Effective Indicators of Partially Automated Truck Platooning [techbrief]

Federal Highway Administration2021PDFBriefRoldan, Stephanie M.Gonzalez, Tracy B.United States. Federal Highway Administration. Office of Research, Development, and TechnologyUnited States. Federal Highway Administration. Office of Research, Development, and TechnologyUnited StatesTraffic platooningAutonomous intelligent cruise controlAutomationTravel behaviorTruck platoonPlatooningPartial automationCooperative adaptive cruise controlDriver behaviorSafetyFHWA-HRT-21-016DTFH61-13-D-00024The development of automated trucking technology is progressing rapidly, and increasing numbers of on-road pilots suggest that full-scale commercial deployment of partially automated truck platoons on public roads is forthcoming.(1) In the United States, platoons typically consist of two to four trucks equipped with cooperative adaptive cruise control (CACC) to achieve close-distance following over long trips to yield fuel and cost savings.(2\u20134) As widespread commercial deployment of automated trucking technology draws near, it is important to assess the potential effects of partially automated truck platoons on other road users. In addition to the novelty of partially automated vehicle operations, the sheer size of a group of trucks engaged in close-distance following may be a physical obstacle for\u2014and pose safety concerns to\u2014other road users. Supporting safe interactions between other road users and truck platoons also benefits platoons since non-platoon vehicles cutting between or abruptly cutting off platooning trucks risks disrupting the constant-speed and close-distance following that is necessary for partially automated truck platoons to achieve financial and environmental benefits. Despite the advanced progress in automated trucking and platooning technologies, the effects of truck platoons on other road users, and vice versa, remain unclear. Interactions between light and heavy vehicles have important implications for road safety as well as public acceptance of heavy truck automation. In addition to other drivers' potentially disruptive or risky behavior around truck platoons, the way in which road users perceive and respond to truck platoons is likely to influence societal trust in, and continued adoption of, similar automated driving technologies. Given that most drivers of light vehicles will be unfamiliar with platooning technology during its early deployment, communicating information about truck platoon operations to surrounding road users may improve drivers' comfort and perceived safety near platoons, facilitate earlier and safer navigational planning, and discourage cut-ins between platooning trucks. However, standards regarding signing or indicators for automated vehicles and truck platoons have yet to be established. Therefore, this research effort first sought to identify terms and language that appropriately reflect platoon operations and characteristics. After identifying recognizable terms and essential platoon characteristics, the research team developed a set of four novel signs and indicators designed to support road user comprehension, comfort, and safety near truck platoons. A follow-up experiment evaluated the effectiveness of these novel signs and indicators in supporting road user comprehension and perceived safety of a simulated partially automated two-truck platoon.105