This report describes the design and development of the Site Observer, an automated site-based video system for capturing and analyzing vehicle trajectories for the purpose of highway safety research. Many highway safety problems currently are unsupported in terms of high-quality objective data that adequately describe real-world traffic conflicts. Although much effort has been devoted to instrumenting vehicles for naturalistic driving studies, the vehicle-based approach has several limitations, particularly for addressing site-specific safety questions. Some examples of limitations are (a) monitoring sites with specific geometries of interest, (b) evaluating the effects of site-specific countermeasures, and (c) addressing conflicts and crashes that result from the kinematics of several vehicles simultaneously (e.g., path crossing at intersections). In such cases, it is more efficient and effective to use fixed sensors and data acquisition strategically situated at a site of interest, provided they are capable of measuring the continuous positions, speeds, and accelerations of all relevant vehicles passing through the site. The purpose of the Site Observer system is to fill this technology gap and provide research data and actionable data to support future developments in areas such as geometric design, signal timing, road markings, and signage and systematically improve highway safety. (Author/publisher)
Abstract