This report presents the findings of a research project to develop recommended design guidelines for safe and aesthetic roadside treatments in urban areas and a toolbox of effective roadside treatments that balance pedestrian, bicyclist, and motorist safety and mobility. The report will be of particular interest to designers and safety practitioners responsible for the design of arterial and collector-type facilities in urban areas. Many challenges are encountered when designing highway projects that pass through urban areas. Arterial and collector highways are typically designed to move vehicles as quickly and efficiently as possible. However, many times these highways are the centers of communities that have developed around them. Increasingly, citizens of these communities have requested that these highways be redesigned using roadside solutions that enhance the appearance and, in many cases, the functional use of the highway. Many of the solutions involve introducing roadside treatments such as trees, sculptures, and signs. In addition to enhancing the appearance of these highways, these treatments are often also intended to slow or “calm” traffic to enhance safety. However, many of these treatments are considered fixed objects, as defined in the AASHTO Roadside Design Guide, and they will often be located within the design clear zone. Recommended clear zone dimensions generally represent minimum lateral offset distances. Thus, reducing existing, wider clear zones by introducing fixed objects, even at these minimum distances, reduces the recovery distance. In addition, slowing traffic may cause changes in traffic operations. Therefore, it is crucial that the impacts of these designs be understood so that decisions can be based on facts. There is also a need to identify designs that have performed acceptably and a need to develop new design guidelines that enhance the roadside environment while being forgiving to errant vehicles. Under NCHRP Project 16-04, “Design Guidelines for Safe and Aesthetic Roadside Treatments in Urban Areas,” researchers at Oregon State University and the Georgia Institute of Technology developed recommended design guidelines for roadside treatments in urban areas and a toolkit that includes strategies for placing roadside objects with respect to driveways, intersections, merge lanes, and so forth. They also developed a draft of Chapter 10 for the AASHTO Roadside Design Guide. Two analysis approaches were used in developing the guidelines. First, a corridor assessment of urban roadside conditions was performed and contrasted with 6 years of historic crash data. The goal was to identify potential configurations that posed a greater risk using cluster crash analysis. By contrast, assessment of locations with similar features but without these crashes provided insight into prospective alternative treatments for roadside safety in urban environments. In the second analysis approach, the researchers assembled case studies in which jurisdictions had performed roadside enhancement or “beautification” projects without companion major road reconstruction. 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. (Author/publisher) This report may be accessed by Internet users at http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_612.pdf
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