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How can we optimize public transport systems to create efficient, user-friendly networks?

A recent study by CID faculty affiliates Rema Hanna, Gabriel Kreindler and co-authors Arya Gaduh, Tilman Graff, and Benjamin Olken entitled "Optimal Public Transportation Networks: Evidence from the World’s Largest Bus Rapid Transit System in Jakarta" examines how public transportation networks can be optimized, focusing on Jakarta’s TransJakarta Bus Rapid Transit (BRT) system. By analyzing the expansion of 93 bus routes in Jakarta between 2016 and 2020, the authors examine how improvements in direct routes, reduced travel times, and shorter wait times affect bus ridership. They estimate a commuter demand model and develop a framework for designing optimal bus networks.

Key Findings:

• Impact of Route Improvements: Adding new direct routes and reducing wait times significantly increased ridership. For example, launching a quicker direct route increased ridership by around 27%, while adding more buses to existing routes (via new routes that overlap with old direct routes) increased ridership by roughly 9%. These improvements highlight the critical role of service quality dimensions—speed, frequency, and directness.
• Commuter Preferences: The study finds that commuters in Jakarta are 2-4 times more sensitive to waiting times than actual travel times on the bus. Commuters also pay less attention to bus options with significantly longer travel times compared to the fastest available route.
• Optimal Network Design: Based on the estimated preferences, the authors propose a more expansive and better-balanced bus network for Jakarta, which would cover 66% of all locations compared to the current 42%, increase ridership by 64%, and enhance commuter welfare. The study emphasizes that the current system concentrates too many buses in central areas, while optimal networks would spread services more evenly across the city, particularly benefiting underserved areas.

Impact and Relevance:

This study offers crucial insights for cities in low- and middle-income countries (LMICs) grappling with rapid urbanization and overburdened public transportation systems. By highlighting how reducing wait times and improving direct routes can significantly increase bus ridership, the research shows that even small service improvements can have large impacts on commuter welfare. This is particularly relevant in cities like Jakarta, where expanding efficient public transport can ease congestion, reduce pollution, and provide better access to economic opportunities, especially for lower-income populations.

The findings underscore the need for policymakers to rethink the allocation of resources in public transport networks. In Jakarta, the proposed optimal network would not only expand coverage to underserved areas but also redistribute buses more effectively, increasing ridership by over 60%. This approach could help reduce inequality in access to transportation, ensuring that more residents, especially those living in peripheral areas, benefit from improved connectivity and shorter travel times.

Globally, as more cities invest in Bus Rapid Transit (BRT) systems, the lessons from this study provide a data-driven framework for designing more effective transit networks. The emphasis on commuter preferences—particularly the strong sensitivity to waiting times—suggests that cities can significantly enhance the attractiveness of public transport by focusing on these service quality dimensions. By improving network design, cities can boost public transport usage, contributing to more sustainable and equitable urban growth for millions of urban residents in fast-growing cities around the world.