Anaheim Advanced Traffic Control System Field Operational Test Task C: Video Traffic Detection System

Problem

As one part of the City of Anaheim's Advanced Traffic Control Field Test (in partner with Caltrans, FHWA, and JHK Consulting), we conducted an evaluation of a video detection system marketed by Odetics, Inc. as a low-cost alternative to loop detectors. Using video cameras, the system detects vehicles at intersection approaches in "virtual detection windows" for signal phase actuation. It can be set up and calibrated in the field using only a TV monitor and a PC mouse; up to four detection window setups can be stored; and it can also be set up and calibrated remotely. The user interface is simple but effective.

Method

Nine vehicle detection event classes and six phase actuation event classes were defined for this test, with different lighting, weather, and traffic conditions. Videotapes acquired in the field were slowed down, analyzed, and compared to the system's detection results.

Findings

In general, we found that detection was good under ideal lighting and light traffic conditions, but degraded at higher traffic levels and low light, night, and rainy conditions.

65% of vehicles were detected properly, which is similar to the performance of loop detectors. 80.9% were detected adequately for the purpose of signal phase actuation, and there was an average 8.3% false and latch detection rate (latch detection happens when the system detects a vehicle but fails to notice when it has moved on).

The manufacturer, Odetics, says it has since replaced both hardware and software to address these problems, but we have not tested the new system.