The objectives of this study were to assure that through critical reassessment of elements affecting width standards that the standards are indeed an up-to-date flection of the best of available technical knowledge past and present; and to furnish the engineer facing the public a documentation of sound reasons for the stands he is called upon to observe and defend. The study involved a multi-dimensional approach including a study of present professional practice, as historical review, and an evaluation of the safety, operation environmental and cost aspects of width elements. Variables considered include human factors responses, basic driver-vehicle-road relationships, system or network considerations, costs of construction and maintenance, and environmental impacts. The project included the collection and synthesis of data, studies, information unit values, etc. which describe each of the important variables and where necessary reflect the sensitivities of Minnesota conditions. This synthesis process enabled formal evaluation of all pertinent width elements resulting in a series of statement and recommendations concerning optimal values for input to Minnesota state aid design standards. A rational process for considering exceptional cases is suggested.
Abstract