*Please pass this article along to your non-horsey friends who may not realize how dangerous it is to pull out in front of a fully loaded truck and horse trailer.*
Do you drive a truck and horse trailer with your horse to an event? If you are like most horse owners I know, you sure do.
And we all have stories of when someone pulled out in front of us and nearly caused an accident. It’s so common, I took a quick informal survey among friends the other day and all of us — ALL — had someone pull in front of them and force them to brake suddenly within recent memory.
It’s helpful to understand the science behind driving a truck and trailer, and the simple physics behind speed, movement, weight, and stopping. To start with, the working number is 15 feet per second. This is the typical deceleration rate of a passenger car or light truck on dry pavement, with good tire tread, without loss of control.
At 60 miles per hour, velocity factors state that it takes 6.87 seconds (including a 1 second delay for driver reaction), to come to a complete stop, over a distance of 302 feet, the length of a football field or a good sized show arena. However, in actual field tests, the stopping distance is often 120 to 140 feet, less than half of the projected safety distance. (See the Braking/Stopping Table here)
Remember: these distances and speeds are for a passenger vehicle on dry ground with good tires. The typical passenger vehicle weighs between 2,200-4,500 pounds, average about 3,400 pounds – a ton and a half.
Towing a horse trailer changes ALL of that. Why?
A horse trailer adds WEIGHT. Do you know how much your horse trailer weighs? A better question is how much does your rig, in total, weigh?
Lets start with an abbreviation: GVWR. Gross Vehicle Weight Rating – GVWR is the combined weight of a vehicle with all its passengers and cargo added in. Take a look at your horse trailer ID plate. The GVWR is stamped on it. Mine read 9,800 pounds. That’s its rating, the maximum I can load it.
The trailer itself weighs about 5,000 pounds, so that means I can only load three horses at roughly 3,000 pounds total, and I’m pretty close to my max. Add 500 or so pounds of equipment – I’m at 8,600 pounds. and that’s just the trailer. Let’s add the truck, too.
A Dodge Ram 3500 pick-up truck weighs 11,000 pounds; compact cars range in weight from 3,000 to 4,500 pounds. Mid-size cars and sedans have a weight range of 4,500 pounds to 5,500 pounds depending on model. Light trucks, minivans and sport utility vehicles or SUV’s can weigh 5,000-7,000 pounds. The larger pick-up trucks range from 7,500 to 12,000 pounds.
An aluminum-skin horse trailer, a basic two-horse with a dressing room, can weight 2,500 pounds empty. Steel trailers, 1,000 to 2,500 pounds more. Larger trailers, the kind that hold three or more horses, can vary widely depending upon materials and additions like living quarters. Water, hay, grain all add up the weight, and horses themselves are also heavy – 1,000 pounds (453 kg) is average for our competition horses but a draft cross can be well over 1,200 pounds.
Say you’re pulling a three-horse slant, yourself, a friend, your stuff, two horses – you’re at 8,000-10,000 lbs. with just trailer, add truck — possibly up to 15,000 to 18,000 lbs. — 7 to 9 tons. If you can’t estimate what your stuff weighs, consider that each armload/trip you make to load stuff in the dressing room would be 25 to 50 pounds; six trips, 50 pounds each trip – 300 pounds. Don’t forget yourself, and your friend, spouse, groom — another 200-300 pounds. A bag of grain, 50 pounds; two or three bales of hay? Add another 100 pounds.
Now let’s consider a comparison: a semi truck, for instance. Online I found some generalizations on the weights of over-the-road tractor-trailers. Empty semitrailers can weigh 11,000 pounds. The tractor can weigh 14,000-20,000 pounds. That’s empty — 25,000 to 31,000 pounds; 10 to 15 tons in total for a tractor-trailer combination. Let’s add some cargo — fully loaded can vary, but the total can reach well over 20 tons. Just my three-horse loaded as described above is about half the over the road weight of a semi. Wow. Us, with our loaded truck and horse trailer — we’re about half the size of a fully loaded semi. But don’t get too smug. A regular passenger car is just one TENTH the size of a fully loaded semi. That’s a sobering thought, isn’t it?
So the most important question is: what’s the effect of speed, and mass, on stopping distance?
Here’s the science. When a vehicle is moving, it has kinetic energy.
I’ll let eventer, horseman and scientist Reed Ayers take it from here.
“Kinetic energy is defined by the equation: E = 1/2*mass*velocity squared. Thus if you double the mass of the vehicle, the kinetic energy is twice it was at the same speed.
If you keep the same mass but double the speed, the kinetic energy is 4 times what it was.
The baseline assumption is that with double the mass, stopping distance is roughly doubled. If you double the speed, stopping distance is up to 4 times longer.
To build the complexity, the generic equation for stopping distance is d= velocity squared/2*g* coefficient of friction.
You will see that mass suddenly drops out of the calculation. It is replaced by the friction coefficient and things get more complicated. Friction is function of the mass of the vehicle. (That’s when your tires skid on the pavement, basically, how your vehicle is sticking to the ground as you decelerate.)
But again, it suggests that doubling the mass will double the stopping distance.
The simple take-home lesson is that when you double the mass of the rig, figure you doubled your stopping distance. If you triple the mass, triple the distance, and so forth.”
And so the math tells us we need more room to stop with a trailer than with a car. Especially fully loaded.
What we all know is that we have to drive very defensively with a trailer, keeping a stopping space in front of us at all times and being vigilant about that stopping space, keeping backed off the cars in front of us, and driving with eyes open. I don’t know how to inform an average Joe Driver that when we have horses in our trailers, we can’t stop on a dime, and when you pull out, or pull into our stopping spaces, you cause us to brake suddenly endangering our horses at the very least, and causing an accident at worst. Our defense is to drive slowly and leave plenty of room.
I drive extensively for my regular job and I think the chief reason ordinary drivers don’t give trucks and trailers the same kind of respect they give large tractor-trailers and semis is the profile. A tractor and trailer loom large at you when you are sitting only about 18 inches off the road in a normal passenger car. A pickup with a trailer doesn’t seem so big or imposing and doesn’t have the height, but as I’ve shown, my small rig contains almost half the weight of a big semi.
Many drivers simply misjudge a truck and horse trailer’s stopping distance, thinking they have room to get in your lane in front of you, not realizing that’s a sacred amount of space to a trailer driver. All of us who drive trailers have experienced this, and anxiously stood on the brake to avoid an accident.
In doing a public equestrian “camp” once, an educational day at a local racetrack, we provided a horse trailer, loaded a horse in the trailer, showed what the trailer looked like inside and let them walk through an empty trailer. The kids loved it, but the parents (adult drivers) were fascinated. One told me she’d always wondered what the inside looked like. She asked about the padding. We explained that it was basically to protect the horse for when the trailer had to swerve, or brake. That led to a discussion of braking distance and suddenly we were surrounded by the adults, all listening intently, to what we have to go through when hauling a horse trailer. Most of them had no idea why we needed that MUCH stopping space.
I think there needs to be more education by state motor vehicle departments about the difficulties trailer drivers have in stopping. We need to involve state horse councils, our clubs, and our associations in offering short, punchy, informative and generalized educational programs, demonstrations, or seminars to DMV’s on how passenger car driving habits affect horse trailer drivers. We need to do what we can to show others how dangerous it is to pull out in front of a fully loaded truck and horse trailer. We owe that to Ulando, Icarus, and Jude’s Law.