Evaluation of the OCTA Transit Probe System

Problem

The OCTA (Orange County Transit Authority) Transit Probe Project is a field operation test of an automatic vehicle-location (AVL) system operating in Orange County, California. The system software was designed to estimate roadway congestion levels based on bus travel times over route segments and communicate this information to Caltrans, the City of Anaheim, and the City of Santa Ana.

This report presents the final evaluation of the project, concentrating on the year-long field operational test period. The report provides a detailed description of the system and its design. It also provides analyses of data reliability and accuracy, and analysis of the usefulness of Transit Probe data for predicting automobile travel times. Institutional issues are evaluated, based on interviews with involved personnel, direct observation, and review of project documents. Surveys of bus riders and kiosk users are also documented.

Findings

Bus tracking systems provide many potential benefits related to scheduling, problem response, and bus arrival information for users. However, these benefits cannot be captured without carefully planning operational procedures, data maintenance, system interfaces, and ensuring that the equipment is reliable. These important issues did not receive adequate consideration in the system design phase of the project. Although the evaluation produced important insights as to how bus tracking should be implemented and the likely problems to expect, the OCTA Probe failed to live up to its promise because the system was not used by drivers, dispatchers, planners, schedulers, or the general public.

Transit Probe did not meet reliability standards for an actual deployment. The majority of schedule data points are either missing, undetected, or duplicated, thus confounding data analysis.

Transit Probe never created its intended interfaces to Caltrans, the City of Anaheim, or City of Santa Ana due to a reduction in scope of the deployment and a reduced budget.

Only one public interface kiosk was installed, and though it was well-received in a test evaluation, it wasn't functional until the end of the project and therefore didn't have any positive impact.

Customers perceived that bus schedule adherence had improved during the Transit Probe project, though whether this represents a real improvement or merely public perception is not altogether clear. From bus driver interviews, it seems that the installation of a clock in driver view may have encouraged better schedule adherence. However, drivers generally ignored Transit Probe indicator lights, and therefore the improvement could not have resulted from Transit Probe's schedule adherence capabilities.

The congestion measurement component of Transit Probe was never fully established due to many factors, including: 1) inadequate congestion information dissemination, 2) improperly established baseline bus route segment speeds, 3) inaccurate speed estimation algorithm in Transit Probe, 4) lack of relationship between slow bus speeds and general traffic speed.

In terms of the institutional performance of OCTA Transit Probe, OCTA involved partner agencies commendably while moving the project forward and meeting deadlines during the design phase. However, once the project progressed to the test phase, the organization became rather conventional with a contractor and contract manager and outside participation virtually disappeared.