Runaway truck ramps are used along sections of Arizona highways where we have steep grades. And primarily the
purpose is when a truck or any vehicle loses their brakes, this gives them an option to go into these and get stopped. Runaway truck ramps are used
more often than you would think. If we didn’t have the truck escape ramp on I-17, we probably would have had at least
three crashes within the last year. When we built the
runaway truck ramp for this section of State Route 87, we
looked at the steepness of the grade, the length of the grade and the
frequency of the crashes. A full-size truck lost its brakes and ended up turning over onto the
highway and dumped a lot of oil and road tar all over
the road, which resulted in the highway being closed for
about five hours. We have two types of runaway truck ramps. We have an ascending
and a descending. This is a descending runaway truck ramp. As the truck enters the gravel bed
it, the friction that’s created as the truck
buries its axles, that’s what actually stops the truck. We have an ascending runaway truck ramp, as an example on I-17
near Camp Verde. On an ascending runaway truck ramp, as
the truck enters the arrestor bed, it starts going uphill and
so gravity helps to stop them. The arrestor bed material that is used
to stop the trucks, is really, it’s a rock
about an inch-and-a-half in size. At the beginning of the arrestor bed, the thickness of it begins at about three inches and tapers to about
48 inches within about 150 foot. We put wrecker
anchors along the access road every 100 feet so that when a tow truck has to pull a vehicle out, it can anchor itself
to that position. We’re putting loop detectors on this runaway truck ramp so that when a vehicle crosses over
those, it alerts our Traffic Operations Center in Phoenix
and then they can alert DPS, who can come out and investigate. Every time a runaway truck ramp is
used, it reduces crashes, it reduces road
closures, it reduces injuries and possible fatalities. At ADOT safety is our number one priority, and this is just another method to help
keep the traveling public safe. ADOT… Keeping Arizona moving.