Thesis (M.Eng., Civil Engineering) -- University of Idaho, 2016 | Typical vehicle detection systems used in traffic signal operations are comprised of inductive loop detectors. Because of costs, installation challenges, and operation and maintenance issues, many alternative “non-intrusive” systems have been developed and are now commercially available. Field-testing was conducted to evaluate eight alternative vehicle detection systems (four video, one radar, one infrared, and two hybrid) at the stop bar zone of a signalized intersection under six conditions: (a) daytime, (b) nighttime, (c) favorable conditions, (d) windy conditions, (e) rain, and (f) snow. With several exceptions, performance generally degraded in nighttime when compared with day light conditions, and in adverse versus favorable weather conditions. In general, radar and hybrid systems performed with the greatest accuracy.