BLACKSBURG — Virginia Tech transportation safety researchers cast a man-made fog bank along the university's Smart Road experimental highway at 6 a.m. on a recent morning.
A white SUV approached. At the wheel was a volunteer registered for a sign-visibility study.
As she encountered the fog, the driver hunched forward as if straining to see in conditions ripe for a bad crash. But this was a test.
The test track had been doctored to simulate one of Southwest Virginia's most dangerous highway segments, Interstate 77 at Fancy Gap, at its worst: in a whiteout caused by an occurrence of the same blinding fog that has preceded nine multivehicle wrecks during the past 15 years.
The goal: Find the ideal blend of color and brightness for new changeable speed limit signs designed to break a pattern of I-77 crashes and associated injuries and deaths.
The most recent pileup on I-77 in Virginia, which killed three and injured 25 six months ago, "kind of drove home the point that this is something that we need," said research faculty member Brian Williams.
In 1976, Virginia highway officials dotted the outer edges of Interstate 64 on Afton Mountain in Nelson County with embedded pavement lights to guide motorists who must cross the mountain in fog. They say Fancy Gap's traffic will get a different kind of technical assist with the fog in about a year or two.
The plan is to quickly drop the speed limit between Fancy Gap and the North Carolina line when visibility fades because of fog or other hazards. It's a technology called variable speed limit, and state officials say they're encouraged by the success that Europeans have had with it.
The Virginia Department of Transportation advertised this month for a contractor to design and build the system for the Carroll County mountainside. The new equipment is not a response to the latest crash — it was already in the works — and is scheduled to be completed by July 2015 to assist the estimated 36,000 vehicles that use the road daily.
It'll cost an estimated $8.5 million and rely on electricity and fiber-optic lines being brought to the area at a cost of an additional $6 million.
State officials estimate that fog causes only 7 percent of the wrecks near Fancy Gap, with driver inattention being the main cause. That said, fog-related wrecks tend to be bad, involving an average of 11 vehicles compared with an average of two vehicles in non-fog-related crashes, according to a 2002 study by the Virginia Highway and Transportation Research Council, which combines the efforts of VDOT and the University of Virginia. Fog-related wrecks led to 2.6 injuries apiece, compared with 0.6 injuries apiece for non-fog-related crashes, the 2002 study said.
The area between mile markers 2 and 9 on I-77 is a "relatively dangerous area even when fog is not present," the report said.
Right now, there is one electronic message board in each direction near the fog-prone area and several well outside it to give warning. When the latest project is done, there will be 22 variable speed limit signs in both directions between mile marker 12, two miles south of Hillsville, and the North Carolina line, along with cameras and detectors for fog, wind and traffic.
What the changeable speed limit signs look like is expected to be determined by the study at Tech.
"Basically the approach that VDOT is taking is to try and gather as much information as possible about the road and sort of mass it into a cohesive message and deliver that message to the driver," said Ronald Gibbons, who directs the Center for Infrastructure Based Safety Systems at the Virginia Tech Transportation Institute.
The message will take the form of a speed limit tailored to the conditions. It's not yet clear in what increments the limit will fall below 65 mph.
Determining the visibility sweet spot
Two test subjects participated in the sign-visibility test performed on the Blacksburg test bed Sept. 4.
To make the fog, a crew activated jets above the two-lane track that loudly hissed with moist, compressed air. The drivers kept their windows up and their lights on, and were allowed to accelerate up to 20 mph in the fog in the university test vehicles, aging white Ford Explorers, Gibbons said.
In all, Tech has lined up 48 members of the public to drive a looping course, view electronic speed limit signs and say what they see. Each driver runs the course 12 times with fog and 12 times without, and between each pass, researchers change a sign at two locations. The combinations include black on amber, amber on black, white on black, black on white, and blue, green and red on black. Brightness is varied as well.
To mix it up, there are day studies and night studies. All drivers are either age 35 or younger or age 65 and above.
A researcher riding along records data live with a press of a button — one press when the driver first announces seeing the sign, another press when the driver correctly states what's on the sign, and another press when the vehicle reaches the sign, Williams said.
A roof-mounted green laser feeds visibility measurements into the system, allowing researchers to later calculate how well each sign configuration showed up in relation to the fog. The goal is to find the most-legible combination or combinations.
A fall 2012 VDOT study looked at decades of use of variable speed limits in Europe. Germany reported that crash rates fell by 20 percent after variable advisory speed limits were installed on a section of the Autobahn highway, which has no speed limit but a normal advisory limit of 80 mph, the study said.
In the Netherlands, variable speed limits were credited with a 16 percent decline in crashes.
Whether Virginia drivers will comply with variable speed limits is unknown, Gibbons said, and is a concern. But until cars can stop themselves before an impact, the technology may help.
Some people aren't willing to wait to find out. They have sworn off using I-77 in the Fancy Gap area.
"I don't travel that road even when the weather's pretty," said Phil McCraw of Cana, a member of the Carroll County Board of Supervisors who gets where he is going on Virginia 52.
That's the old, curving two-lane highway that has been around since before I-77 was built. He thinks it's a safer road.
So do school officials.
Carroll County school buses consistently use Virginia 52 in lieu of I-77 between Fancy Gap and Cana. They take Virginia 52 for all northbound trips, but school buses could not meet a weight limit for southbound Virginia 52 last year and had to use I-77 instead. However, highway officials granted school buses access to southbound Virginia 52 effective at the beginning of the current school year last month at the school system's request, said Mark Burnette, assistant superintendent.
Parents in the area voiced "concerns about the welfare of their kids coming up and down Interstate 77," Burnette said, citing heavy tractor-trailer traffic and steepness.
Joey Haynes, a Carroll County school board member with a son who rides the school bus across the mountain, called the planned new technology "encouraging" in that the community would welcome an improvement in safety. He couldn't say whether school officials will revisit school bus routing after the project has been installed.
"You'll still have the same mix of commercial vehicles and fast-moving traffic and weather conditions. I think those things will always be a constant. Whether or not technology can figure out a way to secure those concerns is just something we'll have to wait and see," he said.
The crash on March 31, 2013, was the latest of nine multivehicle collisions in 15 years along the sloped stretch of Interstate 77 hugging a mountainside between Hillsville and the North Carolina line and the one involving the most fatalities and vehicles.
|March 31, 2013||95||3||25||South|
|Nov. 16, 2010||75||2||16||South|
|Oct. 27, 2006||30||0||10||South|
|Sept. 25, 2005||50||0||25||Both|
|Jan. 21, 2005||20||0||5||Both|
|May 21, 2001||40 to 50||0||12||South|
|Jan. 18, 2000||60||2||na||South|
|Oct. 5, 1998||46||0||10||North|
|Feb. 14, 1997||65||0||11||South|
About this report
This package is based on more than 369 photographs obtained from Virginia State Police, 24 crash reports obtained from the Virginia Department of Motor Vehicles, court papers, a visit to the crash scene and about a dozen interviews with motorists, police and transportation experts.