Pedestrians' estimates of their own nighttime conspicuity are unaffected by severe reductions in headlight illumination

Road Users Fail to Appreciate the Special Optical Properties of Retroreflective Materials

OBJECTIVE

To determine whether typical road users appreciate the special optical properties of retroreflective materials.

BACKGROUND

Retroreflective surfaces reflect light back towards the source of the illumination. All drivers benefit from retroreflective materials, as they are required on road signs, on large trailers, in lane delineation, and other traffic control devices. Retroreflective markings can also greatly enhance the conspicuity of pedestrians at night, but pedestrians typically underuse retroreflective markings. One possible reason is that pedestrians may not appreciate the special optical properties of retroreflective materials.

METHOD

Two experiments tested whether observers could correctly predict that retroreflective materials appear remarkably bright when illuminated by a source that is aligned with the observers' eyes. Observers used a magnitude estimation procedure to predict how bright retroreflective and non-retroreflective stimuli would appear during a demonstration designed to highlight retroreflectivity. They then judged the brightness again during the demonstration.

RESULTS

In general, observers underestimated how bright retroreflective stimuli would be and overestimated how bright diffuse reflective and fluorescent stimuli would be. The underestimates for retroreflective stimuli were particularly striking when the observers had not closely examined the stimuli in advance.

CONCLUSION

The fact that road users do not appreciate retroreflectivity may help explain why pedestrians underuse retroreflective markings at night.

APPLICATION

Educational interventions could prove useful in this domain.

Pedestrians' perception and response towards vehicles during road-crossing at nighttime

Pedestrian being involved in road traffic accidents (RTA) is about 22% of all road traffic related deaths. In this study, we have estimated the pedestrian's response towards an approaching vehicle and the time taken to correctly recognize it while they crossed the road in dim-light nighttime conditions. This is also extendable to cycles and other low powered vehicles. Thirty volunteers participated in this study. A collection of six videos, which comprised of different vehicle scenarios were shown to each of the participants. It was observed that correct identification and time to recognize the vehicle was fastest when light emitting diode (LED) strip was fixed between headlights of a four-wheeler. Average time to recognize a low beam car and a high beam car with an LED strip was 7.62±2.39s and 11.23±2.94s respectively, whereas correct identification rates of the said low beam and high beam cars with LED strips were 93.33% and 86.67% respectively. Earlier when no LED was used, time to recognize low beam car and high beam car without LED strip were 20.55±3.50s and 25.57±4.14s respectively whereas correct identification of low beam car without LED strip and high beam car without LED strip were 90.00% and 56.67% respectively. Pedestrians are therefore less confused and can take right decision while crossing the road - particularly in a poor lighting environment - when there is a demarcating illumination between headlights of vehicle.

The conspicuity of pedestrians at night: a review

Drivers' visual limitations are a leading contributor to night-time traffic crashes involving pedestrians. This paper reviews the basic changes in vision that occur at night for young and old visually healthy drivers, as well as those with common ocular pathology. To maximise their safety at night, pedestrians should be conspicuous. That is, beyond being simply visible (detectable as an ambiguous object), they should attract the attention of drivers and be readily perceivable as pedestrians. Research has established that the conspicuity of pedestrians can be optimised by attaching retroreflective markings to the pedestrian's extremities. Doing so highlights the pedestrian's 'biological motion,' which facilitates the accurate perception of a person; however, retroreflective markings on the torso (for example, vests) are less effective. Importantly, behavioural evidence indicates that most road users - drivers and pedestrians alike - are not aware of the limitations of night vision. For example, drivers typically 'overdrive' the useful range of their headlight beams and under-use their high beam headlight setting. Further, pedestrians overestimate their own conspicuity at night and fail to appreciate the extent to which their own conspicuity depends on their clothing. The widespread misunderstanding of the challenges associated with night driving reflects a lack of awareness of the fundamental limitations of night vision. Educational interventions are needed to ameliorate these dangerous misunderstandings and to improve the safety of all road users at night.

Investigating the risk factors associated with pedestrian injury severity in Illinois

INTRODUCTION

Pedestrians are known as the most vulnerable road users, which means their needs and safety require specific attention in strategic plans. Given the fact that pedestrians are more prone to higher injury severity levels compared to other road users, this study aims to investigate the risk factors associated with various levels of injury severity that pedestrians experience in Illinois.

METHOD

Ordered-response models are used to analyze single-vehicle, single-pedestrian crash data from 2010 to 2013 in Illinois. As a measure of net change in the effect of significant variables, average direct pseudo-elasticities are calculated that can be further used to prioritize safety countermeasures. A model comparison using AIC and BIC is also provided to compare the performance of the studied ordered-response models.

RESULTS

The results recognized many variables associated with severe injuries: older pedestrians (more than 65years old), pedestrians not wearing contrasting clothing, adult drivers (16-24), drunk drivers, time of day (20:00 to 05:00), divided highways, multilane highways, darkness, and heavy vehicles. On the other hand, crossing the street at crosswalks, older drivers (more than 65years old), urban areas, and presence of traffic control devices (signal and sign) are associated with decreased probability of severe injuries.

CONCLUSIONS AND PRACTICAL APPLICATIONS

The comparison between three proposed ordered-response models shows that the partial proportional odds (PPO) model outperforms the conventional ordered (proportional odds-PO) model and generalized ordered logit model (GOLM). Based on the findings, stricter rules to address DUI driving is suggested. Educational programs need to focus on older pedestrians given the increasing number of older people in Illinois in the upcoming years. Pedestrians should be educated to use pedestrian crosswalks and contrasting clothing at night. In terms of engineering countermeasures, installation of crosswalks where pedestrian activity is high seems a promising practice.