考虑eHMI的行人过街行为研究与决策模型构建

目的 针对行人与自动驾驶汽车的交互过程,从行人的角度出发,探索性地提出行人在自动驾驶汽车前的过街行为决策模型。方法 首先,将行人过街情景进行分析定义,针对行人的过街意向和与自动驾驶汽车沟通意愿总结出两个典型场景;然后,利用潜变量分析方法将行人在自动驾驶汽车前过街行为的影响因素进行降维分类,并对车外人机交互界面进行设计定义,构建各潜变量的影响因子与测量量表;最后,运用有序Logistic回归方法分析各影响因素对行人过街意向和沟通意愿的影响,构建行人在自动驾驶汽车前的过街行为决策模型。结果 量化分析行人过街行为影响因素与其过街决策间相关性及内在关系,提出过程中决定性人车交互方式及各影响因素的变化过程。结论 研究提出考虑eHMI的行人过街行为决策模型,将行人过街决策过程分为三个阶段,并总结出车辆行为线索和eHMI线索作用过程的决定性变化曲线及行人与自动驾驶汽车交互流程与关键性节点。     

Pedestrians' crossing behaviors and safety at unmarked roadway in China

Pedestrians’ crossing out of crosswalks (unmarked roadway) contributed to many traffic accidents, but existing pedestrian studies mainly focus on crosswalk crossing in developed countries specifically. Field observation of 254 pedestrians at unmarked roadway in China showed that 65.7% of them did not look for vehicles after arriving at the curb. Those who did look and pay attention to the traffic did so for duration of time that followed an exponential distribution. Pedestrians preferred crossing actively in tentative ways rather than waiting passively. The waiting time at the curb, at the median, and at the roadway all followed exponential distributions. During crossing, all pedestrians looked at the oncoming vehicles. When interacting with these vehicles, 31.9% of them ran and 11.4% stepped backwards. Running pedestrians usually began running at the borderline rather than within the lanes. Pedestrians preferred safe to short paths and they crossed second half of the road with significantly higher speed. These behavioral patterns were rechecked at an additional site with 105 pedestrians and the results showed much accordance. In terms of safety, pedestrians who were middle aged, involved in bigger groups, looked at vehicles more often before crossing or interacted with buses rather than cars were safer while those running were more dangerous. Potential applications of these findings, including building accurate simulation models of pedestrians and education of drivers and pedestrians in developing countries were also discussed.     

An accelerated failure time model for investigating pedestrian crossing behavior and waiting times at signalized intersections

The waiting process is crucial to pedestrians in the street-crossing behavior. Once pedestrians terminate their waiting behavior during the red light period, they would cross against the red light and put themselves in danger. A joint hazard-based duration model is developed to investigate the effect of various covariates on pedestrian crossing behavior and to estimate pedestrian waiting times at signalized intersections. A total of 1181 pedestrians approaching the intersections during red light periods were observed in Beijing, China. Pedestrian crossing behaviors are classified into immediate crossing behavior and waiting behavior. The probability and effect of various covariates for pedestrians’ immediate crossing behavior are identified by a logit model. Four accelerated failure time duration models based on the exponential, Weibull, lognormal and log-logistic distributions are proposed to examine the significant risk factors affecting duration times for pedestrians’ waiting behavior. A joint duration model is developed to estimate pedestrian waiting times. Moreover, unobserved heterogeneity is considered in the proposed model. The results indicate that the Weibull AFT model with shared frailty is appropriate for modelling pedestrian waiting durations. Failure to account for heterogeneity would significantly underestimate the effects of covariates on waiting duration times. The proposed model provides a better understanding of pedestrian crossing behavior and more accurate estimation of pedestrian waiting times. It may be applicable in traffic system analysis in developing countries with high flow of mixed traffic.     

The effects of age and traffic density on street-crossing behavior

Past research has shown that road users accept shorter time gaps when the waiting time/number of vehicles they let pass before attempting to merge into the traffic increases. While elderly pedestrians are known to be an extremely vulnerable group of road users, very few studies dealt with the effect of environmental constraints and crossing complexity on this population's safety. The present study aimed at determining whether or not street-crossing decisions and behavior of younger and older pedestrians were differently affected by a traffic flow. In an interactive street-crossing task, we assessed whether mean time gap and crossing decisions depended on the position of the gap pedestrians selected into the traffic stream. Results revealed that irrespective of their age pedestrians accepted a smaller time gap when they chose the second interval of the traffic compared to the first one. Contrasting with previous hypotheses, this traffic-related behavior was not accompanied by an increase in the decisions risk. The findings also showed that the transition threshold from rejecting to accepting time gaps was shorter when the second interval was selected compared to the first one. This increment in task constraints might help younger and older pedestrians alike to perceive action possibilities more accurately and to be better attuned to traffic conditions by comparing gaps between each other. This opens an interesting perspective in the understanding and the training of the ability of elderly road users to remain accurate in their judgements.     

Gender differences in pedestrian rule compliance and visual search at signalized and unsignalized crossroads

Male pedestrians are over-represented in road crashes. Among pedestrians, males violate more rules than females do. For now, it is not known whether gender differences in pedestrian behaviors only concern rule compliance. The objective of this study was to explore gender differences in pedestrian rule compliance and in gaze targets before and during crossing. 400 adult pedestrians were observed at two signalized and two unsignalized crossroads, using a taxonomic observation grid which detailed 13 behavioral categories before, during and after crossing. The results show that the temporal crossing compliance rate is lower among male pedestrians but spatial crossing compliance does not differ between genders. Furthermore, different gaze patterns emerge between genders before and during crossing, notably as women particularly focus on other pedestrians during these two periods whereas men focus on vehicles. Moreover, females’ gazes vary with the type of crossroads, but males’ gazes do not. Spatial crossing compliance and gaze targets are furthermore modulated by the crossroad configuration. These results are discussed in terms of pedestrian visual strategy and compliance.     

Pedestrian behavior and safety on a two-stage crossing with a center refuge island and the effect of winter weather on pedestrian compliance rate

Despite a burgeoning research effort directed at understanding the effects of age, gender, disability, group size, traffic control condition and street width on pedestrian safety and compliance rate as they cross a signalized intersection, remarkably little is known about the compliance rate at a signal controlled two-stage crossing and how pedestrians react to different weather conditions. The purpose of this study was to determine whether pedestrian behavior becomes more risky in inclement weather through the investigation of street crossing behavior and compliance under different weather and road surface conditions at a busy two-stage crossing. Road crossing behavior was filmed at one eight-lane divided road strip at a downtown site in Toronto metropolitan area. The intersection was filmed unobtrusively from a rooftop by one camera set to record both oncoming near-side traffic and pedestrian movements. Pedestrian behavior and compliance rate were scored for a number of determinants of safe road crossing actions. Overall, the results show that road crossing behavior in inclement weather conditions was less safe than in fine weather. The designs of signal timing and configuration of the center refuge island also adversely influenced pedestrian behavior at this crossing, and adverse weather conditions further exacerbated the noncompliance rate. This paper presents new information on compliance rate at a two-stage crossing that emphasizes the need to consider the influence of traffic signal design and weather conditions on pedestrians’ behavior. More studies are needed to develop traffic control techniques to allow pedestrians to cross wide two-stage crossings in safety.     

Pedestrians’ crossing behaviors and safety at unmarked roadway in China

Pedestrians’ crossing out of crosswalks (unmarked roadway) contributed to many traffic accidents, but existing pedestrian studies mainly focus on crosswalk crossing in developed countries specifically. Field observation of 254 pedestrians at unmarked roadway in China showed that 65.7% of them did not look for vehicles after arriving at the curb. Those who did look and pay attention to the traffic did so for duration of time that followed an exponential distribution. Pedestrians preferred crossing actively in tentative ways rather than waiting passively. The waiting time at the curb, at the median, and at the roadway all followed exponential distributions. During crossing, all pedestrians looked at the oncoming vehicles. When interacting with these vehicles, 31.9% of them ran and 11.4% stepped backwards. Running pedestrians usually began running at the borderline rather than within the lanes. Pedestrians preferred safe to short paths and they crossed second half of the road with significantly higher speed. These behavioral patterns were rechecked at an additional site with 105 pedestrians and the results showed much accordance. In terms of safety, pedestrians who were middle aged, involved in bigger groups, looked at vehicles more often before crossing or interacted with buses rather than cars were safer while those running were more dangerous. Potential applications of these findings, including building accurate simulation models of pedestrians and education of drivers and pedestrians in developing countries were also discussed.     

Safety effects of exclusive and concurrent signal phasing for pedestrian crossing

This paper describes the estimation of pedestrian crash count and vehicle interaction severity prediction models for a sample of signalized intersections in Connecticut with either concurrent or exclusive pedestrian phasing. With concurrent phasing, pedestrians cross at the same time as motor vehicle traffic in the same direction receives a green phase, while with exclusive phasing, pedestrians cross during their own phase when all motor vehicle traffic on all approaches is stopped. Pedestrians crossing at each intersection were observed and classified according to the severity of interactions with motor vehicles. Observation intersections were selected to represent both types of signal phasing while controlling for other physical characteristics. In the nonlinear mixed models for interaction severity, pedestrians crossing on the walk signal at an exclusive signal experienced lower interaction severity compared to those crossing on the green light with concurrent phasing; however, pedestrians crossing on a green light where an exclusive phase was available experienced higher interaction severity. Intersections with concurrent phasing have fewer total pedestrian crashes than those with exclusive phasing but more crashes at higher severity levels. It is recommended that exclusive pedestrian phasing only be used at locations where pedestrians are more likely to comply.     

Relations between temperamental fear and risky pedestrian behavior

Objective

Child pedestrian injury poses a significant global public health challenge. This study examines relations between temperamental fear and children’s risky pedestrian behavior, utilizing mediation analytic strategies to study underlying mechanisms of the hypothesized relation.

Methods

As part of a larger study, 240 seven- and eight-year-old children completed 30 crossings in a virtual reality (VR) pedestrian environment. Three pedestrian behaviors were considered: start gap (lag after a traffic gap appears before child initiates crossing into the gap), time to contact (TTC; gap between avatar and the lead oncoming vehicle), and hits (collisions with vehicles in simulated crossings). Temperamental fear was measured by parent report.

Results

Fearful children were more likely to be struck by virtual vehicles, and the relation between fear and risky pedestrian behaviors was mediated by start gap and TTC. Specifically, children who were temperamentally more fearful were more likely to hesitate before initiating crossing, which led to shorter gaps between themselves and the oncoming vehicle, hence causing them to be more likely to be hit by virtual vehicles. Gender interacted with fear, such that fearful girls were most likely to be hit.

Conclusions

Both temperamental fear and gender influenced the risk of child pedestrian injuries. Delayed entry into traffic and shorter gaps between children and oncoming vehicles may underlie this relation. Future research should explore how these factors might influence the effectiveness of prevention programs.     

Pedestrian- and driver-related factors associated with the risk of causing collisions involving pedestrians in Spain

This study aimed to quantify the association between pedestrian- and driver-related factors and the risk of causing road crashes involving pedestrians in urban areas in Spain between 1993 and 2011. From the nationwide police-based registry of road crashes with victims in Spain, we analyzed all 63,205 pairs of pedestrians and drivers involved in crashes in urban areas in which only the pedestrian or only the driver was at fault. Logistic regression models were used to obtain adjusted odds ratios to assess the strength of association between each individual-related variable and the pedestrian’s odds of being at fault for the crash (and conversely, the driver’s odds of not being at fault).The subgroups of road users at high risk of causing a road crash with a pedestrian in urban areas were young and male pedestrians, pedestrians with psychophysical conditions or health problems, the youngest and the oldest drivers, and drivers with markers of high-risk behaviors (alcohol use, nonuse of safety devices, and driving without a valid license). These subgroups should be targeted by preventive strategies intended to decrease the rate of urban road crashes involving pedestrians in Spain.     

Economic development's effect on road transport-related mortality among different types of road users: a cross-sectional international study

The relationship between a country's stage of economic development and its motor vehicle crash (MVC) mortality rate is not defined for different road users. This paper presents a cross-sectional regression analysis of recent national mortality in 44 countries using death certificate data provided by the World Health Organization. For five types of road users, MVC mortality is expressed as deaths per 100,000 people and per 1000 motor vehicles. Economic development is measured as gross national income (GNI) per capita in U.S. dollars and as motor vehicles per 1000 people. Results showed overall MVC mortality peaked among low-income countries at about US$ 2000 GNI per capita and at about 100 motor vehicles per 1000 people. Overall mortality declined at higher national incomes up to about US$ 24,000. Most changes in MVC mortality associated with economic development were explained by changes in rates among nonmotorized travelers, especially pedestrians. Overall MVC rates were lowest when pedestrian exposure was low because there were few motor vehicles or few pedestrians, and were highest during a critical transition to motorized travel, when many pedestrians and other vulnerable road users vied for use of the roadways with many motor vehicles.     

The effect of road and environmental characteristics on pedestrian hit-and-run accidents in Ghana

The number of pedestrians who have died as a result of being hit by vehicles has increased in recent years, in addition to vehicle passenger deaths. Many pedestrians who were involved in road traffic accident died as a result of the driver leaving the pedestrian who was struck unattended at the scene of the accident. This paper seeks to determine the effect of road and environmental characteristics on pedestrian hit-and-run accidents in Ghana. Using pedestrian accident data extracted from the National Road Traffic Accident Database at the Building and Road Research Institute (BRRI) of the Council for Scientific and Industrial Research (CSIR), Ghana, a binary logit model was employed in the analysis. The results from the estimated model indicate that fatal accidents, unclear weather, nighttime conditions, and straight and flat road sections without medians and junctions significantly increase the likelihood that the vehicle driver will leave the scene after hitting a pedestrian. Thus, integrating median separation and speed humps into road design and construction and installing street lights will help to curb the problem of pedestrian hit-and-run accidents in Ghana.     

Illegal road crossing behavior of pedestrians at overpass locations: Factors affecting gap acceptance,crossing times and overpass use

The aim of designing overpasses is to provide safe road crossings for pedestrians by helping them to avoid conflicts with motor vehicles. However, the number of pedestrians who do not use overpasses to cross the road is very high. An observational survey of illegal road crossings was conducted at four overpass locations in Izmir, Turkey to determine the crossing time, crossing speed of the pedestrians and their distance and time gap perception for safe road-crossing within 25 m of the overpasses in both directions. Crossing time is the time needed for a pedestrian to cross a particular road. Time gap is strongly related with safety margin. If a pedestrian chooses a larger time gap, then the arrival time of the oncoming vehicle to the crossing point of the pedestrian increases thus, the possibility of a collision decreases. Each overpass was observed on weekdays during peak afternoon (12.30–13.30) and evening hours (17.00–18.00). At all overpass locations 454 illegal crossings were observed. ANOVA results revealed that age had a significant effect both on safety margin and crossing time. During the observations a survey was conducted among pedestrians who completed their crossings either using the overpass or at street level within 25 m of the overpass (n = 231). Factors affecting the crossing choice of pedestrians were specified in the surveys. The major part of the respondents (71.7%) indicated that time saving was the main reason for crossing at street level. Pedestrians’ crossing speeds were extracted from the video recordings to observe the effect of speed limit on pedestrian behavior. As a result, at locations where the speed limit was 70 km/h, pedestrians’ average crossing speed was found to be 1.60 m/s and 1.73 m/s while at locations where the speed limit was 50 km/h, pedestrians’ average crossing speed was found to be 1.04 m/s and 0.97 m/s. This shows that pedestrians feel safer while crossing when the vehicle speed is low.     

Mapping patterns of pedestrian fatal accidents in Israel

This study intends to provide insight into pedestrian accidents by uncovering their patterns in order to design preventive measures and to allocate resources for identified problems. Kohonen neural networks are applied to a database of pedestrian fatal accidents occurred during the four-year period between 2003 and 2006. Results show the existence of five pedestrian accident patterns: (i) elderly pedestrians crossing on crosswalks mostly far from intersections in metropolitan areas; (ii) pedestrians crossing suddenly or from hidden places and colliding with two-wheel vehicles on urban road sections; (iii) male pedestrians crossing at night and being hit by four-wheel vehicles on rural road sections; (iv) young male pedestrians crossing at night wide road sections in both urban and rural areas; (v) children and teenagers crossing road sections in small rural communities. From the perspective of preventive measures, results suggest the necessity of designing education and information campaigns for road users as well as allocating resources for infrastructural interventions and law enforcement in order to address the identified major problems.     

Pedestrian risk decrease with pedestrian flow. A case study based on data from signalized intersections in Hamilton,Ontario

A unique database provided information on pedestrian accidents, intersection geometry and estimates of pedestrian and vehicle flows for the years 1983-1986 for approximately 300 signalized intersections in Hamilton, Ont., Canada. Pedestrian safety at semi-protected schemes, where left-turning vehicles face no opposing traffic but have potential conflicts with pedestrians, were compared with pedestrian safety at normal non-channelized signalized approaches, where right-turning vehicles have potential conflicts with pedestrians. Four different ways of estimating hourly flows for left- and right-turning vehicles were explored. Hourly flows were estimated for periods of 15 min, hours, two periods a day (a.m. and p.m.) and the 'daily' period (7 h). Parameter estimates were somewhat affected by the time period used for flow estimation. However, parameter estimates seem to be affected far more by the traffic pattern (left- or right-turning traffic), even though approaches were selected such that the situation for left- and right-turning turning traffic was similar (no opposing traffic, no advanced green or other separate phases and no channelization). Left-turning vehicles caused higher risks for pedestrians than right-turning vehicles. At low vehicular flows right turns and semi-protected left turns seemed to be equally safe for pedestrians. When risks for pedestrians were calculated as the expected number of reported pedestrian accidents per pedestrian, risk decreased with increasing pedestrian flows and increased with increasing vehicle flow. As risk decreases with increasing pedestrian flows, promoting walking will have a positive effect on pedestrian risk at signalized intersections.     

Pedestrian environment and behavior in Karachi, Pakistan.

Pedestrian road traffic accidents (RTAs) are responsible for a substantial number of injuries and deaths in Karachi. To better understand the situations facing pedestrians we selected ten of Karachi's highest risk locations for pedestrian RTAs and observed 250 pedestrians for each of three activities--crossing the street, walking on the street, and walking on the sidewalk. We also observed the extent and effect of street and sidewalk encroachments. A total of 35% of the pedestrians crossing the street caused traffic to swerve to avoid them. Pedestrians crossing one lane at a time were 2.9 times more likely to cause the traffic to swerve than pedestrians who crossed the whole street at once (53 vs. 18%, RR = 2.9, 95% CI = 1.9-4.3). Pedestrians crossing in a group were 1.8 times more likely to cause traffic to swerve compared to those crossing singly (49 vs. 28%, RR = 1.8, 95% CI = 1.3-2.5, P = 0.001). A total of 36% ran while crossing and were 1.8 times more likely to cause traffic to swerve than those who walked (48 vs. 27%, RR = 1.8, 95% CI = 1.3-2.5). An average of 77% of the sidewalk width was blocked by encroachments which forced pedestrians to step on the road resulting in vehicles swerving. An average 33% of the street width was blocked by illegally parked vehicles. Pedestrians in Karachi indulge in risky behaviors. Encroachments on streets and sidewalks compound the problem. Piloting efforts to modify pedestrian behavior and the environment they negotiate should be considered to reduce pedestrian deaths.     

Where did that car come from?: Crossing the road when the traffic comes from an unfamiliar direction

Using a virtual road crossing environment, the reported research investigated the road crossing behavior of 12 male pedestrians in familiar and unfamiliar environments. Environment familiarity was manipulated using traffic direction. Seven of the participants were from a country where traffic flows from right to left and five were from countries were traffic flows from left to right. Each participant was asked to cross the road when traffic was coming from both the familiar and the unfamiliar direction for them. Results showed that pedestrians had lower safety ration, or a lower margin of error, in crossing the road when traffic was flowing in an unfamiliar direction, suggesting that pedestrians might be at greater risk of accident in such environments. Implications of these findings are discussed.     

Left-turn gap acceptance models considering pedestrian movement characteristics

Pedestrian–vehicle conflicts are considered as a common safety problem at signalized intersections. The threat to pedestrian safety is mainly related to the interaction with turning vehicles, especially left-turners (left-hand traffic system). This study aims to analyze the lag/gap acceptance behavior of left-turners considering pedestrian movement at signalized crosswalks. Furthermore, the severity of pedestrian–vehicle conflicts is addressed by analyzing vehicle speeds at the conflict points. User behavior at several signalized intersections in Japan is observed by using video cameras. It is assumed that pedestrian movements have their origin at either the near-side (the side of the exiting vehicular traffic) or far-side of the crosswalk. Accepted/rejected lags and gaps are extracted, classified depending on the direction of pedestrian movement, and modeled by using Cumulative Weibull distribution function. The results show that drivers tend to accept shorter lags/gaps between near-side pedestrians compared to far side pedestrians. Furthermore, drivers tend to accept short lags while being conservative about short gaps. Simultaneously vehicles clear the conflict area with significantly higher speeds when accepting lags with single pedestrians. This indicates that the conflicts that occur at low pedestrian demand levels are more severe compared to those at high demand levels.     

Factors influencing safety in a sample of marked pedestrian crossings selected for safety inspections in the city of Oslo

This paper reports an analysis of factors influencing safety in a sample of marked pedestrian crossings in the city of Oslo, Norway. The sample consists of 159 marked pedestrian crossings where a total of 316 accidents were recorded during a period of five years. The crossings were selected for inspection because of they were, for various reasons, regarded as sub-standard. The sample of crossings is therefore not representative of all pedestrian crossings in Oslo. Factors influencing the number of accidents were studied by means of negative binomial regression. Factors that were studied included the volume of pedestrians and vehicles, the number of traffic lanes at the crossing, the location of the crossing (midblock or junction), the type of traffic control, the share of pedestrians using the crossing and the speed of approaching vehicles. The analysis confirmed the presence of a “safety-in-numbers” effect, meaning that an increase in the number of pedestrians is associated with a lower risk of accident for each pedestrian. Crossings located in four-leg junctions or roundabouts had more accidents than crossings located in three-leg junctions or on sections between junctions. A high share of pedestrians crossing the road outside the marked crossing was associated with a high number of accidents. Increased speed was associated with an increased number of accidents.