Understanding Public Transport Substitution and Mode Shift in Motorcycle-Dominated Cities: Evidence from Indonesia

Urban transport decarbonization in Indonesia requires strategies that address the persistent dominance of private motorized mobility, particularly motorcycles, while strengthening the competitiveness of public transport. This study examines travel activity patterns, the current role of public transport, and potential mode-shift responses to improved public transport services across 11 Indonesian urban areas. Primary data were collected through a structured face-to-face interview survey involving 5,532 respondents. A mixed logit model was estimated to examine how travel cost, public transport fare, access cost, travel time, waiting time, and electric propulsion influence mode choice. The descriptive results show that public transport currently performs two roles in urban mobility. Among current public transport users, 82.69% had previously made the same trip using another mode, indicating a substitution role, while 17.31% reported that the trip had not been made before public transport became available, indicating a mobility-enabling role. Motorcycles were the dominant previous mode for several public transport services, reflecting their strong position in Indonesian urban travel. For public transport alternatives, travel time produced the largest direct elasticities in absolute terms, followed by access cost. Access-cost elasticities consistently exceeded fare elasticities in absolute terms, while waiting-time elasticities were not statistically significant. Interactions with gender, age, income, and urban context further revealed systematic differences in modal preferences, with women and older respondents more oriented toward buses and minibuses relative to motorcycles, higher-income respondents more oriented toward cars, and rail utility consistently lower outside the Jakarta Metropolitan Area. These findings suggest that public transport strategies in Indonesian cities should prioritize reductions in door-to-door journey time and first- and last-mile burdens, complement these measures with fare integration, and adapt interventions to local urban contexts and user-group needs.