Battery electric buses are seen as a well-suited technology for sustainable urban transit system because it has high energy efficiency and generates zero tailpipe emissions. Therefore, conventional buses are likely to be continuously replaced by electric buses. However, the limitations of electric buses, such as range limitations, battery capacity loss and required charging times of battery, are critical issues for the service quality of the urban transit system. Therefore, it is more realistic to develop a sustainable urban transit system mixed with conventional and electric buses in a transitional period until the limitations of electric buses are overcome.