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17 On the basis of the established performance information, ing the overall condition of the existing pavement and the a preliminary list of feasible preservation treatments should individual distress types (and associated severities and extents) then be identified. This list represents a first cut of treatments that are present. Combined with historical condition/distress capable of preserving the pavement structure and preventing data, pavement structure data (current age and design life, or delaying future deterioration, given the pavement's cur- cross-section and materials), drainage data, and surface char- rent physical condition and rate of deterioration. acteristics data (smoothness, friction, noise), this information Next, the performance needs and construction constraints will first indicate whether a major rehabilitation is warranted of the project should be assessed. On the basis of the traffic or if preservation options can be considered. If major reha- and climatic characteristics of the project and an acceptable bilitation is not warranted, then this same collection of data level of risk, the list of feasible treatments can be narrowed to can be evaluated in greater detail to identify the most feasible those whose expected performance satisfies the required or preservation treatments. targeted performance level. Further refining of the list may Table 3.1 lists the types of distresses important in assessing occur after considering constraints such as available funding, preservation need. For each distress listed, information is pro- the expected timing and allowable duration of the work, geo- vided that indicates whether preservation adequately addresses metrics issues, and traffic control issues. the distress and, if so, the manner in which it addresses the Once a final set of feasible preservation treatments has been distress (i.e., prevention or slowing of future deterioration, identified, a cost-effectiveness analysis should be performed restoration of functional attributes). If the existing distresses to determine which treatment provides the greatest return are primarily treatable through preservation and there is no for the investment. This analysis may be done using either excessive distress (large quantities and/or severe levels of costbenefit analysis or life-cycle cost analysis (LCCA) tech- distress) associated with structural or subsurface materials niques. Results of the cost-effectiveness analysis should then problems, then the pavement is likely a good candidate for be evaluated in conjunction with other economic factors and preservation techniques. Otherwise, the agency should pursue several nonmonetary factors to select the preferred preserva- a plan for major rehabilitation. tion treatment. If preservation is deemed an acceptable approach, then the process of identifying candidate treatments can proceed. Tables 3.2 and 3.3 are evaluation matrices that can be used in Preliminary Identification of Feasible the preliminary identification of feasible preservation treat- Preservation Treatments ments for existing HMA- and PCC-surfaced pavements. The As discussed previously in these guidelines, many pavement tables list the "windows of opportunity" for each treatment preservation treatments may be applicable for use on high- in terms of the age and overall condition (using a PCI/PCR traffic-volume roadway pavements. Although a variety of scale of 1 to 100) of the existing pavement at time of treatment factors must be considered in determining the feasibility of application. They also identify how appropriate each treat- each treatment, a preliminary indication can be obtained by ment is for a given application in terms of how well it addresses examining the current and historical performance of the pave- a particular distress and corresponding severity level and how ment and the historical record of the pavement structure. By commensurate it is for addressing that distress and severity knowing the structural and functional adequacy of the pave- level. A similar representation is given concerning the appropri- ment, its rate of deterioration, materials durability, and ateness of treatments for surface characteristics issues (smooth- drainage adequacy, treatments can be identified according to ness, friction, and noise). In interpreting this matrix, it is their ability to address performance issues, whether through assumed that each distress exists in significant enough quan- preventive or restorative means. tities to warrant considering a preservation treatment. Perhaps the most crucial aspect of the treatment selection The "windows of opportunity" in the evaluation matrices process is the proper assessment of pavement conditions. provide a general sense as to when the preservation techniques Although there is a common basis for the process used by are most beneficial. To key in on specific treatments suitable SHAs to conduct field condition surveys and analyze/report for an existing pavement, the distress and surface characteris- the results, each process is unique in terms of survey mode tics issues must be evaluated according to the indicator sym- (manual/visual versus automated), frequency, and sampling bols provided in the matrices. In these matrices, a series of level; distress identification and recording protocol; and over- symbols are used to identify the appropriateness of a treatment: all condition computation and reporting technique. More- over, each agency has different testing (e.g., coring, deflection, = highly recommended for application friction/texture, noise) practices. = generally recommended Because preservation seeks to address a variety of pavement = provisionally recommended deficiencies, good, up-to-date information is needed concern- = not recommended.

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18 Table 3.1. Distresses Considered for Potential Preservation and the Manner in Which They Are Addressed by Preservation HMA-Surfaced Pavements PCC-Surfaced Pavements Manner Addressed Manner Addressed Distress Type by Preservation Distress Type by Preservation Alligator/fatigue cracking -- Blowups --a Bleeding/flushing Restore StrInt/Funct Corner cracking Prevent/Slow Det Block cracking Prevent/Slow Det D-Cracking --a Bumps Restore StrInt/Funct Joint faulting Restore StrInt/Funct Prevent/Slow Det Corrugations Restore StrInt/Functb Joint seal damage Restore StrInt/Funct Depressions/settlements -- Joint spalling Restore StrInt/Funct Edge cracking Prevent/Slow Detc Longitudinal cracking Prevent/Slow Det Heaves/swells -- Map cracking Non-ASR Restore StrInt/Funct ASR -- Joint Reflection cracking Prevent/Slow Detc Patches/patch deterioration Prevent/Slow Det Longitudinal cracking Polishing Restore StrInt/Funct Wheelpath -- Nonwheelpath (cold joint) Prevent/Slow Detc Patches/patch deterioration Prevent/Slow Det Popouts Restore StrInt/Funct Polishing Restore StrInt/Funct Punchouts --a Potholes -- Scaling Restore StrInt/Funct Raveling/weathering Restore StrInt/Funct Transverse cracking Prevent/Slow Det Prevent/Slow Det Rutting Water bleeding/pumping Prevent/Slow Det Wear Restore StrInt/Funct Stable (densification) Restore StrInt/Funct Structural -- Mix/instability -- Sags Restore StrInt/Funct Prevent/Slow Det Segregation Restore StrInt/Funct Prevent/Slow Det Shoving Restore StrInt/Functb Slippage cracking Deflection/fatigue-related -- Bond-related Restore StrInt/Functb Strippingd -- Transverse thermal cracking Prevent/Slow Detc Water bleeding/pumping Subsurface drainage -- Porous surface Prevent/Slow Det Note: -- = Not adequately addressed by preservation; StrInt = Structural Integrity; Funct = Functionality; Det = Deterioration. a Preservation suitable for isolated or limited occurrences of this distress. b Effectiveness depends on depth of problem. c Not suitable for severely deteriorated cracks. d Manifested in other forms of distress, such as rutting, cracking, raveling, and shoving/corrugation.