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Jon Osburn and OOIDA’s tour truck, the Spirit of the American Trucker, are taking a break. We’ll let you know when they’re back on the road. Meanwhile, you can still join OOIDA at a $10 discount by calling (816) 229-5791 and mentioning our show. See the full Spirit Schedule. Air date: June 24, 2018.

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The big silly in Big Sky Country

For years I’ve been hearing about California’s split speed limit. And for the most part I think the anger is justified.

Honestly, in the modern parlance, I think you could refer to that phrase as a “trucker trigger word.” It generates anger the moment you say the words “California speed limit.”

That’s why we spend time talking about it. And it’s why OOIDA has put the California split on the Association’s “to do” list for 2017.

But a trucker recently pointed out to me that it is far from the worst example of split speeds in our nation.

That honor may well go to the state of Montana.

On Montana’s interstate highways, cars have a speed limit of 80 mph, while trucks are limited to 65 – a 15 mph differential, among the highest ever.

The problem with split speeds, as I’ve said many times before, is that when different parts of traffic move at different speeds, it causes faster vehicles to bunch up behind slower ones and leads to those drivers passing in a rush when they get the chance.

In short, a speed differential creates the very conditions necessary for accidents to occur while at the same time purporting to be a safety feature.

That’s what surprised me so much when I looked over the Montana Department of Transportation’s web page on speed limits.

Right on the page, just below where the various speed limits are listed, is the gold standard – the 85th Percentile Rule, the basis for uniform speeds created by the federal government so many years ago.

Here’s what it says on the Montana website, right under those speed limits:

“Decisions about rational speed limits are based in part on something called a speed study. During the speed study, data is collected at select locations along the roadway. This data is then analyzed to identify the 85th percentile – the speed at which 85 percent of the people drove the roadway during ideal conditions.

“The 85th percentile speed is typically used as a starting point for setting a rational limit and is considered to be the maximum safe speed for that location.”

To their credit, state officials have correctly and clearly stated the basic rule – accepted across the country and confirmed by decades of research. However, they kind of missed the point.

The 85th percentile rule is the basis for a single, uniform speed limit. And that isn’t being followed when you deliberately force a huge percentage of the vehicles to move at a significantly slower speed.

You can pretty much plug in your cliché of choice here. Can’t see the forest for the trees, missed the boat, as dense as London fog – they all fit in some way. It seems inconceivable that Montana would miss the obvious contradiction on their own website.

For my part, I’ll stick with “it’s as plain as the nose on your face” – for how obvious it is that Montana’s split speed needs to go.


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