Virginia Tech Transportation Institute researchers' new project could change the way motorists navigate through traffic lights, making the everyday action safer, smarter, and cheaper – the last by cutting fuel costs and likewise reducing pollution.

The effort is designed to keep vehicles as close to “fuel optimum speed” as possible, basically that sweet spot when a car’s speed is sufficiently high but fuel use is at a minimum with little slow-and-go maneuvering. Leading the study is Hesham Rakha, director of the transportation institute’s Center for Sustainable Mobility and the Samuel Reynolds Pritchard Professor of Engineering with the Charles E. Via, Jr. Department of Civil and Environmental Engineering.

In the coming weeks, Rakha and his team will put volunteer drivers through a series of real-world tests at the Virginia Smart Road, located at the institute’s Blacksburg campus, where the very idea of how participants enter an intersection will undergo a great change because of automated-vehicle technology. (The project for now involves cars only, not trucks or buses.)

Called Eco-Cooperative Adaptive Cruise Control, this in-development driver-assistance, connected-vehicle technology tool can assist the motorist in or fully automate the action of slowing or accelerating a vehicle according to the traffic light ahead, be it red, green or yellow. 

Through connected infrastructure installed on the side of the road, a vehicle equipped with the Eco-Cooperative technology will “know” when the light ahead will change color. Removing the guess work will improve the driving experience for driver and car, said Rakha.

“This is important to drivers because it will enhance safety, reduce their fuel consumption, delay or reduce idling, and definitely reduce wear and tear of the vehicle,” said Rakha adding that the more drivers who use the technology in a given area would boost overall savings of fuel. “The hook will be safer driving and fuel savings that they can achieve from this system.”

Every act of acceleration, braking, and idling deviates the car from its fuel optimum speed, reducing fuel efficiency, said Rakha. The so-called “dilemma zone” – when the light is briefly yellow before turning red – will be considered. “From an environmental and traffic mobility standpoint, it is better that drivers run a yellow light if they can do so prior to the traffic signal turning to red,” said Rakha. “This basically reduces the queue length upstream of the traffic signal by one vehicle and also eliminates a full stop.”

Using either computerized assistance for the driver or automating all acceleration or deceleration actions, a driver can see fuel savings as high as 30 percent in more than two dozen top-sold vehicles in the United States, said Raj Kishore Kamalanathsharma, a senior consultant at Booz Allen Hamilton, who was Rakha's research partner in Virginia Tech's civil engineering program when the two wrote their study proposal.

“The average reduction in the total delay reaches 65 percent within the vicinity of traffic signalized intersections,” Rakha and Kamalanathsharma wrote in their research proposal for the test project. “The results also demonstrate that at levels of market penetration less than 50 percent, the system does not produce system-wide fuel and delay savings.”

In some cities, the Eco-Cooperative could become a reality within five years, added Rakha.

Connected-vehicle technology already is a growing trend, led in part by the institute, which has been conducting research into the field since 2001. In 2014, the U.S. Department of Transportation called for an eventual requirement for vehicle-to-vehicle communication technology in all cars and light trucks on the nation’s highways. The institute was tapped to design the integration framework that would allow vehicles to “talk” with drivers and with other automobiles on the roadway, in addition to highway wireless infrastructure and devices.

The institute, in partnership with the Virginia Department of Transportation, previously launched a $14 million connected-vehicle test bed near Fairfax, Virginia – one of the most congested corridors in the nation – that contains dozens of wireless infrastructure devices along roadways, all communicating with dozens of cars, trucks, and motorcycles equipped with wireless technology. The system launched in 2013.

During the Eco-Cooperative study on the Smart Road – where wireless infrastructure devices are installed – test scenarios will include allowing the car to take full driving control as it enters an intersection or assisting the driver in part when entering the section or merely making an oral suggestion to the driver on what action to take as he or she nears a signalized intersection.

Live road tests of the technology will move from the Smart Road test bed to the highways of Qatar as the project is perfected, said Rakha.

Joining Rakha and Kamalanathsharma in the study are Hao Chen, a research associate; Hao Yang, a post-doctorate researcher; and Ihab El-Shawarby, a senior research associate, all with the institute; and Mani Venkat Ala of Hyderabad, India, and Mohommed Almannaa of Riyadh, Saudi Arabia, both master’s students in civil and environmental engineering.

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