Performance of collision damage mitigation braking systems and their effects on human injury in the event of car-to-pedestrian accidents

Matsui, Yasuhiro; Han, Yong; Mizuno, Koji

Affiliations

¹National Traffic Safety and Environment Laboratory, Japan

³Hunan University, China

Abstract and keywords

The number of traffic deaths in Japan was 4,863 in 2010. Pedestrians account for the highest number (1,714, 35%), and vehicle occupants the second highest (1,602, 33%). Pedestrian protection is a key countemleasure to reduce casualties in traffic accidents. A striking vehicle's impact velocity could be considered a parameter influencing the severity of injury and possibility of death in pedestrian crashes. A collision damage mitigation braking system (CDMBS) using a sensor to detect pedestrians could be effective for reducing the vehicle/pedestrian impact velocity. Currently in Japan, cars equipped with the CDMBS also have vision sensors such as a stereo camera for pedestrian detection. However, the ability of vision sensors in production cars to properly detect pedestrians has not yet been established. The effect of reducing impact velocity on the pedestrian injury risk has also not been determined. The first objective of this study is to evaluate the performance of the CDMBS in detecting pedestrians when it is installed in production cars. The second objective of this study is to evaluate the effect of reducing impact velocity on mitigating pedestrian injury. Firstly, impact experiments were perfomled using a car with the CDMBS in which the car collided with a pedestrian surrogate. In these tests, the velocity was chosen for the various test runs to be 20, 40 and 60 km/h, respectively, which were based on the velocity distribution in real-world pedestrian crashes. The results indicated that the impact velocity reduction ranged approximately from 10 to 15 km/h at the standing location of a pedestrian surrogate at both daytime and nighttime lighting conditions. These results show that the system has the potential to reduce pedestrian casualties from car-to-pedestrian contacts. Secondly, finite-element analyses were perfomled simulating vehicle-topedestrian impacts with the THUMS pedestrian models. The vehicle models selected for the study included a medium sedan, a minicar, and an SUV. Since head and chest injuries are the most typical causes of pedestrian deaths in car-to-pedestrian accidents, the risk of head and chest injuries was calculated when the impact velocity was reduced from 50 km/h to 40 km/h, 30krm/h, and 20 kmlh. The results revealed that an impact velocity reduction of 10 km/h mitigated severe pedestrian injury at impact velocities greater than or equal to 40 km/h. Specifically, a significant effect was observed in collisions with the medium sedan and SUV. In Japan, the CDMBS has just started to be installed in medium sedans. The pedestrian injury mitigation will be greatly improved if the system can be applied to various types of vehicles including SUVs in the future.

Keywords: CDMBS, Car Collision Velocity, Pedestrian Injury Risk

Cited Works (9)

Year	Entry
2010	Matsui Y, Nishimoto T. Nerve level traumatic brain injury in in vivo/in vitro experiments. Stapp Car Crash J. 2010;54:197-210. SAE 2010-22-0010.
1995	Anderson RWG, McLean AJ, Farmer MJB, Lee BH, Brooks CG. Vehicle travel speeds and the incidence of fatal pedestrian crashes. In: Proceedings of the 1995 International IRCOBI Conference on the Biomechanics of Impact. September 13-15, 1995; Brunnen, Switzerland.107-117.
1998	EEVC Working Group 17 Report: Improved Test Methods to Evaluate Pedestrian Protection Afforded by Passenger Cars. European Enhanced Vehicle-Safety Committee (EEVC); 1998.
2010	Helmer T, Ebner A, Samaha RR, Scullion P, Kates R. Injury risk to specific body regions of pedestrians in frontal vehicle crashes modeled by empirical, in-depth accident data. Stapp Car Crash J. 2010;54:93-117. SAE 2010-22-0006.
2005	Mizuno Y. Summary of IHRA pedestrian safety WG activities (2005): proposed test methods to evaluate pedestrian protection afforded by passenger cars. In: Proceedings of the 19th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 6-9, 2005; Washington, DC.
2001	Maeno T, Hasegawa J. Development of a finite element model of the total human model for safety (THUMS) and application to car-pedestrian impacts. In: Proceedings of the 17th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 4-7, 2001; Amsterdam, The Netherlands.
2009	Rosén E, Sander U. Pedestrian fatality risk as a function of car impact speed. Accid Anal Prev. May 2009;41(3):536-542.
2011	Matsui Y, Takahashi K, Imaizumi R, Ando K. Car-to-pedestrian contact situations in near-miss incidents and real-world accidents in Japan. In: Proceedings of the 22nd International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 13-16, 2011; Washington, DC.
1997	Pintar FA, Yoganandan N, Hines MH, Maltese MR, McFadden J, Saul R, Eppinger R, Khaewpong N, Kleinberger M. Chestband analysis of human tolerance to side impact. In: Proceedings of the 41st Stapp Car Crash Conference. November 13-14, 1997; Lake Buena Vista, FL. Warrendale, PA: Society of Automotive Engineers:63-74. SAE 973320.

Cited By (3)

Year	Entry
2012	Watanabe R, Katsuhara T, Miyazaki H, Kitagawa Y, Yasuki T. Research of the relationship of pedestrian injury to collision speed, car-type, impact location and pedestrian sizes using human FE model (THUMS Version 4). Stapp Car Crash J. October 2012;56:269-321.
2013	Matsui Y, Oikawa S, Ando K. Risks of pedestrian serious injuries and fatalities associated with impact velocities of cars in car-versus-pedestrian accidents in Japan. Stapp Car Crash J. November 2013;57:201-217.
2014	Matsui Y, Oikawa S, Aoki Y, Sekine M, Mitobe K. Features of the vision of elderly pedestrians when crossing a road. Stapp Car Crash J. November 2014;58:233-250.