Naturalistic Driving Behavior Analysis under Typical Normal Cut-In Scenarios

Cut-in scenarios are common and of potential risk in China but Advanced Driver Assistant System (ADAS) doesn’t work well under such scenarios. In order to improve the acceptance of ADAS, its reactions to Cut-in scenarios should meet driver’s driving habits and expectancy. Brake is considered as an express of risk and brake tendency in normal Cut-in situations needs more investigation. Under critical Cut-in scenarios, driver tends to brake hard to eliminate collision risk when cutting in vehicle right crossing lane. However, under less critical Cut-in scenarios, namely normal Cut-in scenarios, driver brakes in some cases and takes no brake maneuver in others. The time when driver initiated to brake was defined as key time. If driver had no brake maneuver, the time when cutting-in vehicle right crossed lane was defined as key time. This paper focuses on driver’s brake tendency at key time under normal Cut-in situations. Environment factors (for example, traffic condition and road type), cutting-in vehicle type and motion factors were considered as influence factors. To comprehensively take those factors into account, cluster analysis was adopted to extract typical Cut-in scenarios from naturalistic driving database. Seven typical scenarios as well as driver’s behavior data were obtained. It is found that there exists certain linear relationship between Time headway (THW, equals to relative distance divided by subject vehicle velocity) and relative velocity. The linear correlation of brake cases is good, but linearity of no brake cases is weak. In each typical Cut-in scenario, driver's brake behavior was demonstrated by scatter plot on THW-relative velocity plane. This plane was divided into several zones where driver tends to brake or not to brake. A special situation is that cutting-in vehicle surpasses subject vehicle and merges in a brutal way and under such situation driver will brake hard.