Investigating Vulnerable Road Users’ Unsafe Interactions with Right-Turn Warning Zones at Urban Intersections: A Combination of Field Observation and Questionnaire Survey

The growing deployment of right-turn warning zones (RTWZs) at urban intersections in China aims to enhance the operational safety of urban traffic systems, yet encroachment upon these zones by pedestrians and non-motorized vehicle (NMV) users remains a practical concern. This study combined a field observation at two intersections in Hefei, China, to examine these vulnerable road users’ actual unsafe RTWZ encroachment behaviors, with an extended theory of planned behavior (TPB) questionnaire survey to explore the cognitive mechanisms underlying intentions of such encroachment. Observational results showed that NMV riders encroached on RTWZs significantly more frequently than pedestrians, and such encroachments occurred more often during morning peak hours. The questionnaire survey on 402 respondents revealed that attitude, perceived behavioral control (PBC), and past behavior showed the strongest positive effect on encroachment intention, both directly and indirectly through PBC. In contrast, perceived risk and safety knowledge negatively predicted intention indirectly, while also showing significant indirect effects on intention impacting attitude. Subjective norm, sociodemographic characteristics, and travel patterns were not significant predictors. These findings not only provide a deeper understanding of the real-world effectiveness of RTWZs, but also offer an evidence-based basis for developing countermeasures to improve operational safety of urban slow traffic systems.