The purpose of this study was to determine hazards in run-offthe-road accidents. The major data sources were accident data from specially trained State police, and road and roadside data from State files. Data were collected in six States; and the sample consisted of almost 8,000 accidents on rural roads. The findings show (1) sample descriptors, (2) factors influencing the occurrence of run-off-the-road accidents, (3) haracteristics of road departures and factors influencing them, (4) off-road events and factors influencing them, including the effects of offset and clear'zones, (5) impact behavior, speed, area of damage, and objects struck, (6) effects of impact characteristics on severity, and (7) effects of driver, road, maneuver, departure, and roadside characteristics on severity. In addition, there were a number of special studies including the role of impact characteristics in the relationships among severity and ditch depth, border offset, horizontal alignment, and degree of curvature. Also studied were guardrail and culvert impacts, extent of damage and injury relationships, and ADT versus accident rate. Finally, there is a discussion of countermeasures in terms of their classification, cost, need, and current practice. This report will serve best as a documentation of road and roadside factors influencing vehicle behavior and accident severity. Volume 1 contains a literature review, and the methodology for the data collection and preparation for analysis. Volume 2 contains the study results. (Author/publisher)
Abstract