Modelling pedestrian crossing behaviour in urban roads: A latent variable approach

As pedestrians are the most exposed and vulnerable road users to traffic accidents, urban planners frequently propose alternatives to improve their safety. However, some solutions, such as pedestrian bridges and crosswalks at signalized intersections, usually imply longer walking distances compared to the direct crossing alternative which, in its turn, involves a higher risk.In this article, a hybrid framework is proposed to analyse the pedestrians’ choice on how to cross an urban road where three crossing options are available: crossing directly, crossing by using a pedestrian bridge or using a crosswalk at a signalized intersection. The decision process is modelled as a discrete choice model incorporating latent variables to consider perceptions and psychological factors, using stated preference data coming from a survey applied in Bogotá, Colombia.Results show that the latent variables security/safety and attractiveness of each crossing alternative are relevant to understand the pedestrian crossing behaviour. These latent variables are strongly determined by socioeconomic characteristics of the individual (age, gender, level of study) and conditioned by the circumstances of the trip (main mode of transport, walking or not with children). It was found that a longer walking distance to a pedestrian bridge or a signalized crosswalk increases the probability of direct crossing, having a more relevant effect in the case of the pedestrian bridge.     

A Note on Motor Learning Without Post-Response Knowledge of Results

The authors studied the adjustment of the 2 distinct known expressions of gait velocity, the velocity of the center of gravity (CG) and the velocity of the center of foot pressure (CP) at the end of the 1st step in 2 experimental situations: natural gait initiation (the control situation, CS) and heel-off gait initiation (the test situation, TS). Gait was initiated by 7 healthy participants, from an erect spontaneous posture in the CS and from a posture with heels raised in the TS, on a force platform at 3 self-selected speed conditions. Biomechanical data from the force platform were collected in both experimental situations, and the authors used a particular gait analysis based on the differential method of Y. Brenière (2003) in order to approach velocity modulation by means of step length and frequency. Results showed that CG and CP velocities were adjusted differently during heel-off gait initiation than during natural gait initiation. CP velocity, as compared with CG velocity, was overestimated in TS. Results also established the relevance of the expression of step velocity by means of step length and frequency: The central nervous system, taking into account the specific postural constraints of each experimental situation, uses a reference value and a regulating parameter to modulate step velocity. Moreover, the contributions of 1st step length and frequency to the expression of step velocity in TS and CS were different. Thus, a specific locomotor behavior corresponds to a given experimental situation that is characterized by its own initial biomechanical constraints.     

Modeling ratings of in-vehicle alerts to pedestrian by leveraging field operational tests data in a controlled laboratory study

We show how to leverage expensive field operational tests (FOT) data in a controlled laboratory study when defining an in-vehicle algorithm that alerts drivers to pedestrians. We used an empirical approach that quantifies the relative level with which drivers are likely to accept alerts to pedestrians. The approach was used in two studies to investigate a range of contextual factors known to influence driver ratings of alerts to pedestrians issued by a driver-assistance system. Regression analysis shows that four factors consisting of combinations of pedestrian location and motion relative to the road ahead of the vehicle explain 85% of the variability in drivers’ ratings of alerts. Adding two factors related to the uncertainty of the pedestrians’ future path improves the model slightly. These findings suggest that drivers’ assessment of the danger associated with pedestrians derives largely from the possibility that they might move into the vehicle’s path, even when the vehicle is not on a collision course with the pedestrians. The less probable such an event seems, the less accepted an alert will be. Time to arrival (TTA) improved the regression model only when restricted to pedestrians in clear need of an alert, but was also found to have an effect in alert timing. This finding suggests that four contextual factors largely define the perceptual cues that drivers use to rate alerts to pedestrians.     

Can rail pedestrian violations be deterred? An investigation into the threat of legal and non-legal sanctions

Collisions between trains and pedestrians continue to be the most likely accident to result in severe injuries and fatalities on the rail network. While a range of countermeasures have been utilised in an attempt to reduce the incidence of risky behaviours at level crossings, limited focus has been directed towards deterrence-based approaches to improve crossing safety. As a result, this study explored pedestrians’ perceptions of legal and non-legal sanctions at level crossings, with particular emphasis directed towards identifying factors that maximise perceptual deterrence and reduce the occurrence of rule violations. In total, 636 individuals volunteered to participate in the study that required completion of either an online or paper version of a questionnaire that focused on behaviours and perceptions. Participants were more likely to report intentionally violating level crossing rules (24.52%, n = 156) compared to making crossing errors (3.46%, n = 22). Knowledge of the possibility of sanctions (e.g., monetary fines) was low. The threat of being injured and feeling shame when breaching crossing rules were the highest reported perceptual deterrent factors, higher even than the certainty and severity of sanctions. Regression analysis revealed that males who had lower perceptions of certainty of apprehension and displayed a tendency to repeat the behaviour were most likely to deliberately break crossing rules. However, this group also recognised the physical risks of violating rules and that it breached social norms. In regards to identifying effective countermeasures, increasing police presence was considered the most effective approach to reduce violations, which is directly linked to deterrence processes such as increasing perceptual certainty. This paper will further outline the study findings in regards to perceptual deterrence-based research as well as provide direction for future research efforts to develop effective countermeasures designed to improve pedestrian safety.     

Differential Effect of Two Mental Stress Tasks on Arterial Stiffness

Acute mental stress is believed to induce transient arterial dysfunction, but relatively few data are available. We therefore examined the effect of mental stress tasks that could induce differential hemodynamic responses on arterial dysfunction. Forty‐eight participants conducted either a mental arithmetic (MA) task or a mirror‐tracing (MT) task. Cardiovascular indices and arterial stiffness were measured before, during, and after these tasks. Analysis revealed that increases in arterial stiffness during the task and during recovery were more pronounced for the MA than for the MT, and that evoked hemodynamic response was more myocardial for MA than for MT. These results clearly show that MA and MT tasks that induce differential hemodynamic responses have a differential effect on arterial stiffness. This finding sheds light on the underlying mechanism that may account for the relationship between cardiovascular reactivity and cardiovascular disease.     

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.     

Higher investment levels into pre-planned routes increase the adherence of pedestrians to them

Extensive research has focused on identifying the principles in pedestrian route choice, often assuming that pedestrians follow an optimal route measured by factors, such as route length and busyness. However, the question of the extent to which pedestrians adhere to their planned route has not been convincingly resolved. Here, we form the hypothesis that the more pedestrians invest into a planned route by walking further along it, the bigger their tendency to stick to this route, even when it becomes less attractive than other options due to congestion, for example. We term this behaviour “route commitment effect” and conduct an online survey with over 300 participants to test and establish the existence of this effect. We propose a novel model to formalise this effect. Using simulations of our model, we give illustrative examples for the consequences of the route commitment effect. Our findings suggest that the route commitment effect can significantly influence pedestrian route choice in a simple scenario with only two possible routes. In more complex scenarios with many routes, the impact of the route commitment effect on the overall dynamics is much weaker, as pedestrians are distributed across routes. In general, we find that the route commitment effect reduces the efficiency of pedestrian flow and leads to more predictable pedestrian dynamics. Our study sheds light on the role of cognitive bias in pedestrian decision-making and may thus be helpful for facility design or operations.     

Comparison of pedestrian behaviors between drivers and non-drivers in Chinese sample

Road safety is a serious problem worldwide. Pedestrians, as the most vulnerable road users, deserve more attention. The aims of this study were to examine the validity of the Chinese version of the pedestrian behavior scale (CPBS) in both driver and non-driver samples, and to compare pedestrian behaviors between the two samples. In addition, we assessed the association of attention with pedestrian behaviors by exploring the relationships among CPBS, Mindful Attention Awareness Scale (MAAS) and Attention-Related Cognitive Errors Scale (ARCES). Two groups were assessed, including 302 members in the population with driving experience and 307 individuals in the non-driver group without driving experience. All participants completed the CPBS, MAAS, and ARCES, and provided sociodemographic parameters. The results showed that the CPBS had acceptable internal consistency and stability structure. More importantly, pedestrian behaviors were significantly different between drivers and non-drivers. Drivers reported significantly less transgressive and aggressive behaviors compared with non-drivers. As for the relationship between attention and pedestrian behavior, the MAAS score showed a significant negative correlation with aggressive behavior in the CPBS among drivers, while the ARCES score had significant positive correlations with all three CPBS factors. In non-drivers, the MAAS score was negatively correlated with aggressive behavior and positively associated with positive behavior; the ARCES score was positively correlated with aggressive behavior.     

时间结构和速度线索对碰撞时间估计的影响

估计被遮挡的运动物体何时到达某一特定位置被称为碰撞时间估计,本研究利用遮挡范式,通过控制时间结构、物理速度及运动过程是否可见设计两个2（物理速度）×3（时间结构）实验来探究三者对碰撞时间估计的影响。结果：当时间结构一致时,不论物理速度快慢及是否存在视觉速度线索,被试的绩效都没有显著差异;当时间结构不一致时,不论物理速度快慢,存在视觉速度条件下被试的绝对偏差小于无视觉速度条件。结论：时间结构一致时,被试主要使用时间线索进行碰撞时间估计;时间结构不一致时,被试通过整合时间结构和视觉速度线索进行估计。     

Differential Method of Characterizing Gait Strategies From Step Lengths and Frequencies: Strategy of Velocity Modulation

The differential method consists of the analysis of the variation of gait parameters length, frequency, and velocity with respect to their mean values, respectively, ΔL = L — L_m , Δf = f — f_m , and Δv = v – v_m , where L_m , f_m , and v_m represent the mean values of those parameters. Assuming that the strategy of modulation of velocity implies that L and f are functions of v and that statistical analyses of ratios ΔL/Δv and Δf/Δv have established that there is a very significant linear correlation, close to 1, between those ratios, the mathematical procedure allows one to determine the equation of step length, L = a · f + b · v + K, where a and b are the slope and the intercept of the linear regression and K is close to L_m . The equation was experimentally tested on 140 gait sequences performed by 6 participants and for gait velocities ranging from 0.6 to 2.2 m/s and was found to be very representative of all individual values. The differential method provides another way of using the derivative of velocity, v = L·f, to characterize the strategy of velocity modulation, which then permits one to determine the linear equation of velocity, v = f · L_m + L · f_m — L_m · f_m , and to show that the respective parts played by each parameter in the progression velocity are approximately equal. The author establishes the uniqueness of the different linear adjustments and discusses the differential method's own modes of use, that is, interindividually or globally.