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1 SUMMARY Safe and Aesthetic Design of Urban Roadside Treatments Roadside safety in rural environments has been the focus of considerable study, but direct application of this knowledge to the urban environment is challenging because the urban environment is constrained in ways that the rural environment isn't. In urban environments, restricted right-of-way, with a greater demand for functional use of the space adjacent to roads, makes the maintenance of a wide clear zone impractical. This report summarizes work performed under NCHRP Project 16-04 to identify urban roadside safety issues and seek solutions for mitigating hazards where possible. The objectives of NCHRP Project 16-04 were to develop (1) design guidelines for safe and aesthetic roadside treatments in urban areas and (2) a toolbox of effective roadside treatments that can balance the safety and mobility of pedestrians, bicyclists, and motorists and accommodate community values. The guidelines that were developed are based on an evaluation of the effects of roadside treatments such as trees, landscaping, and other features on vehicle speed and overall safety. The guidelines generally focus on arte- rial and collector-type facilities in urban areas with speed limits between 40 and 80 km/h (25 and 50 mph). The research included two analysis approaches. In the first approach, the authors assessed roadside conditions in various urban corridors, performed a cluster crash analysis to identify locations with an overrepresentation of fixed-object crashes during a 6-year period, and identified fixed-object crash features for each location. This analysis enabled the authors to identify the road and roadside configurations that posed the most risk for fixed-object crashes. These higher risk road and roadside configurations were referred to as urban control zones. The road and roadside configurations most commonly associated with fixed-object crashes included those with the following: Obstacles in close lateral proximity to the curb face or lane edge; Roadside objects placed near lane merge points; Lateral offsets not appropriately adjusted for auxiliary lane treatments; Objects placed inappropriately in sidewalk buffer treatments; Driveways that interrupt positive guidance and have objects placed near them; Three kinds of fixed-object placement at intersections; Unique roadside configurations associated with high crash occurrence; and Roadside configurations commonly known to be hazardous. In the second approach, the authors assembled case studies in which jurisdictions had per- formed roadside enhancement projects (often known as beautification projects) without

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2 companion major road reconstruction. For these case studies, a simplified before-after crash analysis, crash summaries, and project descriptive information were assembled to help determine the safety influence of the enhancement projects. The results of this case study task varied, but can be used by agencies to estimate the potential safety implications of their future roadside enhancement projects.