The objective of this paper is to synthesize information from successful city-wide bus system reforms in three world cities, London (Europe), Sao Paulo (Latin America) and Seoul (Asia). All reviewed systems improved system wide ridership, significantly improved conditions for commuters and produced other positive externalities such as reducing air pollution and improving traffic safety. The reforms were undertaken amidst varying political, economic and social contexts. The main focus of the reviews was to identify the common elements in successful reform processes in an attempt to assist planners and decision makers implementing city-wide bus system reforms. Individual case studies were prepared for each city and are presented in separate documents. The reviews are based on material available on the internet. The following seven aspects or commonalties stood out as the key factors for implementing successful bus system reforms across the three cities.
1. Strong Political Leadership in the Decision Making process
2. Strong local technical institution developing demand based route planning
3. Implementing bus Priority and/or building segregated infrastructure for buses
4. Use of Technology
5. Innovations in contracting and tendering processes
6. Need for managed subsidies to improve quality of service
7. System Performance Monitoring and User Feedback.

The paper is divided in three sections. The first section provides a short description and indicator information about the performance of bus systems in each city. The second section examines each of the seven commonalties for each system. The final section summarizes the learning from the three systems.