Knowledge Resources

In response to growing traffic congestion and consequent passenger demands for more reliable service, many transit operators are seeking to improve bus operations by investing in technology such as automatic vehicle location (AVL) and automatic passenger counters (APCs).

Transit providers have yet to take advantage of low-cost performance and passenger-activity data associated with AVL-APC technology. This is due, in part, to the traditional separation of operations functions (where the AVL-APC technology has been deployed) from the scheduling and service planning functions of transit organizations (where the needs for data and analysis are located). Pockets of excellent AVL-APC data management for specific applications can be found, but integrated approaches that can be applied across the industry do not exist.

The report, Uses of Archived AVL-APC Data to Improve Transit Performance and Management: Review and Potential, provides a working plan for reviewing the needs, practice, and potential in relation to the use of archived AVL-APC data. Several case studies are presented in the report representing a broad range of transit agencies. Successes as well as failures have been documented in the report.

In Portland Oregon, Tri-Met is a leading example of an agency that has deployed both AVL and APC and has archived AVL-APC data analysis. Their integrated AVL-APC system provides route stop-level records that, for the 65 percent of the fleet, include passenger counts. The data is stored and managed in an Oracle database. Using a query language, selected data (e.g., by route, direction, times, dates) can be extracted. Extracted tables are then imported to statistical analysis software (SAS) for statistical analysis; scripts for standard analyses are stored and reused. Sometimes results are imported to Microsoft Access for easier formatting. The agency has gained a reputation as an industry leader in the areas of data archiving and the application of archived data to performance monitoring and analysis.

RESULTS

Initial performance impacts:

• a 9 percent improvement in on-time performance
• an 18 percent reduction in running time variation
• a 3 percent reduction in mean running time
• a 4 percent reduction in headway variation.

Archived AVL data were used to construct running time distributions by route and time period. From these distributions, typical running, recovery and layover times were calculated and compared to published standards, as well as Tri-Met’s own scheduling standards. It was found that 81 of the agency’s 104 routes had excessive running, recovery, and layover times, while the scheduled times in the other 23 were inadequate. It was estimated that adjusting the schedules would potentially yield a $7 million per year savings in operating cost. The contribution of operators to running time variability was assessed with a fixed effects model, since the data were assumed to be normally distributed.

The implementation of the bus dispatch system (BDS) and its AVL/APC components has yielded tangible improvements in service quality and measurable savings in operating and administrative costs at Tri-Met.

Notes:
See Also:

Strathman, J.G., et al. "Evaluation of Transit Operations: Data Applications of Tri-Met’s Automated Bus Dispatching System," Transportation Research Board, Transportation Research Record. Washington, DC. 2002.