Spatial bus priority schemes, implementation challenges and needs: an overview and directions for future studies

Urban transit systems consist of multiple modes of transport of which cars and buses make up the largest portion, particularly in developing countries. Thus, theories on the best means of allocating existing road spaces for cars and buses in city-centers and suburban corridors in order to improve operational transport efficiency has become a frontier research topic. Today, bus priority (BP) methods, as one of the most widely used Public Transport Priority (PTP) strategies, are commonly recognized as effective in lowering traffic congestion and reducing bus travel times. PT authorities, urban planners/designers, and researchers dealing with PT issues (i.e. buses), need to investigate existing BP methods in detail and assess relevant research before setting about designing or implementing new policies. Of course, evaluating such studies is a time-consuming process. In order to address this constraint, the present study proposes a general typology of existing BP methods and evaluates the challenges and requirements regarding their implementation by conducting a comprehensive literature review of existing studies related to PTP. Academic papers (theoretical, analytical, and simulation-based), technical reports, and design manual/guidelines in the context of both developed and developing countries have been searched as part of the literature review process. The study concludes by proposing two comparative summary tables of all spatial bus priority schemes in terms of “min. requirements to justify BP schemes” and “advantages and disadvantages of time-based and spatial BP treatments”. These may provide engineers, urban planners or transit policy-makers with an accessible guide with which to refer in the evaluation stage. However, future research is recommended in order to bridge existing gaps concerning conditions required for the successful implementation of spatial bus priority strategies.