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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
