Analysis of Spatial and Environmental Factors Beyond Speed Limits Affecting Drivers’ Speed Choice

Managing vehicle speed is crucial for reducing crash risks and crash severity. South Korea’s ‘Safety Speed 5030’ policy introduced lower urban speed limits to enhance road safety, but speed limit reductions alone may not be sufficient to change driver behavior. This paper investigates how spatial and environmental factors beyond speed limits affect drivers’ speed choice. Using point-level speed data from Jeju Island’s C-ITS dataset combined with GIS information, spatial econometric techniques were employed to capture spatial dependencies in speeding degree. Results show that a spatial lag model (SLM) outperforms ordinary least squares (OLS) and spatial error models (SEMs), providing higher explanatory power and more consistent parameter estimates. Key factors influencing drivers’ speed choice include road geometry (e.g., curvature, number of lanes), node-level features (e.g., intersections, property change points), and the presence of enforcement measures. The findings suggest that the reduction in speed limits alone may not guarantee a corresponding decrease in vehicle speed. This underlines that sustainable traffic safety requires not only regulation but also careful consideration of spatial and environmental contexts.