Identifying and Structuring Discretionary Lane-Changing Stimuli Using a Mixed-Methods Approach

This paper identifies and categorizes factors influencing discretionary lane-changing behavior. A mixed-methods approach combining qualitative and quantitative analysis is employed to structure lane-changing stimuli into clusters and determine their relative importance. Three focus groups of drivers with experience in the United States generated forty discretionary lane-changing reasons. These stimuli were subsequently evaluated through a stated-preference survey of 220 respondents. Exploratory Factor Analysis (EFA) revealed three latent categories: Hazard & Evasive, Situational & Environmental, and Operational & Efficiency factors. Quantitative assessment indicated that safety-critical stimuli, such as encountering a stopped emergency vehicle or road debris, were the highest-ranked individual factors triggering a lane change. Furthermore, preliminary cluster comparisons suggest that the “Hazard & Evasive” cluster is the most influential group of motives. This study offers a foundational step toward developing a “lane-changing propensity” scale. Rather than providing ready-to-integrate mathematical parameters, it contributes a foundational behavioral basis for future model development and validation, highlighting non-traditional driver motivations that future microscopic simulations may eventually explore.