附录：
Safety Assessment of Driver Overtaking Behavior on Two-Lane Highways
Yaqin QIN1, Jian XIONG1, Xiujuan ZHU1, and Jianshi LI1
Faculty of Transportation Engineering，Kunming University of Science and Technology (KUST), Kunming, Yunnan 650224, China; PH (86) 0871-3802298; email: qyq_email@foxmail.com
ABSTRACT
Safety study of driving behaviors to reduce traffic accidents is of great significance. The primary objectives of the study were to investigate the relation between driver overtaking behaviors and traffic safety. Twelve drivers of different proficiency were selected for an experiment on a driving simulation system platform. A simulation scene of overtaking on a two-lane highway was set up. The subjects overtook in the virtual scenarios at different speeds. A total of twelve parameters - including speed, acceleration, time of overtaking process, the changes of distance and other parameters - were extracted during the experiments. These data together with the results of a DBQ (Driving Behavior Questionnaire) were analyzed and evaluated by the multiple linear regression method. The results showed that three motion parameters had a strong correlation with drivers' safety. Finally, the study presents a linear model of safety assessment of driver overtaking behavior on two-lane highways. The model may help to identify safe and unsafe drivers and reduce the number of traffic accidents.
INTRODUCTION
Two-lane rural roads make up the majority of the road network in many countries. In 2009, China’s rural mileage reached 3.2 million km, and highway mileage of rural roads accounted
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for more than three-quarters of the total mileage (Li, 2009). Rural roads are also dominant in traffic fatality statistics. Lamm et al. (2007) has estimated that more than 60% of all fatalities in traffic occur on two-lane rural roads.
Overtaking maneuvers on rural two-lane highways is a common phenomenon. When drivers have potential to overtake and there is sufficient space to overtake on the road, overtaking demands will be created. In the process of overtaking, the driver determines whether there is sufficient and adequate passing sight distance and time headway of the opposing lane and whether there is an adequate inserting gap of the same lane. Then drivers decide whether the overtaking should be implemented. Since overtaking conditions and drivers behavior varies, the overtaking process is very complex. It is affected by road conditions, alignment, sight distance, vehicle type, speed, and drivers, among other things. Greenshields et al. (1935) was the first to establish the minimum requirements for safe passing under average traffic conditions. Bar-Gera, H. and Shinar, D. (2005) have shown this maneuver is associated with an increase in crash risk, because it involves driving in the lane of the opposing traffic direction. At the same time, Harris (1988) found that most drivers are indeed aware that overtaking is a risky maneuver by self-report ratings. At present, many existing studies (see reviews by Tang, 2007; Geertje, et al., 2007; Wei, et al, 2000; Rong, et al., 2007; Shao, et al., 2007) focus on overtaking modeling. A few studies assessing the safety of driving overtaking behaviors generally examine driver gender, age and other characteristics (David, et al., 1998), or by DBQ questionnaire to survey (Ozkan and Lajunen, 2005). It is difficult to obtain drivers’ real-time direct performance of overtaking maneuvers due to the danger of the experiment on a real road.
To assess driving behaviors in overtaking, we employ a driving simulator. Various studies have shown that driving simulators can provide reliable observations of drivers’ behaviors (Blana, 1996; Desmond, and Matthews, 1997; Van der Winsum and Brouwer, 1997; Ellingrod et al. 1997.). In this study, we focus on individual differences in the safety of
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overtaking maneuvers with DBQ and real-time behaviors on a driving simulator. The results of the study are designed to distinguish unsafe drivers from other kinds of drivers. METHOD Participants
Twelve volunteers participated in the experiment. The sample comprised six men and six women between 24 and 55 years old (M= 28.08 years, S.D. = 5.6). There was an equal balance of males and females. All had a valid driver’s license. The mean number of years driving experience was 5.25 years and, on average, drivers drove 3.08 hours per week. All had normal or corrected-to-normal visual acuity, and did not take any kind of medicine. Apparatus
A full-size advanced driving simulator (KMRTDS, developed by the simulation laboratory of Faculty of Transportation in Kunming University of Science and Technology, China) was used in this study. The simulated vehicle cab, an Axial, featured all normal displays and controls (steering, brakes, and accelerator) found in a vehicle. Different driving scenarios were projected onto a 1500 cycle screen, with sound effects of the vehicles in motion broadcasted by two-channel amplifiers. With the optimized image processing speed of more than 30 frames per second and the calibration for the speed and visual, KMRTDS can ensure the real-time of the system and the fidelity of the experimental scene. Outlook of the driving simulator is shown in Figure 1. KMRTDS can provide up to 68 motion parameters to analyze the behaviors of the vehicle and drivers. Experimental design
The purpose of this experiment is to evaluate the safety of driving behaviors during driver overtaking at different speeds on two-lane highways. In China, the largest design speed of a two-lane highway is 80km/h. On the other hand, the sight distance of overtaking is different with the different speeds of experimental vehicles. In this experiment, we set the speed of experimental passed and oncoming vehicles to 30, 37.5, 45 and 60km/h respectively. The
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