Distance-Dependent competitive dynamics of high-speed rail: A comparative machine learning approach for predicting mode choice and market share redistribution

• The study models the impact of HSR on other modes across various distances. • Road transport retains market dominance in short-distance (0-300 km) segments. • HSR triggers a substantial road-to-rail shift in medium-haul (300–500 km) trips. • HSR replaces air travel as the dominant mode in upper-medium (500-800 km) routes. • SHAP analysis reveals non-linear, distance-dependent choice behaviors. The introduction of high-speed rail (HSR) fundamentally alters intercity transport equilibrium, yet its competitive impact exhibits significant heterogeneity across travel distances and operational configurations. This study establishes a rigorous comparative framework to forecast mode choice behavior and market share redistribution along Thailand’s planned Bangkok-Chiang Mai corridor. Utilizing Stated Preference (SP) data from 3,139 respondents, we benchmark a baseline multinomial logit (MNL) model against five advanced machine learning (ML) algorithms. Empirical results demonstrate that ensemble tree-based models significantly outperform both MNL and deep neural networks, with CatBoost emerging as the superior classifier. Integrating SHapley Additive exPlanations (SHAP) with a comprehensive sensitivity analysis, this research uncovers distinct, distance-dependent competitive regimes and non-linear "threshold effects." In short-distance segments (0–300 km), HSR demand is primarily governed by price sensitivity. In medium-distance segments (300–500 km), a significant "road-to-rail" shift is observed, with demand saturating at an optimal operational velocity of 250 km/h. For longer distances (500–800 km), HSR achieves market dominance as a formidable air transport substitute, provided it breaches a critical 300 km/h tipping point. However, the findings reveal a fragile equilibrium: an "Air Rebound" effect occurs if HSR fares exceed a rigid price ceiling, causing demand to surge back to aviation. These results suggest that a tiered HSR service strategy—balancing high-velocity performance for long hauls with price competitiveness for regional segments—is essential to maximize commercial viability and social sustainability within a multi-modal ecosystem.