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Page 42
Suggested Citation:"Chapter 5 - Conclusions." National Academies of Sciences, Engineering, and Medicine. 2021. Maintenance and Surface Preparation Activities Prior to Pavement Preservation Treatments. Washington, DC: The National Academies Press. doi: 10.17226/26269.
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Page 42
Page 43
Suggested Citation:"Chapter 5 - Conclusions." National Academies of Sciences, Engineering, and Medicine. 2021. Maintenance and Surface Preparation Activities Prior to Pavement Preservation Treatments. Washington, DC: The National Academies Press. doi: 10.17226/26269.
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Page 43
Page 44
Suggested Citation:"Chapter 5 - Conclusions." National Academies of Sciences, Engineering, and Medicine. 2021. Maintenance and Surface Preparation Activities Prior to Pavement Preservation Treatments. Washington, DC: The National Academies Press. doi: 10.17226/26269.
×
Page 44
Page 45
Suggested Citation:"Chapter 5 - Conclusions." National Academies of Sciences, Engineering, and Medicine. 2021. Maintenance and Surface Preparation Activities Prior to Pavement Preservation Treatments. Washington, DC: The National Academies Press. doi: 10.17226/26269.
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Page 45

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42 Pavement preservation plays an important role in how state agencies manage their roadway networks. Preservation practices help the states improve pavement performance and safety at a lower life-cycle cost than alternative approaches, making such practices an essential program component for agencies tasked with cost-effectively keeping their networks in a state of good repair. One of the gaps in understanding preservation treatment performance arises from the relationship between (1) maintenance and surface preparation activities applied prior to the construction and (2) the preservation treatment itself. This synthesis report documents the types of maintenance and surface preparation activities performed by DOTs before pavement preser- vation treatments are applied. The purpose of the synthesis is describing how agencies address maintenance and surface preparation needs prior to pavement preservation by exploring the following topics: • Types of maintenance and surface preparation prior to preservation on flexible- and rigid- surfaced pavements. • Methods to identify the need for maintenance and surface preparation. • Methods to complete maintenance and surface preparation. • Agency practices to track maintenance and surface preparation. The report objective was met by collecting and analyzing information from three primary sources: a review of relevant literature, an electronic survey of state DOT practices, and docu- mentation of specific agency practices through the development of case examples. Key Findings from the Literature While the body of literature on pavement preservation is growing, few documents identify or elaborate on links between the maintenance and surface preparation that might be completed prior to the placement of a preservation treatment. This topic is most frequently addressed in agency guidelines or manuals on pavement preservation, maintenance, or management (now available on agency websites). For flexible pavement maintenance, most of the explicit guidelines are related to crack sealing and filling, with some also addressing patching. (Other preparation activities are discussed, such as removing pavement markings and surface cleaning, but these do not fall within the scope of this report.) Guidance from several agencies specifies a time lag between crack sealing or patching followed by thin surface treatments, noting either a specific time interval or the general desirability of such a gap. The literature was much thinner on maintenance and surface preparation before concrete pavement preservation. This situation can be explained in part by inconsistencies in terminology. C H A P T E R   5 Conclusions

Conclusions 43   Some actions that might be considered maintenance for concrete pavements are also identified as steps in the sequence of concrete pavement preservation or restoration. Two studies of the performance of preservation treatments applied with and without prior crack sealing both reported better performance when the preservation treatments—chip seals in Washington State and microsurfacing in National Center for Asphalt Technology tests—were preceded by crack sealing. Key Findings from the Survey For flexible pavements, the most common maintenance and surface preparation actions prior to pavement preservation are as follows: • Crack sealing and filling (89%). • Partial-depth patching (84%). • Full-depth patching (76%). • Rut filling (69%). For rigid pavements, the most common actions are the following: • Full-depth repair (74%). • Partial-depth repair (69%). • Joint resealing (62). While 56% of the responding agencies report no set time interval between the maintenance and surface preparation and the pavement preservation, 16% do have a set time lag, and 27% say that it depends on the project. A large majority of the agencies (84%) report that it is a local decision to complete maintenance before preservation. However, almost half of the agencies also indicate that the central office plays a role in the decision. Although pavement preservation is eligible for federal funding, 78% of the respondents report using state agency funds. Respondents confirm the link between how the maintenance and surface preparation work is completed and how the preservation work is executed: 42% of responding agencies perform the maintenance in-house if the preservation work is scheduled for completion in-house. Although 13% also conduct the maintenance in-house if the preserva- tion work is performed under contract, 38% of the agencies fold the preparation work into the same contract. No standard method is used to track the maintenance and surface preparation actions prior to preservation. The state agencies identify use of a maintenance management system (MMS) in 29% of the responses and a pavement management system (PMS) in 16%, with other responses suggesting no tracking, tracking only if the work is conducted under contract, tracking in both an MMS and a PMS, or tracking that depends on the project. Key Findings from the Case Examples Case examples from Georgia, Indiana, Kentucky, Montana, New Jersey, and Washington State offer additional insights into agency actions associated with maintenance and surface preparation prior to pavement preservation. The practices of these agencies represent a range of experience with pavement preservation programs, from developing to emerging to mature. All of the agencies provide some sort of policy guidelines covering maintenance actions, but some are more explicit about specific maintenance actions while others offer general guidance.

44 Maintenance and Surface Preparation Activities Prior to Pavement Preservation Treatments Washington State goes as far as mandating the application of maintenance prior to preservation, in part for financial reasons; other states focus more on describing the interrelationship between maintenance and preservation. In each case, the required maintenance actions are determined locally. However, in four of the case examples, the respondents describe a collaborative decision process between local district staff and a central office. The two instances where maintenance and preservation are almost exclusively local decisions represent agencies with at least 10 years of experience with these types of decisions. The states do not implement a standard approach to maintenance and surface preparation work, mirroring the responses to the survey. Such work is accomplished both with in-house forces and under contract; the deciding factors in contracting this work are the agency’s crew resources (personnel and equipment) combined with the level of effort required to complete the work. Different agency systems track maintenance and surface preparation activities, again mirroring state survey responses. Maintenance management systems and pavement manage- ment systems are the most common tracking programs, with distinctions based on the type of work and on whether it is contracted or completed internally. Additional Observations Several general observations supplement the findings summarized in the preceding sections. Many agencies suggest that the resources necessary to complete maintenance prior to pavement preservation are not always available. Consequently, in some instances, identified maintenance actions are not carried out, which in turn affects preservation performance. Several studies conclude that needed maintenance improves the performance of some preservation treatments, so knowing whether the work is completed represents an important part of demonstrating the contribution of maintenance or surface preparation to preservation performance. Tracking the timely completion of maintenance and surface preparation is in part a function of who does the work. If such work is performed in-house and tracked, that information is likely to be recorded in an MMS; in contrast, if the work is under contract, that information is more likely to be recorded in a construction management system or perhaps a PMS. Data recorded in an agency’s maintenance management system and pavement management system are not automatically mutually compatible. Even if the systems employ the same linear referencing system, they may use different approaches to project segmentation, complicating information sharing. Such systems also track different data, with MMS focusing on resources such as materials, equipment, and personnel and PMS emphasizing road condition and treatments. Knowledge Gaps and Suggestions for Future Research • No widely available or clearly established links are documented between specific pavement conditions (distresses), appropriate maintenance responses, and subsequent preservation treatments. • An interval of time is specified for some maintenance and surface preparation actions prior to some preservation treatments. However, no consensus indicates what that gap should be— or the combinations of maintenance actions and preservation treatments to which it should be applied. • Agencies find it difficult to document the effect of maintenance on the performance of preservation treatments. Different information is collected about maintenance actions and

Conclusions 45   preservation treatments, and data about maintenance and preservation applications are stored in different databases within agencies, recorded in different ways, and inconsistently shared. In some cases, maintenance actions are not tracked at all or are tracked only if the mainte- nance action is performed under contract. These identified knowledge gaps could be addressed in future research such as the following to further the practice of maintenance and surface preparation before preservation: • Development of documentation regarding the links among pavement conditions, maintenance and surface preparation actions, and specific preservation treatments would help improve the performance of pavement preservation. • The performance of pavement preservation would be improved by the identification of tran- sition thresholds that indicate when maintenance before preservation is not cost-effective. While a pavement requiring too much maintenance prior to preservation clearly is not a good candidate for pavement preservation, a quantification of “too much” would be helpful. Similarly, some preservation treatments can be placed without any advance maintenance. The level of required maintenance could pinpoint a project as true preservation, a stopgap maintenance effort, or something in between the two. • While 59% of the agencies note that planned maintenance work does not always occur, demonstrating the effect of missed maintenance work on the performance of preservation is difficult. Research would be helpful if it documented a process that allows agencies to analyze the impacts of failing to perform maintenance. • Consistent system data inputs would help create seamless transitions between the work moni- tored in construction management and maintenance management systems and the perfor- mance of treated sections tracked in pavement management systems. Useful products would include a consistent vocabulary of preservation treatments and maintenance actions, compat- ible route identification locations and segmentation, standard work types, and consistent measures and entry of the amount of work performed as well as the identified but unmet needs. This topic is considered in NCHRP Report 820: Framework for a Pavement-Maintenance Database System (White et al. 2016) but remains a challenge to this date. • Guidance would be useful on how pavement management systems can model preservation treatment performance based on the type and amount of preliminary maintenance and surface preparation work. Such guidance would help agencies calculate and analyze the performance effects and cost-effectiveness of various pavement actions.

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Pavement preservation is broadly acknowledged to provide network-wide benefits such as extending pavement life, enhancing system performance, reducing operation and maintenance costs, and improving safety. However, the performance of each pavement preservation project hinges on many factors.

The TRB National Cooperative Highway Research Program's NCHRP Synthesis 565: Maintenance and Surface Preparation Activities Prior to Pavement Preservation Treatments documents the types of maintenance and surface preparation activities performed by departments of transportation before pavement preservation treatments are applied.

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