As we have discussed before, speeding is a major cause of 18-wheeler accidents. It's the number one cause of deadly tractor-trailer crashes, according to a federal government study based on 2017 statistics. The 2015 South Carolina Commercial Driver’s License Manual spells out in stark detail why speed can kill in a semi-trailer crash. Bear in mind, all truckers study this manual so they can qualify for their license to drive these monster machines—so we know they know this stuff.

The manual makes clear bringing these behemoths to a stop is a matter of distance, speed, and weight.

Stopping Distance—Way More Than You Think

Stopping distance is a combination of three separate distances, measuring how fast the truck travels between the point there is a reason to stop and the point the vehicle actually comes to rest. Remember, these distances are under ideal conditions:

  • Perception distance. This is the distance traveled from the time the trucker sees a hazard—such as your brake lights—until his brain recognizes it. This averages 1.75 seconds. At 55 miles per hour, the 18-wheeler plows another 142 feet before the trucker even thinks to stop.
  • Reaction distance. The truck keeps going until the trucker hits the brakes. On average, this takes another .75 seconds to 1 second. At 55 mph, another 61 feet.
  • Braking distance. This is the distance the big rig strains against the brakes to keep going. At 55 mph on dry pavement with good brakes, the machine chugs another 216 feet before stopping. That’s about as far as some talented NFL quarterbacks can throw the ball. No wonder federal law requires brakes to be inspected before every trip. But the real wonder is, bad brakes remain a critical factor in semi-trailer crashes.

Total stopping distance. Adding all this up under the best of conditions, it takes a semi moving at 55 mph a stunning 419 feet to stop.

Speed’s Effect on Stopping Distance? Worse Than You Think

For full effect, the manual reminds truckers the faster they drive, the worse the impact. It also tells them slowing down reduces braking distance. Then it makes abundantly clear how speed endangers us all: at 60 mph, stopping distance is greater than the length of a football field. At 80 mph, braking distance is 16 times higher than at 20 mph.

The manual instructs truckers they should always drive at a speed enabling them to stop the tractor-trailer in the distance they can see ahead. Fog, rain, or other conditions may require slowing down to meet this requirement. And driving at night with low headlight beams requires slowing down.

The Shocking Truth About Vehicle Weight

Believe it or not, it’s harder to stop an empty truck. This is because 18-wheeler brakes are designed to perform best on a fully loaded vehicle. Kudos to the designers of these brake systems who realized the most important safety system for the vehicle should be geared towards its most typical use.

Don’t Let The Trucking Insurance Company Run Over You

If you’re the victim of an 18-wheeler crash, you’ll face an insurance company that wants to run over your legal rights. You’ll need an experienced lawyer who can handle both the insurance company and the complexities of proving fault and thoroughly presenting the severity of your injuries and the impact on your life. If this speaks to you, check out our site for more information on these topics and feel free to start a live chat with us to tell us your story, right where you are.

Rob Usry
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Rob is a Spartanburg personal injury lawyer. Rob also practices as a workers' compensation attorney.