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Frequently Asked Questions
- Part 3 Markings
The following list of questions relates to the MUTCD Part 3 Markings:
- I noticed that Section 2A.09 is reserved for future
minimum levels of sign retroreflectivity but there is no section reserved
for pavement marking retroreflectivity. Was pavement marking retroreflectivity
left out and what is the status of pavement marking retroreflectivity?
- I am interested in the historical aspects of pavement
markings. For example, when did yellow start being used as the color
of a left edge line on a one-way roadway or ramp?
- Why do the MUTCD and the AASHTO Green Book have different
values for passing sight distance?
- Does a solid white lane line prohibit crossing to
change lanes on the approach to an intersection?
- Is it illegal to cross a double yellow centerline
on a road when making a left turn into a private driveway?
- How far in advance of a lane drop should the special
lane drop markings begin?
- When black markings are used to provide enhanced contrast
for white or yellow pavement markings, what widths and patterns of
black markings should be used?
- Does the MUTCD allow the stop line (or yield line)
to be "staggered" by lane? That is, can the stop line for
the right lane be closer to the intersection than the stop line for
the other lanes on an approach?
- Is it mandatory that a stop line be used with all
STOP signs and traffic signals?
- Can a stop line be used in advance of a midblock
crosswalk to show vehicles where to stop for a pedestrian?
- What are the warrants for installing a marked crosswalk
at a midblock location?
- My city is trying to make the downtown area more
aesthetically pleasing and pedestrian-friendly. We are installing
brick sidewalks, benches, trees, and other "streetscaping"
features along the business district streets. As part of the project,
we plan to install brick pavers or other similar treatments to serve
as the crosswalks at intersections. Can this type of crosswalk meet
the MUTCD requirements?
- Are "detectable warnings" (truncated
domes) required for all curb ramps and, if so, what are the design
requirements?
- Are rumble strips considered traffic control devices
and, if so, does the MUTCD govern their design, spacing, etc.?
- I have seen yellow curbs to the right of traffic,
contrary to the general principles of yellow and white markings. Does
this yellow curb mean no parking?
Part 3 Markings: Frequently Asked Questions
- Q: I noticed that Section 2A.09 is reserved
for future minimum levels of sign retroreflectivity but there is no
section reserved for pavement marking retroreflectivity. Was pavement
marking retroreflectivity left out and what is the status of pavement
marking retroreflectivity?
A: Pavement marking retroreflectivity was not omitted.
It is in Section 3A.02, which states that markings that must be visible
at night shall be retroreflective unless ambient illumination assures
that the markings are adequately visible, and that all markings on
Interstate highways shall be retroreflective. A section on specific
minimum levels of retroreflectivity was not reserved for markings,
however when FHWA develops the guidance or standards for this item
it will be proposed for insertion in Section 3A.02 in the future.
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- Q: I am interested in the historical
aspects of pavement markings. For example, when did yellow start being
used as the color of a left edge line on a one-way roadway or ramp?
A: The 1971 edition was the first time a yellow
left edge line appeared in the MUTCD. A yellow left edge line was
recommended (Guidance) "on divided highways where medians are
extremely narrow or where obstructions exist to restrict the area
beyond the edge line from use as an emergency refuge." In the
1978 edition, the use of the color yellow for all left edge lines
became mandatory. For more information on this and other questions
involving the history of pavement markings, the 2000 report entitled
"Evolution of the U.S. Pavement Marking System" by Dr. H.
Gene Hawkins is an excellent reference. The report may be viewed and
downloaded at: http://tcd.tamu.edu/Documents/evolution.stand-alone.pdf.
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- Q: Why do the MUTCD and the AASHTO
Green Book have different values for passing sight distance?
A: On pages 123-124 of the 2001 AASHTO Green Book
the statement is made that the "values as shown in the MUTCD
are substantially less than design distances and are derived for traffic
operating-control needs that are based on different assumptions from
those for highway design." Like many aspects of highway design,
the values used for design of a new facility are often more conservative
than what operating agencies find to be "reasonable minimums"
for actual operating highways, given the practicalities involved and
the wide mix of vehicle types, driver behaviors, etc.
The difference in values between the MUTCD and the Green Book are
due to the different methodologies (consideration of oncoming vehicles
or not) and different assumptions of the acceleration rate. The values
of passing sight distance in MUTCD Table 3B-1 used to determine where
no-passing zones are to be established are the same as were in effect
in the 1948 edition. That edition has a footnote to the table that
states: "Adapted from 'A Policy on Criteria for Marking and Signing
No-Passing Zones on 2-and 3-Lane Highways', American Association of
State Highway Officials, 1940." FHWA does not have that 1940
document, but the ITE "Traffic Engineering Handbook", 1999,
states: "A no-passing zone is defined in the MUTCD on the basis
of the distance from which a driver can see a fixed object in the
roadway...It is important to realize that this definition does not
account for vehicles moving toward the driver. The consideration of
oncoming vehicles (as described in the AASHTO Green Book) significantly
increases the sight distance required by a driver to perform a passing
maneuver." The Traffic Engineering Handbook also states that
the acceleration rates assumed by AASHTO for the initial phase of
the passing maneuver are very conservative and are "based on
research conducted between 1938 and 1941"---they are only about
one-third to one-fourth of the "maximum" acceleration rates,
and only about one-half of the "normally observed rate"
of today's modern vehicles.
An NCHRP research effort (#15-26) is aimed at trying to gather more
current data upon which to better evaluate the issues of AASHTO highway
design values vs. "operational" values of the MUTCD for
marking of no-passing zones
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- Q: Does a solid white lane line
prohibit crossing to change lanes on the approach to an intersection?
A: MUTCD Section 3B.04 says to use a single solid
white line to "discourage" crossing the lane line and a
double white line to prohibit crossing it. A single solid white line
is used for a variety of lines that drivers should be discouraged
from crossing in "normal" situations but which drivers do
need to cross in some situations. An example is the "edge line"---the
line that separates the rightmost travel lane from the shoulder. The
single solid white line discourages crossing onto the shoulder but
does not prohibit it because it is obviously desirable and/or necessary
to cross it in some situations. The MUTCD sets the national standards
for pavement markings, but it does not establish what the laws of
the individual States may define as the legal meanings of various
types of lines in each State. Some States may have laws that prohibit
crossing a single solid white line in specific circumstances. Some
states also have laws that go beyond just the meaning of the lines,
by making certain driving maneuvers illegal under certain situations
regardless of the markings, such as changing lanes when it is "unsafe
to do so".
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- Q: Is it illegal to cross a double
yellow centerline on a road when making a left turn into a private
driveway?
A: Usually this is not illegal, but it is necessary
to check individual State and/or local laws to be sure. The MUTCD
calls for "two-direction no-passing zone" centerline markings
to separate opposing directions of traffic on undivided multilane
roads. That is, the double yellow line separates the opposing flows
and prohibits travel to the left of the centerline for "passing"
(i.e., overtaking a slower moving vehicle) in either direction. The
text in the MUTCD does not in itself preclude left turns into driveways.
That is an issue that can vary from state to state. The Uniform Vehicle
Code, which is a model for state and local traffic ordinances that
is published by the National Committee on Uniform Traffic Laws and
Ordinances (www.ncutlo.org), states
in section 11-301(c) that on any two-way roadway having four or more
lanes of moving traffic no vehicle shall be driven to the left of
the centerline, and "this shall not be construed as prohibiting
the crossing of the centerline in making a left turn into or from
an alley, private road, or driveway." Most States have patterned
their laws on the Uniform Vehicle Code but there are a very few States'
laws and/or local jurisdictions' traffic ordinances that make it illegal
to make a left turn across any double yellow line into a driveway.
Also, State laws often prescribe certain conditions, such as obstruction
of lanes, in which it is legal to drive to the left of the centerline.
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- Q: How far in advance of a lane
drop should the special lane drop markings begin?
A: Section 3B.05 and Figure 3B-10 both note that
a lane drop marking consists of a wide, white dotted line, 3 feet
in length with a 9 feet gap separation, that should begin about ½
mile in advance of the theoretical gore point of the freeway exit
ramp. Some agencies also use the lane drop marking on arterial roads
or city streets, in advance of where a through lane becomes a "trap
lane" (that is, a turn only lane) to provide additional notice
to road users in that lane. Engineering judgment is used to determine
how far in advance of the mandatory turn to begin the lane drop marking
on conventional roads.
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- Q: When black markings are used
to provide enhanced contrast for white or yellow pavement markings,
what widths and patterns of black markings should be used?
A: The MUTCD is silent on this, other than saying
that black may be used with standard color markings to increase contrast
with light colored pavements. There are many different practices around
the U.S. To highlight broken lines, some states put 1"-2"
black stripes along both outside edges of the line segments, some
States fill in the entire gap between line segments with a normal
width black line, some put a length of normal width black line in
front of the line segment, and some put the black after the line segment.
There does not appear to be any research evaluating relative effectiveness
of these different practices. Anecdotally, they all seem to be effective
in making the white or yellow lines stand out more on a light colored
pavement.
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- Q: Does the MUTCD allow the stop
line (or yield line) to be "staggered" by lane? That is,
can the stop line for the right lane be closer to the intersection
than the stop line for the other lanes on an approach?
A: Although it is not specifically mentioned or
illustrated in the MUTCD, the use of staggered stop lines is not in
conflict with the MUTCD. This type of application of stop lines is
a valuable tool used by some jurisdictions to address certain safety
and operational issues, including sight distance for right turns on
red after stop and visibility of pedestrians. It is a practice that
is specifically mentioned in the Traffic Safety Toolbox, a publication
of the Institute of Transportation Engineers. The NCUTCD has recommended
that text specifically describing use of staggered stop lines and
yield lines be added to Section 3B.16 and FHWA expects to propose
this for the next edition of the MUTCD.
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- Q: Is it mandatory that a stop
line be used with all STOP signs and traffic signals?
A: The MUTCD, in Section 3B.16, states the following
Guidance: "Stop lines should be used to indicate the point behind
which vehicles are required to stop, in compliance with a STOP sign,
traffic control signal, or some other traffic control device."
As Guidance, this is a recommended but not mandatory condition. States
can adopt policies or supplements to the MUTCD that are more restrictive
than the national MUTCD. Some States do make the use of a stop line
mandatory with all STOP signs in their State. Most States require
stop lines on all signalized approaches.
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- Q: Can a stop line be used
in advance of a midblock crosswalk to show vehicles where to stop
for a pedestrian?
A: Yes, but only if there is a State law that requires
vehicles to STOP for (rather than yield to) pedestrians in crosswalks.
In describing the intended uses of stop lines, Section 3B.16 states,
"Stop lines should be used to indicate the point behind which
vehicles are required to stop, in compliance with a STOP (R1-1) sign,
traffic control signal, or some other traffic control device,
except YIELD signs." A crosswalk is a traffic control device,
and if State law requires road users to stop (rather than yield) if
a pedestrian is in the crosswalk, a stop line for this application
would be appropriate. However, if the State law requires drivers to
YIELD to pedestrians in crosswalks, a Yield Line marking must be used
rather than a stop line if a transverse marking is needed in advance
of the crosswalk.
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- Q: What are the warrants for
installing a marked crosswalk at a midblock location?
A: Part 3 of the MUTCD does not contain specific
warrants for installing crosswalks at any location. Section 3B.17
states: "Marked crosswalks…should be provided at other
appropriate points of pedestrian concentration, such as at loading
islands, midblock pedestrian crossings, or where pedestrians could
not otherwise recognize the proper place to cross." It also states:
"Crosswalk lines should not be used indiscriminately. An engineering
study should be performed before they are installed at locations away
from highway traffic signals or STOP signs." A study performed
for FHWA in 2002 by Zegeer, Stewart, and Huang provides a good reference
for factors to consider in performing the engineering study. The report,
entitled "Safety Effects of Marked vs Unmarked Crosswalks at
Uncontrolled Locations: Executive Summary and Recommended Guidelines",
may be viewed and downloaded at: http://www.walkinginfo.org/pdf/r&d/crosswalk_021302.pdf.
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- Q: My city is trying to make
the downtown area more aesthetically pleasing and pedestrian-friendly.
We are installing brick sidewalks, benches, trees, and other "streetscaping"
features along the business district streets. As part of the project,
we plan to install brick pavers or other similar treatments to serve
as the crosswalks at intersections. Can this type of crosswalk meet
the MUTCD requirements?
A: The brick pavers alone would not constitute a
legal crosswalk. White pavement marking lines must be used to officially
establish a legal crosswalk. As discussed in Chapter 3E of the MUTCD
(Colored Pavements), brick pavers and colored decorative paving treatments
that simulate brick or other patterns may be used between the white
crosswalk lines. However, colors that degrade the contrast of the
white crosswalk lines with the adjoining areas and colors that might
be mistaken by road users as a traffic control application should
not be used for this purpose. So, for example, the standard colors
of red and yellow used for STOP signs and warning signs should not
be used, nor should the colors white and yellow used for pavement
marking lines. Also, an FHWA Official Interpretation (#3-169) issued
in 2004 ruled that any use of retroreflective colored pavement surfaces
between crosswalk lines would be considered non-compliant with the
MUTCD, because such use would obviously be for purposes of traffic
control rather than decoration and such a traffic control application
for a crosswalk is not provided for in the MUTCD.
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Return to Frequently Asked Questions.
- Q: Are "detectable warnings"
(truncated domes) required for all curb ramps and, if so, what are
the design requirements?
A: Currently, detectable warnings are not included
in the MUTCD as a traffic control device. However, they are a requirement
stemming from the Americans with Disabilities Act (ADA), to warn visually-disabled
(blind or low-vision) pedestrians of the change from sidewalk to roadway
as they leave the ramp to enter the crosswalk. On July 30, 2004, FHWA
issued a memorandum reiterating that agencies must continue to comply
with current ADA standards -- including those for detectable warnings
at curb ramps and blended transitions -- when building new and altering
existing pedestrian facilities. Further, the U.S. Access Board, part
of the U.S. Department of Justice, the agency that administers the
ADA, has initiated a rulemaking process for adopting ADA Accessibility
Guidelines for the Public Right-of-Way. The latest information on
current and proposed design and placement requirements for detectable
warnings may be viewed on the Access Board's website at http://www.access-board.gov/adaag/dws/update.htm.
The current guidance does not specify a particular color but requires
the detectable warning to be a color that contrasts with the sidewalk---light
on dark or dark on light. Research is in progress to help define a
specific color or colors for maximum effectiveness.
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- Q: Are rumble strips considered
traffic control devices and, if so, does the MUTCD govern their design,
spacing, etc.?
A: It depends on whether the rumble strips are made
of colored marking material or cut into the pavement (and thus have
the same color as the pavement.) Section 3A.04 states that markings
shall be red, yellow, white, or blue. In other words, markings always
have a color that is not the color of the pavement itself. Rumble
strips can be formed by the use of strips of thermoplastic pavement
marking material (i.e., transverse markings as covered in Section
3B.15) so they must be white if placed across the travel lanes. If
placed diagonally on the shoulder to discourage or prohibit driving
on the shoulder, these strips of marking material would have to be
yellow if on the left shoulder or white if on the right shoulder.
However, the MUTCD does not provide guidance concerning spacing between
the transverse or diagonal strips. Rumble strips cut into the pavement
as grooves and in essence the same color as the pavement are not considered
pavement markings in the MUTCD. Thus, permanent rumble strips consisting
of longitudinal patterns of grooves cut on the shoulder or adjacent
to a centerline are not considered traffic control devices and are
not governed by the MUTCD. Section 6F.84 contains standards, guidance,
and options for temporary rumble strips used in temporary traffic
control zones. That section does cover both types of rumble strips---those
formed from marking material and those formed from grooves in the
pavement---and describes spacing, placement, and other application
information. (It should be noted that Part 6 is unique in the MUTCD
in covering certain treatments that are not traffic control devices,
including glare screens, attenuation devices, etc.).
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- Q: I have seen yellow curbs
to the right of traffic, contrary to the general principles of yellow
and white markings. Does this yellow curb mean no parking?
A: Curb markings are discussed in Section 3B.21
and the marking of islands is discussed in Chapter 3G. Retroreflective
solid yellow markings are generally used on the nose of raised medians
and island curbs where all traffic must pass to the right, for delineation
and visibility. Since yellow and white are frequently used for island
curb delineation and visibility, it is advisable to establish parking
regulations through the installation of standard signs discussed in
Sections 2B.39 through 2B.41 rather than via colored curbs. However,
Section 3B.21 does allow local highway agencies to prescribe special
colors for curb markings to supplement standard signs for parking
regulations. In those cases where curb markings are used without signs
to convey parking regulations, Section 3B.21 recommends that a legible
word marking regarding the regulation (such as "No Parking")
should be placed on the curb.
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Return to Frequently Asked Questions.
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