Understanding complex traffic road scenes: The case of child-pedestrians' hazard perception

Pedestrians' intent to cross in a fully autonomous vehicle environment; looking at crossing opportunity, eHMI message and wait time

OBJECTIVES

Currently, pedestrians' road-crossing decisions depend on the traffic at the crossing point, crossing opportunities, and circumstantial elements. Longer wait times on the curb and time pressure raise the number of traffic violations among pedestrians. The era of fully autonomous vehicles (FAVs) promises new interactions. External Human-Machine Interfaces (eHMIs) aim to increase the understanding of FAVs' intentions and will influence pedestrians' intent to cross. Yet, how pedestrian behaviors will change in the FAV era remains unclear. Further, there are no good metrics for evaluating the intricate interaction of crossing-related factors.

METHODS

In a laboratory study, sixty participants observed crossing scenarios of a typical one-lane road with 10-12 FAVs driving along, two possible eHMI messages ("Cross!"/"Stop!"), and varying crossing opportunities (safe, risky, and unsafe). Participants had to indicate when they intended to cross the road using a designated button. Half of the participants were induced to feel time pressure. We developed index scores to convey the complexity of such crossing situations from the perspective of a pedestrian and used them to analyze the experimental data.

RESULTS

In total, 48% of participants' indications were to cross in safe crossing opportunities, 34% risky, and 18% unsafe; 69% were made when the eHMI proposition was "Cross!" and 31% for "Stop!". High, significant, and negative correlations were found for compatible responses, e.g., with a safe crossing gap and an eHMI sign to "Cross!". The opposite was true for incompatibility, e.g., a safe crossing gap and an eHMI sign to "Stop!" or an unsafe crossing gap and an eHMI sign to "Cross!". The time pressure group's median times to cross were shorter, making riskier decisions.

CONCLUSION

Our findings reflect a tendency to comply with the eHMI. In more complex scenarios where the crossing opportunity was uncertain or waiting times were longer, we observed that pedestrians were more inclined to follow the eHMI's guidance to cross. These findings suggest that pedestrians may be more likely to follow the eHMI's suggestion to cross than their self-skill, especially under time pressure. Our indices and metrics reflect the intricate interaction aspects of pedestrian behavior with eHMIs.

The human-factors' challenges of (tele)drivers of Autonomous Vehicles

Autonomous capabilities, including Autonomous Vehicle (AV) technology, aim to reduce human effort, extend capabilities, and enhance safety. While AVs offer societal benefits, human intervention remains necessary, especially in complex situations. As communication technology advances, human intervention is possible from remote sites. In such remote locations, highly skilled tele-drivers (TEDs) are ready to face situations too complicated for the AV. However, current work still needs a comprehensive mapping of the challenges that TEDs would face. Some of these challenges are shared with IVDs but may have stronger or weaker effects on the remote driver's ability to maintain safety. Other challenges, such as limited situational awareness of the road scene, the indirect experience of vehicle motion, and communication latency, are unique to TEDs. We assess the challenges, comparing their impact on TEDs versus IVDs, and explore technological countermeasures aimed at mitigating specific challenges encountered by TEDs. Lastly, we identified knowledge gaps and areas lacking understanding in the literature, highlighting avenues for future research and practical implications for practitioners.

Developmental differences in children's adaptation to vehicle distance and speed in street-crossing decision-making

INTRODUCTION

Young children cannot effectively adapt their behaviors to vehicles at varied distances and speeds, which is a critical cause of road accidents. However, the impact of this crucial ability on children's street-crossing decision-making and the age at which they acquire it remain unclear.

METHOD

This study examined the crossing decision-making behavior of children at 6, 8, and 11 years of age in facing 51 different videotaped traffic scenarios with varying vehicle distances and speeds. Sixty Chinese elementary school students, with 20 children evenly distributed into each of the three age groups (6 years, 8 years, and 11 years old), participated in a simulated street-crossing task using video projections. Hierarchical logistic regression models were used to analyze how age moderated the effects of vehicular motion factors (vehicle-pedestrian distance, vehicle speed) on children's crossing safety, including dangerous crossing and crossing decision-making.

RESULTS

The results showed that when either vehicle-pedestrian distance decreased or vehicle speed increased all age groups tended to cross less frequently but probability of dangerous crossing increased. Compared to 8-year-old and 11-year-old children, 6-year-old children showed a less pronounced tendency toward both of these crossing decision-making behaviors, and had more dangerous crossing outcomes.

CONCLUSIONS

These findings suggest that inadequate adaptation to vehicle-pedestrian distance and vehicle speed may partly contribute to the inferior safety of street-crossing behavior in 6-year-olds compared to 8-year-olds. No significant differences were observed between 8- and 11-year-old children, suggesting the turning point for this ability might occur between 6 and 8 years of age.

PRACTICAL APPLICATIONS

Preventive measures aimed to reduce crossing risks for children should consider children's developmental stages.

Road safety hazards for children while commuting to school: Findings from a pilot study in Karachi, Pakistan

INTRODUCTION

Road traffic injuries are a leading cause of mortality and morbidity among children. Travelling to and from school is a major risk exposure for children around the globe.

OBJECTIVE

The purpose of this study was to assess road traffic injury hazards for school children during dropp-off or picked-up times.

METHODS

This observational cross-sectional study included 94 public and private schools in Karachi, Pakistan. A structured observational tool was used to collect data on school demographics, the road traffic environment, infrastructure, injury hazards in vehicles used by school children, and child pedestrian injury risk and road use behaviors.

RESULTS

A total of 860 observations of school children, drivers of vehicles transporting children, schools, and vehicles were recorded. Most schools (n = 83, 88%) did not have designated parking spaces around the school; only one public school had a parking area. Only one private school had a zebra crossing around the school premises. Very few schools (n = 13, 14%), mostly private (n = 12) had pedestrian sidewalks. Only 35 (18%) adult motorcyclists, out of 199, were wearing a helmet, and eight (6%), out of 145, car passengers were wearing seatbelts. Compressed natural gas (CNG) cylinders were installed in 83 (35%), out of 235, observed vehicles. The remaining 152 (65%) did not have CNG cylinders or they were not visible to our data collectors. In 55 (23%) observations, bus passengers stepped off the bus in the middle of the road. Most pedestrians (n = 266, 99.5%) did not use a Zebra crossing. More than a quarter (n = 74, 28%) of pedestrians looked left and right before crossing the road.

CONCLUSION

While traveling to school, either by walking or taking vehicular trips, children face many road traffic injury hazards in Karachi. Pedestrians and passengers exhibited risky behaviors while using roads. Further initiatives are advised from a public health viewpoint aiming at minimizing transport-related hazards.

A comprehensive study of child pedestrian crash outcomes in Ghana

Pedestrians are considered as one of the vulnerable road user groups. Among pedestrians of all ages, children are the most at risk. Previous studies have shown that children have inadequate knowledge of road safety and are unable to identify risks on road. Despite these limitations associated with children, society places the burden on them to protect themselves. However, to be able to adequately address child pedestrian safety issues there is the need to understand the factors that influence their crash involvement and severity of injury they sustain. To address this gap, this study performed a comprehensive analysis of historical crash data in Ghana to find holistic countermeasures for these crashes. The study used five years of child pedestrian (below 10 years) crash records obtained from the Building and Road Research Institute (BRRI) in Ghana. A temporal analysis of the data revealed that the highest number of the crashes coincide with when school-going children go to and close from school. A random parameter multinomial logit model was developed to identify crash variables that are significantly associated with child pedestrian crash outcomes. The estimation results revealed that children are likely to be killed in crashes when the driver is speeding and inattentive. Also, it was found that children walking along the road, crossing the road, and those in urban areas are more susceptible to incapacitating injury crashes. Male drivers accounted for 95.8% of child pedestrian crashes, and crashes involving male drivers are 7.8% more likely to be fatal. The findings from this study provide a deeper, data-driven understanding of child pedestrian crashes and how temporal characteristics, vehicle type, location of pedestrian, traffic operation, and environmental and human factors affect crash outcomes. These findings will help in developing countermeasures like providing conspicuous pedestrian crossings, footbridges on multi-lane high-speed roadways, and the use of school buses to convey students to help mitigate the number and severity of child pedestrian crashes in Ghana, and by extension other countries in the sub-region.

Investigation of intervention methods based on different leading roles in family regarding child road safety education: An experimental study

Children are vulnerable to traffic injuries due to their low hazard perception. Previous studies have indicated that both parents and children have potential leading roles in safety education within the family. However, the effects of different leading roles (parents or children) on the hazard perception of children have not yet been revealed, and interactive education with children in the leading roles could also be an important means to enhance children's road safety. To fill this gap, based on constructivism theory and the Feynman learning method, this study proposed two methods of enhancing children's hazard perception based on different leading roles in the family regarding child road safety education and investigated the effectiveness of the above intervention methods. Thirty sets of parents and children participated in this experiment and were divided into three groups. The children received one of three different road safety interventions: a constructivism intervention, a parental guidance intervention or a children's Feynman learning intervention. Compared with the constructivism intervention, the hazard perception of children who received road safety educations within the family were significantly improved; these children were more sensitive to potential traffic hazard factors and presented better visual search patterns. A comparative analysis showed that the two educational interventions based on different leading roles in the family regarding child road safety education were not identical with respect to effectiveness. The children's Feynman learning intervention had a more significant effect than the parental guidance intervention. The findings of this study provide insightful information for safety education researchers, governments, educators and families with children.

An Examination of Child Pedestrian Rule Compliance at Crosswalks around Parks in Montreal, Canada

This study aims to examine child pedestrian safety around parks by considering four rule-compliance measures: temporal, spatial, velocity and visual search compliance. In this regard, street crossing observations of 731 children were recorded at 17 crosswalks around four parks in Montreal, Canada. Information on child behaviors, road features, and pedestrian-vehicle interactions were gathered in three separate forms. Chi-square tests were used to highlight the individual, situational, behavioral and road environmental characteristics that are associated with pedestrian rule compliance. About half of our sampled children started crossing at the same time as the adults who accompanied them, but more rule violations were observed when the adult initiated the crossing. The child's gender did not have a significant impact on rule compliance. Several variables were positively associated with rule compliance: stopping at the curb before crossing, close parental supervision, and pedestrian countdown signals. Pedestrian-car interaction had a mixed impact on rule compliance. Overall, rule compliance among children was high for each of our indicators, but about two-thirds failed to comply with all four indicators. A few measures, such as longer crossing signals and pedestrian countdown displays at traffic lights, may help to increase rule compliance and, ultimately, provide safer access to parks.

Objective and Perceived Traffic Safety for Children: A Systematic Literature Review of Traffic and Built Environment Characteristics Related to Safe Travel

The literature on children’s active transportation has shown the influence of the built environment characteristics on walking and crashes. Various reviews have examined those two questions. One influence on walking is the perception of traffic safety. However, it is not clear how, or even if, the built environment affects such perceptions. This research aims to understand which traffic and built environment characteristics influence objective and subjective/perceived traffic safety for children based on the analysis of previous studies in the field. Two types of research were used: the first examines the association between traffic and built environment characteristics and child pedestrian and/or cyclist collisions/injuries; the second relates to the perception of safety by parents and children for active transportation and, where studied, its relationship with built environment characteristics. A systematic review was conducted using five electronic databases. The total number of articles retrieved was reduced to 38 following the eligibility criteria and quality assessment, where 25 articles relate to injuries among children and 13 articles pertain to perception of safety. The results showed that high traffic volume and high vehicle speed are the main reasons children and parents feel unsafe when children use active travel, which matches the main findings on objective safety. Few articles on perception of safety related to the objective built environment were found. However, consistent findings exist. The presence of sidewalk was related to the safety of children. The presence of a crossing guard was positively related to perceived safety but was associated with higher rates of injuries among children. Intersection density was related to unsafe perceptions but was not statistically associated with objective traffic safety. Additionally, population density was found to be positively related to injuries among children, but not to perception of safety. The results help policy strategy to enhance the safety of children when using active transport modes.

Child-Pedestrian Traffic Safety at Crosswalks—Literature Review

Child pedestrians make up 30% of the total number of children injured in road traffic in the EU. They are a particularly vulnerable subgroup because they exhibit specific traffic behavior related to cognitive and physical development, sociodemographic characteristics, and environmental conditions. This paper provides an overview of research of parameters that affect the safety of children in the conflict zones of the intersection—crosswalks. The overview was undertaken targeting available research mostly conducted in the last 10 years all over the world, related to the identification of parameters that affect the safety of child-pedestrians, and models developed for the prediction of pedestrian and child-pedestrian behavior. Research conducted on various urban networks provides insight into locally and more widely applicable impact parameters connected to child characteristics and infrastructural and traffic elements, but also distractors (e.g., electronic devices) as new phenomena influencing children’s road safety. A review of pedestrian behavior-prediction models suggests that models are being developed for the general population, and models for children’s behavior, with specific parameters, are missing. For further research, more detailed analysis of the impact of distractors and of COVID–19 pandemic non-mobility, as well as an analysis of possible infrastructural solutions to increase children’s road traffic safety, is suggested.

Development of Models for Children—Pedestrian Crossing Speed at Signalized Crosswalks

Modeling the behavior of pedestrians is an important tool in the analysis of their behavior and consequently ensuring the safety of pedestrian traffic. Children pedestrians show specific traffic behavior which is related to cognitive development, and the parameters that affect their traffic behavior are very different. The aim of this paper is to develop a model of the children-pedestrian’s speed at a signalized pedestrian crosswalk. For the same set of data collected in the city of Osijek—Croatia, two models were developed based on neural network and multiple linear regression. In both cases the models are based on 300 data of measured children speed at signalized pedestrian crosswalks on primary city roads located near a primary school. As parameters, both models include the selected traffic infrastructure features and children’s characteristics and their movements. The models are validated on data collected on the same type of pedestrian crosswalks, using the same methodology in two other urban environments—the city of Rijeka, Croatia and Enna in Italy. It was shown that the neural network model, developed for Osijek, can be applied with sufficient reliability to the other two cities, while the multiple linear regression model is applicable with relatively satisfactory reliability only in Rijeka. A comparative analysis of the statistical indicators of reliability of these two models showed that better results are achieved by the neural network model.

A Model to Predict Children’s Reaction Time at Signalized Intersections

Traffic accident statistics in urban areas, both locally in Croatia and at the European level, identify children as a group of vulnerable road users. The analysis of the parameters that influence the interaction of child pedestrians and other road users requires special attention. This paper presents the results of research about the reaction time of children, measured both in laboratory conditions, via a computer reaction time test, and in actual traffic conditions. The results of the reaction time test in a situation with expected stimuli (a computer test) of children aged 6 to 10 years were compared with the results of the reaction time of adult traffic participants, drivers, who also took part in the computer test. Standard deviations of the reaction times between the control group (drivers, adults) and each subgroup of children were significantly different (p < 0.05). The results suggest that the largest developmental jump occurs between preschool children and first-grade children. In actual traffic conditions, the reaction time of children aged 4 to 16 years at the signalized intersection was measured. The model for predicting the reaction time of children in real traffic conditions was created using a neural network. The model prediction results matched well with the values measured in actual traffic conditions, for the observed intersection (correlation coefficient is 94.56%) and for the validation intersection (correlation coefficient is 92.29%). Parameters influencing children’s reaction times in real traffic conditions were identified by applying both statistical analysis and the neural network model developed. Using both methods, the same key distractors were identified—the movement of children in the group and the use of mobile phones. The case study was conducted at selected signalized intersections in the city of Osijek, Croatia.