The impact of curve radius variations on vehicle driving states on 2-lane roads

The complex alignment of 2-lane roads results in a higher risk of traffic crashes. This study aims to identify key factors influencing vehicle driving states on curves. Five curve radii were selected to create simulated driving scenarios. Vehicle operation data were collected from 36 drivers using a driving simulator. Vehicle speed and lateral lane position were chosen as indicators of driving states. A 3-factor analysis of variance (ANOVA) was conducted to assess the effects of curve radius, curve direction, and curve position on driving speed and lateral lane position. Polynomial fitting models were also developed to examine the relationship between curve radius, mean speed, and mean lateral lane position magnitude. Curve radius had the most significant effect on driving speed (partial η² = 0.536), and curve position had the greatest influence on lateral lane position (partial η² = 0.283). The polynomial fitting models for right turns (adjusted <i>R</i>² = 0.768) and left turns (adjusted <i>R</i>² = 0.754) both exhibited adjusted <i>R</i>² values greater than 0.75, indicating that the models adequately explain the relationships among the 3 variables. Smaller curve radii result in lower average driving speeds. In the circular curve sections of the road, lateral lane position tends to be larger. As curve radius decreases, the influence of driving speed on lateral lane position magnitude becomes more pronounced. Higher average speeds on curves are associated with larger lateral lane position magnitudes. Under the same speed conditions, vehicles making left turns exhibit larger lateral lane position magnitudes compared to those making right turns. These findings highlight the significant impact of curve geometry on vehicle driving behavior, providing insights for curve alignment design.