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27 signs (see Figure 2C-1) may be used in advance of situations where the horizontal curve signs. The wording that had been proposed the horizontal roadway alignment changes, and should be used here and reviewed by the practitioners referred explicitly to when the alignment change would result in an advisory speed horizontal curves and not all instances where advisory speed equal to or lower than the posted speed limit. A One-Direction Large Arrow. . . . plaques might be used. The Winding Road (W1-5) sign should be used where there Final Proposed Statement is a series of turns or curves that requires driving caution and where curve or turn signs would be too numerous to be effective. Where any of the curves has an advisory speed that The final proposed revision is for a new section that would is 10 mph or more below that of the first curve, then a curve be applicable only to horizontal curves and based, in part, on or turn warning sign and an advisory speed plaque should the 2003 wording is as follows: be used. An Advisory Speed (W13-1) plaque should be used to indicate The speed of 10 mph is inserted in the second paragraph above the advisory speed for a change in horizontal alignment when based on the responses to other questions in the final survey. the advisory speed is 10 mph or more below the applicable speed limit. This is also discussed below. An additional question, chang- ing the "should" condition to "shall" had very little support Another option is to replace 2C.46 in the 2003 edition with a because as it was apparently interpreted as potentially caus- variation on the wording given above--that is, to eliminate ing too many liability or litigation-related problems and being the words "for a change in horizontal alignment" thus making too prescriptive. Thus, the more emphatic language is not the proposed revision more generic. recommended. As was the case for the first recommendation, the speed of 10 mph is inserted in the proposed revision above based on the SECOND RECOMMENDATION responses to other questions in the final survey. The selection of "10" as the speed increment to be used is based on the final Initial Proposed Statement survey responses and consistent with general comments from drivers and practitioners during the focus group and earlier Section 2C.42 of the MUTCD should be changed to read: survey exercises. The possibly more significant addition to the section on An Advisory Speed (W13-1) plaque should be used to indicate advisory speed plaques in 2003 was the "option" section where the advisory speed for a change in horizontal alignment when the advisory speed is X mph or more below the applicable the advisory speed was defined: speed limit. The advisory speed may be the 85th percentile speed of free- flowing traffic, the speed corresponding to a 16-degree ball This recommendation also garnered good support although bank indicator reading, or the speed otherwise determined by the objections from some respondents were basically the same an engineering study because of unusual circumstances. as reported for the first recommendation. It is also noted that the first two conditions are thought to be Existing Statements in the MUTCD approximately equal for horizontal curves. This definition for determining appropriate advisory speeds has the potential to In the ME, the discussion of advisory speed plaques was significantly increase existing advisory speeds and to have in 2C.42. In the 2003 edition, this discussion was in section adverse impacts on motorist speeds through horizontal curves. 2C.46. The precise wordings of these two versions are given The latter occurs if motorists continue to assume that they below with changes in the 2003 edition shown in italic: can travel at speeds that are typically as high as "+10 mph" over the posted advisory speed. If the advisory speed is "set" ME (2C.42): The Advisory Speed (W13-1) plaque at a speed approximating the 85th-percentile speed, the aver- may be used to indicate the recommended speed for a age motorist may actually exceed what would be the normal condition. 85th-percentile speed by 5 to 10 mph or more. That is, they 2003 (2C.46): The Advisory Speed (W13-1) plaque (see might maintain what they perceive to be a safe increment Figure 2C-5) may be used to supplement any warning over the posted advisory. While the higher advisories may be sign to indicate the recommended speed for a condition. "more realistic," motorist reaction is not clear and it is like- wise not clear how the revised guidelines might be phased in While one of the changes between the ME and 2003 edition is within and between jurisdictions. At least in the short term, merely a clarifying comment, the other change is potentially the lack of consistency among speed advisory applications may more sweeping--referring to all instances where the plaque be exacerbated rather than ameliorated by exercising the new is used to supplement a warning sign. The earlier version also option. Based on responses to the survey questions, it seems had general application but it was placed in the section with likely that practitioners would be critical of this option in terms