission, Region 11 and publishes TheWiseDrive.com.