Performance Monitoring of Bus Priority Using Automatic Data
C D'Souza, Transport for London; N Hounsell, B Shrestha, University of Southampton, UK
This paper presents the performance monitoring capabilities of iBus and ASTRID demonstrated in a study, covering some 840 traffic signal installations along 60 bus routes in London, carried out by TfL and the Transportation Research Group in 2011.
Transport for London (TfL)'s iBus is an Automatic Vehicle Location (AVL) system for supporting various public transport applications including: real time passenger information, bus fleet management and bus priority at traffic signals. For bus priority at traffic signals, iBus has provided the opportunity to cover a large area of London and implement more innovative priority strategies. Its benefits over the loop and beacon solutions include: reduced equipment installation, easier rollout and a range of data that present new opportunities in the performance monitoring of the system. For this purpose, iBus provides facilities to collect a variety of bus detection and operational data automatically over all equipped routes.
The data available from iBus varies from detailed information such as the time buses arrive at every bus stop to aggregated information such as average bus journey time for a route for a defined period. The disaggregate data can then be analysed in detail, or aggregated to provide more general statistics, depending on the depth of the monitoring/evaluation required. For example, iBus produces a standard periodic report illustrating the number of bus acknowledgments received for all the iBus signals in London during 4-weekly periods. TfL's Fault Control Centre currently uses this information to maintain the bus priority system.
In addition to iBus data, traffic signals controlled under the SCOOT UTC system which have iBus-enabled bus priority capabilities store information regarding bus priority activity data centrally in ASTRID (Automatic SCOOT Traffic Information Database). The information available from the database can be used to monitor overall bus flows, the number of the buses passing through the signals when on green, the number of buses awarded priority green extensions and number of buses awarded recalls. Such information is very useful in monitoring bus priority operations across the whole network with a relatively low resource requirement. For more detailed information, junction level performance (delays, stops, etc.) can be analysed from SCOOT messages at various levels of temporal aggregation.
These performance monitoring capabilities of iBus and ASTRID were demonstrated in a study carried out by TfL and the Transportation Research Group (TRG) in 2011. This study was to monitor the performance of iBus enabled bus priority at some 840 traffic signal installations in London, covering 60 bus routes. This paper summarises these automatic data collection facilities and then demonstrates the use of them for performance monitoring, using data from the 2011 surveys as a Case study. The paper concludes with a discussion of some issues related to the use of automatic data and suggests further research and development opportunities in this area.
Association for European Transport