My good friend Jeff Mann, the true Yard Ramp Guy, has asked me to revisit some of my original contributions. And so: my From the Archives series. This week: Honoring runaway truck ramps.
If you've ever taken I-70 through the Rockies, you've probably seen those steep gravel turnoffs leading up from the road, then abruptly dead-ending, as well as all the signs advertising them.
A Fields Inspection
Those are runaway truck ramps, and they're for semis whose brakes have blown.
The idea is pretty simple: an out-of-control truck can't stop, so the driver keeps his foot off the gas, waits for a truck ramp, then expends all the truck’s momentum going up it.
In practice, though, these ramps are pretty complicated.
First off, you've got to make sure the truck won't roll back down. One way to do that is to have a long flat stretch after an initial rise (though this obviously doesn't work in the Rockies).
Another version uses sand to absorb all the momentum: semi tires are big, but not big enough to take a semi through sand. The problem with sand ramps is that the semis have a tendency to flip on them.
A Glass of McCoy
Finally, there are the ones made of loose, ungraded gravel. They work great but rip up tires and undercarriages.
Steep gravel ramps—like the ones on I-70 are the most common. Moderate damage is better than overturning or rolling back onto the road. It's not an overly complicated issue, but the sheer force of a fast-moving semi complicates the solution, especially since they're nowhere near as durable as they are in movies.
All of that said: never, ever drive a non-semi vehicle up there. It will not survive.
