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Home > Road Departure Safety > Nighttime Visibility > Pavement Marking Retroreflectivity Workshops Summary Report

Chapter 2 - Summary of Workshop Discussions

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The workshops were essentially divided into three main parts. During the first part of the workshop, the participants introduced themselves and the background material was presented, including the latest research findings (2,3). In the second part of the meeting, the workshop participants identified and discussed key factors pertinent to potential minimum pavement marking retroreflectivity language for the MUTCD. The third part of the workshop was devoted to soliciting input from the participants regarding the FHWA effort to develop a proposed rule on minimum pavement marking retroreflectivity levels. This input was the main reason for conducting the workshops and it will provide great value to the FHWA in future rulemaking efforts.

MAJOR DISCUSSION TOPICS

The main discussion topics from the participants are listed below by subheadings and in no particular order.

Maintenance Methods

  • It does not seem possible to have a “one-size-fits-all” policy for the nation.
  • What are the processes that can be used to identify when pavement markings fall below certain retroreflectivity levels?
  • What type of equipment is available to measure retroreflectivity of pavement markings?
  • In one workshop, the following methods were identified as being reasonable in terms of managing pavement marking retroreflectivity (the other workshop did not attempt to develop such a list):
    • Measurement
    • Nighttime inspections
    • Programmed replacement or expected life (based on service life)
    • Representative section
  • The expected life of pavement markings is difficult to project because of the variety of factors that impact pavement markings when they are installed. More research is needed to determine the factors that impact pavement marking durability so that more reliable life cycle figures can be developed to allow agencies to establish robust pavement marking management programs.
  • Methods to manage pavement marking retroreflectivity need to be fully identified and developed and tied to minimum retroreflectivity levels.
  • Having the flexibility in the MUTCD to develop and implement agency-by-agency customized pavement marking management programs is an essential requirement to offset the expected burdens of the rulemaking.

Seasonal/Regional Constraints

  • How can the MUTCD language accommodate agencies that receive regular snowfall and therefore have winter snow removal activities that can destroy pavement markings until the spring time when the markings can be refurbished?
  • Seasonal pavement marking application periods in many regions of the country (those with snow).

Minimum Pavement Marking Retroreflectivity Factors

  • Many participants would like to see lower numbers when raised retroreflective pavement markers (RRPMs) and/or lighting are present.
    • How should RRPMs be incorporated in the MUTCD language? Can the retroreflectivity of RRPMs be measured? If RRPMs are used in the MUTCD minimum pavement marking retroreflectivity language, should they also have minimum retroreflectivity requirements?
    • What if a roadway is lighted? Should the lighting level of the roadway be measured if lighting is used as a factor in the MUTCD minimum pavement marking retroreflectivity language? Continuous lighting can be defined a number of ways.
  • Should white and yellow pavement markings have different retroreflectivity levels? Some participants thought that the yellow line was more important than the white line, but many others felt that in order to keep the requirement simple, the color of the marking should not be used to specify different levels.
  • Credit (lower minimum retroreflectivity pavement marking values) should be provided for snow belt agencies that use continuous roadside delineation to supplement their markings.
  • Should wider lines be given a credit?
  • Can ceramic buttons or other raised markers be used in lieu of pavement markings? (MUTCD Section 3B.14)
  • Transverse markings (crosswalks, symbols, word messages, stop lines, yield bars, lane reduction arrows, railroad symbols, etc.) are completely different from longitudinal markings. Many of the participants felt that transverse markings should be excluded from the requirements.
  • Should speed or functional classification of the roadway be used to distinguish between different levels of retroreflectivity if a constant preview time is going to be the goal?
  • Should the pavement type be addressed in the MUTCD?
  • Average daily traffic (ADT), lane width, and horizontal alignment can impact the service life of markings.
  • If different minimum levels are used in the MUTCD or in a supplemental document, then there should be a large enough difference between the values such that it makes sense to have two values. One participant thought the difference should be at least 50 millicandelas per square meter per lux (mcd/m2/lx).
  • If retroreflectivity is so important, should the requirement also include a contrast requirement?
  • FHWA should consider the information a driver really needs from a marking. Is a curb in an urban area enough guidance for a driver in that environment? Why must markings be maintained on lower speed urban streets with curbs and often with lighting?

Economic Impacts

  • The following question was raised in various forms at both workshops: What will the economic impact be? (The FHWA is completing a study of the economic impacts of the expected rulemaking effort.)
  • How will local agencies that currently only restripe every 3 years be able to meet the minimum retroreflectivity levels?
  • There will be a significant budget/financial concern for local agencies.
  • If the FHWA goes forward with rulemaking, then a phase-in time is needed so that agencies can begin to build a case for the needed increase in budget, equipment, and personnel. Many local agencies will have to fight for the money and it will take time to convince board members and elected officials of the need for an increased budget.

Retroreflectivity Measurements

  • How should pavement marking retroreflectivity be measured? Every inch of a long line can have a different retroreflectivity value. Is there a standard sampling technique that can be used when assessing the retroreflectivity for purposes of comparing to a minimum threshold? How long of a line should be measured? What if it is near an intersection with heavy turning movements, or near a gravel pit, or along a horizontal curve (or other areas where pavement marking retroreflectivity generally wears out in a localized fashion before the rest of the same line)?
  • How and where would an agency measure retroreflectivity to determine if it is in compliance with MUTCD requirements?
  • If values are generated, then they should be average values over a certain length of line or classification of roadway, but not each individual measurement.
  • Can rumble stripes and other profiled markings be measured accurately?
  • Is there a reliable method to measure wet markings?
  • Is a windshield survey adequate? Many participants thought that a large difference in mcd/m2/lx is needed before a driver, even a trained driver, can notice a difference. However, others felt that trained drivers could detect differences less than 50 mcd.
  • The cost of equipment to measure retroreflectivity is high for local agencies.
  • What is the correlation between hand-held measurements and mobile measurements?
  • Having long periods without rain in some areas can cause dirt/dust build up that leads to a low retroreflectivity measurement. Should pavement markings be cleaned before measuring?
  • Many participants felt that the minimum retroreflectivity levels should only apply to clean and dry markings, realizing that clean is subjective.

Safety Benefit

  • Does the B/C ratio of minimum retroreflectivity justify the effort? Is there an associated crash reduction factor?
  • Is there any evidence linking maintained retroreflectivity levels and safety? The NCHRP research project 17-28 was not designed to evaluate the safety relationship of retroreflectivity levels near the minimum values so it only provides indirect information – and the information it does provide says that the important thing is that markings are present and visible to drivers, but what is less important with respect to safety is whether the markings are: “new marking bright” or “old marking bright.” The researchers think drivers adjust their driving to compensate for lower visibility conditions, but little research exists to support their hypothesis. The data they used (from CalTrans) had very little samples of pavement marking retroreflectivity less than 100 mcd/m2/lx.

Tort Liability

  • Will tort liability potential increase with minimum pavement marking retroreflectivity standards established in the MUTCD?
  • Setting a threshold in the MUTCD will increase liability for agencies needing to maintain the markings to that standard.
  • Having a maintenance management system in place and documented will be key to avoid tort liability.
  • Some participants expressed preference not to have the values in the MUTCD.

MUTCD Language

  • It does not seem reasonable to expect that agencies meet minimum retroreflectivity levels 24 hours a day, 7 days a week, 365 days a year. Many times snow and debris cover the roadway. Even rainy or just wet conditions can have a significant impact on retroreflectivity. How will FHWA address these issues?
  • The standard should be simple with many options.
  • It was felt that maintenance methods need to be included in the MUTCD and possibly should be included as a Standard statement without having the minimum retroreflectivity levels included in a Standard statement – although many participants questioned whether this approach would truly satisfy the Congressional directive since the minimum retroreflectivity levels would not be included as a standard.
  • Can the MUTCD language look like the edge line and center line warrants so that they include “shall,” “should,” and “may” language (i.e., Standard, Guidance, and Option statements)?
  • When markings fall below the minimum levels, they should be “programmed for replacement”?
  • Since the sign rulemaking has excluded some signs, it is probably OK to exclude some pavement markings.
    • About half of the participants thought that the retroreflectivity requirements should only apply to markings that are required by the MUTCD. One of the thoughts supporting this position was that if requirements are included for all markings, then agencies might choose not to provide markings that are not required by the MUTCD.
    • Do temporary markings in work zones have to meet minimum retroreflectivity levels?
  • The MUTCD language should be flexible enough so that agencies can be considered to be in compliance as long as they have a pavement marking program in place so that if a marking is found to be deficient, it should be programmed for replacement in a reasonable time frame, but the agency would not be held liable as long as the program was in place, documented, and a schedule for refurbishing exists.
  • If agencies conduct and document their own research, they should be allowed to set the requirements as per the research recommendations.
  • Is there a way for the FHWA language to end up specifying certain types of materials based on ADT (similar to the exemptions that FHWA included in the minimum retroreflectivity rule for sign sheeting)? For instance, if you have an ADT > 4,000, then do not use waterborne paints.

Other Comments

  • A supplemental document, like that being proposed along with the minimum sign retroreflectivity levels, is needed to address the plethora of issues pertinent to pavement marking retroreflectivity minimums that will not be evident in the typically condensed MUTCD language. Potential items for the supplemental document include:
    • Effect of climate on pavement marking retroreflectivity
    • Expected Pavement Marking Life Table
    • Color shift, particularly of yellow pavement markings
    • Assessment methods – take into consideration various methods for assessment and can even use multiple methods in different geographical areas of a jurisdiction or at different times of the year.
      • Nighttime visual inspections – at night in a sedan using individuals trained in marking inspection. Agencies shall adopt an inspection procedure that relates the inspection to the minimum values in Table 3A-1. The visual inspection evaluation point should be located 30 meters in front of the vehicle.
      • Retroreflectivity measurement – using American Society for Testing and Materials (ASTM) standard method (method under development) or a formal measurement procedure adopted by an agency.
      • Representative section – a specific portion of a roadway segment is identified as representative of that roadway. The retroreflectivity of the segment is monitored to determine retroreflectivity of the full roadway section.
      • Predictive model – an agency develops a model that considers material type, pavement surface, traffic volume, weather conditions, and other factors to predict the expected life of a marking.
    • Management methods
      • Agencies should maintain a record keeping process that identifies materials, application dates, contractor information, retroreflectivity test results, and other factors.
      • Programmed replacement interval.
    • Marking materials
      • Agencies should consider using marking material and/or applications (such as recessed markings) that are durable enough to last through a period of time when it is not feasible to replace markings whose retroreflectivity falls below the minimum values.
    • Potential for lower retroreflectivity values for rumble strips. Related situations are internally illuminated markers.
  • A general increased focus on pavement markings is needed. Many participants believed that the Congressional directive will provide the catalyst and might even lead industry to develop brighter and longer lasting pavement marking materials.
  • One of the possible outcomes of the rulemaking is that agencies might begin using more durable materials. However, others pointed out that in snow areas it has been shown that retroreflectivity is only a dream in the spring time. These participants felt that what might happen is that more and more agencies will move away from durable products to using more two-cycle waterborne paint applications – one installation as early as possible in the spring and then one more as late as possible in the fall.

FACTORS TO BE CONSIDERED

The first half of each workshop included many discussions related to the factors that should be addressed, or at least discussed, in terms of the FHWA’s role in developing minimum pavement marking retroreflectivity levels for the MUTCD. The discussions up to this point were all group discussions. As the first day was closing, the facilitator from each workshop asked the participants to spend some time thinking about and developing a table of minimum retroreflectivity levels that might be appropriate for the MUTCD. The homework assignments were collected the morning of the second day of the workshop and summarized in order to develop a priority of topics to help facilitate the discussions. The following factors were included in the submitted assignments, shown in the order of their respective frequency of appearance:

21 Rulemaking requirement should be applicable for longitudinal lines only
17 Allow a discount for Retroreflective Raised Pavement Markers (RRPMs)
16 Retroreflectivity levels should be classified by roadway speed
11 Retroreflectivity levels should be classified by color of markings
9 Retroreflectivity levels should be classified by marking configuration (center line or center line with lane lines/edge lines)
6 Allow a discount for roadway lighting
2 The requirements should be coordinated with pavement marking warrants
2 Retroreflectivity levels should be classified by function classification
2 Retroreflectivity levels should be classified by ADT
1 Retroreflectivity levels should be classified by pavement type
1 Retroreflectivity levels should be classified by environment (urban versus rural)
1 Allow a discount for continuous roadside delineation
1 Allow a discount for rumble stripes
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