FedEx drivers piloted a platoon of three Volvo trucks down North Carolina’s Triangle Expressway. (image: NCDOT)
Volvo Trucks, FedEx demonstrate 3-truck platoon on North Carolina highway
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Volvo Trucks North America and FedEx are working together to study the benefits of platooning, recently driving three tractors pulling double 28-foot trailers down a public highway with unrestricted traffic. The vehicles used dedicated short range communications (DSRC) to maintain steady following distances as unknown drivers traveled the same tollway.
The three FedEx trucks drove at around 60 mph (97 km/h) with a separation of 1.5 seconds, or about 130 ft (40 m) at that speed. That’s close enough to begin studying the fuel savings gained by drafting, which can be around 10%, while also demonstrating ways platooning can improve safety.
In the late June demonstration, public vehicles freely entered highways and merged between platooning trucks, with trucks automatically slowing to maintain a safe distance. FedEx CEO John Smith focused on safety, noting that response times for braking can be significantly shorter.
Vehicle-to-vehicle (V2V) communications using DSRC lets trailing trucks hit the brakes milliseconds after the first truck slows down, responding far faster than a human responding to brake lights. The test is among the first in the U.S. to take place on open roads with no support vehicles or warnings.
“The U.S. Dept. of Transportation designated the Triangle Expressway as one of 10 proving grounds,” said Beau Memory, Executive Director of the North Carolina Turnpike Authority. “Some of the others are testing facilities. We’re one of the first to allow this type of testing on a public highway without restrictions.”
Volvo calls the technology Cooperative Adaptive Cruise Control (CACC). It augments conventional radar-based ACC with V2V communications. Ten messages are sent every second using DSRC.
“We’re using DSRC, which is IEEE 802.11p, using two SAE standards,” said George Bitar, a Volvo R&D engineer. “J2945 is for message types, J2735 is for individual vehicle data items.”
Bitar explained that the V2V and DSRC messages are constantly compared, and actions are only taken when the two agree. If communications are disrupted, the vehicle relies on ACC. Drivers always steer and remain active while driving.
“This is SAE Level 1 or 2 driving. We’re not doing anything close to autonomous driving," said Keith Brandis, vice president for product planning at Volvo Trucks North America.
Brandis noted that antennas are located on the top of the cab, projecting out so they can be in the line of sight. DSRC is a line-of-sight communication link, he explained. Volvo is also using electronic control units designed internally. The trucks are equipped with cameras and other recording data that gather information being analyzed by FedEx and Volvo.
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