Child Dev Perspect

Successfully perceiving and acting on dynamic affordances is critical for children and adults to function. In our work, we look at how children cross roads as a model for understanding how they learn to perceive and act on dynamic affordances. Ten- to 14-year-old children and adults ride an interactive bicycling simulator through an immersive virtual environment where they cross intersections with continuous cross traffic. We consistently find developmental and individual differences in children's ability to tightly time their entry into the roadway relative to the lead car in the gap. Given that children do not adjust their gap choices to match their less precise timing abilities, children take more risks when crossing roads than adults. We conclude by discussing possible reasons for these developmental differences in movement timing.R01 HD052875/HD/NICHD NIH HHS/United StatesR49 CE001167/CE/NCIPC CDC HHS/United States2015-12-01T00:00:00Z25530798PMC426769

The efficacy of a brief hazard perception interventional program for child bicyclists to improve perceptive standards

Introduction: Even though child bicyclists are highly vulnerable in traffic only few studies focused on providing child bicyclists with means to enhance their abilities to deal with the complexity of dynamic traffic situations. The current study therefore evaluated whether a brief hazard perception intervention might be effective to improve hazard perception skills in child bicyclists towards a level more comparable to adult bicyclists. Methods: Eighty children of the fourth grade (9.03 +/- 0.43 years; 34 girls) and forty-six adults (34.67 +/- 14.25 years age; 24 woman) first performed a Hazard Perception test for bicyclists. Response rate, reaction times, first fixation, duration of the first fixation, dwell time and total number of fixations on the events were measured. Next, the children took part in the HP intervention in which video clips of dangerous traffic situations were presented. The intervention comprised two classroom sessions of one hour (1/week). A post-test was performed one day after and the retention-test three weeks after the intervention. Results: Children responded to more covert hazards immediately after the intervention (p < 0.05), but did not improve their response rate for overt hazards. Reaction times for the covert hazards improved on the post-test (p < 0.001) compared to the pre-test but this effect was reduced on the retention test. There was no effect of the intervention for entry time of the first fixation but the duration of the first fixation increased for the covert hazards (p < 0.05). Children made fewer fixations on the event compared to adults (p < 0.001), except for the covert hazards on the retention-test. The training also increased the number of fixations for the overt hazards on the post-test (p < 0.001) and the retention-test (p < 0.001) but only increased on the retention test for the covert hazards (p < 0.001). Conclusion: The results demonstrated that a brief intervention for training hazard perception skills in child bicyclists is able to improve children's situation awareness and hazard perception for potential dangerous situations. The training, however, was too short to improve children to higher adult levels

Ecol Psychol

Unlike affordances involving stationary objects, affordances involving moving objects change over time. This means that actions must be tightly linked to decisions, making perceiving and acting on affordances involving moving objects challenging for children and adults alike. Here, we overview our program of research on how children and adults perceive and act on moving objects in the context of bicycling across roads in an immersive virtual environment. This work shows that although children attempt to adjust their actions to fit their risky decisions, they do not fully adjust their decisions to fit their action capabilities. This mismatch between child cyclists' decisions and actions may be a risk factor for car-bicycle collisions in late childhood and early adolescence.R01 HD052875/HD/NICHD NIH HHS/United StatesR49 CE001167/CE/NCIPC CDC HHS/United States2015-01-01T00:00:00Z24891809PMC403908

The role of visual information in the steering behaviour of young and adult bicyclists

In a first series of experiments, the visual behaviour during different steering tasks, and under different constraints, was investigated in an indoor environment. Young learner, and experienced adult bicyclists were asked to steer through narrow lanes, a curved lane, and a slalom. Participants directed their gaze to the future path about one to two seconds ahead, and moved forward using optokinetic nystagmus-like eye movements. Both cycling speed and task demand were found to affect the visual behaviour of bicyclists. Although these shifts of visual attention were in line with earlier findings in pedestrians and car drivers, they did not seem to be entirely in line with the two-level model of steering behaviour. Therefore, a redefined version of this model was proposed as the ‘gaze constraints model for steering’. During a simple linear steering task, the visual behaviour of children (between 6 and 12 years of age) was similar to that of adults. However, in a more demanding slalom task children adopted a different visual-motor strategy. Whereas adults made more use of anticipatory fixations and often looked at the functional space between two cones, children mainly focussed on the upcoming cone. These findings suggest that adults plan their route through the slalom whereas children focus on steering around one cone at the time. In a second series of experiments, the distribution of visual attention was investigated in an actual traffic environment and the influence of a low quality cycling track on visual behaviour was studied. Results showed that children direct their gaze more to the environment and less to the path than adults. However, both adults and children made an apparent shift of visual attention from distant environmental regions towards more proximate road properties on the low quality cycling track. In general, the current thesis provides insights into how visual attention of young and adult bicyclists is distributed during different steering tasks and how this is affected by individual, task, and environmental constraints. Based on the current results, a gaze constraints model for steering was proposed. Furthermore, it seems that children adapted their visual behaviour to their limited capabilities, but that children’s visual behaviour changes in a similar way to changing task constraints as the visual behaviour of adults. These findings suggest that traffic rules, road infrastructure and traffic education should take into account the limited capabilities of children. However, it should be noted that this work only focussed on the lane-keeping task. Future research should therefore study the integration of these findings in the visual control of other traffic tasks such as hazard perception. A better understanding of the development of information processing of young learner bicyclists could potentially lead to better traffic education and more appropriate road infrastructure. Additionally, a new fixation-by-fixation analysis method to analyze head-mounted eye tracking data was tested in this thesis. This method was found to be a good alternative to the time-consuming frame-by-frame method, provided that the areas of interest were large, and the analysis is done over an extended period of time

ASSESSING THE IMPACT OF BICYCLE TREATMENTS ON BICYCLE SAFETY: A MULTI-METHODS APPROACH

Compared to other modes, bicyclists are disproportionally affected by crashes considering their low mode share. There is evidence that crashes between bicyclists and motorized vehicle take place at road segments and signalized intersections where bicycle treatments (e.g., bike lanes) are present, urging for in-dept analysis of the safety impact of the various bicycle treatment types. Additionally, it is important to identify sensor types that have the potential to advance field data collection and traffic monitoring in multi-modal road environments. In this dissertation, three approaches, namely crash analysis, traffic conflict analysis, and analysis of driver speeding and glancing behavior, were implemented to investigate the safety impact of bicycle treatments at the segment- and the intersection-levels on bicycle safety. Prediction models were developed to predict bicycle-motorized vehicle crashes at road segments and signalized intersections, and traffic conflicts between straight-going bicyclists and right-turning vehicles at signalized intersections. Driver speeding and glancing behavior was analysed for the segment and the intersection levels. A mode classification framework to classify trajectories recorded using a radar-based sensor was developed to test the feasibility of using radar-based sensors in field studies. The findings of this dissertation contribute to bicycle safety research in terms of quantifying the safety impact of various bicycle treatment types and how to assess and also, by showing how to assess bicycle safety. The findings of this research have the potential to stand as a valuable tool for transportation policymakers and officials in charge of establishing safe bicycle networks

Improved Safety and Efficiency of Protected/Permitted Right Turns for Bicycles in the Pacific Northwest

DTRT13-G-UTC40Conflict between bicycles and right-turning vehicles on the approaches to intersections is a critical safety concern in urban environments. To understand the safety and operational implications of using protected-permitted right turns (PPRT), a full-scale bicycling simulator experiment was performed. The velocity and lateral position of bicyclists were evaluated during conflicts between bicycles and right-turning vehicles. Two independent variables were analyzed: the signal indication for right-turning vehicles (circular red or green, solid red or green arrow and flashing yellow arrow) and the pavement markings in the conflict area (white lane markings with no supplemental pavement color and white lane markings with solid green pavement applied in the conflict area). Forty-eight participants (24 women and 24 men) completed the experiment. Signal indications and pavement markings had statistically significant effects on bicycle velocity and lateral position, but these effects varied at different levels of the independent variables. Use of PPRT phasing in conjunction with colored pavement markings was associated with increased bicyclist conflict with right-turning vehicles, whereas PPRT phasing with no supplemental colored pavement markings was associated with improved bicyclist safety. The results provide guidance to transportation professionals about how traffic control devices could be applied to conflict areas before signalized intersections

Modeling Drivers’ Strategy When Overtaking Cyclists in the Presence of Oncoming Traffic

Overtaking a cyclist on a two-lane rural road with oncoming traffic is a challenging task for any driver. Failing this task can lead to severe injuries or even death, because of the potentially high impact speed in a possible collision. To avoid a rear-end collision with the cyclist, drivers need to make a timely and accurate decision about whether to steer and overtake the cyclist, or brake and let the oncoming traffic pass first. If this decision is delayed, for instance because the driver is distracted, neither braking nor steering may eventually keep the driver from crashing—at that point, rear-ending a cyclist may be the safest alternative for the driver. Active safety systems such as forward collision warning that help drivers being alert and avoiding collisions may be enhanced with driver models to reduce activations perceived as false positive. In this study, we developed a driver model based on logistic regression using data from a test-track experiment. The model can predict the probability and confidence of drivers braking and steering while approaching a cyclist during an overtaking, and therefore this model may improve collision warning systems. In both an in-sample and out-of-sample evaluation, the model identified drivers’ intent to overtake with high accuracy (0.99 and 0.90, respectively). The model can be integrated into a warning system that leverages the deviance of the actual driver behavior from the behavior predicted by the model to allow timely warnings without compromising driver acceptance

J Exp Psychol Hum Percept Perform

This investigation examined how children and adults negotiate a challenging perceptual-motor problem with significant real-world implications--bicycling across two lanes of opposing traffic. Twelve- and 14-year-olds and adults rode a bicycling simulator through an immersive virtual environment. Participants crossed intersections with continuous cross traffic coming from opposing directions. Opportunities for crossing were divided into aligned (far gap opens with or before near gap) and rolling (far gap opens after near gap) gap pairs. Children and adults preferred rolling to aligned gap pairs, though this preference was stronger for adults than for children. Crossing aligned versus rolling gap pairs produced substantial differences in direction of travel, speed of crossing, and timing of entry into the near and far lanes. For both aligned and rolling gap pairs, children demonstrated less skill than adults in coordinating self and object movement. These findings have implications for understanding perception-action-cognition links and for understanding risk factors underlying car-bicycle collisions.R01 HD052875/HD/NICHD NIH HHS/United StatesR01-HD052875/HD/NICHD NIH HHS/United StatesR49/CE001167/CE/NCIPC CDC HHS/United States2014-05-29T00:00:00Z22924952PMC403790