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1 CHAPTER 1 INTRODUCTION RESEARCH PROBLEM STATEMENT only (1) assemble a collection of examples of longitudinal traf- fic barriers exhibiting aesthetic characteristics and (2) develop In response to local expectations and the traveling public, engineering design guidelines for aesthetic surface treatments there is a national need for aesthetic improvement of typical of concrete safety shape barriers (e.g., New Jersey and F-shape highway features. Requests for barrier treatments and bridge profiles). Design guidelines for single-slope and vertical- rails that contribute to the overall aesthetic experience are face concrete barriers had been finalized after the initiation increasing. Research will assist owners in responding to of this project in a California DOT study that is discussed in design requests for aesthetic improvements to transportation this report. systems. This report summarizes the entirety of the findings of the Concrete barriers (e.g., New Jersey, F-shape, and single- project, including work performed prior to the modification slope, and vertical-face designs) are often the barriers of choice of the scope and objectives. Chapters 2 and 3 focus on the in urban and suburban environments. Many agencies and com- work performed by the researchers prior to the modification munities have expressed a desire for aesthetic treatments for of the scope and objectives. Chapter 2 summarizes (1) the these standard shapes. To date, there has been limited evalu- state of the practice pertaining to the features and methods ation to determine which aesthetic treatments are safe and prac- that contribute to the aesthetics of longitudinal barriers and tical. Current standards do not provide guidelines to improve the aesthetic experience provided by the roadway; (2) the lit- the appearance of concrete barriers. erature reviewed; and (3) the use of aesthetic longitudinal Local communities and agencies are also demanding traffic barriers and treatments as identified through a survey increasingly that state DOTs provide bridge rails with an of U.S. and foreign sources. Many aesthetic barrier examples enhanced "see-through" appearance. Existing designs do not were provided by transportation organizations from around fully meet the desire of the public for a see-through appear- the world and are presented in Chapter 2. Chapter 3 focuses ance. However, the use of innovative designs and materials primarily on barrier form and how it is perceived by the may result in the development of aesthetic bridge rails with driver in its environment. The chapter defines aesthetics and improved view spaces. discusses assessment, factors, and techniques for changing Designers need guidelines for aesthetic treatments of con- the aesthetic character of longitudinal concrete barriers. In crete barriers and additional options for see-through bridge addition, Chapter 3 discusses a viewer preference survey that rails. was performed. Chapter 4 describes the development approach for the aesthetic concrete barrier design guideline. Chapter 5 RESEARCH OBJECTIVE describes the finite element simulation pilot study, model validation, and development of a surrogate measure of occu- The initial objectives of this research were to (1) assemble pant compartment deformation. In addition, Chapter 5 pre- a collection of examples of longitudinal traffic barriers exhibit- sents preliminary design guidelines based on finite element ing aesthetic characteristics; (2) develop design guidelines simulation. Chapter 6 presents the selection considerations for aesthetic concrete roadway barriers; and (3) develop spe- and results of the full-scale crash tests performed in support cific designs for see-through bridge rails. of the finite element simulations and the development of the Following the submittal of the project interim report and final design guidelines. The final design guidelines for aes- the project panel members' meeting with the researchers, the thetic safety shape concrete barrier design are presented in scope of the project and research objectives were modified to Chapter 7.