http://worldcat.org/entity/work/id/505110078

Impact of shoulder width and median width on safety

The objectives of this research were to quantify the safety and operational impacts of designelement trade-offs and to develop guidelines to assist designers in making reasonable choiceswhen applying context-sensitive solutions and design exceptions. Existing research results were combined with recent practical field experience to provide a guide for planners and designersto understand relationships and quantify the trade-offs for selected design elements. This research provides the highway design community with information resources and decisiontools for designing roadways where design flexibility may be appropriate to the roadway context. The research was completed in two phases. The first phase was a literature review and thedevelopment of a methodology for data collection and analysis to be used in the second phase. In the second phase, data were collected and analyzed to develop the resources andtools needed for understanding the safety and operational impacts from design elementtrade-offs. This report documents the findings of the research. The literature review determined that a significant amount of research had been undertaken in an attempt to quantify the relationshipsbetween safety and roadway design elements, but that these relationships were not availablefor cross-section elements on multilane rural roads. Therefore, in an investigation to determinethe safety impacts of design flexibility on rural multilane highways, the NCHRP project panel recommended that the second phase of the research focus on three geometric elements:lane width, shoulder width, and median type and width.

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