Assessing travel time impacts of measures to enhance bus operations. Part I: Past Evidence and Study Methodology

There have been a variety of bus priority measures used for at least 25 years in various areas throughout the world. European countries, particularly the UK, have pioneered many of the bus priority systems on arterial streets. Many of the systems associated with freeway operations have been developed in the United States. Bus lanes and traffic signal priority are the most common forms of bus priority and these systems can provide significant travel time savings for congested arterial roads. This paper presents the main findings regarding evidence from past work and the methodology used in a recent study that focused on the efficiency of the overall journey time of bus transport on arterial roads. The analysis of the various treatments will focus on reducing travel time for buses, which is fundamentally linked to the cost and efficiency of this form of public transport. The work undertaken considers the travel time savings obtained for buses and the associated impacts on the remainder of the general purpose traffic to minimise the person delay through the network. The inclusion of other parameters that may affect the justification of bus priority measures such as vehicle costs and the environmental costs is a logical extension of this research. A methodology for the selection of bus priority is outlined in this paper. This is based on detailed analysis of the travel time impacts of various bus priority treatments. However, it is stated that the selection process should entail the consideration of these issues in conjunction with the wider transport planning context. Furthermore, this paper recommends that bus priority treatments be part of an overall traffic management strategy for a transport corridor. It is suggested that there may be significant travel time savings associated with bus priority treatments. However to obtain these benefits with manageable impacts on other traffic, the type and nature of the bus priority treatments need to be matched to the road and traffic conditions. This will ensure that the efficiency of the road infrastructure is maximised for each traffic management strategy.