Driving in circles

News Roads & Bridges June 07, 2001
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A 2,000-ft-long bridge over Wilson Creek in Montgomery County, Virginia, was opened on May 30, but not to the public. The bridge completes the first 2-mile test track of the Virginia Smart Road, a research laboratory where transportation technology will be tested under various controlled traffic and weather conditions.

The bridge connects a turnaround on one side of the Ellett Valley to the rest of the Smart Road on the other. The 1.7-mile test track was completed in March 2000. With the bridge and the turnaround, test vehicles can now drive non-stop around the research road.

At 175 ft, the Smart Road bridge is the tallest bridge in Virginia. It features cantilever construction using cast-in-place segments with concrete-embedded tension steel cables. To build the bridge, concrete was poured in segments proceeding outward from each of the bridge’s four piers.

The bridge’s box girders are hollow, with power and communication lines running the length of the bridge so researchers can install testing equipment. Figg Engineering Group, Tallahassee, Fla., designed the bridge for the Virginia Department of Transportation (VDOT).

The Smart Road is being operated as a research facility by Virginia Tech and the Virginia Tech Transportation Institute (VTTI). Public or private organizations can propose research projects and, if approved, Virginia Tech allocates time on the road.

VDOT, which owns the road, plans to continue to extend the Smart Road in phases until it stretches 5.7 miles between Blacksburg, Va., and mile marker 121 of I-81, after which it will be opened to public traffic. When the road will reach that total length is uncertain.

"There’s not funding currently that’s been identified in Virginia’s transportation budget to finish it," said Laura Bullock, community relations manager for the Salem District of VDOT. "I’ve heard our leaders say they’d like to see it done by the end of the decade." The state budget is revised each year, so each year brings another chance to allocate money for the Smart Road.

The Federal Highway Administration provided the initial funding of $5.9 million in 1991, and Virginia’s governor at the time, George Allen, committed to building a 2-mile test bed. Construction began in July 1997.

"His administration thought that the potential of the road not only for transportation but for research and for economic development in southwest Virginia was so great," Bullock commented, "that he thought that Virginia should go ahead and build this first two miles."

VDOT is also willing to accept funding from other public or private organizations that want to supply money for a phase of the road in order to test the organization’s products. "That’s part of the flexibility of having a research road," said Bullock. "You want it to be able to incorporate the latest technology when that technology is ready to be tested."

Among the research projects scheduled to be conducted on the Smart Road is a one-year study, which began in October 2000, of the surface characteristics of new Superpave pavements. The study is being conducted by the Center for Innovative Technologies. Other research under way includes comparing ultraviolet headlights and ultraviolet-sensitive signs and markings with conventional headlights and markings, an evaluation of multi-sensor weigh-in-motion technology and a study of the behavior of drivers distracted by cell phones and other in-vehicle devices.

A fiber-optic cable network links 400 embedded electronic sensors for monitoring concrete stress, asphalt strain, soil pressure, moisture penetration, vehicle speed and weight and other parameters. The road also features 12 asphalt test sections and two hydraulic cement concrete pavement designs, in addition to three kinds of overhead lights on adjustable-height poles.

Located on a half-mile of the Smart Road are 75 snow- and rain-making towers that rotate 360°, with a peak height of 40 ft. The towers can make up to 2 in. of rain per hour in droplets of various sizes or up to 4 in. of snow or a layer of ice on the road. Bullock estimated that there was about one month a year when the weather in that part of Virginia would be cold enough (28°F) for making snow. The precipitation can be duplicated consistently, allowing researchers with the VTTI or another public or private organization to study new road maintenance methods and automotive products.

VDOT plans to begin this winter training maintenance crews and testing various products for clearing ice and snow off the road without ruining the pavement markings.

"We’re going to be putting down snow anyway," said David Clarke, VDOT’s assistant resident engineer at the Smart Road. "We don’t want to have to wait for [drivers] to learn out on the real streets with real mailboxes and other stuff in their way." Clarke is in charge of maintenance on the Smart Road and the three counties around Blacksburg.

Last winter, the agency did some visibility testing to see how well drivers could see in bad weather and different lighting conditions.

During the ceremony dedicating the Smart Road bridge, General Motors announced that it had signed a three-year agreement with VTTI that could total $4.8 million for several research projects involving collision warning methods and driver-vehicle interfaces.

Virginia Tech President Charles W. Steger remarked, "The research, outreach and economic development partnerships that are being formed will help make Virginia Tech, the Virginia Tech Transportation Institute and the Virginia Department of Transportation the world leader in advanced transportation technology."

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