Click for next page ( 5


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 4
4 are typically based on a subjective evaluation or on viewer- ducted. All 50 states were contacted, but some interviews were preference studies. Why any structure would be considered to unable to be completed. In total, 41 states were interviewed. be aesthetic in nature is rarely discussed. To be sure, the The questions asked were: viewer preference aspect is and will always be an important consideration. But in the potentially dangerous highway Does your DOT have guidelines on aesthetic treatments roadway, it would be good to know the functional effects of for structures? design on driver perception. What type of longitudinal concrete barrier (LCB) does There is little in the way of tested techniques for designers the DOT typically use? regarding the use of aesthetic treatments and how these affect Does your DOT incorporate any type of aesthetic treat- the driver's performance. Except for areas of signage and sig- ments into LCBs or bridge rails? naling, how a driver perceives other elements in the roadside Do you use any aesthetic steel rail or barrier designs? is poorly understood. Driver simulation studies with real- Do you get requests from the public for aesthetic barriers world verification would provide the needed science to enable and rails? designers to have a much better idea of how their designs Do you have and use see-through bridge rail designs? might affect driver performance and safety. Do you incorporate any use of colors into your LCBs? Until such information is available, the single most critical Have you used any veneer products such as precast imi- guiding principle should be the delineation of the roadway tation stone or brick on LCBs? edge. This implies that: Have you used any sandblasted patterning on LCBs? Does your DOT conduct any testing of barriers or rails? Colors or shades should provide contrast at least between What type? Results? Test levels (TL-1 thru TL-4)? Meet the base of the barrier and the pavement. requirements of NCHRP Report 350? Impact areas of the barrier should be in appropriate con- Is there some design you would like to see tested? trast to the background given a specific design speed and the view quality of the potential scene. Of the states that were interviewed, only 22% have guide- lines in place for the aesthetic treatment of roadside struc- The following section discusses a viewer preference survey tures. The most common type of concrete barrier being used that was performed in this study. The study applies some of was the New Jersey or F-shape barrier (68%), with the Kansas the concepts presented in the review of the literature. Corral coming in a distant second (7%). Since the New Jersey and F-shape barriers are essentially identical in appearance, they are considered the same for aesthetic design purposes. Fig- SURVEY OF STATE DOTS ure 1 shows the breakdown of concrete barriers currently in use. Fifty-nine percent of the surveyed state DOTs do not incor- The researchers conducted a telephone survey of state DOTs porate any aesthetic treatments into their concrete barriers, with the intention of gaining insight into the present practice while 39% do. The remaining 2% of respondents were unsure. of aesthetic barrier design. The research team prepared a set Thirty-two percent of states use a tube-type steel rail, and of interview questions and tested the questions with three 44% stated that they do not use any type of steel rail or bar- interviews. Based on the results of those interviews, the ques- rier design. Figure 2 shows the breakdown of steel rails used tions were revised and the rest of the interviews were con- by the various states. pe ha -s F y, se r Je Figure 1. Concrete barriers in use in the United States.