Stopping Distance

I tend to stay a safe distance from any vehicles in front of me, therefor avoiding a short stop loaded or empty.

 

I thought it was kind of funny. I used to take the CDL test as truth. Till I started driving. A loaded, granted 76K total, trailer. Does not stop as quickly as an empty. At least from my personal experience. Or at least it doesn't feel like it does.

 

Truck and trailer are designed to stop with 80,000. If the trailer is empty, it takes longer to stop. Because you have to many tires on the ground for the weight. The same with bobtail, it's should be the most difficult to stop. Because you have to many tires on the ground for the weight. Even with antilock brakes. The drive tires can't grab onto the pavement because not enough weight on them. They will just slide on top, with antilock brakes they won't lockup. Most of the stopping power when bobtail is all on the steer axle. If you notice when stopping bobtail and your truck has Applied Brakes pressure gauge. You will see it takes a lot more air pressure on the brakes to stop a bobtail

That's how it was explained to me

 

Here is an article from the NHTSA

A new NHTSA stopping distance chart was published in the last decade. A precise physics equation involving mass, velocity, and kinetic energy is what’s behind determining stopping distance. Thankfully, you don’t have to be a physicist to understand the braking standards. All you have to do is refer to the NHTSA stopping distance chart. It outlines what kind of space your vehicle should be able to stop in.

In ideal conditions, two main things influence stopping distance: truck load and driver awareness. On a dry, clear day a well-rested, sober driver should completely stop from a 60 mph speed in 235 feet, 250 feet carrying loads up to 70,000 pounds. Semis carrying more than than that or ones with three or more axles must stop within 310 feet.

Since a semi weighs over four times as much as a passenger car, it needs much more space to stop fully. And that’s on flat ground. Put the truck on a downgrade and the truck will need even more room to stop. The weather is another issue that affects stopping distance. Rain, snow, and ice create a slick surface on the road that makes it hard for any size vehicle to stop.

While the weather isn’t something drivers can control, there are other factors that affect stopping distance that drivers can take charge of. Keeping to the speed limit, driving defensively, and getting enough rest are important, as is maintaining your rig. It’s an essential step that will help ensure your truck can meet the required stopping distance. Naturally, you’ll always want to make sure everything about your truck is working properly. Well-maintained brakes and properly inflated, good-quality tires make all the difference when it comes to stopping a heavy-duty truck in the shortest distance. Paying especially close attention to brakes and tires during inspections and PMs will help ensure your truck can stop according to the requirement on the NHTSA stopping distance chart.

The NHTSA stopping distance chart requirement for a semi to stop in 250 feet gives big rigs 110 feet less than the length of a football field to come to a complete halt. That might sound like a lot of room, but, all things considered, it’s really not. What’s more, the NHTSA stopping distance chart isn’t a suggestion. The measurements listed are required. Therefore, drivers and fleets typically have to undergo tests to prove their vehicles can stop in the distances stipulated.

At the bottom of it all, it’s a safety issue. Fleet management software is the best way to stay on top of the aspects involved with safety and regulations. Software like Fullbay keeps all your parts and maintenance info in one easy-to-use program. It manages your PM schedules and keeps the data handy for mandatory inspections, whether you have one truck or 100. Give Fullbay a try to see how helpful it can be managing your fleet and helping ensure your trucks meet the NHTSA stopping distance chart requirements.

 

My personal experience is the same. Just basic physics tells us that kinetic energy is greater for a vehicle weighing 80,000+ pounds than one weighing 35,000 pounds, and it would take longer to come to a complete stop.

 

So here you (well, they) are indicating that heavier loads require more stopping distance.

And does that not apply to drivers that are not well rested and possibly drunk?

And the language used about stopping distance... 'should stop in' and 'must stop within' is a bit funny to me.

 

That's odd because I just seen a magic carpet express driver skid straight through an intersection in a new Volvo the other day, unironically after seeing a FedEx driver drop one of their pups at the previous intersection. In Atlanta of course.

 

Anti-lock brakes are of little use when the tires don't have the weight on them for enough traction.

Most truck tires are not even designed for traction in adverse conditions.

 

You can maintain all the safe distance you want. You can't stop the cars from taking up that space.

You give em 10 feet. They're going to take it.. Give them 100 feet and 10 cars will take it.

Cars are ignorant idiots.

 

Attending the Natl Safety Council training to teach their Professional Drivers Safe Driving Course along with the safety director and his boss who was a retired LT from the NJ State Police.

The instructor is droning on and on how he always leaves XX amount of space between his and the vehicle ahead when the boss turns his head cracks a big smile and says "he MUST get cut off a lot!"