- Email: [email protected]
9731640 Modeling for passenger car tire
92
Abstracts / JSAE Review 19 (1998) 89-109
9731541 Numerical Simulation of Flow around a Production Vehicle Configuration using Unstructured Grid System Yuji Hanaoka, Yuichi Tsuyuki, Kohichi Kasai, Kiyohira Aoki (Isuzu Motors Ltd.) Reduction of meshing effort is one of the key issues for the practical CFD. In order to treat this problem, an FEM solver using all tetrahedral elements, which leads to automatic grid generation and solution adaptive mesh, is applied to the flow around an automobile. Firstly, influences of the selection of turbulence models) k e & SGS) and of adaptive meshing are discussed and validated using Ahmed's experiment. then application to the production vehicles are presented, in which high ability of reproducing complicated configuration is shown. Also, reliability of the method is discussed through comparison with wind tunnel tests.
9731550 Numerical Investigation of Aerodynamics of Vehicle Underbody with Overset Grid System Yoshihiro Kato, Nariaki Horinouchi, Sayoko Shinano (Toyota Central R&D Labs., Inc.), Masaki Suzuki (Toyota Motor Corporation) An overset grid technique for numerical simulation of flow around a vehicle is described, which is employed to analyze vehicle underbody flow. Sedan and van-type vehicles with fiat underbodies are considered, where square-section cylinders are set at various locations on underbodies as obstacles of flow. Based on the computational results, we investigate the relation between the obstacle location and drag increase. The results also show the reason for drag increase, from which an effective method of drag reduction by improving underbody shape is suggested.
9731569 Mathematical Models for the Study of Motorcycle Handling and Stability Tsuyoshi Katayama (Japan Automobile Research Institute) This paper is a review of mathematical models for the study of motorcycle handling and stability. A basic four-degree of freedom model is reviewed briefly. Then some theoretical models for the treatment of frame flexibility are described chronologically. It is shown that the frame flexibility strongly affects the straight running stability. The effects of rider's body motion are also reviewed. The last part of the paper is devoted to a review of the models for rider's control behavior.
9731578 Motorcycle-Rider System Dynamics by Multibody Dynamics Analysis- Parameter Study on Wobble Mode Dynamics by Experiments and Simulations Hirohide Imaizumi, Takehiko Fujioka (The University of Tokyo) Parameter studies by running experiments and simulations are focussed on Wobble mode oscillation dynamics. Tire internal pressure, road surface friction, accelerating and decelerating maneuvers and dummy load applied to the handle bar, which can be changed easily at the test course, are selected. Further, the effects of front frame and main frames stiffness are simulated by MDA model.
9731587 The Conditions of Stability of Motorcycle and Rider System at Low Speed Motomu Yokomori (Meijo University), Takio Ooya (Meiji University) To maintain the stability of a motorcycle in straight ahead running, the rider steers the handlebars with his hands and leans his body to right and left on the seat at a dead time (time lag) to the motion (banking) of the motorcycle's frame and the motorcycle is moved by lateral motion and yawing, from road disturbances. Since these five movements relate to one another and it is difficult to analyse the motion of the motorcycle-rider system, we have been treating the motorcycle and the rider as one rigid body. In this report, we studied the conditions for stability and the rider's body operation in hand-free riding at low speed, by the equations of motion in which are included the characteristics of the type, the movement of the center of gravity of rider to right and left and the motion of the steering system about the steering axis.
9731596 Development of Motor Actuated Antiiock Brake System for Light Weight Motorcycle Takeshi Wakabayashi, Takushi Matsuto, Kazuhiko Tani, Atsuo Ohta (Honda R&D Co., Ltd. Asaka R&D Center) A brake system with the function of Combinod-Brake System on the rear brake, which distributes the controlled braking force to front, and Antilock-Brake System on front and rear brakes was developed for light weight motorcycles. Using a single channel actuator which consists of reversible motor, electromagnetic brake, double planetary differential gear, etc., this brake system has achieved a low cost and small size, and was applied successfully on a 50 cc motor scooter. 9731604 Development of Riding Simulator for Two-Wheeled Vehicle Hajime Uchiyama, Ichiro Kageyama, Akiko Hirano (Nihon University) This paper describes a fundamental design for a riding simulator of two wheeled vehicle which is used to analyze human factor of riders. At the first step of this research, the relationship between the movement of rider and the behavior of a two wheeled vehicle was observed by experiments on a proving ground. Based on the results, the degrees of freedom which are required by simulator and the main input of the rider are decided. This study continues with examination of an expression method of simulated movements, and production of the riding simulator.
9731613 Development of Motorcycle Simulator for Safe Driving Education Yoshiyuki Takahashi, Tetsuaki Takahashi, Toshiharu Kamijou, Masaaki Ohnuki (Mitsubishi Precision Co., Ltd.) In this paper, the development of a motorcycle simulator for safe driving education is described. The motorcycle simulator consists of a riding unit, a computer, an image generator, a display unit, a sound generator and an instructor operating console. Concepts are as follows: (l) This simulator is used for studying dangerous situations in traffic, not for driving training. (2) Low price, low power consumption and compact size. 9731631 Survey on the Headlamp for Motor-driven Cycles Class 1 in Use Hiroshi Hashimoto, Tsutomu Asoh (Japan Automobile Research Institute) Headlamp illuminance was measured on 133 motor-driven cycles. According to the ITARDA report, the number of fatal accidents resulting from motor-driven cycles colliding with parked vehicles at night was 10.8 times more than the fatal accident rate of passenger vehicles colliding with parked vehicles at night, and 2.4 times more than the fatal accident rate of motorcycles. One of the contributing factors of these accidents is thought to be headlamp illuminance. The minimum illuminance for safe visibility at night is said to be around 4Ix. The results of this survey indicated that 94% of the motor-driven cycles had illuminance levels of at least 41x 15 m in front of the motor-driven cycles. However, other factors concerning nighttime accident rates should also be considered. 9731640 Modeling for Passenger Car Tire Takashi Unoki, Ichiro Kageyama (Nihon University) This study describes the modeling of vehicle tire for static cornering characteristics. As the first step of this research, phenomena of a physical tire model are examined. Transformation of the steel belt in the tire at side slip angle as the displacement of tread base is observed using a 3-D internal displacement meter. The result of the displacement is used to confirm the calculation results of two typical physical tire models which are called "Fiala model" and "String model". It is found that the result of the String model expresses the actual displacement better than that of the Fiala model. 9731659 Transient Tire Horce and its Modeling - Part 1: Slip Angle Input Akira Higuchi (Toyota Motor Corporation), H.B. Pacejka (Delft University of Technology)
Abstracts/JSAE Review 19 (1998) 89-109 The objective of this study is to understand the transient force and moment characteristics of tires involving large wheel slip, and to develop a tire model which is capable of describing those characteristics. It is confirmed that the stretched string tire model is able to reflect major fundamental characteristics of tires with sufficient accuracy under conditions of relatively small slip quantities. The tire model combines a dynamic part based on the physical aspect using the relaxation length concept of stretched string theory, and a steady-state part which is often described empirically, such as the Magic Formula, to ensure accurate steady state description under large wheel slip conditions. 9731668 The Determination of Tire Parameter for Real-Time Estimation of Tire and Road Friction Shunichi Yamazaki, Tadashi Suzuki, Izumi Yamaguchi, (Japan Automobile Research Institute, Inc.), Yoshimi Furukawa (Honda R&D Co., Ltd.) To estimate the friction coefficient between a tire and the road during running, the numerical values of tire parameters, which vary depending on the tire tread wear, are measured. These values of the new tire, however, differ from those of a worn tire as well as from others. This paper describes the determination method of tire parameters for the real time estimation of tire and road friction by use of small braking and driving forces. 9731677 Slip Friction Factor, Amount of Water Formation and Amount of Drainage by Sipe Edge on Ice Eizou hiroki (Hokkaido National Industrial Research Institute) Using an indoor tire friction tester equipped with an inside drum, the relation between amount of drainage by sipe edge and improvement of coefficient of slip friction was studied at various slip ratios and tirelock conditions. Relation between the amount of drainage by sipe edge and slip friction factor of sipe edge rubber surface was determined for the ribbed tire with sipe edge. The results were compared with the relation between slip friction factor of tread rubber surface and the amount of water formation of ribbed tire without sipe edge.
9731686 Measurement of Tire Contour and Surface Strain Distribution under Static and Dynamic Conditions using Fourier Transform Grid Method Masanori Iwase (Toyo Tire & Rubber Co., Ltd.) The sidewall contour area is one of the most important variables in designing automobile tires. Several attempts have been made to measure the sidewall contour in service conditions and several methods have been proposed and are in use. However, it has been very difficult to measure the sidewall contour and surface strains under dynamically loaded conditions. This paper reports a new method which employs an image processing method based on the Fourier transform grid method. A brief description of the method and some results of application under statically and dynamically loaded conditions are presented. 9731695 Macroscopic Analysis of Traffic Accidents in Japan Nobuaki Takubo (Institute of Traffic Accident Research and Data Analysis) Traffic accidents are a serious problem in Japan, as ten thousand people are killed in accidents every year. To solve this problem, scientific accident analyses are necessary. ITARDA (Institute of Traffic Accident Research and Data Analysis) is the only organization integrating various data concerned with accidents, and collecting the detailed data by in-depth accident investigation for accident analysis. We describe the current activity of ITARDA, and the trend of accidents in Japan, by macroscopic analysis.
9731703 The Effects of Declining Tolerance to Impact and Sensorymotor Function Caused by Aging Traffic Accident Rates Goro Fujita (National Research Institute of Police Science, National Police Agency) Older driver's traffic accident rates per kilometers-driven were estimated, analyzing kilometers-driven data from a nationwide questionnaire survey in Japan and police-reported accident data in 1993-1995.
93
The results showed the risks of older drivers killing other road users are about 1.3 times larger than that of 25-64 drivers, while risks of older drivers killing themselves are 2~4 times larger than that of 25-64 drivers. These results suggest the greater effect of older driver's weakness of tolerance to impact on accidents rates.
9731712 The Compatibility Problems in Collisions Analyzed Using Accident Data Koji Mizuno (Traffic Safety and Nuisance Research Institute), Janusz Kajzer (Nagoya University) The compatibility problem is discussed using traffic accident data in Japan. The number of serious and fatal injuries is calculated by the subject cars, which are categorized by their classes and masses. The sports utility vehicle and mini car are found to be the most incompatible car types with high and low aggressivity, respectively. 9731730 Detection of Vehicle Crossing Path at Intersection Nobuyuki Uchida, Kazuo Fujita, Tsuyoshi Katayama (Japan Automobile Research Institute, Inc.) A possible explanation of causative factors in intersection accidents is proposed. General consideration shows that a vehicle which may collide does not move in the visual field. It is shown that a vehicle remaining in the same position in the visual field is difficult to find, and it can be detected only when it comes very close to an intersection, whereas a vehicle which moves in the visual field can be detected easily. These findings show that the human visual search system has inherent characteristics which are a risk factor for accidents in certain types of traffic situation. 9731749 A Study on Secondary Tasks while Driving Miki Mutoh (National Research Institute of Police Science) In order to investigate the state of inattentive driving caused by secondary tasks such as using cellular phones and operating a navigation system, a questionnaire survey was conducted on drivers. Subjects were asked to rate their frequencies and subjective risk level concerning 15 items of secondary tasks. As a result of cluster analysis, the 15 items were classified into 3 groups. Some items which make drivers look aside were classified into one group and were rated dangerous. In spite of the results, statistic analysis shows that accidents were more often caused by looking aside.
9731758 Research on Relationship between Safety and Road Environmental Recognition of Driver Akiyoshi Arai, Ichirou Kageyama (Nihon University), Akihiro Nakazato (Akebono Brake R&D Center Ltd.) This paper describes an analysis of control algorithm for drivers. In the first step of this research, a driver model is constructed using the neural network system. Data on two courses are used for learning to construct the model. One course has a lot of accidents, and the other does not. From the learning, it is found that the model has good description of the driver's control manner not only qualitatively but also quantitatively. Using the model, the sensitivities between each input and output for the model are analyzed. It was shown that the control algorithm method and environmental recognition of the driver are different between two courses. 9731767 Behavior of Drivers on Yellow Traffic Signals-Quantification of Disparity of Behavior by Entropy Sadayuki Tsugawa, Kiyoko Shigeta (Mechanical Engineering Laboratory, MIT1) Disparity of driver behavior, which is a cause of accidents, is considered with data of speeds and positions of vehicles approaching a signaled junction during a yellow period, captured with a roadside vision sensor, and is quantified by entropy. The data features a twodimensional Gaussian distribution, and the common region of two sets of data of the vehicles stopping and of those passing is an area of co-existence of vehicles of different characteristics. Two kinds of data of speeds and distinction of stopping, at and passing through, the junction in the area are quantified by entropy.
Abstracts / JSAE Review 19 (1998) 89-109
9731541 Numerical Simulation of Flow around a Production Vehicle Configuration using Unstructured Grid System Yuji Hanaoka, Yuichi Tsuyuki, Kohichi Kasai, Kiyohira Aoki (Isuzu Motors Ltd.) Reduction of meshing effort is one of the key issues for the practical CFD. In order to treat this problem, an FEM solver using all tetrahedral elements, which leads to automatic grid generation and solution adaptive mesh, is applied to the flow around an automobile. Firstly, influences of the selection of turbulence models) k e & SGS) and of adaptive meshing are discussed and validated using Ahmed's experiment. then application to the production vehicles are presented, in which high ability of reproducing complicated configuration is shown. Also, reliability of the method is discussed through comparison with wind tunnel tests.
9731550 Numerical Investigation of Aerodynamics of Vehicle Underbody with Overset Grid System Yoshihiro Kato, Nariaki Horinouchi, Sayoko Shinano (Toyota Central R&D Labs., Inc.), Masaki Suzuki (Toyota Motor Corporation) An overset grid technique for numerical simulation of flow around a vehicle is described, which is employed to analyze vehicle underbody flow. Sedan and van-type vehicles with fiat underbodies are considered, where square-section cylinders are set at various locations on underbodies as obstacles of flow. Based on the computational results, we investigate the relation between the obstacle location and drag increase. The results also show the reason for drag increase, from which an effective method of drag reduction by improving underbody shape is suggested.
9731569 Mathematical Models for the Study of Motorcycle Handling and Stability Tsuyoshi Katayama (Japan Automobile Research Institute) This paper is a review of mathematical models for the study of motorcycle handling and stability. A basic four-degree of freedom model is reviewed briefly. Then some theoretical models for the treatment of frame flexibility are described chronologically. It is shown that the frame flexibility strongly affects the straight running stability. The effects of rider's body motion are also reviewed. The last part of the paper is devoted to a review of the models for rider's control behavior.
9731578 Motorcycle-Rider System Dynamics by Multibody Dynamics Analysis- Parameter Study on Wobble Mode Dynamics by Experiments and Simulations Hirohide Imaizumi, Takehiko Fujioka (The University of Tokyo) Parameter studies by running experiments and simulations are focussed on Wobble mode oscillation dynamics. Tire internal pressure, road surface friction, accelerating and decelerating maneuvers and dummy load applied to the handle bar, which can be changed easily at the test course, are selected. Further, the effects of front frame and main frames stiffness are simulated by MDA model.
9731587 The Conditions of Stability of Motorcycle and Rider System at Low Speed Motomu Yokomori (Meijo University), Takio Ooya (Meiji University) To maintain the stability of a motorcycle in straight ahead running, the rider steers the handlebars with his hands and leans his body to right and left on the seat at a dead time (time lag) to the motion (banking) of the motorcycle's frame and the motorcycle is moved by lateral motion and yawing, from road disturbances. Since these five movements relate to one another and it is difficult to analyse the motion of the motorcycle-rider system, we have been treating the motorcycle and the rider as one rigid body. In this report, we studied the conditions for stability and the rider's body operation in hand-free riding at low speed, by the equations of motion in which are included the characteristics of the type, the movement of the center of gravity of rider to right and left and the motion of the steering system about the steering axis.
9731596 Development of Motor Actuated Antiiock Brake System for Light Weight Motorcycle Takeshi Wakabayashi, Takushi Matsuto, Kazuhiko Tani, Atsuo Ohta (Honda R&D Co., Ltd. Asaka R&D Center) A brake system with the function of Combinod-Brake System on the rear brake, which distributes the controlled braking force to front, and Antilock-Brake System on front and rear brakes was developed for light weight motorcycles. Using a single channel actuator which consists of reversible motor, electromagnetic brake, double planetary differential gear, etc., this brake system has achieved a low cost and small size, and was applied successfully on a 50 cc motor scooter. 9731604 Development of Riding Simulator for Two-Wheeled Vehicle Hajime Uchiyama, Ichiro Kageyama, Akiko Hirano (Nihon University) This paper describes a fundamental design for a riding simulator of two wheeled vehicle which is used to analyze human factor of riders. At the first step of this research, the relationship between the movement of rider and the behavior of a two wheeled vehicle was observed by experiments on a proving ground. Based on the results, the degrees of freedom which are required by simulator and the main input of the rider are decided. This study continues with examination of an expression method of simulated movements, and production of the riding simulator.
9731613 Development of Motorcycle Simulator for Safe Driving Education Yoshiyuki Takahashi, Tetsuaki Takahashi, Toshiharu Kamijou, Masaaki Ohnuki (Mitsubishi Precision Co., Ltd.) In this paper, the development of a motorcycle simulator for safe driving education is described. The motorcycle simulator consists of a riding unit, a computer, an image generator, a display unit, a sound generator and an instructor operating console. Concepts are as follows: (l) This simulator is used for studying dangerous situations in traffic, not for driving training. (2) Low price, low power consumption and compact size. 9731631 Survey on the Headlamp for Motor-driven Cycles Class 1 in Use Hiroshi Hashimoto, Tsutomu Asoh (Japan Automobile Research Institute) Headlamp illuminance was measured on 133 motor-driven cycles. According to the ITARDA report, the number of fatal accidents resulting from motor-driven cycles colliding with parked vehicles at night was 10.8 times more than the fatal accident rate of passenger vehicles colliding with parked vehicles at night, and 2.4 times more than the fatal accident rate of motorcycles. One of the contributing factors of these accidents is thought to be headlamp illuminance. The minimum illuminance for safe visibility at night is said to be around 4Ix. The results of this survey indicated that 94% of the motor-driven cycles had illuminance levels of at least 41x 15 m in front of the motor-driven cycles. However, other factors concerning nighttime accident rates should also be considered. 9731640 Modeling for Passenger Car Tire Takashi Unoki, Ichiro Kageyama (Nihon University) This study describes the modeling of vehicle tire for static cornering characteristics. As the first step of this research, phenomena of a physical tire model are examined. Transformation of the steel belt in the tire at side slip angle as the displacement of tread base is observed using a 3-D internal displacement meter. The result of the displacement is used to confirm the calculation results of two typical physical tire models which are called "Fiala model" and "String model". It is found that the result of the String model expresses the actual displacement better than that of the Fiala model. 9731659 Transient Tire Horce and its Modeling - Part 1: Slip Angle Input Akira Higuchi (Toyota Motor Corporation), H.B. Pacejka (Delft University of Technology)
Abstracts/JSAE Review 19 (1998) 89-109 The objective of this study is to understand the transient force and moment characteristics of tires involving large wheel slip, and to develop a tire model which is capable of describing those characteristics. It is confirmed that the stretched string tire model is able to reflect major fundamental characteristics of tires with sufficient accuracy under conditions of relatively small slip quantities. The tire model combines a dynamic part based on the physical aspect using the relaxation length concept of stretched string theory, and a steady-state part which is often described empirically, such as the Magic Formula, to ensure accurate steady state description under large wheel slip conditions. 9731668 The Determination of Tire Parameter for Real-Time Estimation of Tire and Road Friction Shunichi Yamazaki, Tadashi Suzuki, Izumi Yamaguchi, (Japan Automobile Research Institute, Inc.), Yoshimi Furukawa (Honda R&D Co., Ltd.) To estimate the friction coefficient between a tire and the road during running, the numerical values of tire parameters, which vary depending on the tire tread wear, are measured. These values of the new tire, however, differ from those of a worn tire as well as from others. This paper describes the determination method of tire parameters for the real time estimation of tire and road friction by use of small braking and driving forces. 9731677 Slip Friction Factor, Amount of Water Formation and Amount of Drainage by Sipe Edge on Ice Eizou hiroki (Hokkaido National Industrial Research Institute) Using an indoor tire friction tester equipped with an inside drum, the relation between amount of drainage by sipe edge and improvement of coefficient of slip friction was studied at various slip ratios and tirelock conditions. Relation between the amount of drainage by sipe edge and slip friction factor of sipe edge rubber surface was determined for the ribbed tire with sipe edge. The results were compared with the relation between slip friction factor of tread rubber surface and the amount of water formation of ribbed tire without sipe edge.
9731686 Measurement of Tire Contour and Surface Strain Distribution under Static and Dynamic Conditions using Fourier Transform Grid Method Masanori Iwase (Toyo Tire & Rubber Co., Ltd.) The sidewall contour area is one of the most important variables in designing automobile tires. Several attempts have been made to measure the sidewall contour in service conditions and several methods have been proposed and are in use. However, it has been very difficult to measure the sidewall contour and surface strains under dynamically loaded conditions. This paper reports a new method which employs an image processing method based on the Fourier transform grid method. A brief description of the method and some results of application under statically and dynamically loaded conditions are presented. 9731695 Macroscopic Analysis of Traffic Accidents in Japan Nobuaki Takubo (Institute of Traffic Accident Research and Data Analysis) Traffic accidents are a serious problem in Japan, as ten thousand people are killed in accidents every year. To solve this problem, scientific accident analyses are necessary. ITARDA (Institute of Traffic Accident Research and Data Analysis) is the only organization integrating various data concerned with accidents, and collecting the detailed data by in-depth accident investigation for accident analysis. We describe the current activity of ITARDA, and the trend of accidents in Japan, by macroscopic analysis.
9731703 The Effects of Declining Tolerance to Impact and Sensorymotor Function Caused by Aging Traffic Accident Rates Goro Fujita (National Research Institute of Police Science, National Police Agency) Older driver's traffic accident rates per kilometers-driven were estimated, analyzing kilometers-driven data from a nationwide questionnaire survey in Japan and police-reported accident data in 1993-1995.
93
The results showed the risks of older drivers killing other road users are about 1.3 times larger than that of 25-64 drivers, while risks of older drivers killing themselves are 2~4 times larger than that of 25-64 drivers. These results suggest the greater effect of older driver's weakness of tolerance to impact on accidents rates.
9731712 The Compatibility Problems in Collisions Analyzed Using Accident Data Koji Mizuno (Traffic Safety and Nuisance Research Institute), Janusz Kajzer (Nagoya University) The compatibility problem is discussed using traffic accident data in Japan. The number of serious and fatal injuries is calculated by the subject cars, which are categorized by their classes and masses. The sports utility vehicle and mini car are found to be the most incompatible car types with high and low aggressivity, respectively. 9731730 Detection of Vehicle Crossing Path at Intersection Nobuyuki Uchida, Kazuo Fujita, Tsuyoshi Katayama (Japan Automobile Research Institute, Inc.) A possible explanation of causative factors in intersection accidents is proposed. General consideration shows that a vehicle which may collide does not move in the visual field. It is shown that a vehicle remaining in the same position in the visual field is difficult to find, and it can be detected only when it comes very close to an intersection, whereas a vehicle which moves in the visual field can be detected easily. These findings show that the human visual search system has inherent characteristics which are a risk factor for accidents in certain types of traffic situation. 9731749 A Study on Secondary Tasks while Driving Miki Mutoh (National Research Institute of Police Science) In order to investigate the state of inattentive driving caused by secondary tasks such as using cellular phones and operating a navigation system, a questionnaire survey was conducted on drivers. Subjects were asked to rate their frequencies and subjective risk level concerning 15 items of secondary tasks. As a result of cluster analysis, the 15 items were classified into 3 groups. Some items which make drivers look aside were classified into one group and were rated dangerous. In spite of the results, statistic analysis shows that accidents were more often caused by looking aside.
9731758 Research on Relationship between Safety and Road Environmental Recognition of Driver Akiyoshi Arai, Ichirou Kageyama (Nihon University), Akihiro Nakazato (Akebono Brake R&D Center Ltd.) This paper describes an analysis of control algorithm for drivers. In the first step of this research, a driver model is constructed using the neural network system. Data on two courses are used for learning to construct the model. One course has a lot of accidents, and the other does not. From the learning, it is found that the model has good description of the driver's control manner not only qualitatively but also quantitatively. Using the model, the sensitivities between each input and output for the model are analyzed. It was shown that the control algorithm method and environmental recognition of the driver are different between two courses. 9731767 Behavior of Drivers on Yellow Traffic Signals-Quantification of Disparity of Behavior by Entropy Sadayuki Tsugawa, Kiyoko Shigeta (Mechanical Engineering Laboratory, MIT1) Disparity of driver behavior, which is a cause of accidents, is considered with data of speeds and positions of vehicles approaching a signaled junction during a yellow period, captured with a roadside vision sensor, and is quantified by entropy. The data features a twodimensional Gaussian distribution, and the common region of two sets of data of the vehicles stopping and of those passing is an area of co-existence of vehicles of different characteristics. Two kinds of data of speeds and distinction of stopping, at and passing through, the junction in the area are quantified by entropy.