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.
- 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.
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
- 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".
- 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.
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.
- 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.
- 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.
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.
- 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.
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.
- 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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- 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.
- 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.).
- 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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