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14 for pavement markings. Background information on Bonding requirements including bond value, accept- this mandate and its importance is discussed in NCHRP able bond rating, and other administrative and proce- Synthesis 371 (Markow 2007). Accomplishments to dural requirements. date are compiled on an FHWA Safety Program website Maintenance responsibilities and work approvals. ("Pavement Markings Visibility" n.d.) and an FHWA Method of conflict resolution including requirement research website ("Establishing Criteria for Minimum for a conflict resolution team, its composition, criteria . . ." n.d.). Technical and economic research contributing for invoking the team's involvement, and the resolution to this effort has been performed (Debaillon et al. 2007, process. 2008; Hawkins et al. 2008). Two workshops were con- Contractor responsibilities regarding the warranty ducted in Summer 2007 to solicit input from state and including threshold performance values that trigger the local transportation agency representatives regarding need for remedial work, provisions governing materials how the minimum retroreflectivity levels could be and construction methods as applicable, the specified end incorporated into the Manual on Uniform Traffic Con- product, elective or preventive maintenance actions, and trol Devices (MUTCD) (Falk and Carlson 2008). Work insurance requirements. is proceeding on this effort. Department (agency) responsibilities including bond The FHWA is conducting pavement marking demonstra- and insurance approvals, inspection, approvals of work tion projects in Alaska and Tennessee that are required plans, reports, and work performed, and criteria and by Section 1907 of the Safe, Accountable, Flexible, requirements to meet emergency situations. Efficient Transportation Equity Act: A Legacy for Users Performance indicators that will be used to guide (SAFETEA-LU, P.L. 109-59, Aug. 10, 2005). The pur- work needed under the warranty and criteria to deter- pose, features, and funding of these demonstration proj- mine whether defects are beyond the contractor's ects are described in an FHWA Fact Sheet ("Pavement control. Marking Demonstration Projects" 2006), with additional Requirements for corrective actions including any detail on a contractor website ("FHWA Project 475980- agency approvals needed, the types of activities and 00001 . . ." n.d.). Because the legislation specified a num- allowable time period for remedial actions, and proce- ber of requirements, the FHWA is conducting research in dures that void the need for corrective action by the con- four major topic areas ("FHWA Project 475980-00001 tractor (e.g., utility relocation or destructive testing by . . ." n.d.): the department). 1. Durability study: to investigate the cost-effective- Method of measurement of the warranted end product. ness of different pavement marking systems, includ- Basis of payment; for example, amount, limits, and pay- ing advanced acrylic waterborne markings. ment schedule. 2. Safety study: to evaluate the impacts and effective- ness of increasing the width of pavement marking Some details have advanced since 1998; for example, edge lines from 4 in. to 6 in. the introduction of contractor or third-party inspection in 3. Environmental study: to evaluate the potential lieu of agency inspection during the warranty period and environmental impacts of the different pavement improved understanding of pavement marking perfor- marking systems that are included in the demonstra- mance. However, the basic structure of this framework, tion projects. interpreted broadly, can provide a guide in formulating cur- 4. State bidding and procurement processes study: rent warranty provisions. The examples of current pave- to review the effects of state bidding and procurement ment marking specifications included in Appendix D processes on the quality of pavement marking mate- (included as a web-only document), with key aspects dis- rials that are employed in state highway projects. cussed in chapter three, illustrate different ways in which This website includes status reports describing progress and these basic elements have been incorporated within con- plans within each active topic area. Work is proceeding on temporary warranty specifications. these projects. PERFORMANCE ISSUES RELATED WARRANTY FRAMEWORK DEVELOPED TO PAVEMENT MARKINGS FROM HISTORICAL EXPERIENCE Research and field experience with updated pavement marking Based on a review of state highway warranty specifications materials and practices has accompanied the increasing use of covering various types of work through 1998, Russell et al. warranty specifications for these markings. These concurrent (1999) compiled a road construction warranty framework com- advances have enabled DOTs to include more refined installa- prising 11 key categories of information that were typically tion and performance requirements, as well as provisions for included: items such as multi-year performance measures/criteria and staged payment schedules. The following subsection describes A description of the warranty scope and work required. general categories of pavement marking performance typi- The duration of the warranty period. cally included in warranty specifications. Specific examples,

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15 with threshold criteria and measurement procedures for var- Color: Color retention or stability may be specified with ious marking materials, are given in Appendix D (web only). reference to standardized color chips and color tolerance Later subsections summarize the current status of research on charts and, depending on agency practice, by providing prediction models for pavement marking performance and chromaticity coordinate limits for use with a colorimeter. impacts of pavement marking quality on road mobility and The warranty specifications may refer to test methods or safety. Past experience with asphalt pavement warranties has standards of the International Commission on Illumina- shown these topics to be important issues in developing effec- tion [CIE (English acronym) or ICE (French)], ASTM tive warranty specifications. They continue to be important International (originally the American Society for Test- subjects of investigation and the focus of ongoing DOT ing and Materials), AASHTO, or other organizations. interest regarding pavement marking performance and In addition to these color-related requirements, specifi- related benefits. cations may also call for minimum daytime reflectance values for white and yellow markings, respectively. Measures of Performance Examples of the use of these measures are provided in each of the specifications included in Appendix D (web only). Pavement marking performance is commonly specified in war- ranties using the following measures. (These measures relate to Agencies also specify a number of administrative steps to the warranty period as defined in chapter one. Other measures promote quality, including meetings before and during the job; may also be included in specifications, relating to initial accep- contractor submittal of work plans, spill plans, and progress tance or observation or performance periods that precede the status reports; and required testing by agencies noted previ- warranty period.) ously or the National Transportation Product Evaluation Pro- gram (NTPEP). Readers who would like additional informa- Retroreflectivity, visibility: The visibility of pavement tion on the types of pavement marking materials in use today markings is critical to safety and the orderly movements and measures of their performance can refer to a number of and interactions among motor vehicles, bicyclists, and recent documents; for example, NCHRP Synthesis 306: Long- pedestrians. Retroreflectivity is the ability of marking Term Pavement Marking Practices (Migletz and Graham materials to reflect light back to its source and can be mea- 2002), Pavement Marking Handbook (Texas) (2004), sured quantitatively by instruments. Warranties typically "ODOT's Pavement Marking Program" (Oregon) (2008), specify minimum retroreflectivity requirements (under and the chapter on pavement marking materials, with cited dry, wet, or rainy conditions) through the warranty period, references, in NCHRP Synthesis 371 (Markow 2007). but may also allow for visual inspections in daytime or nighttime. Allowable minimum retroreflectivity levels are usually specified separately for white and yellow Predicting Pavement Marking Performance markings and, depending on individual agency practice, may or may not vary during the warranty period. Tech- The compilation of good historical data on pavement mark- nical discussions of retroreflectivity are contained, for ing performance and the ability to predict performance reli- example, in the FHWA Delineation Handbook (Migletz ably would assist both public and private sector organizations et al. 1994) and the synthesis of pavement markings to address warranty requirements more dependably and effi- research performed for the Iowa DOT (Thomas and ciently. This idea is suggested by experience to date in the Schloz 2001). The issue of the minimum level of reflec- pavement arena. tivity needed for safe and effective traffic movements has been a subject of continuing research and agencies The earlier discussion of WisDOT's pavement warranty have adopted different approaches and threshold values. experience shows the importance of good historical data Durability: Durability, also referred to as presence, refers on performance. Contractors and sureties have both to the resistance of a pavement marking to physical dam- gained confidence from these data in (1) the proven track age; for example, cracking, chipping, breaking, spalling, record of existing WisDOT pavements, which provided flaking, blistering, crazing, delamination, shrinkage, loss realistic estimates of life expectancies; and (2) the like- of adhesion to the pavement surface, or other damage that lihood that warranty requirements were achievable by causes the marking to appear worn out or unsightly. The the contractor. durability of a pavement marking depends not only on the Pavement management systems, with predictive models marking material, but also on traffic (average annual daily based on periodic inspections and accumulated historical traffic), weather and resulting maintenance activity (e.g., data, enable agencies to forecast trends in condition and winter maintenance), the quality of materials, preparation, the need for corrective work. The timing of maintenance installation, and the type and condition of the pavement and rehabilitation treatments can thus be optimized to surface. An issue in assessing durability is defining when provide satisfactory performance at the lowest long- a marking has degraded to the threshold that requires term cost. replacement. Agencies have adopted different approaches With an available model to predict performance (in the and threshold values for evaluating durability. WisDOT pavement case, the AASHTO pavement design

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16 model) researchers have formulated a method of risk- Contributing to a longer life of the warranted marking, cost analysis that can be used by agencies and contractors implying that the greater safety is being achieved through to analyze short-term, warranty-based specifications for additional safety benefits accumulated through the longer pavement projects (Zhang and Damnjanovic 2006). useful life, but not necessarily to greater brightness dur- Researchers have shown how a pavement management ing the warranty period. system can be used to track the performance of both warranted and nonwarranted pavement projects, and Current research is ambiguous on this point (e.g., Bahar et al. have demonstrated this approach in five states: Florida, 2006, in addition to references cited previously). A study in Indiana, Michigan, Ohio, and Wisconsin (Wang et al. New Jersey suggests that there may be a "threshold effect" in 2005). which increases in retroreflectivity above this threshold value do not significantly affect drivers' ratings of visibility (Parker Work has already been undertaken to develop pavement and Meja 2003). Again, these issues relate to the justifications marking management systems in Minnesota (Pavement Mark- for warranty use and the potential benefits to be achieved, and ing Management System . . . 1999), Missouri (Weinkein et al. not to the management or administrative aspects of warranty 2002), and Iowa (Hawkins et al. 2006). Work is proceeding use. A somewhat analogous issue has been raised by Bayrak- on predictive models that can help analyze the factors affect- tar et al., who noted that based on current warranty use in the ing pavement marking performance and assist in making deci- United States, the practical outcome appears to be protection sions on when corrective work might be needed; for example, against premature failures rather than, say, promotion of Parker and Meja (2003) and Sathyanarayanan et al. (2008). contractor innovation or reduced life-cycle costs. This does This work tends to be performed for a single agency or at a not mean that such benefits cannot be achieved; rather, given single site. Indications from a survey of practice nationwide the way in which warranties are now used, a main result is in the management of pavement markings suggests however essentially that of an "insurance policy" (Bayraktar et al. that considerable variability will exist in comparing results 2006, pp. 46). from different agencies until models better account for a greater number of influencing variables, including road characteristics and driver behavior (Markow 2007). Implications for Study Findings This evolving research in pavement marking performance Impacts of Pavement Marking Performance and its impacts for road users is reflected in the variety of cur- rent state DOT practices documented in chapter three and The impacts of pavement marking performance in terms of Appendix D (web only). For example, agencies differ in the effects on crash rates, for example, are likewise subject to conceptual approach they take to warranty development. Only variability, including sometimes apparently counterintuitive a few apply true performance-based concepts in which the effects. At the heart of this issue is the relationship between specifications deal solely with required outcomes, leaving to retroreflectivity and crash rates, or retroreflectivity and drivers' the contractor the decisions on specific materials and methods ratings of pavement marking acceptability. Although there is a of installation to achieve these requirements. The great major- broad relationship between the two variables in each of these ity of state DOTs that responded to the project survey pairs, it is confounded by details of the road site, traffic char- employs rather a combination of prescriptive, methods-based acteristics, and driver characteristics and behavior. This issue materials and installation provisions, plus performance-based has been addressed in a number of sources and is reviewed, provisions covering the service life of pavement markings. for example, in NCHRP Synthesis 306 (Migletz and Graham Technical standards for satisfactory performance likewise 2002) and NCHRP Synthesis 371 (Markow 2007). Although vary across agencies in the measures of performance used the literature on other types of warranties (particularly those as well as the numerical threshold values that define for pavement projects) suggests no direct linkage between acceptable performance over time. Further distinctions are performance impacts and an agency's ability to administer also found in particular aspects of warranty coverage; for warranties, there would be a direct relationship between the example, the degree to which winter-related damage is impacts of asset performance and the presumed benefits or regarded as the contractor's or materials manufacturer's value-added owing to the warranty. For example, with respect responsibility, as opposed to exclusion of these factors to pavement markings specifically, further studies may be from warranty requirements. Although broad-based com- needed to determine whether pavement marking warranties parisons are highlighted in chapter three, the details of spe- contribute to safety by: cific provisions are purposely left for the reader to investi- gate in Appendix D. The reason is that it was believed Maintaining a brighter line through the warranty period important for the reader to understand the full context of (because higher retroreflectivity leads to higher driver each warranty specification when assessing specific tech- ratings of visibility and/or lower crash rates), or nical requirements.