Interaction between pedestrians and automated vehicles: Exploring a motion-based approach for virtual reality experiments

External human machine interfaces (eHMI) might contribute to an enhanced traffic flow and road safety by providing relevant information to surrounding road users. To quantify the effect of eHMI on traffic flow, the majority of studies required participants to indicate their crossing decision in an explicit manner, such as pressing a button. While this approach proved to be efficient, the transfer to real-world behavior is unclear. Here, we propose a more realistic, motion-based approach allowing pedestrians to actually cross the road in front of a vehicle in a virtual reality environment. Participants (N = 51) encountered simulated automated vehicles (AVs) in two scenarios. We investigated the effect of different eHMIs on traffic flow and road safety. Pedestrians’́ body movements were obtained using a motion capturing system with six sensors. Our approach was validated using a two-step procedure. First, we assessed crossing behavior and subjective safety feeling while approaching AVs with and without eHMI. Second, we tested to which extent objective crossing behavior matched self-reported safety feeling. For this purpose, we evaluated if subjective safety feeling can be reliably predicted from actual crossing behavior using a functional data analysis. The proposed motion-based approach proved a valid investigation method for eHMI designs. The results indicated that eHMIs have a beneficial effect on traffic flow and road safety. Regarding traffic flow, participants crossed the road earlier and felt significantly safer when encountering an AV with an eHMI compared to no eHMI. In addition, in situations in which only some of the AVs were equipped with an eHMI, participants’ crossing behavior and safety feeling became more conservative for encounters without eHMI, indicating higher road safety. Further, subjective safety feeling was significantly predicted from actual crossing behavior. These findings highlight that eHMIs are beneficial for pedestrians’ crossing decision, both from an objective and subjective perspective.     

Impact of time pressure on acceleration behavior and crossing decision at the onset of yellow signal

This study investigates acceleration behavior and crossing decision of the drivers under increasing time pressure driving conditions. A typical urban route was designed in a fixed-base driving simulator consisting of four signalized intersections with varying time to stop line (4 s and 6 s) and maneuver type (right-turn and go-through). 97 participants’ data were obtained under No Time Pressure (NTP), Low Time Pressure (LTP), and High Time Pressure (HTP) driving conditions. The acceleration behavior was examined at the onset of yellow signal in four ways: continuous deceleration, acceleration-deceleration, deceleration-acceleration, and continuous acceleration. A random forest model was used to build an acceleration behavior prediction model for identifying the significant explanatory variables based on variable importance ranking. Further, a Mixed Effects Multinomial Logit (MEML) model was developed using the explanatory variables obtained from a random forest model. Additionally, a generalized linear mixed model was incorporated for estimating the likelihood of crossing an intersection by considering all the explanatory variables. A MEML model result revealed that the odds of adopting acceleration-deceleration, deceleration-acceleration, and continuous acceleration instead of continuous deceleration increased by 63 %, 123 %, and 77 %, respectively under HTP driving conditions. Moreover, the likelihood of crossing a signalized intersection increased by 2.73 times and 4.26 times when the drivers were under LTP and HTP driving conditions, respectively as compared to NTP driving condition. Apart from this, time to stop line (reference: 6 s) and age showed negative association with crossing probability. Overall, the findings from this study revealed that drivers altered their acceleration behavior for executing risky driving decisions under increasing time pressure driving conditions.     

A systematic review of observational studies investigating the influence of mobile phone distraction on road crossing behaviour of pedestrians

The growing prevalence of technological distractions amongst pedestrians makes it an important road safety concern. Observational studies are considered a reliable method to investigate the influence of mobile phone distraction on pedestrian road crossing behaviour and crash risks. The present study conducts a systematic review of international literature on pedestrian distraction observations by following the Preferred Reporting Items for Systematic Reviews and meta-Analyses (PRISMA) guidelines. A total of 792 studies were identified from the literature search on six research databases: Scopus, Google Scholar, Web of Science, PubMed, Cochrane library, and Transportation Research International Documentation (TRID). Finally, 39 research articles were assessed using the systematic classification scheme based on the following five research aspects: prevalence of mobile phone distraction, study locations, performance measures, analysis techniques, and additional factors associated with mobile phone use among pedestrians. Over 35% of the studies were conducted in the United States of America (USA) and 69% of the investigations were done in the last five years. Overall, the findings across the studies indicate that mobile phone distraction plays a major role in pedestrian risky road crossing behaviour and violation tendencies. Visual distractions (such as texting) exhibited higher behavioural impairment compared to cognitive distractions (e.g., listening to music, and conversations). Pedestrian characteristics such as gender and age were the key factors examined in 77% and 67% of the observational studies. Finally, important directions for future research are illustrated to aid the researchers working in the area of pedestrian safety.     

Footbridge usage in high-traffic flow highways: The intersection of safety and security in pedestrian decision-making​

In the Decade of Action for Road Safety, the vulnerability of pedestrians to severe outcomes from road crash is well-recognised. This study explored the factors that are influential in pedestrians’ decisions to cross a high-traffic highway in Barranquilla, Colombia, by using a footbridge over the highway, or by cutting across the highway in close proximity to a footbridge. Participants were recruited at each crossing (n = 105 footbridge, n = 105 ground; n = 117 males; M(SD) age = 23.28(5.98) years) and completed a paper survey exploring demographics, highway crossing behaviour, and attitudes regarding the safety and security of the crossing. Despite the majority of participants reporting the ground crossing was dangerous, and that the footbridge crossing was safe, one third of participants never or rarely (approximately 0% and 25% of the time) used the footbridge to cross the highway. Logistic regression revealed that the decision regarding the highway crossing mode (footbridge or ground) was predicted by (a) the frequency in which the footbridge is crossed, (b) the perception of footbridge security in relation to crime, (c) the perception of footbridge safety about traffic conflicts in general, (d) the proximity of the footbridge to the highway ground crossing, and (e) if the subject had experienced an injury during a previous highway crossing. The findings extend our understanding of pedestrian behaviour in crossing highways, not only in relation to the use of footbridges which separate both road user groups, but also ground crossings which place the pedestrians at significant risk especially those in areas with high traffic flow density. Moreover, the findings highlight the complexity involved in improving pedestrian road safety, particularly as the provision of an engineering solution (a footbridge) in close proximity to a high-risk zone (highway) is clearly not the only solution in the much larger road safety system.     

Pedestrian behaviors at and perceptions towards various pedestrian facilities: an examination based on observation and survey data

This paper presents findings from an observational study of pedestrian behaviors at various urban crosswalks and a pedestrian user survey which sought pedestrian perceptions toward various pedestrian facilities in a divided urban boulevard located next to a large university campus, Michigan State University, East Lansing, MI, USA. Such facilities included signalized and unsignalized intersection crosswalks, unsignalized marked and non-striped midblock crosswalks, physical barriers (vegetation and two-foot high concrete wall), midblock crosswalk shelters, colored paving (red brick pavement) at medians and curbs, and pedestrian warning signs at midblock crossing locations, messaging “cross only when traffic clears.” Pedestrian behavior data were obtained from the reduction of video images of pedestrian movements recorded throughout the study site. Pedestrian perceptions information was obtained through a user survey completed by pedestrians using the study site. It was found that unsignalized midblock crosswalks were the treatment of preference to pedestrians (83% reported a preference to cross) and also showed high crossing compliance rate of pedestrians (71.2%). It was also evident that the crosswalk location, relative to the origin and destination of the pedestrian, was the most influential decision factor for pedestrians deciding to cross at a designated location (90% said so). Proper traffic control can further encourage pedestrian crossings at designated locations since the effect of the availability of pedestrian signal to influence pedestrians’ decisions to cross at a specific location was quite high (74% said so). Moreover, vegetation and concrete barriers influenced the decision to cross of a significant number of pedestrians surveyed (65%). It is expected that the findings from this study will help traffic engineers, urban planners and policy makers understand pedestrian behaviors and attitudes at/towards pedestrian crosswalks.     

Illegal crossing behavior of pedestrians at signalized intersections: Factors affecting the gap acceptance

Purpose of designing crosswalks is to allow pedestrians to cross the roads safely avoiding conflicts between pedestrians and motorized vehicles. However, pedestrians do not always comply with the crossing rules, whether it is timing (signalization) and/or location (crossing facility). An observation survey of illegal crossings was conducted at six intersections in Izmir, Turkey to determine the distance and time gap perception of the pedestrians for safe road-crossing within the 25 m of the crosswalk. Each intersection was observed on weekdays during afternoon (12.30–13.30) and evening peak hours (17.00–18.00). Totally, 444 illegal crossings were observed at all intersections. Data were analyzed playing the video recordings in office. All roads were consisted of two lanes. In this study pedestrians’ illegal crossing behavior at signalized intersections depending on the position of the oncoming vehicle is of interest. Safety margins and crossing times of the pedestrians were also reported. Position of the vehicle was determined for the first lane at the instant the pedestrian stepped the lane. Pedestrians’ distance gap perception was categorized into five groups depending on the position of the oncoming vehicle which are; vehicle is within the 25 m of the crosswalk, vehicle is within the 25–50 m of the crosswalk, vehicle is within the 50–75 m of the crosswalk, vehicle is just beyond 75 m, and vehicle is out of field of view. Factors affecting the distance gaps, safety margins and crossing times were analyzed by ANOVA. The most significant effect was the vehicle speed in all analysis. Pedestrians based their decision of crossing on distance rather than time gap.     

Initial Implementation of the ARC Framework in Juvenile Justice Settings

Virtually all youth in detention have been exposed at least one traumatic event in their family system or in the community, and a vast majority have experienced cumulative traumatic events that led to major dysregulated states. Building on several seminal works on trauma-informed juvenile justice programs and on implementation research, this theoretical research-based paper aims to describe the preparation stage for implementation of the Attachment, Self-Regulation, and Competency framework (ARC) to a population of youth in detention. The ARC framework is well-suited to meet the complex needs of young offenders by focusing on building blocks that promote resiliency, including caregiver affect management and attunement, affect identification and modulation, and executive functions and self-identity. Based on this extensive preparation stage and a case illustration, recommendations and best practice protocols for making a shift towards a trauma-informed youth justice system are highlighted.     

To cross or not to cross: Impact of visual and auditory cues on pedestrians’ crossing decision-making

The controlled study of pedestrians’ crossing decision-making is relevant to the search for better safety conditions for this class of vulnerable road users. Several risk factors have been identified in the literature related to the crosswalks’ surrounding environment, the socio-demographic characteristics of the pedestrians crossing the road and the place where the crosswalks are inserted, as well as situational variables, such as speed and distance of the approaching vehicle during the crossing. In this work, the roles of visual and auditory cues in crossing decisions were analysed, comparing different speeds and distances, and taking into consideration different speed patterns of the approaching vehicle, aiming to identify what can affect pedestrians’ crossing behaviour. Experiments were performed in a virtual environment. Participants were presented with 10 different stimuli featuring a vehicle approaching with different speeds and movement patterns, combined with 2 auditory conditions: one concerning a vehicle with a gasoline combustion engine and another one with no sound cues. Participants were tasked with indicating the moment they decided to cross the street when they thought it was safe to do so by pressing a response button. Percentage of crossings, response time (RT), and time-to-passage (TTP) were recorded and subsequently analysed. The results showed that lower speeds and higher distances lead to higher percentages of crossings and RTs. The auditory condition did not significantly affect participants’ responses, leading to the conclusion that participants’ crossing decision was especially based on their visual perception of the movement characteristics of the approaching vehicle, particularly its speed and distance. These results may have relevance for the development of communication strategies between the vehicles, especially the automated ones, and pedestrians.     

Modeling the impact of traffic conditions and bicycle facilities on cyclists’ on-road stress levels

Past research efforts have shown that cyclists’ safety, stress, and comfort levels greatly affect the routes chosen by cyclists and cycling frequency. Some researchers have tried to categorize cyclists’ levels of traffic stress utilizing data that can be directly measured in the field, such as the number of motorized travel lanes, motorized vehicle travel speeds, and type of bicycle infrastructure. This research effort presents a novel approach: real-world, on-road measurements of physiological stress as cyclists travel across different types of bicycle facilities at peak and off-peak traffic times. By matching videos with stressful events, it was possible to observe the circumstances of those stressful events. The stress data was normalized, and the method was carefully validated by a detailed analysis of the stress measurements. Novel statistical results from a multi-subject study quantifies the impact of traffic conditions, intersections, and bicycle facilities on average stress levels.     

Pokemon gaming causes pedestrians to run a red light: An observational study of crossing behaviours at a signalised intersection in Taipei City

Since the launch of the smartphone game “Pokemon Go”, the worldwide craze has led to numerous traffic crashes and injuries resulting from falling or tripping. This paper investigates the effects of several smartphone distracting activities (gaming, talking, texting, Web surfing, and listening to music) on the street-crossing behaviours of pedestrians in Taipei City, Taiwan. A field study using video cameras was conducted to observe pedestrian crossing behaviours (e.g., crossing time, sudden movements, running a red light, and walking outside the crosswalk) at a selected signalised intersection. Data such as phone features, distracting activities, and personal attributes of the pedestrians were obtained in interviews conducted after pedestrians had completed crossing the street. In total, 1995 pedestrians engaging in various smartphone activities were observed. Results indicate that unsafe crossing behaviours were more prevalent among those playing “Pokemon Go”. Texting via instant-message apps appeared to be the second-most risk distracting activity. Results of the logistic models reveal that contributing factors to unsafe behaviours include being a student, phone screen of 5 in. or larger, and having an unrestricted 4G Internet data allowance. Two interaction terms (gaming × students, and gaming × unlimited 4G data allowance) in the models appear to be important determinants of unsafe crossing behaviours. The current research suggests that to prevent potential crashes and injuries, smartphone gaming while crossing the street should be prohibited.