Rules of the Road

Why are semi trucks allowed to drive between 35 and 45 mph on Mount Baker Highway?

Take a look at some of the hazards on Mount Baker Highway

Doug Dahl of the Washington state Traffic Safety Commission and author of The Bellingham Herald's "Rules of the Road" column takes a look at some of the hazards on Mount Baker Highway. May was a particularly brutal month for traffic deaths in What
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Doug Dahl of the Washington state Traffic Safety Commission and author of The Bellingham Herald's "Rules of the Road" column takes a look at some of the hazards on Mount Baker Highway. May was a particularly brutal month for traffic deaths in What

Question: Why are semi trucks allowed to drive between 35 and 45 mph on Mount Baker Highway? The speed limit is a reasonable 55 mph that people already have a hard time managing. I commute daily to town and the trucks (usually Canadian) are increasing and very frustrating. They don’t care about the road rules and continue to be constant traffic hazards.

International trucks don’t pay into our road taxes in upkeep or patrolling. So in essence, they get a free passage while locals who pay for the roads are unable to go the speed limit.

Answer: For a lot of people, driving is frustrating; maybe the most frustrating part of their day.

One of the big reasons is, according to Ryan Martin in Psychology Today, goal-blocking. Goal-blocking occurs when you have a goal (getting to work on time), someone else interferes with that goal (driving slow and making you late), and there’s nothing you can do about it.

Your frustration is real and shared by enough people to have its own term and an article in a psychology magazine. But that doesn’t fix anything, does it?

Here’s what the law says about slow drivers: “No person shall drive a motor vehicle at such a slow speed as to impede the normal and reasonable movement of traffic except when reduced speed is necessary for safe operation or in compliance with law.”

From your description it appears that the trucks are driving slow enough to impede the normal and reasonable movement of traffic. The question then becomes, is their slow driving necessary for safe operation? If a driver says he doesn’t feel safe going any faster it’d be hard to argue that he broke the law. If he says he just felt like going slower, you could conclude that he has violated the law.

But here’s the hitch: the law that follows next describes when and how a slow driver can resolve the situation. When a driver has five or more vehicles lined up behind him, he’s required to pull over where it’s safe to do so and let the cars by.

I’m not in the business of traffic enforcement, but I’m going to predict that the trigger for an officer making a stop for a slow-moving vehicle would be a driver delaying five or more vehicles and ignoring the opportunity to use a safe pull-out to let those vehicles pass; slow driving alone wouldn’t be enough. If I’m wrong on that, I’d welcome correction from any officer that has stopped a slow vehicle just for being slow.

There is also a provision in the law that allows authorities to establish minimum speed limits if a traffic investigation determines it to be appropriate.

If you’re thinking maybe you can get a minimum speed limit established on Mount Baker Highway, I’d suggest that you keep your expectations slightly higher than your odds of getting hit by an asteroid. Given how few roads in our state actually have minimum speed limits, I’m guessing the threshold for establishing a minimum speed limit is pretty high.

And now, just to add some depth to the conversation, let’s consider the observations that followed the original question:

The speed limit is a reasonable 55 mph: I’m not going to debate the proper speed limit on a given road; that’s up to the traffic engineers and the politicians. I will note that not everyone shares your perspective. I’ve had some people write to ask why the speed limit on Mount Baker Highway is so fast. When some people drive like the speed limit is too slow and others drive like it’s too fast we get speed differentials that are not only frustrating for the fast drivers but dangerous to all drivers.

They don’t care about the road rules: I can’t speak to your personal experience but, as a group, commercial drivers tend to obey the rules of the road better than the rest of us. They get in about a third as many crashes, and when they are involved in a crash the other driver is three times more likely to be at fault. Based on crash frequency, which is a good indicator of traffic law adherence, commercial drivers do pretty well comparatively.

International trucks don’t pay into our road taxes: There’s actually this thing called the International Registration Plan (IRP). It’s a reciprocity agreement between U.S. states and Canadian provinces. It’s required by transportation companies that do business between states and provinces. The trucking companies pay taxes based on the miles that they travel in each state or province. Whether in-state, out-of-state or from Canada, they all pay their share to use the roads.

Nothing I’ve written here will solve the delay in your commute, but hopefully you’ve found it helpful to know that most commercial drivers do actually obey traffic laws, and that all those trucks really do help pay for the roads they drive on. A small consolation, to be sure, but it’s the best I can do.

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Doug Dahl, Target Zero Manager for the Whatcom County Traffic Safety Task Force, answers questions about road laws, safe driving habits and general police practices every Monday. Ask him a question using our form. Target Zero is Washington’s vision to reduce traffic fatalities and serious injuries to zero by 2030. For more traffic safety information visit TheWiseDrive.com.
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