Are those runaway truck lanes on the Siskiyou Pass ever used? Is that something ODOT keeps track of?
— Curious Motorist, Ashland
Runaway truck ramps remain a notoriously intriguing feature of transportation infrastructure — for example, we wonder, why aren't they called "drive-away truck ramps?"
Our trusted source at ODOT, spokesman Gary Leaming, has some answers on their role and frequency of use.
The ramps were put in place to help truck drivers if their brakes fail on the steep downgrade, which usually happens after overheating. Because such overheating is more likely to occur in warmer months, ramps typically see twice as much action in the summer.
"Truck drivers, if they miss a gear or their brakes heat up or if they lose them, it's really an important safety feature," Leaming said.
The Siskiyou Pass ramps, which were put in place in the 1980s, are used about four times every winter and twice that in the summer, Leaming said.
The Siskiyou ramps are unique for a couple of reasons. The first is that they're installed in what Leaming said is the highest-altitude stretch of Interstate 5.
Second, a 1986 report on the ramps show the design is atypical. Runaway truck ramps tend to be carved into the side of an upward gradient adjacent to the downward-sloping road. But in the case of the ramps a few miles north of the Oregon-California border, that wasn't an option because the ground to the right of the road drops off abruptly.
The Oregon Highway Division considered a few options, including "a fill on the right side, and switching northbound and southbound lanes so the northbound would be next to an ascending slope," the report reads. The highway division eventually decided on the descending ramps that exist today.
Tow companies get the business of pulling out the big rigs — as well as the occasional unsuspecting car drivers — who make use of the ramps.
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