Article Transportation Research Record 2018, Vol. 2672(22) 67–77 Ó National Academy of Sciences: Transportation Research Board 2018 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/0361198118796375 journals.sagepub.com/home/trr On Augmenting Adaptive Cruise Control Systems with Vehicular Communication for Smoother Automated Following Jan-Niklas Meier 1 , Aravind Kailas 2 , Oubada Abuchaar 3 , Maher Abubakr 4 , Rawa Adla 5 , Mahdi Ali 6 , George Bitar 7 , Richard Deering 8 , Umair Ibrahim 9 , Paritosh Kelkar 10 , Vivek Vijaya Kumar 11 , Ehsan Moradi-Pari 10 , Jay Parikh 8 , Samer Rajab 10 , Masafumi Sakakida 12 , and Masashi Yamamoto 12 Abstract This paper focuses on evaluating, in a structured manner, the potential benefits, along with the implementation and perfor- mance issues, of utilizing dedicated short range communication-based communication in conjunction with adaptive cruise control (ACC) systems. This work was done in the United States under a cooperative agreement between the Crash Avoidance Metrics Partners LLC and the Federal Highway Administration. Designing cooperative adaptive cruise control (CACC) as an extension of ACC, and by using a combination of a comprehensive simulation framework and test vehicles, benefits of vehicular communication on string stability were established, and the performance of the novel CACC-enabling software modules were validated. Another key contribution of this work is the consideration of vehicles with different dynamic responses as a part of a single string. Four light-duty vehicles (hatchback, mid- and full-size sedans, large SUV), each from a different automotive original equipment manufacturer, were retrofitted with common ACC and vehicular communica- tion systems. They were tested under many different conditions to obtain performance data (such as radar sensor readings, etc.) when operating in a vehicle string. These data were then integrated into the simulation environment to develop and vali- date the CACC modules. The paper concludes with a recommendation of some data elements for over-the-air messages to enable CACC functionality. Cooperative adaptive cruise control (CACC) is an appli- cation that uses longitudinal control to improve traffic flow and driving convenience, and, when used in con- junction with supporting technologies, offers the poten- tial to reduce the congestion on most urban freeways and arterials. The CACC system adapts inter-vehicle dis- tances by leveraging real-time information from vehicles in close proximity along with local sensor measurements. In theory, improving the traffic flow stability can lead to improved fuel economy (or energy savings) (1). The United States Department of Transportation has actively engaged in assessing applications that realize the full potential of connected vehicles, travelers, and infrastruc- tures to enhance current operational practices and trans- form future surface transportation systems management through connected vehicles. Prior Federal Highway Administration-sponsored research suggests a key bene- fit of implementing CACC could be attaining traffic flow stability as a result of dynamic and automatic modula- tion of cruise control speeds of a ‘‘string’’ of vehicles (1). Arnaout and Bowling also highlight the improved throughput on a given road segment as a result of more efficient vehicle distribution and consistent flow of traffic when using CACC (2). Other benefits of CACC include higher fuel efficiency resulting from the increased aero- dynamic efficiency provided by decreasing gaps between 1 Volkswagen Group of America, Auburn Hills, MI 2 Volvo Group North America, Costa Mesa, CA 3 Representing: Self, Farmington Hills, MI 4 SUBARU Research & Development, Inc., Ann Arbor, MI 5 Ford Motor Company, Farmington Hills, MI 6 Hyundai-Kia America Technical Center, Inc., Superior Township, MI 7 Volvo Group North America, Greensboro, NC 8 Representing: CAMP LLC, Farmington Hills, MI 9 Ford Motor Company RIC-PAW, Palo Alto, CA 10 Honda R&D Americas, Inc., Southfield, MI 11 General Motors, Warren, MI 12 Mazda North American Operations, Irvine, CA Corresponding Author: Address correspondence to Aravind Kailas: aravind.kailas@volvo.com