Runawayslow against median walls or in gravel shoulders?

First the median: I'm not certain you could effectively slow a truck against a jersey barrier. Remember they are designed to "bounce" the vehicle away from the barrier. They would surely scrub some speed, how much is the question.

As far as runaway ramps on the shoulder, there is one somewhere that is basically an extra-wide shoulder; although it is cabled off from the roadway as to allow only a straight-in approach. A couple of issues arise if gravel traps were placed along the shoulder, as you suggested.

Firstly would be the carnage inflicted upon cars who 'wandered' into the traps. Bye-bye plastic bumper, hello Mr. Wrecker, to pull them out. Not to mention all the gravel sprayed onto the roadway with every high-speed incursion.

With trucks, the gravel spray is an even larger problem; but the dynamics of dropping only one side of truck into a trap is the larger issue. As a truck enters the trap at an oblique angle, there would be significant yaw to the right as those tires entered the trap, caused by the offset drag on the right side. At this point the trailer has not yet entered the trap, and is effectively unrestrained. This is a classic jack-knife setup, and the trailer will likely push the rear of the tractor, increasing the yaw to the right. If the driver is able to get the entire right side of the rig into the trap there is the possibility of a rollover as those traps are fairly deep, and the left side of the vehicle is still up on the pavement. This is why all the traps only allow head-on entry.

Memory fails me, but someone has a hybrid runaway ramp; a very short trap with narrowing concrete walls beyond. It was done because the geography didn't allow room for a standard length trap. I can't imagine it being much fun to recover a truck wedged between those walls!

 

#### well said Hammer166

 

Need to get this into the Myth Busting crew, they would love test this theory out. And it would make for some good entertainment

 

I always wondered about some of them. This one is on a 10% grade just before a sharp right turn and the only way to it is through oncoming traffic. Of course I don't see any other solutions there, just wouldn't want to be the oncoming traffic if someone ever needed to use it.

 

I'll drive, as long as it's not my truck!!!

 

There is a soft concrete developed for runway overshoots, designed to spare the aircraft from costly damage. Problem is, there is always uncertainty with any extraneous braking, as Hammer166 has alluded to

 

Here's a thought:

Maintain the brakes on your truck and keep them properly adjusted, select the proper gear to control your speed during the descent BEFORE you start down the hill, and you'll never need to use a runaway truck ramp.

If you need to apply your service brakes to control your speed on the way down, you're in the wrong gear. Selecting the proper gear keeps the brakes cool just in case you need to stop somewhere on the downgrade. If you're cooking your brakes on the way down using them to control your speed, you won't be able to stop if you need to.

 

This one uses cables in between concrete barriers.[ame="http://www.youtube.com/watch?v=mzEckdEW0Ak"]http://www.youtube.com/watch?v=mzEckdEW0Ak[/ame]

 

I'd rather take my chances with the mountain. No way in hell am I going to intentionally steer my truck into ANYTHING that will be guaranteed to total it out.