SELECTED RESULTS FROM THE FIRST THREE YEARS OF THE OREGON AUTOMATIC MONITORING DEMONSTRATION PROJECT

Until the 1980s, the majority of highway traffic data was obtained manually. However, with the evolution of microcomputers, cost-effective automatic data-collection equipment has been implemented. A comprehensive system is made up of weigh-in-motion, automatic vehicle classification, and automatic vehicle identification. Weigh-in-motion determines axle and vehicle weight at full speed on the highway, automatic vehicle classification classifies the traffic into groups (19 in Oregon) by identification of axle spacings, and automatic vehicle identification acts as an "electronic license plate," which can be used with weigh-in-motion and automatic vehicle classification to characterize individual vehicles. These new technologies enable continuous and relatively accurate monitoring of traffic, and therefore lead to improved planning, pavement design, and activities that use the data. Oregon State Highway Division is a leader in demonstrating automatic vehicle monitoring, which was initiated in the state in 1983. Data are collected in unprecedented amounts at five sites on Interstate 5 (I-5). Oregon State University has developed prototype BASIC software to process the weekly data from the busiest site in tabular or graphical form, designed to enable data to be distributed in the various units in the highway division. Selected results are included in this paper, and other data are presented that show comparison of weights obtained with weigh-in-motion and with static scales. The advantages of having automatic vehicle monitoring data are demonstrated. In particular, the continuous monitoring of the traffic stream completely defines daily, weekly, and seasonal traffic patterns, and clearly indicates growth.