The increasing application of context-sensitive design solutions for highway projects has created a national need for aesthetic improvement of typical highway features. Requests for concrete barrier treatments and bridge rails that contribute to the overall aesthetic experience are increasing. Concrete barriers (e.g., New Jersey, F-shapes, single-slope, and vertical-face designs) are often the barriers of choice in urban and suburban environments. Many transportation agencies and communities have expressed a desire for aesthetic treatments for these standard shapes. To date, there has been limited evaluation to determine which aesthetic treatments are safe and practical. Designers need guidance regarding the safety implications of aesthetic treatments for concrete barriers. Under NCHRP Project 22-19, “Aesthetic Concrete Barrier and Bridge Rail Design,” the Texas Transportation Institute developed design guidelines for aesthetic safety shape (New Jersey and F-shape profile) concrete barriers. In Phase I, the research team identified the features and methods that contribute to the aesthetics of longitudinal traffic barriers and the aesthetic experience provided by the roadway. The research team conducted a literature review, surveyed U.S. and foreign sources for examples of aesthetic longitudinal traffic barriers, and reviewed existing test results and ongoing research to assess the crashworthiness of the aesthetic concrete barriers and see-through bridge rails. At an interim meeting, the project panel and researchers agreed that the work to develop specific designs for see-through bridge rails should not continue. Also, after the initiation of this project, a California Department of Transportation (Caltrans) study developed guidelines for single-slope and vertical-face concrete barriers. Thus the focus of research under NCHRP Project 22-19 shifted to developing guidelines for aesthetic treatment of safety shape barriers only. In Phase II, the research team conducted a finite element simulation pilot study, performed model validation, and developed a surrogate measure of occupant compartment deformation. Further finite element simulations were performed to develop preliminary design guidelines in terms of asperity depth, width, and angle of inclination. Based on these preliminary guidelines, a crash test plan was developed, in which the outcome of one test determined the configuration evaluated in a subsequent test. Results of the crash tests performed were used in conjunction with the preliminary guidelines developed through simulation to develop final design guidelines for aesthetic treatment of safety shape concrete barriers. For the convenience of an aesthetic designer, guidelines developed for safety shape barriers in this research and the guidelines previously developed by the FHWA and Cal-trans for stone masonry guardrails and for single-slope and vertical-face concrete barriers, respectively, were consolidated into a single set of design guidelines. Designers now have sufficient guidelines to apply aesthetic treatments to various types of barriers. (Author/publisher) This report may be accessed by Internet users at http://gulliver.trb.org/publications/nchrp/nchrp_rpt_554.pdf
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