Development of an optimized bus schedule for Kigali

Abstract

Due to the observed exponential growth of the population in Kigali which goes in parallel with car ownership, alternative green modes of transport need to be developed, among them public transport. Currently, public transport in Kigali is characterized by unscheduled services where in most of the cases buses will wait until full before they depart. For passengers using this mode of transport, their travel times can be very long, even unpredictable and the situation gets worse when these passengers require connections in their daily journeys. This research seeks to develop an optimized bus schedule to enable the public transit patronage to make successful connections within the public transport network. To achieve this, the synchronization problem has been formulated as a mixed integer programming problem and a heuristic algorithm was developed to solve it. In this research, a connection is qualified to be successful when the arrival of two different buses at one node is separated by a fixed transfer time. In order to assess the benefits of the developed model, a part of Kigali bus network was used to test it and a comparison between bus schedules before and after optimization was made. In total, seven routes comprising five nodes were surveyed to attain the objectives of the research. Thereafter, savings in travel times after optimization were calculated and the model was found to have a good performance by achieving between 15 and 77% of savings in travel times for the tested network. The comparison between the two types of bus schedules (before and after optimization) shows the heuristic algorithm used in the research ensures successful connections for the passengers, thus very effective. For further research, specific transfer time should be assigned to each transfer node based on their importance in the network.