Results are presented of a study to review, summarize and evaluate the current state of the art of guardrail design and warranting criteria. Information necessary for the conduction of the investigation was secured from a search of the technical literature and by correspondence with individuals and agencies in the united states and abroad. Data and information are presented concerning present warranting practices, prevailing conditions of off-road vehicle motions, and guardrail performance as determined from accident studies, structural and physical characteristics of various types of guardrails in current use, results of full-scale barrier tests, and research programs currently in progress. It is concluded that there is a need for additional research in the areas of: (1) more comprehensive accident data specifically aimed at providing a realistic assessment of performance of current barrier installations by relating unsuccessful barrier performance to the over-all contact experience, identifying predominant failure modes and impact conditions, and obtaining measures of relative hazards of roadside obstacles and guardrails, (2) development of standardized test procedures, measurements, and reporting of results, and (3) development and application of validated analytical techniques for studying and evaluating guardrail collision dynamics to determine the relative importance of barrier design parameters and to provide guidance for design modifications. An extensive annotated bibliography of reports and articles reviewed in the study is presented in an appendix. /author/.
Abstract