Abstract
Changes in driving behavior caused by reduced visibility in fog can lead to crashes. To improve driving safety in fog weather, a fog warning system based on connected vehicle (CV) technology is proposed. From the perspective of human factors, this study evaluates the driving safety based on drivers’ speed change under different fog levels (i.e., no fog, light fog, and heavy fog) and different technical levels (i.e., normal, with a dynamic message sign (DMS), and with a human-machine interface (HMI)). The driving behavior data were collected by a driving simulation experiment. The experimental road was divided into three zones: clear zone, transition zone, and fog zone. To quantify the change of vehicle speed comprehensively, the speed and acceleration were selected. Meanwhile, the vehicle speed safety entropy and acceleration safety entropy were proposed based on sample entropy theory. Furthermore, the changes of each index in different zones were analyzed. The results show that the use of fog warning system can improve speed stability and driving safety in fog zones and can make the driver decelerate in advance with a smaller deceleration before entering the fog zones. The higher the technical level is, the earlier the driver decelerates. Under the condition of light fog, the fog warning system with HMI has a better effect in terms of improving speed stability, while under the condition of heavy fog, there is little difference between the two technical levels. In general, this study proposed a novel safety evaluation index and a general evaluation method of the fog warning system.
Highlights
With the decrease of visibility on foggy days, the number of traffic accidents increases significantly
In China, traffic accidents caused by foggy conditions are far more likely to cause serious consequences than other adverse weather conditions, and the number of traffic crashes caused by fog in China reached 633 in 2017 [2]. erefore, ensuring the safety of driving on foggy days is the focus of the current research
Connected Vehicle Testing Platform. e connected vehicle (CV) test platform was constructed based on driving simulation technology (Figure 1). e test platform consists of a driving simulator, a data management center, a V2V terminal, and a V2I terminal [14]. e driving simulator system consists of a real car, computers, videos, and audio equipment. e scenario is projected onto three big screens, which provides a 130° field of view; the screen resolution of the driving simulator is 1920 × 1080; and the simulator records the operating data in 30 Hz
Summary
With the decrease of visibility on foggy days, the number of traffic accidents increases significantly. Studies investigated the relationship between drivers’ car-following behaviors and the conditions of reduced visibility and found that changes in the car-following distance and vehicle speed could reflect the driver’s nervousness in foggy weather [3, 4]. Drivers’ speed stability and driving safety in foggy weather was investigated in previous research, and the effect of different fog warning system has attracted a great deal of attention. All of these studies have shown that fog leads to changes in driving behavior and does great harm to traffic safety, while the fog warning system allows drivers to know the fog in advance and reduce driving risk. This paper applies the concept of grading assessment to analyze the indexes in driving safety and speed stability in different zones (i.e., whole zone, clear zone, transition zone, and fog zone). e method proposed in the paper can provide a reference for the optimization design of fog warning systems, evaluation indicators, and general evaluation methods for the safety assessment of a fog warning system
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