EFFECTIVENESS OF ITS SAFETY MERGING SUPPORT AND COLLISION PREVENTION SUPPORT SERVICES BASED ON DRIVERS' BEHAVIORAL ANALYSIS

Tada, Masahiro; Iida, Katsuhiro; Kurauchi, Fumitaka; Hiraoka, Toshihiro; Kanazawa, Fumihiko; Arima, Nobuhiro · 2013 · Journal of Japan Society of Civil Engineers Ser D3 (Infrastructure Planning and Management)

DOI: 10.2208/jscejipm.69.1

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Summary

This study evaluates the effectiveness of Intelligent Transportation Systems (ITS) safety services—specifically merging support and collision prevention support—by analyzing changes in driver behavior. The research was motivated by the need to empirically verify whether these services, deployed during the 2009 "Smart Road" demonstration in Kobe, Japan, effectively reduce traffic accidents and improve safety. While previous studies focused on service availability, this paper investigates actual behavioral changes, such as increased attention to merging vehicles or reduced following distances, using data from natural driving conditions. The experimental design involved 32 drivers (29 male, 3 female) aged 20–50 who drove approximately 7.5 km daily for one month (October–November 2009) on the Kobe Line and Hanshin Expressway. Drivers were assigned to either merging support or collision prevention support groups, with some serving as controls. Data collection utilized GPS units, laser rangefinders to measure inter-vehicle distances, and ITS onboard units to record service activation. The study analyzed 139 valid driving runs, comparing behavior during service activation against control periods (no service) using statistical methods, including Bonferroni-adjusted t-tests and rank-sum tests. Key findings indicate that ITS merging support significantly increased drivers' attention to merging vehicles. Specifically, when the ITS onboard unit provided information, the frequency of lateral steering maneuvers toward the merging lane increased by 38.5% compared to when no service was provided. This suggests the service not only prompts attention but also facilitates smoother merging maneuvers. In contrast, LED display-based merging support did not show statistically significant differences in steering behavior compared to the no-service condition, likely because drivers could not confirm if the information applied to their specific situation. Regarding collision prevention support, the study found that ITS onboard unit activation significantly increased the frequency of steering maneuvers to maintain safe following distances compared to the no-service condition. This indicates that the service effectively prompts drivers to adjust their spacing to avoid rear-end collisions. However, the service did not significantly reduce the frequency of sudden braking or sharp steering maneuvers, suggesting that while it improves proactive spacing, it does not necessarily eliminate reactive emergency maneuvers. The study concludes that ITS services providing direct, vehicle-specific information are more effective in altering driver behavior than general roadside displays, highlighting the importance of information specificity in ITS design.

Key finding

ITS merging support significantly increased driver attention to merging vehicles and reduced steering corrections, whereas collision prevention support increased safe following distance maintenance without significantly reducing sudden braking or steering maneuvers.

Methodology

field_study

Sample size: 32

Provenance

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