Guidelines for the Preservation of High-Traffic-Volume Roadways (2011)

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C H A P T E R 3 Treatment Selection ProcessTreatments for HMA-Surfaced Pavements The following treatments are applicable for use on high- traffic-volume HMA-surfaced pavements: • Crack fill. • Crack seal. • Slurry seal (Type III). • Microsurfacing. • Chip seal:  Single-course;  Multiple-course; and  Polymer-modified. • Ultra-thin bonded wearing course. • Thin HMA overlay (0.875 to 1.5 in.). • Ultra-thin HMA overlay (0.5 to 0.75 in.). • Cold milling and HMA overlay. • Hot in-place recycling (≤ 2.0 in.):  Surface recycling followed by HMA overlay;  Remixing followed by HMA overlay; and  Repaving. • Cold in-place recycling (≤4.0 in.)—rural use only. • Profile milling. • Ultra-thin whitetopping. • Drainage preservation. These treatments are generally considered suitable for both rural and urban roadways and for different climatic conditions. However, some treatments may not be appropriate for all traf- fic and climatic conditions. Hot in-place recycling is composed of the three basic tech- niques listed. While the latter two can be used in a preservation manner, they often are used in the context of major rehabilita- tion. Surface recycling, on the other hand, is well representative of a preservation activity. Like the remixing and repaving tech- niques, cold in-place recycling can be used in a preservation manner but is frequently considered to be major rehabilitation.15Tables A-1 through A-9 in Appendix A contain one- to two- page technical summaries for most of these treatments. The summaries include treatment descriptions, the key pavement conditions they address, and construction and other consider- ations (including expected performance and estimated costs). They also provide a listing of reference materials that users can access to get up-to-date information on each treatment. Treatments for PCC-Surfaced Pavements The following treatments are applicable for use on high-volume PCC-surfaced pavements: • Concrete joint resealing. • Concrete crack sealing. • Diamond grinding. • Diamond grooving. • Partial-depth concrete pavement patching. • Full-depth concrete pavement patching. • Dowel bar retrofitting. • Ultra-thin bonded wearing course. • Thin HMA overlay (0.875 to 1.5 in.). • Drainage preservation. Again, these treatments are generally considered suitable for both rural and urban roadways and for different climatic conditions, but some treatments may not be appropriate for all traffic and climate conditions. Technical summaries for most of these treatments are provided in Tables A-10 through A-14 in Appendix A. Preservation Treatment Selection Selecting an appropriate preservation treatment for a given pavement at a given time is not a simple process. It requires a significant amount of information about the existing pavement,

16as well as the needs and constraints of the treatment to be per- formed. In addition, there are usually several possible solu- tions that can be considered, each with unique advantages and disadvantages. The process is further complicated when costs and cost-effectiveness are factored in. Figure 3.1 presents a sequential approach for evaluating pos- sible preservation treatments for an existing pavement and identifying the preferred one. This approach is developed specifically to address factors that are commonly considered for high-traffic-volume roadways. In this approach, the func-tional and structural performance of the existing pavement should first be established through condition surveys and/or the agency’s pavement management system (PMS). The per- formance information should include both current and his- torical trends of overall condition (i.e., an aggregate/composite indicator of condition or serviceability); type, severity, and amount of individual distresses; and ride quality/smoothness measurements. For pavements perceived as having possible safety or noise issues, surface friction test results, crash data, and pavement–tire noise data should also be compiled.Current and Historical Pavement Performance Data (from field surveys and testing and/or PMS database) Overall condition indicator (e.g., PCI, PCR) Individual distress types, severities, and extents Smoothness (e.g., IRI, PI, PSI/PSR) Surface and subsurface drainage characteristics Safety characteristics Friction/texture (e.g., FN, MPD/MTD, IFI) Crashes Pavement–tire noise Preliminary Set of Feasible Preservation Treatments Historical Design, Construction, and M&R Data Pavement type and cross-sectional design Materials and as-built construction Maintenance and rehabilitation (M&R) treatments (i.e., materials, thicknesses) Assess Needs and Constraints of Project Final Set of Feasible Preservation Treatments Performance Needs Targeted/required performance Expected performance of treatments Existing pavement condition effects Traffic effects (functional class and/or traffic level) Climate/environment effects Construction quality risk effects (agency and contractor experience, materials quality) Construction Constraints Funding Time of year of construction Geometrics (curves, intersections, pavement markings/striping) Work zone duration restrictions (i.e., facility downtime) Traffic accommodation and safety Availability of qualified contractors and quality materials Environmental considerations (e.g., emissions and air quality, recycling/ sustainability) Selection of the Preferred Preservation Treatment • Conduct cost-effectiveness analysis Benefit-cost analysis Life-cycle cost analysis (LCCA) • Evaluate economic and noneconomic factors Pavement Preservation or Major Rehab? Major Rehab Pavement Preservation Develop Feasible Rehab Treatments Figure 3.1. Process of selecting the preferred preservation treatment for high-traffic-volume roadways.

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

18HMA-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. Table 3.1. Distresses Considered for Potential Preservation and the Manner in Which They Are Addressed by Preservation

19The provisional recommendations given in the evalua- tion matrices suggest that engineering judgment is needed to account for other site-specific factors/conditions and for specific agency practices. Ideally, multiple treatment options should be identified, such that each option is shown to be at least generally recommended () for all of the identified distresses and surface characteristics. In some instances, it may be appropriate to consider combining treatments (e.g., crack sealing with chip sealing) to increase the number of feasible options. What constitutes a surface characteristic issue depends in large part on agency policy and the characteristics and demands of the project. Generally speaking, the higher the traffic volume for a given roadway facility, the lower the maximum accept- able threshold for roughness. Also, the more difficult the driving environment (e.g., higher traffic volume, higher speed, more curves and intersections), the higher the minimum acceptable threshold for friction. In rural areas, pavement–tire noise is usually not considered an issue, whereas in urban res- idential areas, the contribution of pavement–tire noise (i.e., at-the-source noise) to overall wayside noise can be an impor- tant issue. This is particularly true where sound walls do not exist, traffic levels and speeds are high, and residences are in close proximity to the roadway. For high-traffic-volume roadways, international roughness index (IRI) values above 100 to 110 in/mi may be perceived as an issue to be addressed by the preservation treatment. IRI val- ues greater than 150 to 200 in/mi may be more indicative of the need for major rehabilitation. For high-speed (≥50 mph), high-traffic-volume roadways, smooth-tire 40-mph friction number (FN40S) values below 30 to 32 may be perceived as marginal or too low, prompting the need for a restoration treatment. Good practice dictates that this need be confirmed by examining wet-weather accident rates along the project length. Although there is no nationally recognized require- ment for the maximum level of noise (either at the source or at a point on the wayside) that can be generated by a highway pavement, it should be pointed out that the quietest pave- ments generate on-board sound intensity (OBSI) levels (at-the- source noise) between 96 and 102 dB(A), whereas the loudest pavements generate OBSI levels in the 108 to 112 dB(A) range. Depending on the characteristics of a project located in a noise- sensitive environment, OBSI values above 106 to 108 dB(A) may be perceived as an issue to be addressed by the preserva- tion treatment. Finally, although the current age and conditions can be used to identify feasible treatments, it is important to con- sider when the preservation activity is expected or scheduled to occur. If there is a significant gap (≥1 year) between the time the latest condition data were collected and the time the treatment is likely to be constructed, then it is recommended that treatment selection be based on forecasted conditions, ifpossible. The forecasted conditions can be developed using the historical performance data (overall indicator, individual distress types and severities, smoothness, friction, and so on) collected for the subject pavement and projecting their trends to the time in which the preservation activity will occur. Depending on the time gap and the historical trends, this could greatly affect the types of preservation treatments iden- tified as being feasible. Final Identification of Feasible Preservation Treatments Once a preliminary list of feasible treatments has been devel- oped, further evaluation is needed to determine which of the treatments largely satisfies the needs and constraints of the project. The evaluation matrices in Tables 3.4 and 3.5 can be used for this purpose. The information presented serves as a guide with respect to the treatments most commonly and successfully used by highway agencies on high-traffic-volume roadways (subdivided by rural and urban settings) located in different climatic regions. In these matrices, the appropriateness of a treatment is des- ignated by the same series of symbols used in Tables 3.2 and 3.3 (● for highly recommended down to  for not recom- mended). In addition to identifying work zone duration restrictions (i.e., the time period needed following the place- ment of a treatment until the treated pavement can be opened to traffic) associated with each treatment, these matrices also provide expected treatment performance ranges and relative treatment cost information. The expected performance ranges are based on high-traffic-volume application, but do not take into account the effects of existing pavement condition, cli- mate, and construction quality risk. To account for these fac- tors on each candidate treatment, it is suggested that values near the lower limit of the performance range be used for pavements in fair condition and located in a severe climate (i.e., deep-freeze climate zone). On the flip side, it is suggested that values near the upper limit of the range be used for pave- ments in good condition and located in a mild climate (i.e., nonfreeze climatic zone). A logical, systematic way of accounting for construction quality risk is to apply a confidence factor to the expected per- formance range, with a factor of 1.0 representing 100% con- fidence, 0.75 representing 75% confidence, and so on. Thus, if the expected performance of a treatment ranges from 4.0 to 6.0 years and the level of confidence is 75% (reflecting some shortcomings in agency/contractor experience and/ or materials quality), then the range would be reduced to between 3.0 to 4.5 years. In addition to the treatment performance and relative cost information (which could be impacted by funding constraints)

20Table 3.2. Feasibility Matrix for Preliminary Identification of Candidate Preservation Treatments for HMA-Surfaced Pavements Distress Types and Severity Levels (L 5 Low, M 5Medium, H 5 High) Surface Distress Cracking Distress Window of Opportunity Preservation PCI/ Age Treatment PCR (yr) L/M/H — — L/M/H — L/M/H L/M/H L/M/H L/M/H L/M/H Crack fill 75–90 3–6d @@@ 8C@ C@@ C@@ ●8C Crack seal 80–95 2–5d @@@ 8C@ ●8C ●8C C@@ Slurry seal (Type III) 70–85 5–8 8●8 @ 8 8C@ 8 8C@ ●8C 8C@ 8C@ 8C@ Microsurfacing: Single 70–85 5–8 8●8 @ 8 ●8C 8 8C@ ●8C 8C@ 8C@ 8C@ Microsurfacing: Double 70–85 5–8 8●8 @ 8 ●8C C 8C@ ●8C ●8C ●8C ●8C Chip seal: Single Conventional 70–85 5–8 8●8 C ● ●8C 8 8@@ ●8C ●8C ●8C 88C Polymer modified 70–85 5–8 C88 @ ● 88C C 8C@ ●88 ●88 ●88 8C@ Chip seal: Double Conventional 70–85 5–8 C88 @ 8 88C @ 8C@ ●88 ●88 ●88 ●88 Polymer modified 70–85 5–8 CC8 @ 8 C8C @ ●8C ●●8 ●●8 ●●8 ●88 Ultra-thin bonded 65–85 5–10 8●8 @ ● 88C C 8C@ 88C 88C 88C 88C wearing course Ultra-thin HMAOL 65–85 5–10 8●8 @ ● 88C C 8C@ 88C 88@ 88@ 88@ Thin HMAOL 60–80 6–12 8●8 C ● 88C C ●8C ●●8 8●8 8●8 88● Cold milling and 60–75 7–12 C8● C C 8●8 @ 88C C88 88● 88● C8● thin HMAOL Hot in-place recycling Surf recycle/HMAOL 70–85 5–8 C8● C C 8●8 C 88C ●8C C8● C8● 88C Remixing/HMAOL 60–75 7–12 @CC C 8 @C8 @ 8●8 8●8 8●8 8●8 8●8 Repaving 60–75 7–12 @CC C 8 @C8 @ 8●8 8●8 8●8 8●8 8●8 Cold in-place recycling 60–75 7–12 @@C C C @C8 @ 8●8 8●8 8●8 8●8 8●8 and HMAOL Profile milling 80–90 3–6 C88 8 C @CC @ @@@ @@@ @@@ @@@ @@@ Ultra-thin whitetopping 60–80 6–12 @@C C 8 @C8 @ C88 C88 C88 C88 C8● Note: ● = Highly Recommended; 8 = Generally Recommended; C = Provisionally Recommended; @ = Not Recommended. a Porous surface mix problem. b Rutting primarily confined to HMA surface layer and largely continuous in extent. c Corrugation/shoving primarily HMA surface layer mix problem and frequent in extent. d For composite AC/PCC pavements, a more probable window of opportunity is 2–4 years for crack filling and 1–3 years for crack sealing. e Localized application in the case of bumps. Water Fatigue/ Ravel/ Bleed/ Segre- Bleed/ Long WP/ Trans Joint Long/ Weather Flush Polish gation Pumpa Slippage Block Therm Reflect Edge(continued on next page)

21Distress Types and Severity Levels Deformation Distress Wear/ Stable Corrug/ Bumps/ Ride Preservation Ruttingb Shovec Sags Patches Quality Friction Noise Treatment L/M/H L/M/H L/M/H L/M/H — — — Crack fill Crack seal Slurry seal (Type III) C@@ @@@ @@@ 8C@ @ 8 8 Microsurfacing: Single 8C@ C@@ C@@ 8C@ C ● 8 Microsurfacing: Double ●8C CC@ CC@ ●8C 8 ● 8 Chip seal: Single Conventional 8C@ CC@ CC@ 88C C ● @ Polymer modified 8C@ CC@ CC@ 88C C ● @ Chip seal: Double Conventional ●8C 8C@ 8C@ ●88 8 8 C Polymer modified ●8C 8C@ 8C@ ●88 8 8 C Ultra-thin bonded 8C@ 8C@ 8C@ 88C 8 ● 8 wearing course Ultra-thin HMAOL 8C@ 8C@ 8C@ 88C 8 ● ● Thin HMAOL 8●8 ●8C ●8C ●●8 ● ● ● Cold milling and 8●8 ●88 ●8C ●●8 ● 8 C thin HMAOL Hot in-place recycling Surf recycle/HMAOL 8●8 88C 88C 88C 8 8 C Remixing/HMAOL 8●● 8●● C8● C88 ● 8 C Repaving 8●● 8●● C8● C88 ● 8 C Cold in-place recycling 8●● 8●● C8● C88 ● 8 C and HMAOL Profile milling ●8C C@@ 88Ce 88Ce 8 C @ Ultra-thin whitetopping C88 C88 @CC C88 8 C @ Surface Characteristics Issues Table 3.2. (continued)

22Table 3.3. Feasibility Matrix for Preliminary Identification of Candidate Preservation Treatments for PCC-Surfaced Pavements Distress Types and Severity Levels (L  Low, M Medium, H  High) Surface Distress PCI/ Age Preservation Treatment PCR (yr) — — L/M/H — — Concrete joint resealing 75–90 5–10 Concrete crack sealing 70–90 5–12 Diamond grinding 70–90 5–12 ●     Diamond grooving 70–90 5–12      Partial-depth concrete patching 65–85 6–15      Full-depth concrete patching 65–85 6–15   ●b   Dowel bar retrofitting 65–85 6–15      Ultra-thin bonded wearing course 70–90 5–12  ●    Thin HMA overlay 70–90 5–12  ●    Note: ● = Highly Recommended;  = Generally Recommended;  = Provisionally Recommended;  = Not Recommended. a May be appropriate in conjunction with partial- and/or full-depth repairs to ensure smooth profile. b Isolated incidences of D-cracking only. c Isolated incidences of faulting only. d Likely needed in conjunction with diamond grinding. Window of Opportunity Map Crack/Scale Water Polish (Non-ASR) D-Crack Popouts Bleed/Pump (continued on next page) provided in Tables 3.4 and 3.5, factors such as the time of year of treatment construction, availability of quality materials and qualified contractors, roadway geometrics (e.g., horizontal and/ or vertical curves, intersections, pavement markings/striping, curb-and-gutter), traffic accommodation and safety issues, and environmental considerations (e.g., emissions and air quality, recycling and sustainability issues), should be prop- erly considered. This process should result in a final list of fea- sible treatments that can be analyzed for cost-effectiveness, leading to a selection of the preferred treatment. Appendix B provides two example illustrations for using the feasibility matrices in Tables 3.2 through 3.5 to identify final treatment candidates. One example is for treatment of an HMA-surfaced pavement, while the other is for treatment of a PCC-surfaced pavement. Treatment Cost-Effectiveness Analysis Cost-effectiveness analysis is an economic evaluation tech- nique for comparing that which is sacrificed (cost) to that which is gained (performance benefit) for the purpose of eval- uating alternatives (Lamptey et al. 2005). Cost-effectiveness can be measured in the short term (i.e., for one or more treat- ments administered at a given time) or in the long term (i.e., for several treatments carried out over an extended periodof time) using analysis procedures that range from detailed and complex to less detailed and simple. In simple terms, the alternative that provides the greatest benefits for the least costs is the “best.” This section presents two different approaches that can be used to evaluate the cost-effectiveness of preservation treatments. These approaches are the equivalent annual cost (EAC) and the benefit-cost ratio (BCR). The first approach, EAC, is the simplest to perform and requires only basic infor- mation regarding cost and performance. It measures cost- effectiveness in the short term for alternatives that are assumed to provide similar benefit (e.g., a chip seal and a slurry seal that are both applied to improve surface texture). The sec- ond approach, BCR, requires much more data and compu- tational effort and measures cost-effectiveness in the long term. It is appropriate for evaluating treatments that do not necessarily provide the same benefit, such as crack sealing and a chip seal. Each approach requires reliable, up-to-date estimates of the cost and performance of the treatments to be analyzed. Histor- ical bid price data are an excellent source for developing treat- ment cost estimates, but these data must be adjusted to current values to account for the effects of inflation. To the extent pos- sible, care should be exercised in developing estimated costs so that they account for project-specific factors, such as size

23(quantity of treatment needed), site-specific surface prepara- tion requirements (such as material removal, patching, and cleaning), special traffic control requirements, and various contingencies (e.g., striping and pavement marker removal/ replacement and associated shoulder work), that may have impacted the documented treatment costs. Also, to ensure a fair cost comparison of all treatment options, the final estimated costs should be based on a common unit of measure, such as $/yd2 or $/lane-mi. Obtaining meaningful estimates of treatment performance is more complicated. Ideally these are developed using data from the PMS database and the pavement history database (if separate from the PMS database). However, few PMS data- bases include information on preservation treatment per- formance or are able to discern the issue of greatest interest: when the treatment stopped being effective. In any analysis of available data, care should be taken to ensure that the data analyzed are from projects with characteristics (e.g., existing pavement type and conditions, traffic loadings, and climatic conditions) that are similar to those of the proposed project. This is sometimes referred to as the pavement “family” con- cept. Although pavement survival analysis techniques (i.e., time until treatment failure or until a specific threshold condi- tion is reached) can be used, estimates of treatment perfor- mance are more easily achieved using pavement performancemodeling techniques (i.e., time-series trends of overall con- dition, serviceability, and/or individual distress development). And, since pretreatment pavement condition can have a sig- nificant impact on treatment performance, the analysis should be limited to projects with pretreatment condition levels that are similar to the proposed project. If historical performance data are not available or are insuf- ficient for analysis, then performance information should be sought from other sources. These may include agencies that have utilized the candidate treatments in similar conditions or from practitioners knowledgeable of the performance of the candidate treatments. Equivalent Annual Cost The EAC method of cost-effectiveness is an inverse measure of the proverbial “bang for the buck.” It involves a simple cal- culation of the treatment unit cost divided by the expected treatment performance, as shown below. In this analysis method, the expected treatment perfor- mance is the extension in service life of the pavement generated EAC Treatment Unit Cost Expected Performance = , years ( )1Table 3.3. (continued) Joint Seal Joint Long/ Ride Damage Spall Corner Trans Faulting Patches Quality Friction Noise Preservation Treatment L/M/H L/M/H L/M/H L/M/H L/M/H L/M/H — — — Concrete joint resealing ●  Concrete crack sealing ● ● Diamond grinding    a ● ● ●  ● Diamond grooving         ● Partial-depth concrete patching  ●●        Full-depth concrete patching   ●●  c ●    Dowel bar retrofitting     ●d     Ultra-thin bonded wearing course      ● ● ●  Thin HMA overlay      ● ● ● ● Surface Characteristics Joint Distress Cracking Distress Deformation Distress Issues Distress Types and Severity Levels

ion Restrictions Expected Performance on High-Volume Relative kend Longer Facility (yr) Cost 2–3 $ 2–6 $ 3–5 $$ 3–5 $$ 4–6 $$/$$$ 4–6 $$ $$$ 6–8 $$/$$$ $$$ 5–8 $$$ 4–7 $$ 5–10 $$$ 6–11 $$$ 5–8 $$$ 6–12 $$$ 6–12 $$$ 5–11 $$$ 2–4 $   NA $$$$ mentsWork Zone Durat High High Overnight Preservation Traffic ADT Deep Moderate Traffic ADT Deep Moderate or Single Treatment >5,000 vpd Freeze Freeze Nonfreeze >10,000 vpd Freeze Freeze Nonfreeze Shift Wee Crack fill ● ● ● ● ● ● ● ● ● Crack seal ● ● ● ● ● ● ● ● ● Slurry seal         ● (Type III) Microsurfacing:   ●    ●  ● Single Microsurfacing:   ●    ●  ● Double Chip Seal: Single Conventional  ●       ● Polymer modified Chip Seal: Double Conventional  ●       ● Polymer modified Ultra-thin bonded   ●    ●  ● wearing course Ultra-thin HMAOL       ●  ● Thin HMAOL ● ● ●  ● ● ●  ● Cold milling and ● ● ●  ● ● ● ● ● thin HMAOL Hot in-place recycling Surf recycle and HMAOL Remixing         ● and HMAOL Repaving Cold in-place         ● recycling and HMAOL Profile milling       ●  ● Ultra-thin whitetopping          Note: ● = Highly Recommended;  = Generally Recommended;  = Provisionally Recommended;  = Not Recommended. $ (lowest relative cost) ↔ $$$$ (highest relative cost). Table 3.4. Feasibility Matrix for Final Identification of Candidate Preservation Treatments for HMA-Surfaced Pave Treatment Durability Rural Roads Urban Roads Climatic Zone Climatic Zone

Work Zone Duration Restrictions Expected Hi Overnight Performance on Preservation Traffi or Single High-Volume Relative Treatment >5,00 nfreeze Shift Weekend Longer Facility (yr) Cost Concrete joint ● ● 4–7 $ resealing Concrete crack ● ● 4–6 $ sealing Diamond grinding ● ● 6–12 $$ Diamond grooving   ● 6–12 $$ Partial-depth ● ●a ●a ● 5–15 $$/$$$ patching Full-depth patching ● ●a ●a ● 10–15 $$/$$$ Dowel bar retrofitting  ● ●a ●a ● 10–15 $$$ Ultra-thin bonded  ● 5–7 $$$ wearing course Thin HMA overlay  ● 5–8 $$$ Note: ● = Highly Recommended;  $ (lowest relative cost) ↔ $$$$ (hi a Use of high early strength or fast end closures. Use of conventional PCC repair materials generally requires “longer” closures. Table 3.5. Feasibility M for PCC-Surfaced Pavementsgh High c ADT Deep Moderate Traffic ADT Deep Moderate 0 vpd Freeze Freeze Nonfreeze >10,000 vpd Freeze Freeze No ●  ● ● ● ● ● ●  ● ● ●  ● ●  ● ● ●  ●    ●   ● ● ● ●   ● ● ● ● ● ● ● ● ● ● ●             ●     = Generally Recommended;  = Provisionally Recommended;  = Not Recommended. ghest relative cost). -track proprietary materials make these treatments suitable options for overnight, single-shift, and week atrix for Final Identification of Candidate Preservation Treatments Treatment Durability Rural Roads Urban Roads Climatic Zone Climatic Zone

26Approach A: Life extension based on pretreatment condition levels Approach B: Life extension based on specified condition threshold levels Condition Threshold Pavement Condition Time, years Preservation Treatment Figure 3.2. Estimation of preservation treatment performance using two approaches to pavement life extension.by the preservation treatment. Although this extension may be easily identified as (a) the time taken for the pavement con- dition or serviceability/smoothness to return to the level it was at immediately prior to the treatment, a more discerning appraisal uses (b) the difference between the time taken for the treated pavement to deteriorate to a certain threshold level and the time taken for the untreated pavement to deteriorate to the same threshold level. Both approaches are illustrated in Figure 3.2. Benefit-Cost Ratio The BCR method of cost-effectiveness combines the results of individual evaluations of treatment benefits and treatment costs to generate a benefit-to-cost (B/C) ratio. The B/C ratios of alternative preservation treatments (and, if desired, a “no treatment” option) are then compared and the treatment with the highest ratio is deemed the most cost-effective. Since the analysis is performed over a long period covering the life cycle of a pavement, the costs and performance char- acteristics of the existing pavement (whether the original structure or the last significant rehabilitation treatment) and all future projected preservation and rehabilitation treat- ments associated with a given preservation strategy must be estimated. In the BCR method, the benefits associated with a particu- lar preservation strategy are evaluated from the standpoint of benefits accrued to the highway user over a selected analysis period (usually 25 to 40 years, beginning from the original construction). They are quantified by computing the area under the pavement performance curve, which is defined bythe expected timings of future preservation and rehabilitation treatments and the corresponding jumps and subsequent deterioration in condition or serviceability/smoothness. The expected timings are determined from service life analyses of the existing pavement and the specific rehabilitation treat- ments, and from the service life extensions estimated for the preservation treatment. The top portion of Figure 3.3 illustrates the assessment of benefits using the area-under-the-performance-curve approach. A treatment alternative with more area under the curve yields greater benefit through higher levels of condition or serviceability/smoothness provided to the high- way users. The costs associated with a particular preservation strategy are evaluated using life-cycle cost analysis (LCCA) techniques. The LCCA must use the same analysis period and the same timings of preservation and rehabilitation treatments as those used previously in computing benefits. A specified discount rate (typically 3% to 5%) is used to convert the costs of the future projected preservation and rehabilitation treatments (and any salvage value at the end of the analysis period) to present-day costs. These costs are then summed together with the cost of the existing pavement (again, either the original structure or the last significant rehabilitation) to generate the total life-cycle cost (expressed as net present value [NPV]) associated with the preservation strategy. The computational formula used in this process is as follows. NPV IC M R i SV ijj k dis n dis j = + × + ⎛ ⎝⎜ ⎞ ⎠⎟ − × + = ∑ & 1 1 1 1 1 ⎛ ⎝⎜ ⎞ ⎠⎟ AP ( )2

27Pavement Condition Time, years Total Benefit = B0 + BP1 + BOL1 + BOL2 Pavement Preservation Treatment 1 COL2 S COL1CP1 C0 New Construction Overlay 1 Overlay 2 Analysis Period BOL1BP1B0 Lower Benefit Limit BOL2 Figure 3.3. Illustration of benefits and costs associated with a pavement preservation treatment strategy.where NPV = Net present value, $; IC = Present cost of initial construction activity, $; k = Number of future preservation/rehabilitation activities; M&Rj = Cost of jth future preservation/rehabilitation activ- ity in terms of present costs (i.e., constant/real dollars), $; idis = Discount rate; nj = Number of years from the present of the jth future M&R (maintenance and rehabilitation) activity; SV = Salvage value, $; and AP = Analysis period length, years. The bottom portion of Figure 3.3 illustrates the stream of costs included in the LCCA. These costs occur in accordance with the preservation and rehabilitation treatment timings established and used in the analysis of benefits. They represent the costs paid by the agency to construct the existing pave- ment and apply the subsequent preservation and rehabilita- tion treatments. Although most state highway agencies have a standardized procedure for conducting LCCA, state-of-the-practice guid- ance has been developed and made available by the FHWA through the Interim Technical Bulletin on LCCA in Pavement Design (Walls and Smith 1998). A companion LCCA spread- sheet program, RealCost, has also been developed and is available for public use at www.fhwa.dot.gov/infrastructure/ asstmgmt/lccasoft.cfm. In the final step of the BCR method, the B/C ratio for each preservation strategy is computed by dividing the “benefit”obtained from the area-under-the-performance-curve analy- sis by the “cost” obtained from the LCCA: As stated previously, the treatment with the highest B/C ratio is deemed the most cost-effective. Consideration of User Costs User costs are defined as nonagency costs that are borne by the users of a pavement facility (Peshkin et al. 2004). User costs can be incurred through various mechanisms and at any time over the life of a project. Overall, there are five primary mechanisms of user costs: • Time-delay costs. Opportunity costs incurred as a result of additional time spent completing a journey because of work zones (i.e., lane restrictions, road closures) associated with construction, maintenance, or rehabilitation activi- ties. The opportunity cost represents the value associated with other activities that cannot be completed because of the extra time that is normally spent completing a journey. • Vehicle operating costs (VOCs). Costs associated with fuel and oil consumption, tire wear, emissions, maintenance and repair, and depreciation due to work zone traffic flow disruptions and/or significantly rough roads. VOCs typi- cally involve the out-of-pocket expenses associated with owning, operating, and maintaining a vehicle. • Crash costs. Costs associated with additional crashes brought about by work zones or by rough or slippery roads. Crash B C Benefit NPV= ( )3

28costs are primarily comprised of the costs of human fatali- ties, nonfatal injuries, and accompanying property damage. • Discomfort costs. Costs associated with driving in congested traffic or on rough roads. • Environmental costs. Costs associated with traffic noise and with the operation of construction equipment in work zones. Additionally, user costs can be incurred during the estab- lishment of a work zone or during normal (nonrestricted) highway operating conditions: • Work zone costs. This category of user costs deals with costs brought about by the establishment of a work zone. A work zone is defined as an area of a highway where maintenance, rehabilitation, or construction operations are taking place, which impinge on the number of lanes available to mov- ing traffic or affect the operational characteristics of traffic flowing through the area (Walls and Smith 1998). A work zone disrupts normal traffic flow, drastically reduces the capacity of the roadway, and leads to specific changes in roadway use patterns that affect the nature of user costs. • Normal operating condition costs. In between work zone periods, user costs are still incurred during normal operat- ing conditions. These include highway user costs associated with using a facility during periods free of construction, repair, rehabilitation, or any work zone activity that restricts the capacity of the facility. The inclusion of user costs as part of any economic analysis of pavements is a controversial issue. While there is general agreement that traffic delays increase user costs, the actual costs can be difficult to quantify and often overwhelm the direct agency costs, particularly for high-volume facilities (Peshkin et al. 2004). Current FHWA-recommended practice is to consider including in the economic analysis only the time-delay and vehicle operating cost components associated with work zones. These components can be estimated reasonably well and make up a large portion of the total user costs. Other work zone user cost components are too difficult to collect or reasonably quantify, or they do not factor to an appreciable amount. Furthermore, for most pavement facilities in fair or good condition (e.g., pavements with a PSR of 2.5 or greater), user costs during normal operating conditions are minimal (Peshkin et al. 2004). For projects in which time-delay and VOC work zone user costs are likely to occur as a result of performing preservation and/or rehabilitation activities, consideration should be given to evaluating these costs as part of the selected cost-effectiveness analysis method. Detailed procedures for computing them are provided in the FHWA’s Interim Technical Bulletin on LCCA in Pavement Design (Walls and Smith 1998), and the RealCost spreadsheet program can be used to perform thecomputations. A somewhat simplified approach for comput- ing work zone time-delay costs is presented in NCHRP Report 523 (Peshkin et al. 2004). The OPTime spreadsheet program developed as part of that study on optimal timing of preventive maintenance can be used to perform the computations. Fol- lowing are brief descriptions of how user costs can be incorpo- rated into the EAC and BCR methods of cost-effectiveness analysis: • In the EAC method, two aspects of user costs can be con- sidered. The first aspect is the work zone user costs asso- ciated with each alternative preservation treatment. Since the work zone characteristics of each alternative will vary based on application rates, material setting/ curing times, and other construction factors, the delays experienced as a result of the different work zone require- ments will also vary. • The second aspect is the work zone user costs associated with the timing of an assumed future rehabilitation at the end of the preservation treatment’s expected life. A preser- vation treatment with a longer forecasted life results in a delay in the timing of the assumed rehabilitation. When discounted to present-day costs, the work zone user costs associated with the rehabilitation will be lower than the same rehabilitation work zone user costs associated with a shorter life-preservation treatment. This is illustrated in Figure 3.4. • In the BCR method, the user costs of all future preserva- tion and rehabilitation treatments associated with each preservation strategy can be computed as part of the LCCA. Although the user cost NPV results may be com- bined with the agency cost NPV results, it is generally rec- ommended that they be examined separately because of the possibility that they will overwhelm the agency costs. Selection of the Preferred Preservation Treatment Although treatment cost-effectiveness is a major consideration in the selection of the preferred treatment, it is not the final answer in the process. The reality of the decision-making process is that many other factors (economic and noneco- nomic) must be considered along with cost-effectiveness. Some of these factors may have been previously considered as part of the steps to identify feasible treatments, yet may also be desired for consideration in the final selection. Examples include the availability of qualified (and properly equipped) contractors and quality materials, the anticipated level of traf- fic disruption, and surface characteristics issues. Upon completion of the cost-effectiveness analysis, it may be desirable to eliminate certain treatment alternatives on the basis of not being able to meet key financial goals. Such elim- ination criteria might include the following:

29Condition Threshold (Trigger for Rehabilitation) Pavement Condition Time, years Preservation Treatment 1 (PT1) Preservation Treatment 2 (PT2) Time, years UCRehab NPV (PT2) UCRehab UCRehab TPT2 TPT1 UCRehab NPV (PT1) Discount future user costs to present day LifePT2 LifePT1 Figure 3.4. Effect of preservation treatment life on discounted rehabilitation user costs.• Substantially lower cost-effectiveness compared with that of other treatment alternatives (e.g., EAC greater than 10% higher than the EACs of the alternatives, B/C ratios greater than 10% less than the ratios of the alternatives); • Initial cost greater than available funding, resulting in neg- ative impact on network-level budgeting; and • Excessive user costs that would have serious negative impact on roadway users. Alternatively, these economic factors can be combined with several noneconomic factors, as described below. A useful mechanism to systematically and rationally evaluate the different factors and identify the preferred treatment is the treatment decision matrix. In a treatment decision matrix, various selection factors are identified for consideration and each factor is assigned a weight. The weights are then multiplied by rating scores given to each treatment alternative, based on how well the treatment sat- isfies each of the selection factors. The weighted scores of each treatment alternative are then summed and compared with the weighted scores of the other treatments. The treat- ment with the highest score is then recognized as the pre- ferred treatment. A fairly complete list of factors that are appropriate for inclusion in the final selection process is provided below. The factors are grouped according to different attributes,which can also be assigned weights as part of a decision matrix: • Economic attributes:  Initial cost;  Cost-effectiveness (EAC or B/C);  Agency cost; and  User cost. • Construction/materials attributes:  Availability of qualified (and properly equipped) con- tractors;  Availability of quality materials;  Conservation of materials/energy; and  Weather limitations. • Customer satisfaction attributes:  Traffic disruption;  Safety issues (friction, splash/spray, reflectivity/visibil- ity); and  Ride quality and noise issues. • Agency policy/preference attributes:  Continuity of adjacent pavements;  Continuity of adjacent lanes; and  Local preference. A decision matrix that incorporates these factors and illus- trates the assignment of weights and the basis for rating scores is provided in Table 3.6.

30Table 3.6. Example of Preservation Treatment Decision Matrix Treatment 1 Treatment 2 Attribute Factor Combined Rating Weighted Rating Weighted Attribute and Selection Factor Weight Weight Weight Score Score Score Score Economic 40 Initial cost 30 12.0 Cost-effectiveness 30 12.0 Agency cost 10 4.0 User cost 30 12.0 Total 100 Construction/materials 25 Availability of qualified contractors 20 5.0 Availability of quality materials 20 5.0 Conservation of materials/energy 30 7.5 Weather limitations 30 7.5 Total 100 Customer satisfaction 25 Traffic disruption 40 10.0 Safety issues 40 10.0 Ride quality and noise issues 20 5.0 Total 100 Agency policy/preference 10 Continuity of adjacent pavements 20 2.0 Continuity of adjacent lanes 20 2.0 Local preference 60 6.0 Total 100 Cumulative Weighted Score Note: Basis for treatment rating scores (1-to-5 scale); initial cost: 1 = highest, 5=lowest; cost-effectiveness: 1 = least cost effective, 5 = most cost-effective; agency cost: 1 = highest, 5 = lowest; user cost: 1 = highest, 5 = lowest; availability of qualified contractors: 1 = low/none, 5 = high; availability of quality materials: 1 = low/none, 5 = high; conservation of materials/energy: 1 = low, 5 = high; weather limitations: 1 = major, 5 = low/none; traffic disruption: 1 = major, 5 = low/none; safety issues: 1 = serious, 5 = none; ride quality and noise issues: 1 = serious, 5 = none; continuity of adjacent pavements: 1 = does not match at either end, 5 = matches at both ends; continuity of adjacent lanes: 1 = does not match, 5 = matches; local preference: 1 = inconsistent with preference, 5 = consistent with preference.