Evaluation of a brake assistance system (BAS) using an injury severity prediction model for pedestrians

Through the years, traffic engineers and researchers have developed a variety of countermeasures to enhance pedestrian safety. Pedestrian-vehicle collisions are regarded as the most serious type of accident since they incur high fatality rates. A fundamental concept in developing effective countermeasures is to analyze pedestrian-vehicle collisions scientifically, which can identify the causes of accidents and accident severity. The objective of this study was to investigate the pedestrian safety benefit of the brake assistance system (BAS) and a functional requirement associated with BAS, namely the time needed to safely detect a pedestrian ahead. An injury severity prediction model for pedestrians was developed to systematically evaluate the BAS in this study. Ordered multinomial logistic regression analysis was used to establish a statistical model capable of predicting pedestrian injury severity. In addition to vehicle characteristics, collision speed and pedestrian characteristics were used as independent predictor variables. The outcomes of this study would be useful in directing the development of safety policies and technologies associated with pedestrian safety.     

Safety benefits of integrated pedestrian protection systems

This study developed a methodology for evaluating the effectiveness of an integrated pedestrian protection system (IPPS) based on simulations. The proposed IPPS consists of active and passive vehicular systems for protecting pedestrians, including a pedestrian warning information system (PWIS), an active hood lift system (AHLS), and pedestrian airbag system (PAS). Two simulation methods were applied in the proposed methodology: a driving simulation and a finite element simulation. A driving simulator was used to obtain the change in collision speed, which is a key parameter for evaluating driving behavior when a PWIS is applied. In addition, a well-known simulator for finite element analysis, LSDYNA was used to simulate the impact of a pedestrian on a vehicle hood in a pedestrian-vehicle collision. The head injury criterion (HIC), which is an outcome of LS-DYNA simulations, is a major parameter for evaluating passive safety systems. The probability of pedestrian fatalities by collision speeds and HICs were estimated to quantify the safety benefits of an IPPS based on the statistical analyses. The results showed that an IPPS is capable of reducing pedestrian fatalities by approximately 90 % associated with jaywalking in the midblock and walking on the roadside. The findings of this study can be used to boost the development of various vehicular technologies for pedestrians. The results can be effectively used for policy making and deriving legislative requirements associated with advanced vehicular technologies for enhancing pedestrian safety.     

Injury analysis of pedestrians in collisions using the pedestrian deformable model

Vehicle safety has become the most important issue in automobile design. However, all efforts to improve safety devices focus on enhancing safety features for occupants. Notably, pedestrians are the second largest category of motor vehicle deaths, after occupants, and account for about 13 percent of motor vehicle deaths. It is essential to design pedestrian-friendly vehicles and pedestrian protection systems to reduce pedestrian fatalities and injuries. To effectively assess pedestrian injuries resulting from vehicle impact, a deformable pedestrian model must be developed for vehicle-pedestrian collision analysis. This study constructs a pedestrian-collision numerical model based on LS-DYNA finite element code. To verify the accuracy of the proposed deformable pedestrian model, experimental data are used in the pedestrian model test. This study applies the proposed model to analyze the dynamic responses and injuries of pedestrians involved in collisions. The modeled results can help assess vehicle pedestrian friendliness and assist in the future development of pedestrian-friendly vehicle technologies.     

无信号控制交叉口行人过街间隙选择模型研究

我国城市道路交叉口中大量行人与机动车冲突导致了交叉口运行效率降低,同时也引发了不容忽视的安全问题。在对无信号控制交叉口进行录像调查的基础上,分析了行人与机动车冲突特性,利用实测数据建立了行人过街间隙选择行为概率与安全间隙之间的数学关系模型,并对模型进行了检验与验证,证明该模型具有较好的拟和度和预测精度,同时与已有的Logit模型进行比较分析。     

基于NAIS数据库中视频信息的人—车碰撞事故特征分析

选取中国国家车辆事故深度调查体系(NAIS)数据库中51例包含视频的人—车碰撞事故,进行了特征分析,分析内容包括:人—车碰撞危险场景、碰撞前人—车相对位置、行人碰撞运动响应、人—车碰撞包络线分布、头部落点分布等。结果表明:提取的10种场景,基本覆盖了各种人—车碰撞事故工况;对行人的探测,视场角(FoV)比探测距离更重要;轿车易导致行人正向旋转,单厢车易导致行人负向旋转;人—车碰撞包络线(WAD)主要集中在车辆两侧;致命伤的头部落点主要集中在前风窗玻璃下半部分、左右侧中部以及A柱附近。因此,基于碰撞视频信息可提高人—车碰撞事故特征分析的准确性。     

低能见度水平下行人交通事故严重程度及异质性分析

为探究在低能见度水平下影响行人事故伤害严重程度的因素, 并分析可能存在的异质性。以某市6 405起行人-机动车交通事故为研究对象, 分别研究高、低能见度水平下机动车-行人事故中行人伤害严重程度影响因素, 建立均值异质性的随机参数Logit模型并通过弹性分析定量分析显著变量对行人受伤情况的影响程度。结果表明, 高、低能见度下影响行人伤害严重程度的因素存在明显差异。(1)低能见度情况下男性驾驶员、高龄行人、卡车、沥青路面、凌晨、较暗的照明条件等因素会增加行人伤害严重程度。(2)低能见度情况下卡车和凌晨这2个因素具有随机参数特征, 分别使行人死亡的概率增加了4.39%和2.67%;此外, 当事故涉及卡车和26~35岁行人这2个因素时会增大行人死亡的概率; 而当夜间有路灯照明与凌晨这2个因素共同作用时行人死亡的可能性降低。(3)高能见度情况下未发现具有异质性的影响因素, 但发现男性行人和摩托车等因素会增大事故严重程度; 而驾驶员年龄、沥青路面、周末和地形等因素对事故严重程度并没有显著影响。      

Pedestrian accessibility and safety around bus stops in Delhi

Safety for public transport (PT) users is least during the access and egress trips. Previous studies have established that improvement in pedestrian safety will improve the safety of PT users as well. We studied the accessibility of pedestrian infrastructure around ~360 sampled bus stops in Delhi by conducting physical audits. 15 indicators in the audit checklist were meaningfully reduced to five factors through Principal Components Analysis. We developed Poisson regression models (with their geographically-weighted counterparts) to assess the association between these five factors for each bus stop with the number of pedestrian fatalities around that stop. Two models were developed— a) for fatalities where the impacting vehicle was known, and b) for fatalities where the impacting vehicle was unknown (hit-and-run cases). For both the models, geographically-weighted Poisson regression (GWPR) performed better than their global Poisson counterparts. Overall improved access was seen to be positively associated with less pedestrian fatalities. Further, we established that the nature of hit-and-run cases differ from those where the impacting vehicle is known, through— a) difference in the effect of the exposure variable, b) different factors being significant in the respective models, especially in the GWPR. The novelty of this study is that we modelled the relationship of pedestrian fatalities around PT stops with factors related to the pedestrian access to these stops. Through the application of GWPR, we found that different types of pedestrian fatalities are related to different aspects of access. We also identified bus stops with higher risk of pedestrian fatalities. Based on this, the methodology presented in this study is useful in guiding city authorities to identify and prioritise a) specific access-related factors which require improvement, and b) bus stops which require improvement in their pedestrian-access infrastructure. These analyses can be extended to study pedestrian safety around PT stops in any city.     

Multivariate modeling of pedestrian fatality risk through on the spot accident investigation

Pedestrians are the most vulnerable users of public roads and represent one of the largest groups of road casualties; their death rate around the world due to vehicle-pedestrian collisions is high and tending to rise. In Spain, as in other countries of the European Union, steps have been taken to reduce the number and consequences of such accidents, with encouraging results in recent years. A key to countering this concern is the accident research activity that has obtained remarkable achievements in different fields, especially when multidisciplinary approaches are taken. This paper describes the development of a multivariate model that is able to detect the most influential parameters on the consequences of vehicle-pedestrian collision and to quantify their impact on pedestrian fatality risk. First, an accident database containing detailed information and parameters of vehicle-pedestrian collisions in Madrid has been developed. The accidents were investigated on the spot by INSIA accident investigation teams and analyzed using advanced reconstruction techniques. The model was then developed with two components: (1) a classification tree that characterizes and selects the explanatory variables, identifying their interactions, and (2) a binary logistic regression to quantify the influence of each variable and interaction resulting from the classification tree. The whole model represents an important tool for identifying, quantifying and predicting the potential impact of measures aimed at reducing injuries in vehicle-pedestrian collisions.     

日本交通安全对策的借鉴与启示

尽管日本的机动车保有量和交通事故数量高于我国,但日本交通事故死亡人数远远低于我国。论文在综合介绍日本道路交通安全对策的基础上,将交通事故发生数量和交通事故造成的死亡数量与日本的乘用车保有量进行回归分析,并以虚拟变量的形式考虑了交通安全相关对策对交通事故量和死亡人数的影响。从分析结果可以看出,交通事故的发生量和死亡人数与乘用车的保有量有很大相关性,但是交通安全的相关对策对交通事故的降低和死亡人数的减少有重大影响,这对我国交通安全管理措施的制定和完善提供了积极的借鉴和启示。     

信号交叉口行人使用手机对其过街行为和安全的影响

针对信号交叉口处行人使用手机对其安全产生不利影响的问题,以武汉市9个信号交叉口的实测数据为基础,对行人使用与不使用手机情况下的过街行为与安全性差异进行统计分析.以往的研究中,评价行人安全多通过简单的对比分析,很少有量化的参数依据;针对行人使用手机对过街安全的影响,以人车冲突为评价指标,建立了基于有序概率(OP)的模型,可以更好地量化评价与预测信号交叉口处的行人安全.结果 表明,有11个因素与人车冲突显著相关,包括行人年龄、使用手机方式、过街速度、行人是否与他人结伴过街、嘹望次数、闯红灯与否、车道数、上游车道左转流量、上游车道右转流量、进口道右转流量和信号周期.其中,使用手机会增加人车冲突的概率:在双向2,4,5,6和7车道上,过街时打电话行人的人均冲突分别是不使用手机行人的3.56,3.42,3.33,3.29和3.00倍;看屏幕行人的人均冲突分别是不使用手机行人的4.78,4.17,3.80,3.59和3.30倍;而听音乐行人和不使用手机行人之间的人均冲突并没有明显差异.      

Characteristics of collision damage mitigation braking system for pedestrian protection

The vehicle travel velocity at pedestrian contact is considered to be an important parameter that affects the crash outcome. To reduce vehicle/pedestrian impact velocity, a collision damage mitigation braking system (CDMBS) using a sensor for pedestrian protection could be an effective countermeasure. The first purpose of this study is to clarify the relation between vehicle travel velocity and pedestrian injury severity due to differences in pedestrians’ ages in actual traffic accidents. The accident analyses were performed using vehicle-pedestrian accident data in 2009 from the database of the Institute for Traffic Accident Research and Data Analysis (ITARDA) in Japan. The result revealed that the fatality risk became higher with the increase in vehicle travel velocity. The second purpose of this study is to determine the safety performance of production vehicles equipped with the CDMBS for pedestrian protection. It was found that the CDMBS was highly effective in reducing the impact velocity from 50 km/h (vehicle travel velocity) to below 17 km/h, that could result in a significant decrease in fatality risk to be 2% or less. Additionally, the authors investigated a detectable zone with respect to a pedestrian’s position in relation to the vehicle. It was shown that the detectable zones for production vehicles tested were limited to be inside the vehicle front width.     

Motorcycle fatalities in Malaysia

Malaysia has the highest road fatality risk (per 100,000 population) among the ASEAN countries and more than 50% of the road accident fatalities involve motorcyclists. This study has collected and analysed data from the police, government authorities, and national and international research institutes. Only fatality data are used due to the severe underreporting of severe injuries (up to 600%) and slight injuries (up to 1400%). The analysis reveals that the highest numbers of motorcycle fatalities occur in rural locations (61%), on primary roads (62%) and on straight road sections (66%). The majority are riders (89%), 16 to 20 years old (22.5%), and 90% of the motorcycles are privately owned. Of those involved in fatal accidents, 75% of the motorcyclists wear helmets, and 35% do not have proper licences. The highest number of fatalities by type of collision is ‘angular or side’ (27.5%). Although fatal motorcyclist crashes mostly involve ‘passenger cars’ (28%), motorcyclists are responsible for 50% of the collisions either by crashing singly (25%) or with other motorcyclists (25%). While male motorcyclists predominate (94% of fatalities), female motorcyclists aged 31 to 70, possessing ‘no licence’, not wearing helmets and travelling during the day, account for a higher percentage than male motorcyclists. Malaysia must acquire more motorcycle exposure data and establish an injury recording system and database based on hospital-records. To reduce motorcycle fatalities, it first has to understand why young male motorcyclists are prone to fatal crashes in the evenings and on weekends on rural primary roads, especially on straight road sections.     

Assessment of distracted pedestrian crossing behavior at midblock crosswalks

Risk of pedestrian-vehicle crashes increased with distraction of pedestrians at roadway crossings. Aims of the study included analysing distracted pedestrian crossing behavior, identifying factors that influence pedestrian crossing speed at a midblock crosswalk, and determining the influence of road cross-section (RCS) on pedestrian walking speed.Three cities in Oregon State in the USA were included in the study: Corvallis, Albany, and Eugene. A combination of digital video and researcher field notes were used to obtain the data at each site. A total of 1045 pedestrian crossings from 23 midblock crossings were observed and analysed to determine the association of distraction type, road cross-section, and other in situ factors with pedestrian walking speed. Data analysis was conducted in two stages. First, the effect of each distraction type (looking at a handheld device, talking on a cell phone, wearing headphones, walking in a pair, walking in a group, and other distractions) on the pedestrian walking speed was examined. The results showed that average walking speed was 4.8 ft./s (1.46 m/s). Pedestrians walking with headphones crossed more quickly (0.91 ft./s) (0.28 m/s) than those with no distractions (5.14 ft./s) (1.57 m/s). In addition, talking on a cell phone was not significantly correlated with walking speed. Moreover, the other four distraction types were associated with decreasing the walking speed by 0.29 ft./s (0.09 m/s) to 0.83 ft./s (0.25 m/s). Second, the influence of pedestrian distraction, crosswalk configuration, land use, compliance rate, and pedestrian demographics on the pedestrian walking speed were examined in this study. Findings indicated that distracted pedestrian in two road cross-sections would require more crossing time than an elderly pedestrian. Pedestrian safety is a key concern in transportation research, and improved understanding of the factors contributing to pedestrian fatalities could enable safer roadways to be designed.     

轿车与6岁儿童行人不同方位碰撞中下肢损伤分析

Euro NCAP发布的行人模型认证技术公告TB024的最新版本对6岁儿童行人模型认证提出了单独要求,旨在加强对儿童行人的保护.本研究应用符合Euro NCAP技术公告(TB024)规定并且具有详细解剖学结构的6岁儿童行人有限元模型,设置了4组不同方位行人-汽车碰撞仿真试验,以探究不同碰撞方位下的儿童下肢损伤机理.结果...     

基于累积前景理论的无信控路段人车通行冲突博弈分析

无信控路段具有强交互性和高事故率,由于缺乏交通信号将人车进行分离,导致其容易形成人车通行冲突,影响道路通行效率和交通安全.为此,以各道路使用者的损失最小为目标,构建了基于累积前景理论的人车通行冲突博弈模型.通过研究过街行人与机动车辆的交互作用,分析双方决策行为影响因素并构建得失矩阵;同时在考虑决策者主观心理感知的前提下...     

基于交通事故深度调查数据的行人头部损伤特征研究

基于未来出行交通事故场景研究 （Future Mobile Traffic Accident Scenario Study,FASS） 数据库中135例人车碰 撞事故深度调查数据,对造成行人头部损伤的来源及车速对头部损伤来源的影响进行了统计分析。采用Spearman相关系 数检验法,建立了车辆速度区间与头部平均 MAIS 的回归模型。结果表明,行人头部致伤物主要来源于车辆,占比约 58%,其次为地面,占比约40%。行人事故中,碰撞车速对行人头部损伤来源的分布情况有一定的影响,当车速低于30 km/h时,行人头部损伤主要来源为地面,当车速为 ［30,50］ km/h时,车辆和地面对行人头部造成的损伤风险相近,当 车速高于 50 km/h时,行人头部损伤主要致伤物来源为车辆。因此,在进行交通损伤流行病学研究、交通损伤事故数据 库构建时,特别是在中低速碰撞中,应重视地面对头部造成损伤的风险。     

What affects pedestrian crossing difficulty at urban intersections in a developing country?

In developing countries, road traffic crashes involving pedestrians have become a foremost concern. At present, road safety assessment plans and selection of interventions are primarily restricted to traditional approaches that depend on the investigations of historical crash data. However, in developing countries such as India, the availability, consistency, and accuracy of crash data are major concerns. In contrast, proactive approaches such as studying road users' risk perception have emerged as a substitute method of examining potential risk factors. An individual's risk perception offers vital information on probable crash risk, which may be beneficial in detecting high-risk locations and major causes of crashes. Since the pedestrian fatality risk is not uniform across the urban road network level, it may be expected that pedestrians' perceived risk measured in terms of “crossing difficulty” would also vary across the sites. In this perspective, the present paper establishes a mathematical association between the pedestrians' perceived “crossing difficulty” and actual crashes. The model outcome confirms that pedestrians' perceived crossing difficulty is a good surrogate of fatal pedestrian crashes at the intersection level in Kolkata City, India. Subsequently, to examine the impact of traffic exposures, road infrastructure, land use, spatial factors, and pedestrian-level attributes on pedestrians' “crossing difficulty”; a set of Ordered Logit models are developed. The model outcomes show that high vehicle and pedestrian volume, vehicular speed, absence of designated bus stop, the presence of inaccessible pedestrian crosswalk, on-street parking, lack of signalized control (for both vehicle and pedestrian), inadequate sight distance, land use pattern, slum population, pedestrian-vehicular post encroachment time, waiting time before crossing, road width, and absence of police enforcement at an intersection significantly and positively increase pedestrian's crossing difficulty at urban intersections. To end, the model findings are advantageously utilized to develop a set of countermeasures across 3E's of road safety.     

Design of emergency braking algorithm for pedestrian protection based on multi-sensor fusion

Globally, safety has become an increasingly important issue in the automotive industry. In an attempt to reduce traffic fatalities, UNECE launched a new EU Road Safety Program which aims to decrease the number of road deaths by half by 2020. AEB (Autonomous Emergency Braking) is a very effective active safety system intended to reduce fatalities. This study involves the design of a multi-sensor data fusion strategy and decision-making algorithm for AEB pedestrian. Possible collision avoidance scenarios according to the EuroNCAP protocol are analyzed and a robust pedestrian tracking strategy is proposed. The performance of the AEB system is enhanced by using a braking model to predict the collision avoidance time and by designing the system activation zone according to the relative speed and possible distance required to stop for pedestrians. The AEB activation threshold requires careful consideration. The test results confirm the advantages of the proposed algorithm, the performance of which is described in this paper.     

山区公路小半径弯道路段事故严重度影响因素及其异质性比较分析

为分析影响山区公路小半径路段典型事故的严重程度的相关因素及其异质性效应，基于某山区双车道公路1 067起交通事故数据，从驾驶员、车辆、道路和环境4个方面选取15个潜在特征变量，采用二项Logit模型和随机参数二项Logit模型，分别构建小半径弯道路段上追尾碰撞、正面碰撞和侧面碰撞3类典型事故的严重度分析模型，分析3类典型事故严重度的显著影响因素，并采用边际弹性系数量化分析影响因素的作用强度。结果表明，小半径弯道路段上不同形态事故的严重度影响因素存在明显差异:①追尾碰撞严重度的显著影响因素依次为摩托车、夜间、弯道转角、驾驶员年龄、季节，摩托车和冬季分别是服从(2.716.1.5642)和(-1.495，2.1162)正态分布的异质性影响因素，导致发生伤亡事故的概率为95.72%和23.58%；②正面碰撞严重度的显著影响因素依次为货车、摩托车、驾驶员超车、弯道转角和弯道长度，货车导致其伤亡事故概率增加108.8%，摩托车和弯道长度分别是服从(6.941，9.9012)和(-0.004，0.0032)正态分布的异质性影响因素，导致发生伤亡事故的概率为76.11%和9.18%；③侧面碰撞严重度的显著影响因素依次为摩托车、驾驶员年龄及弯道有接入口，摩托车和接入口分别是服从(5.211，5.1112)和(-1.408，2.1462)正态分布的异质性影响因素，导致发生伤亡事故的概率为88.87%和25.47%。④与传统二项Logit模型相比，追尾碰撞、正面碰撞和侧面碰撞的随机参数二项Logit模型的拟合优度分别提高了2.85%，4.15%，6.76%，且定量捕捉了异质性影响因素，更适用于事故严重度的精细化分析。      

用于统计与分析的汽车碰撞行人事故深入数据源

结合近年来积累的交通事故调研经验,以北京市汽车碰撞行人事故分析案例为基础,构建了行人事故的深入数据源。该数据源以计算机电子数据表存储和分析与事故相关的人、车、路、环境的数据信息,可用于事故统计、事故再现和深入数据分析等方面的研究。基本数据源中包含事故的基本数据、车辆数据和行人数据3个部分,另外还存储了中国人体相关参数和车辆相关参数供分析时使用。目前,该数据源已收录了近200例行人事故中的深入数据,已用于有关人车碰撞特点分析及辅助事故再现等方面的研究,为汽车被动安全及交通安全研究提供必要的数据基础。