Intention to Use Intercity High-Speed Rail in Thailand: A Multi-Group Analysis of Generational Cohorts Using an Extended Theory of Planned Behavior

This study examines factors associated with the intention to use intercity High-Speed Rail (HSR) in Thailand before its operation, using an extended Theory of Planned Behavior (TPB) that adds External Influence, Trust, and Novelty Seeking. Survey data from 1546 intercity travelers were analyzed with Multi-Group Structural Equation Modeling across Generations X, Y, and Z using robust maximum likelihood. Configural, metric, and scalar measurement invariance and, under the same ΔCFI criterion, structural invariance were supported. In the hypothesized model, Subjective Norm and Perceived Behavioral Control were positively associated with intention in all cohorts, and External Influence was related to intention indirectly through Trust, Subjective Norm, and Perceived Behavioral Control. When direct paths from the added constructs to intention were estimated, Trust was directly associated with intention in every cohort, whereas Perceived Behavioral Control was not. A stronger Perceived Behavioral Control–intention association in Generation Z did not persist under partial measurement invariance, among working adults, without items with overlapping content, or with direct Trust–intention paths. The pathways to intention were therefore largely similar across generations, and apparent generational differences reflected model specification and life stage. Building trust before operation may help strengthen intentions, although such strategies were not tested directly.