Truck Crashes and Coasting – No Clear Correlation.

Written by Gregory Monte.

Coasting Down a Hill in Your Vehicle is Illegal?

My last two blog posts focused on the surprising (to me, at least) fact that coasting a vehicle down a hill is illegal in most states.

Here is the break-down in case you missed those posts:

  • States Where Coasting is Legal for All Vehicles: Pennsylvania, Minnesota, Massachusetts, Missouri, North Carolina, Ohio and Wisconsin.
  • States Where Coasting is Only Illegal for Trucks/Buses: Vermont, Connecticut.
  • All other states prohibit coasting for all vehicles.

When I first wrote about this topic, I ridiculed the prohibition on coasting in a post called Dumb and Dumber – These two Virginia driving laws are as silly as it gets.

But then I received some interesting feedback on Facebook which made me rethink my initial comments.

Richard RubenackerCoasting down a long steep grade can be very dangerous. It makes it very difficult to get the transmission back in gear because the gears inside the transmission are spinning so fast. If you get your brakes hot and are flying downhill in neutral, you might be in serious trouble. That’s why you see the signs on the highway that remind truckers to use a lower gear on downhill grades… it’s about safety👍”

Paul Taylor Stop Sign Ticket Defenseit’s self enforcing, when they find you in the ditch with smoking brakes.”

So, in last Friday’s post Coasting Down a Hill is Illegal in Most States, I included the following caveat related to coasting:

“Before the detractors start chiming in, I already understand why a several ton truck shouldn’t do this. But I made the point in that earlier blog post that I did it all of the time in my 5-speed Honda Civic and had no issues.”

The Research

Which brings me to the point of this particular blog post.  I decided to do a bit of research on the issue of traffic accidents and trucks.  I found a website published by the Federal Motor Carrier Safety Administration which has detailed information about large truck and bus crashes.  The data on this website appears to show that there is not much of a correlation between coasting laws and crashes.

Now, I am not claiming to have done an in-depth statistical study of the issue.  After all, I am not an academic researcher.  Instead, I am just offering a perspective which is backed by at least some element of analysis. 

Here are the results:

  • In the states that prohibit coasting, fatal crashes involving large trucks per million people is an average of 15.64.
  • For those states which allow coasting, the comparable number is 11.73.
  • The most common pre-crash event leading to the eventual disaster is not “Large Truck’s Loss of Control” (2.3%) which might develop as a result of coasting, but “Other Vehicle’s Encroachment into Large Truck’s Lane (36.6%)
  • The only other possible category which might be associated with coasting is the category called “Large Truck Movement.”  This category mentions deceleration as a factor causing a crash, although it doesn’t specify why the truck couldn’t decelerate in time.  The percentage is 20.1%.

It is an undeniable fact that states that allow all vehicles to coast have fewer crashes (11.73) per million people than states that prohibit this very same coasting (15.64).  As indicated earlier, this is not a full-on statistical analysis of the coasting prohibition, but it should offer some “food for thought” on the issue.


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