The Exploratory Advanced Research Program Fact Sheet

Cooperative Taking Cruise Control to the Next Level

Exploratory Advanced Research . . . Next Generation Transportation Solutions

Advancing the State-of-the-Art

sing a combination of sensors and The sensor-based adaptive cruise control (ACC) currently in use has significant performance limita- vehicle-to-vehicle communication, U tions. These include a long delay in responding to cooperative adaptive cruise control motion changes by the preceding vehicle and a (CACC) takes cruise control to the next minimum time gap of 1 second in following the preceding vehicle, which is long enough to encour- level, enabling vehicles to adjust their age other vehicles to cut into the traffic stream. speed to the preceding vehicle in their This EAR project will enable CACC to overcome lane. The CACC system can also respond these limitations and provide significantly better performance for drivers. CACC enables vehicles more quickly to speed changes by the to follow each other more closely and accurately preceding vehicle and other vehicles than does conventional ACC, thus improving farther ahead that are beyond the line traffic flow and allowing drivers to safely use their cruise control at shorter gap settings. These of sight. These advancements improve shorter gaps can make it possible to almost the stability of traffic flow, increase double the capacity of a lane. CACC driver confidence, and make shorter also helps drivers to feel more confident using cruise control, as the system activates braking vehicle-following distances possible. action faster than a driver can react to Ultimately this results in better use of lights on the preceding vehicle. a highway’s effective capacity and Researchers will also fill the gaps in knowl- edge and performance that need to be bridged greater fuel efficiency. before field operational tests of CACC can Overcoming the key remaining begin, which will be needed to enable commer- technical challenges to implementing cialization of the technology. Knowledge gaps include defining the maneuvers that vehicles CACC is the goal of the Exploratory have to perform to join and leave a CACC Advanced Research (EAR) Program “platoon” or stream of vehicles under different project “Using Cooperative ACC to Form conditions and demonstrating how vehicle-to- vehicle message sets can be adjusted to support High-Performance Vehicle Streams.” CACC operations. These sets allow vehicles to The California Partners for Advanced send wireless messages to other vehicles about Transportation Technology (PATH) such data as speed, location, and application of . Program at the University of California, Berkeley (UC Berkeley), is conducting Developing Simulation Models this research, which is funded by the The project researchers began their work by Federal Highway Administration (FHWA). identifying operational concept alternatives to The Technical University of Delft in the study in greater depth, such as multiple strate- gies for operating CACC platoons. The research Netherlands is PATH’s research partner. team next developed simulation models to Cooperative Adaptive Cruise Control Taking Cruise Control to the Next Level

represent diverse real-world conditions, including urban versus rural , highways versus arterial roads with traffic signals, and different levels of traffic volume. Traffic simulation models also included a new program developed in the Netherlands, MOTUS (Microscopic Open Traffic), and the commercially available Aimsun model What Is the Exploratory Advanced Research Program? used by the PATH Program. The researchers then used the simulation models to assess the traffic FHWA’s Exploratory Advanced Research flow and energy impacts of the various opera- (EAR) Program focuses on longer term, tional concepts under different deployment higher risk research with a high payoff scenarios. They divided the simulation model potential. The program addresses under- work among the teams at UC Berkeley and the lying gaps faced by applied highway University of Delft so that each team could vali- research programs, anticipates emerging date the work of the other. Metrics assessed by issues with national implications, and the models included increases achieved in traffic reflects broad transportation industry flow capacity per highway lane, reductions in goals and objectives. To learn more about traffic flow disturbances, reductions in vehicle the EAR Program, visit the EAR Web site energy consumption, and savings in travel times at www.fhwa.dot.gov/advancedresearch. along arterial roadways. The site features information on research solicitations, updates on ongoing research, Analyzing the Data links to published materials, summaries of past EAR Program events, and details on The researchers have been analyzing the results upcoming events. of the simulation studies and using the data to identify the next generation of vehicle exper- iments that should be conducted to verify the feasibility of the most promising CACC strate- Importance to FHWA gies. They also have been analyzing data that PATH previously collected in tests of two gener- The project researchers are making important ations of experimental CACC systems. This advances in overcoming the technical challenges analysis is helping to expand understanding that currently stand in the way of implementing of how drivers choose to use both ACC and CACC. These project results will accelerate prog- CACC and to clarify the safety implications of ress toward testing and evaluation of CACC on the shorter gaps in the vehicle stream enabled the , which is the next step in moving the Photo credit, page 1: by CACC. technology closer to real-world deployment. © Leidos FHWA test vehicles simulate a “platoon” or stream of Next Steps Learn More vehicles using cooperative adaptive cruise control, The project researchers will next test their simu- For more information about the EAR project which improves traffic flow lation models at FHWA’s Saxton Transportation “Using Cooperative ACC to Form High- and allows drivers to use Operations Laboratory in McLean, VA. Performance Vehicle Streams,” contact Bob Ferlis their cruise control at in the FHWA Office of Operations Research shorter gap settings. and Development, 202-493-3268 (email: robert. [email protected]). Publication No. FHWA-HRT-16-044 HRTM-30/02-16(WEB)E