State Route 151 is a popular destination for tourists in Albemarle and Nelson Counties – a scenic road dotted with breweries, wineries and other attractions. It comes to a T at Route 250 – a busy four-lane highway for cars, trucks and buses, so the state decided to install a roundabout to keep that traffic moving. But engineer Will Stowe says a problem was apparent, even before construction was complete.
“We started noticing some commercial vehicles coming down from Afton Mountain and losing their brakes and running into our work zone," he recalls. "We had one truck run into a dirt pile on the side of the road. Another one actually hit a work vehicle that was unoccupied, and our temporary signal cabinet was damaged, and then we had another one just go through the middle of the roundabout and flip over on its side.”
Fortunately, no one was killed or seriously injured, but the Virginia Department of Transportation was concerned enough that it rushed to start another project -- a runaway truck ramp.
“We realized the need for it and went to full design and construction in about a year and a half," Stowe says. "That’s fast. Yes – right-of-way acquisition, utility relocation, design and construction -- about a year and a half is how fast we put this one together."
These special emergency escape lanes typically go up a steep hill, allowing the truck to slow naturally as it sinks into a soft road.
“On a typical gravity fed ramp, the roadbed is made of sand or gravel, so once you get done absorbing the energy the truck has sunk down into the sand or gravel, and it won’t come back down," he explains.
But on 250, at the base of Afton Mountain, that wasn’t possible.
“We just didn’t have the topography here to build something like that. We also looked at a gravel bed, which is kind of like a deep pit of gravel that a truck would sink down into the gravel, and that would absorb some of the energy, but we just didn’t have the length to build one of those here.”
So they turned to that font of all wisdom, the Internet, and discovered a whole different design already used in several states. It’s called a mechanical arrestor escape ramp, and it consists of ten stainless-steel nets arranged to stop almost any vehicle.
“Once you leave the roadway you’ll engage the first net, which is actually designed to stop a car. The first net is pretty light-duty. It’ll stop a car without too much force so that someone inside a car would be okay in it. Then you have about 350 feet of ramp once the truck is in there, and in that ramp we have the car net at first. Then we have additional nets that are designed to stop an 80,000 pound truck going 80 miles an hour.”
And – to prevent cars and trucks from stopping abruptly, causing injury to their drivers, each net is attached to large spools of aluminum tape.
“And that tape getting pulled out is what absorbs that energy, so that net will take the tape with it, and that’s what will slow the truck down.”
Signs on the mountain let drivers know there’s an escape lane ahead -- in case they need it. Once an accident is averted, the driver will require a tow truck and good insurance to pay for the damage.
“If a truck were to use the system we would look for reimbursement to repair the nets. We do the same thing for guardrails and other hardware on the roadside that get struck, so it’d be a similar situation.”
So far, Stowe says, he doesn’t know of anyone using the ramp, but VDOT plans to install a camera so it can keep an eye on its new $5.5 million baby. It might be used sparingly, but the state figures it could prevent costly disasters in the future.
