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16 CHAPTER 3 INITIAL GUIDELINES AND RECOMMENDATIONS FOR CHANGES TO THE MUTCD INTRODUCTION The Chevron Alignment (W1-8) sign may be used to provide additional emphasis and guidance for a change The focus of this project was to address the issue of con- in horizontal alignment. sistency in the use of TCDs to communicate information on On roadways without continuous centerline markings, changes in horizontal alignment to the driver. As noted short sections may be marked with centerline pavement earlier in this report, there was a question as to whether the markings to control the position of traffic at specific millennium edition (ME) of the MUTCD or the 2003 edition locations, such as around curves. . . . should be the "base condition." Early work on the project Delineators may be used on long continuous sections was actually done before the 2003 edition was in wide use, of highway or through short stretches where there are and it was also clear that some practitioners did not even use changes in horizontal alignment. the ME. When it came time to propose guidelines and changes, it was decided to be consistent with the early work and to use The word "may," while used extensively, is not defined the millennium edition as the base version of the MUTCD; per se in the millennium edition of the MUTCD, but is defined differences would be resolved post hoc. Thus, the guidelines in the 1988 edition as "a permissive condition, NO requirement that are discussed in the rest of this chapter use the millennium for design or application is intended." "May" is typically used edition as a base. This is also true for the final practitioner in the context of defining "options." In the ME, it is noted survey discussed in the next chapter. Resolution of differ- (Introduction, p. I-3) in the definition of the term "option" that ences between the millennium edition and the 2003 edition is done in the final chapter wherein final guidelines are presented [An option is] a statement of practice that is a permissive condition and carries no requirement or recommendation. . . . and discussed. The verb may is typically used. The MUTCD provides surprisingly little guidance on the use of individual TCDs for communicating with the driver and Necessary uniformity in the use of devices is defined in no guidance on combinations of TCDs for this purpose. The 1A.06: millennium edition of the MUTCD states the following: Uniformity of devices simplifies the task of drivers because The horizontal alignment turn (W1-1), Curve (W1-2), it aids in recognition and understanding, thereby reducing the Reverse Turn (W1-3), Reverse Curve (W1-4), or Wind- perception/reaction time. . . . Uniformity means treating sim- ilar situations in a similar way. ing Road (W1-5) sign may be used in advance of situa- tions where the roadway alignment changes. In order to achieve this uniformity, the MUTCD relies on A Large Arrow (W1-6) sign may be used on the outside the application of engineering judgment by setting the standard of the turn or curve. that "when engineering judgment determines the need for a An advisory speed plaque (W13-1) may be used to indi- horizontal alignment sign, one of the W1-1 through W1-5 signs cate the speed for the change in horizontal alignment. shall be used." The Turn (W1-1) sign or the Curve (W1-2) sign may be However, the MUTCD provides little guidance that would combined with the Advisory Speed (W13-1) plaque to result in the use of engineering judgment leading to uniform create a combination Horizontal Alignment/Advisory application of TCDs to communicate information on the Speed (W1-9) sign. change in horizontal alignment. The definition of engineering The (W1-1) or (W1-2) sign may be combined with the judgment in the MUTCD is as follows: Cross Road (W2-1) or the Side Road (W2-2 or W2-3) sign to create a combination Horizontal Alignment/Intersection The evaluation of available pertinent information, and the (W1-10) sign that depicts the condition where an inter- application of appropriate principles, standards, guidance and section occurs within a turn or curve. practices as contained in this Manual and other sources for