Introduction to Traffic Signal Data Loggers and their Application to Accident Reconstruction 2018-01-0527

Each year in the United States, approximately 1 million collisions occur at signalized intersections, representing over 15% of all collisions and almost 9% of traffic fatalities. Engineers seeking to understand the roadway, vehicular, and driver factors related to these collisions are often asked to investigate and assess the traffic signal timing, right of way issues, and the signal indications displayed to involved drivers during the period of time leading up to and including the impact events. Until relatively recently, investigators were limited by the absence of any recording devices within the systems used for traffic signal phasing and timing. Accident reconstruction methods have long relied on the generalized signal phasing and timings programmed for that intersection by the responsible jurisdiction, combined with the vehicle dynamics calculated for the collision sequence in conjunction with witness testimony regarding signal indications and phase changes. Recent technological advancements in signal timing data collection, recording, and logging can provide engineers and investigators with a new, time-specific, incident-relatable and more robust method of analyzing signalized intersection collisions. This paper presents the current state of the art for traffic signalization: Signal Timing Data Loggers. This paper also presents how to obtain, analyze, and interpret the data logger data and possible applications of such data to accident reconstruction.