SAFETY IMPACTS OF SELECTED MEDIAN AND ACCESS DESIGN FEATURES. FINAL REPORT

This research investigates the safety of selected median and access design features using reported crash records from multiple years for the State Highway System of Florida. The Florida Department of Transportation's (FDOT's) Roadway Characteristics Inventory (RCI) was used to select systemwide samples of roadways having various design and access features, and then crash records were selected and summarized for these locations. An analysis of over 400 miles of urban roadway samples found a statistically significant positive relationship between crash rate and driveway density, meaning that as driveways per mile increased crashes per million vehicle-miles of travel also increased. This implies that based on safety considerations, direct driveway connections to urban arterials should be minimized. The relationship was not very strong, partly because there are many factors usually contributing to crashes, and partly because driveway traffic volumes would be expected to be a significant factor, but such data are not available in RCI. The crash rates for multi-lane urban arterials that were divided with a median were found to be lower than for those roadways which were undivided. The crash rates for multi-lane urban arterials with restrictive medians were found to be lower than those roadways which had non-restrictive medians. Flush-grass medians appeared to be the preferred median treatment based on safety.