Pavement markings come in a variety of forms (short lines, symbols, long lines) and materials (oil and latex paints, epoxy, thermoplastic, retroreflective beads). They also come with somewhat involved requirements and guidance in the Delaware Manual on Uniform Traffic Control Devices (MUTCD).
Types of Markings
First, let’s explore how we use markings. The primary applications are long line or straight line work. These are your centerlines, lane markings, edge lines, lane drops, and so on. Next is your short line work – think stop bars, yield lines (shark’s teeth), and crosswalks. The third major type are symbols and wording (“STOP AHEAD,” the big swooping arrow, “sharrows”). Each of these come with lots of rules and guidance and the material choices can dictate both effectiveness and life-cycle costs.
Materials
If you like choices, you will love pavement marking materials, because there are several primary types to choose from, the material properties evolve regularly, and most manufacturers have their own special blends that they are sure will revolutionize your world. Which one is the best? You guessed it – that depends. A somewhat dated but useful assessment of durability and costs of marking materials was completed by Maryland State Highway Administration and will give you some insight.
Major material choices start with solvent-based paints (acetone-based or epoxy), although environmental concerns have diminished their use. Epoxy paints have good durability (for a paint) and work well in high-traffic areas and on concrete. Indeed, some epoxy applications can last four years. Specifications vary, but epoxy paint is commonly applied at approximately a 20 mil thickness.
Water-based (latex) paints are the norm these days because they are more environmentally friendly. They are usually the most affordably choice and are fairly easy to work with, but they are the least durable of the choices. While some roads with lower traffic volumes may allow latex to last as long as three years, higher volume roads (>10,000 AADT) require replacement every year or even more frequently. Typical application rates for latex paint is 9 mils or so.
Tapes used to be primarily used as temporary markings during construction, but they are sometimes used as permanent markings as well. In Delaware, though, these are mostly cost effective only for temporary traffic control. Tapes are highly variable, but some can last for several years.
Thermoplastic markings are a more robust choice (at a higher cost, of course). These can be pre-formed, extruded, ribbon, or spray applied, but all are applied to the surface with heat. Depending upon the type and thickness of application, thermoplastic can last 4-6 years. Thermoplastic is commonly applied at a thickness of 125 mils for short line work, symbols, and lettering, but long lines are sometimes as low as 90 mils.
All pavement markings should be retroreflective, just like signs, and we expect rulemaking to finalize soon that will revise the MUTCD so it contains quantitative (numeric) levels of retroreflectivity for some pavement markings (and indeed it did; see the related, late-breaking article in this e-newsletter). The problem is that, while we don’t (commonly) run snow plows over signs, we let them do a number on pavement markings. So, while a sign can hold its retroreflectivity for 10-12 years or more (depending upon the sheeting type), retroreflectivity in pavement markings suffers from a great deal of wear and tear and can last as little as one year. Retroreflection in pavement markings is basically limited to the application of glass and ceramic beads that are partially embedded in the marking material.
Raised pavement markings are also used in locations where greater conspicuity is needed or to highlight the curvature of the roadway.
As you see, there are many choices and combinations, so consider your roads carefully and then talk with your painting contractors about options. And then ask questions, ask questions, ask questions.
The Rules
The Delaware MUTCD has specific requirements and just as many guidance statements for pavement markings in Part 3. There is no substitute for a careful reading of relevant sections of Part 3 for your roadways, but we will highlight a few matters of interest, particularly relevant to municipal streets.
First, while we are not attorneys, we don’t pretend to be one on the television, and we did not stay at a Holiday Inn Express anytime recently, be mindful that the Delaware MUTCD is codified in Delaware law and when it says “shall,” it means exactly that. There are no “traffic control device police” but there are plaintiff’s attorneys and they know the MUTCD better than any of us. Ignoring the MUTCD is a gamble with liability you shouldn’t take, because if it says shall and you didn’t and something bad happened to someone, you are the one left without a chair when the music stops.
Now, there are “should” statements in the MUTCD as well. We would argue to you that when it says should, you…should. But, if you have a reason to go a different route, that should be fine. That said, know why you did that. Maybe jot a note in the file. If questioned in a lawsuit down the line, you want to know why and you preferably want a contemporaneous document from your file to support it.
First up is colors. With traffic control devices, being crazy, neurotic consistent is very important for the safety of road users and color is no exception. Section 3A.05 tells us that white longitudinal lines are for separation of traffic flows in the same direction or the right-hand edge of the roadway, whereas yellow longitudinal markings delineate separation of travel in opposite directions, the left-hand edge of roadways and one-way streets, and the separation of two-way left-turn lanes.
Next, width and purpose. From Section 3A.06, solid lines prohibit or discourage crossing, whereas broken lines indicate permissive conditions. Normal lines are 4-6 inches wide (5” for state maintained roads), a wide line is twice the width of a normal line, a double line is two parallel lines separated by 6”, and a broken line consists of specific lengths of line followed by specific length of gaps (typically 10’ followed by a 30’ gap).
Yellow centerline markings are discussed in Section 3B.01 and let’s start with paragraph 05 – “A single solid yellow line shall not be used as a center line marking on a two-way roadway.” This is a common mistake when striping municipal streets. In most instances, passing is not appropriate on municipal streets and so two normal solid yellow lines is the correct centerline marking, if one is warranted.
Section 3B.01 discusses these warrants and guidance. In short, paved roadways with at least 500 vehicles per day (average daily traffic, ADT) and a traveled way ≥19’ shall have centerline markings. Roadways with ≥19’ traveled width but less than 500 ADT may be provided with centerline markings if engineering judgement indicates a need. When traffic counts are unavailable, the MUTCD permits the use of estimates based on engineering judgement. Finally, engineering judgement should also be used to determine, “whether to place center line markings along roadways with on-street parking. At a minimum, center line markings should be installed at the beginning and end of a roadway for 30 feet and approaching and departing horizontal traffic calming devices.” Finally, centerline markings are usually not recommended for subdivision streets.
White edge lines are discussed in Section 3B.06 of the MUTCD. White edge lines, when used, delineate the right edge of the traveled way. This can get a tad tricky. On a normal two-lane, two-way street, both edge lines would be white. If a two-lane, two-way street is divided by a median (concrete or otherwise), the left edge of the traveled way on either side gets a yellow edge line. If you have a one-way street, the left edge of the roadway is yellow, while the right is white. In essence, if the driver looks left and sees a yellow line, it should be an indication that there is either no more road there or there is an opposing lane of traffic.
Do you have to put in edge lines? Section 3B.07 says that “Roads with a traveled way of 20 feet or more in width and an ADT of 3,000 vehicles per day or greater,” shall require edge lines. They may be used on other streets where engineering study indicates a need. Finally, contrary to occasional rumors, the MUTCD is clear that, “Edge line markings may be placed on streets and highways with or without center line markings.”
Moving on to short line work, there are many requirements and much guidance for stop lines and yield lines, starting with Section 3B.16. For example, stop lines should be used on all approaches to signalized intersections and stop-controlled approaches with crosswalks, but generally not on stop-controlled approaches with less than 100 vehicles per day. Stop lines shall extend across approach lanes and should be 16” wide. There are similar requirements for yield lines within Section 3B.16. When used, stop and yield lines should be placed a minimum of 4’ in advance of a crosswalk line.
Crosswalks are addressed in Section 3B.18 and these also get complicated quickly. But some of the fundamentals include that when used, “they shall consist of solid white lines that mark the crosswalk. They shall not be less than 6 inches or greater than 24 inches in width.” Crosswalk markings on roadways with a posted speed limit less than 40 mph should be 6 feet wide. Finally, “crosswalk markings should be located so that the curb ramps are within the extension of the crosswalk markings.”
When it comes to pavement word, symbol, and arrow markings (Section 3B.20), there are again a long list of particulars, so we will highlight just a few. First, with occasional exceptions, these pavement markings shall be white, the minimum height of letters and numerals should be 6’ and they should be elongated. If there is more than one line of wording (and there can be a maximum of three), it should read in the direction of travel (i.e., the first word of the message should be closest to the road user on approach).
With one exception, word, symbol, and arrow markings should be contained within one lane of travel. Part 7 of the MUTCD (dealing with school areas) allows in Section 7C.03 that the School, “marking may extend to the width of two approach lanes in one direction.” That being said, the example in the (training world’s most over-used) photo below crosses lanes in both directions and is incorrect.
Oh yeah. And check your spelling.
Maintenance
As a final word on pavement markings, remember that a poorly maintained pavement marking is a liability, rather than an asset. It is very easy to overlook the degradation of pavement markings, but if you aren’t diligent with them, they can turn against you if there is a serious crash. Attorneys that practice in that arena make compelling arguments that go something like this. “Your agency installed this traffic control device [sign, pavement marking, temporary traffic control device] and because Section 1A.02 of the Delaware Manual on Uniform Traffic Control Devices says a TCD should meet five basic requirements, one of which is to ‘fulfill a need’ and another which is ‘command respect from road users,’ we know that you wouldn’t have put the TCD in place if it was not essential to protect the traveling public. By doing so, you either established a duty to the public or acknowledged it. But your agency did not adequately maintain the TCD, creating a breach of your duty. And now, my client has been seriously injured because of your negligence, and it’s all your fault, and we have to talk about compensation.” Or however attorneys talk.
The point is that, just with signs and other traffic control devices, it is important to develop an inventory of your pavement markings, periodically assess their condition for scheduling replacement, or establish a blanket schedule for replacement based on reasonable life cycles for the type of marking materials you use. Place only the pavement markings that fulfill a need, maintain them regularly, and everyone has what they need to travel the roads safely…and then the rest is up to them.
The Delaware T2/LTAP Center’s Municipal Engineering Circuit Rider is intended to provide technical assistance and training to local agencies, so if you have pavement marking questions or other transportation issues, contact Matt Carter at matheu@udel.edu or (302) 831-7236.
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