In this paper, unprotected left turn across path - opposite direction (LTAP/OD) events are studied based on data from Vehicle-Based Safety Systems (IVBSS) Database. To collect these data, sensors were installed on two types of vehicles, light vehicles (LV) and heavy trucks (HT). Then, each vehicle were operated in real world environment for a certain time. Event of left turns were extracted from the sensor data gathered. In a LTAP/OD event, two vehicles, turning vehicle (TV) and straight vehicle (SdV) were considered. After the exaction of left turn events, the trajectory of TV and SdV were reconstructed. Conﬂict is used to describe risky events when collision will occur if the movements of TV and SdV remain unchanged. Through the evaluation of LTAP/OD events, when the straight vehicle is an HT, the driver of the TV tends to turn in a more conservative fashion, with a wider margin. The weather effects on LTAP/OD events were also evaluated, and surprisingly, weather difference in winter and summer doesn’t have strong influence on drivers’ behavior.
Future research opportunity:
LTAP/OD risk can be evaluated based on multiple factors. This article talked about how would the size of the vehicle and the whether condition change the left turn vehicles’ behavior. More information can be extracted and studied in the future, and these information can be used to increase the efficiency and safety of auto-driving vehicles.