Investigating and modeling motorcycle crash rates at urban unsignalized intersections in India

OBJECTIVE

The present study focuses on understanding the behavior of motorized 2-wheeler (MTW) riders at urban unsignalized intersections in India. In the Indian context, over 60% of road crash fatalities are attributed to vulnerable road users, with MTWs serving as the predominant contributors, accounting for 44% of total fatalities. Notably, unsignalized intersections have emerged as critical sites for accidents involving vulnerable road users.

METHODS

Postencroachment time is used to assess traffic conflicts of MTW users. Furthermore, the study employs the exceedance property of extreme value theory to calculate crash probabilities. Tobit and grouped random parameters Tobit regression models are developed to model crash probabilities, incorporating variables such as traffic volume, traffic composition, gap acceptance time, intersection characteristics, and intersection conflict area at 4 urban unsignalized intersections in Surat, India.

RESULTS

MTW riders have the lowest gap acceptance time among vehicles in the traffic stream. Cars and other heavy vehicles readily accept gaps when MTWs are in the conflicting stream at unsignalized intersections, which increases traffic conflicts. MTWs have the highest crash rates in the traffic stream. Among the developed models, the grouped random parameters Tobit regression captures the spatial unobserved heterogeneity of the study sites and outperforms the simple Tobit regression model. The results also indicate that MTW riders are exposed to a higher risk of crashes while turning at unsignalized intersections. The presence of a central traffic island has varied implications; it raises crash rates at 3-legged intersections but lowers them at 4-legged intersections for 2-wheelers.

CONCLUSION

The study concludes that MTW crash rates are influenced by traffic and intersectional factors. Increased gap acceptance time correlates with lower crash rates. Countermeasure selections require detailed investigations, because it was observed that the presence of central traffic islands has varied effects on crash rates at 3-legged and 4-legged unsignalized intersections.

Effects of penetration rates on the application of in-vehicle traffic lights at unsignalized intersections

OBJECTIVE

In-vehicle traffic lights have been demonstrated as an effective method to assist drivers in crossing unsignalized intersections, by displaying virtual traffic lights inside vehicles based on vehicle-to-vehicle communications. However, previous studies assumed that all the vehicles were equipped with vehicular communications, of which the deployment might last for decades. Therefore, it is necessary to consider the application of the system in partial deployment scenarios. This study aimed to analyze the influences of in-vehicle traffic light system on driving safety at unsignalized intersections within different penetration rates.

METHODS

Driving simulator experiments involving 18 participants were performed. Evaluation indexes including post-encroachment time, maximum acceleration stroke of ego vehicle, and times of near miss incidents were investigated for different penetration rates of vehicular communications.

RESULTS

Significant differences were observed between the conditions when no in-vehicle traffic light was used and when the penetration rate was 100% for the post-encroachment time (p = 0.02), and the maximum acceleration stroke of ego vehicle (p = 0.05). Meanwhile, it was found that the post-encroachment time slightly decreased, and the times of near miss incidents slightly increased when the penetration rate increased from 0% to 50%. However, the post-encroachment time was still longer for different penetration rates, compared to the condition when no in-vehicle traffic light was applied.

CONCLUSIONS

The results indicated that the in-vehicle traffic light system could significantly improve driving safety at unsignalized intersections when the penetration rate was 100%. For partial deployment conditions, it is essential to speed up the deployment of vehicular communication-based driver assistance systems within early deployment stage, especially when the penetration rate was within 50%, to ensure driving safety.

Gap acceptance behavior at unsignalized intersections: Effects of using a phone and a music player while driving

Objectives: The present study is an attempt to analyze and compare the distraction effects caused by the use of a phone and a music player at unsignalized intersections. Method: Eighty-eight participants performed simulated driving experiments where they faced a sequence of gaps in the major road traffic at 2 unsignalized intersections. In this process, their driving behavior was evaluated in terms of gap acceptance probability, accepted lag, and maneuver completion time. These parameters were modeled with a generalized estimating equation (GEE) method by considering distraction, demographic factors, driving history, maneuver types, and driving attributes in the approach and completion zones as independent variables. Results: The results showed that gap acceptance probability decreased by 46% during the conversation task, whereas it increased by 66% during the music player task. Lower gap acceptance could be a compensatory behavior adopted by drivers during the conversation task, whereas no such measure was adapted during the music player task. The results indicate that a higher approach speed during the music player task might have led to increased gap acceptance. Further, though the effect of distraction on the accepted lag was not evident, the completion time was reduced during the conversation task. Conclusions: Overall, the results suggest that drivers are more likely to adopt a compensatory measure in complex driving situations only if they perceive a high risk. Hence, drivers are exposed to a greater risk while operating a music player, because this is not perceived as risky behavior.

Statistical analysis of bicyclists' injury severity at unsignalized intersections

OBJECTIVES

This study investigated factors correlated with the severity of injuries sustained by bicyclists in bicycle-motor vehicle crashes at unsignalized intersections to develop site-specific countermeasures and interventions to improve bicycle safety.

METHOD

Crash data were extracted from accident reports entered into the Kentucky State Police's Kentucky Collision Database in 2002-2012. A partial proportional odds model was developed for data analysis.

RESULTS

According to our modeling results, stop-controlled intersections, one-lane approaches, helmet usage, and lower speed limits were associated with decreased injury severity, whereas uncontrolled intersections, older (age > 55) drivers and bicyclists, child (age < 16) bicyclists, foggy and rainy weather, inadequate use of lights in dark conditions, and wet road surfaces were linked with increased injury severity.

CONCLUSIONS

Based on these results, we suggest the development of educational programs focused on the following groups: child bicyclists, older bicyclists, and older drivers. Investigating and modifying street lighting could improve bicycle safety. Implementing road diets/traffic calming methods could create a safer traffic environment. Certain traffic control strategies (e.g., stop control) could be considered for uncontrolled intersections with high bicycle exposure, and helmet campaigns should be launched to increase helmet awareness and use. The study also suggests some interesting future research directions, including examining driver/bicyclist behaviors at uncontrolled intersections and studying the riding behaviors of child bicyclists in Kentucky.