It's often the worst part of many people's day - bottlenecked, rush-hour traffic. When the daily commute backs up, drivers lose time, burn fuel and waste energy. Researchers at the U.S. Department of Energy's National Transportation Research Center at Oak Ridge National Laboratory are tackling this problem with cooperative driving automation (CDA), an emerging technology that allows vehicles and traffic infrastructure to communicate, keeping traffic flowing efficiently and safely.
Working in partnership with Argonne National Laboratory, Lawrence Berkeley National Laboratory and the National Laboratory of the Rockies, ORNL brings a unique advantage with the Connected and Automated Vehicle Environment Laboratory (CAVE lab). This immersive facility allows scientists to place real vehicles into virtual traffic scenarios, aiming to represent a digital twin of the real-world interaction between drivers and the environment.
Paired with ORNL's Real-Sim anything-in-the-loop (XIL) platform , a system that connects vehicle hardware and sensors to virtual traffic environments, researchers can link vehicle controls directly to realistic traffic simulations. This allows them to model how traffic patterns and infrastructure interact.
"Autonomous driving often brings to mind self-driving vehicles," said Adian Cook, ORNL's lead researcher on the project, "but there's also a significant infrastructure piece, such as intelligent signal control or cooperative infrastructure. For example, traffic lights can have optimized signals that may also interact directly with connected vehicles to keep traffic moving along."
For the project, the four national laboratories divided the research into categories aligned with each laboratory's strengths, based on real-world mobility challenges. ORNL addressed cooperative merging, using the CAVE lab and Real-Sim XIL to develop and test algorithms that smooth the unpredictable stops and starts of human drivers. ANL led car-following studies leveraging a developed XIL framework, with live demonstrations occurring on controlled onsite roadways. Berkeley Lab advanced modeling and field-test integration through Digital Twin and Vehicle-in-the-Loop evaluations to quantify traffic flow and energy impacts. NLR developed a scalable cellular vehicle-to-everything co-simulation framework to assess communication performance and evaluate the energy- and fuel-saving potential of coordinated vehicle operations such as platooning.
"When looking at merging, you get these weird bottlenecks because people are braking and making sudden moves that disrupt the flow," Cook said. "With CDA, infrastructure can coordinate with vehicles and traffic patterns to keep everything moving smoothly."
This collaboration not only focused on the technical challenges but also demonstrated how inter-laboratory teamwork accelerates innovation.
"We met regularly and delivered as a team," Cook said. "You can get a lot more done with the same amount of time when each group focuses on what it does the best."
For their efforts, the team earned DOE's Vehicle Technologies Office Team Award for Outstanding Collaboration , presented at the 2025 VTO Annual Merit Review in Arlington, Virginia. They were recognized for collaboration between laboratories and projects to advance the understanding and implementation of CDA.
The payoff goes beyond smoother commutes; it also helps save energy.
"If you're getting through intersections quicker and there's less idle time, you're burning less fuel," Cook said. "Our goal in this project is to optimize energy and overall traffic efficiency."
This work positions the U.S. to shape the next generation of intelligent transportation systems, reducing bottlenecks and frustrations on America's roadways.
In addition to Cook, ORNL's team includes Anye Zhou, Joe Beck, Nate Goulet and Hanlin Chen.
UT-Battelle manages ORNL for DOE's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. This CDA project was developed under VTO. For more information, please visit energy.gov/science . - Julya Johnson
