RESULTS

The 100 Volvo Class 8 tractors deployed were divided into three groups. The first group of 20 “Baseline” tractors was operated without the three safety systems for approximately two years. The second group of 30 “Control” tractors was operated with the CWS only. Additionally, some Baseline tractors were converted to Control tractors by the activation of the CWS at the conclusion of the two year period during which Baseline data were collected. The third group of 50 “Test” tractors was operated for 3.5 years with active CWS, ACC, and AdvBS.

All 100 tractors were equipped with a data acquisition system designed by the Army’s Aberdeen Test Center. Engineering data were collected onboard the tractors to evaluate the dynamic state of the vehicle (e.g., speed), the dynamic state of a lead vehicle (e.g., range and range rate), the location of the vehicle in the United States, the driver’s actions (e.g., braking or turning), and the functions of technologies (e.g., alarm sounded by the VORAD CWS).

For commercial vehicles, the CWS alone and the bundled system of the CWS, ACC, and AdvBS were found to provide a significant safety benefit during periods of prolonged highway speed driving (>24.6 m/s, or >55.0 mi/h) and during near-crash events that happen at a high speed. Specifically, when more than 75 percent of the time spent was spent at highways speeds, there is a statistically significant reduction in the exposure to conflicts for trucks equipped with the CWS, demonstrating that the CWS is more effective at preventing conflicts when used at highway speeds than at lower speeds. The results for the bundled system compared to no safety system indicated that there is a significant reduction in the exposure to conflicts for trucks with the bundled system as compared to trucks with no safety system when more than 47 percent of the time is spent at highway speeds in a three hour period, independent of cruise control usage.