FIELD EVALUATION OF SAFETY IMPACTS OF ADAPTIVE CRUISE CONTROL By: Hesham Rakha 1 ., Jonathan Hankey, Angela Patterson, and Michel Van Aerde ABSTRACT This paper provides an attempt at evaluating the safety impacts of an Adaptive Cruise Control (ACC) system relative to Conventional Cruise Control (CCC) utilizing data that were gathered as part of a Field Operational Test (FOT) in Ann Arbor, Michigan. The safety of the ACC system is quantified considering three surrogate safety measures. The first safety measure considers the car-following behavior of an ACC system relative to manual driving in order to identify potential differences in driver/vehicle aggressiveness. The second safety measure considers changes in demands on driver resources associated with ACC technology. The third, and final safety measure, considers differences in number of braking maneuvers and near encounters associated with ACC and CCC driving. These three surrogate safety measures are utilized to identify any potential hazards that could be associated with an ACC system. The three surrogate safety measures demonstrate consistency between ACC and manual car-following behavior, an increased usage of cruise control with adaptive features, reductions in driver manual resources and potential reductions in visual resources, and no differences in braking interventions and “near encounters.” These findings collectively suggest that the use of ACC does not appear to impose a safety hazard on the transportation system. Keywords: Adaptive Cruise Control, Intelligent Transportation Systems, Intelligent Vehicle Initiatives, and Traffic Safety 1. INTRODUCTION Prior to describing the specifics of the study approach this section provides a brief background of the similarities and differences between conventional and adaptive cruise control systems. Finally, the objectives of the paper are identified together with the layout of the paper. 1.1 Conventional Cruise Control Operation Conventional cruise control takes over the accelerator operation at speeds over 40 km/h (25 mph) when it is engaged. Activation requires that the ON button is pressed and setting a desired speed requires pressing the SET button, as illustrated in Figure 1. The user has to press the ON button to activate the system every time the engine is started. In order to deactivate the system while maintaining the set speed in memory, the driver has the choice of either making a soft tap on the brake pedal or pressing the CANCEL button. Pressing the OFF button or turning off the ignition turns the speed control system off and erases the memory. In order to resume to a previously set speed, the driver needs only to press the RESUME button as long as the speed exceeds 40 km/h (25 mph). The driver can also vary the speed setting by either pressing and holding the ACCEL button and releasing the button when the new set speed is established, or by tapping the ACCEL button. Each tapping of the ACCEL button results in a 3.2 km/h (2 mph) increase in the vehicle speed. In order to decrease the speed while the speed control is ON, the driver needs to hold the COAST button and release it when the desired speed is reached. 1 Corresponding Author: Assistant Professor at the Charles Via Department of Civil and Environmental Engineering, Virginia Tech. Virginia Tech Transportation Institute, 3500 Transportation Research Plaza (0536), Blacksburg, VA 24061. E-mail: rakha@vtti.vt.edu. Telephone: (540) 231-1505.