National Academies Press: OpenBook

Preservation Approaches for High-Traffic-Volume Roadways (2011)

Chapter: Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways

« Previous: Chapter 2 - Information Gathering and Review
Page 33
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 33
Page 34
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 34
Page 35
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 35
Page 36
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 36
Page 37
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 37
Page 38
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 38
Page 39
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 39
Page 40
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 40
Page 41
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 41
Page 42
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 42
Page 43
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 43
Page 44
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 44
Page 45
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 45
Page 46
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 46
Page 47
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 47
Page 48
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 48
Page 49
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 49
Page 50
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 50
Page 51
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 51
Page 52
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 52
Page 53
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 53
Page 54
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 54
Page 55
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 55
Page 56
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 56
Page 57
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 57
Page 58
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 58
Page 59
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 59
Page 60
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 60
Page 61
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 61
Page 62
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 62
Page 63
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 63
Page 64
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 64
Page 65
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 65
Page 66
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 66
Page 67
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 67
Page 68
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 68
Page 69
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 69
Page 70
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 70
Page 71
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 71
Page 72
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 72
Page 73
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 73
Page 74
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 74
Page 75
Suggested Citation:"Chapter 3 - Development of Preservation Guidelines for High-Traffic-Volume Roadways." National Academies of Sciences, Engineering, and Medicine. 2011. Preservation Approaches for High-Traffic-Volume Roadways. Washington, DC: The National Academies Press. doi: 10.17226/14508.
×
Page 75

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

The results of the literature review and the questionnaire sur- vey are an excellent starting point for identifying the state of the practice for preservation of high-traffic-volume facilities. The information indicates the types of treatments that can be successfully used on pavements with high traffic volumes, and it also reveals much about other key factors that can influence the selection of treatments at the project level. Specific insights obtained relate to the following: Performance Attributes • Effect of existing pavement condition (distress) and service- ability (smoothness) on treatment performance. • Effect of traffic volume on treatment performance. • Effect of climate and environment on treatment performance:  Direct climatic and environmental stresses; and  Stresses associated with snowplowing and studded or chained tire use. • Effect of treatment on pavement condition, serviceability, safety (friction, surface drainage [splash/spray, cross slope]), and noise. Constructability Issues • Costs (agency and user). • Complexity of construction. • Availability of skilled and experienced or qualified contractors. • Need for specialized equipment or materials. • Availability of quality materials. • Environmental constraints. • Traffic disruption. • Traffic control constraints. • Restrictions on available time for lane closures to complete the work. This chapter draws upon the findings presented in Chap- ter 2 and incorporates additional information, concepts, and ideas that convey the state of the practice within the backdrop of the treatment selection process depicted in Figure 3.1. In this process, the current and historical conditions of the existing pavement are first established through condition surveys or the agency’s pavement management system (PMS) records or both. A preliminary list of preservation treatments that best address the deficiencies of the existing pavement is then developed. The candidate treatments are evaluated according to their ability to satisfy the performance needs and construction constraints of the project. A final list of feasible treatments is then generated and these treatments are analyzed for cost-effectiveness and other considerations to arrive at the preferred treatment. Preliminary Analysis of Treatment Feasibility: Consideration of Existing Pavement Conditions Applying preservation treatments at the correct time is often cited as a key to cost-effectively extending pavement service- ability. If a treatment is applied too soon, funds are expended on roads that do not require treatment or do not exhibit sufficient benefit to justify the costs. If a treatment is applied too late, the road may have deteriorated to the point that the treatment is ineffective or does not add sufficient life to the pavement to justify the cost. Thus, the correct time represents a “window of opportunity” in terms of the condition or service- ability of the pavement. Most practitioners agree that preservation treatments should be applied during the period when the pavement remains in fair to good condition. A recent NCHRP survey on pavement preservation revealed that more than two-thirds of the report- ing agencies treat roads while they are still in fair to good condition, whereas less than 5% treat pavements in very poor condition (Peshkin and Hoerner 2005). This leads to the conclusion that most state agencies try to restrict treat- ment to pavements in fair to good condition. Findings from C H A P T E R 3 Development of Preservation Guidelines for High-Traffic-Volume Roadways 33

the SHRP SPS-3 and SPS-4 studies of PM on both HMA and PCC support this, concluding that “treatments applied to pavements in good condition had shown good results” (Morian et al. 1997). Preservation treatments have often been applied according to a predetermined schedule based on a time (or a window of time) since original construction or the last major reha- bilitation (e.g., crack seal at Year 5, apply a chip seal between Years 7 and 10). In some cases, recurring intervals were estab- lished (e.g., reseal joints every 7 years). This is also referred to by some agencies as cyclic maintenance. The schedule was usually established based on information obtained from maintenance surveys or on agency experience with the types and rates of deterioration incurred by certain pavement types. However, whereas a schedule-based approach has the advantage of ease of budgeting and programming, it often results in poor treatment choices for existing problems (Shober and Friedrichs 1998) because pavement condition is only indirectly considered through the proxy of time. A variation of the schedule-based approach is remaining service life (RSL). In this approach, a minimum time period before an expected rehabilitation is assigned to each treatment, based either on the number of years remaining in the design life of the existing pavement structure or on the projected performance trend (overall condition or smoothness curves and corresponding terminal and threshold levels), as illustrated in Figure 3.2. An example of RSL-based windows of opportunity is featured in a report covering the development of a pave- ment PM program in Colorado (Galehouse 2004). The recom- mended RSL criteria for various HMA- and PCC-surfaced treatments are listed in Table 3.1. These criteria are used in conjunction with distress index scores (discussed later in this chapter), which provide the direct tie-in needed with pave- ment condition. With the advancements in PMSs in recent years, the iden- tification of candidate treatments can be more closely tied to the existing pavement conditions. Using historical data on overall condition (pavement condition index/rating [PCI/ PCR]), serviceability (present serviceability index/rating [PSI/PSR]), or roughness (international roughness index [IRI]), performance models can be developed for groups of 34 Establish existing pavement condition. Identify preliminary set of feasible treatments. Determine project needs and constraints. Identify final set of feasible treatments. Perform cost-effectiveness analysis and evaluate economic and noneconomic factors. Identify preferred treatment. Figure 3.1. Process of selecting the preferred preservation treatment. Minimum Remaining Service Life (RSL) Terminal/Threshold Condition Level Existing Pavement Condition Time Treatment Application Window Projected Year of Major Rehabilitation Figure 3.2. Remaining service life approach to establishing treatment application windows.

similar pavements (i.e., pavement families), which can then be used to set condition-based windows of opportunity for individual treatment types. As overall condition, serviceability, or roughness is tracked at the project level, feasible treatments can be identified according to the established windows of opportunity (see Figure 3.3). Overall condition, serviceability, and roughness measures do not indicate specific pavement deficiencies or problems; they can only provide a general indication of when specific treatments should be considered for use. Hence, it is criti- cal that they be augmented with application criteria pertaining to individual pavement distresses. The next section presents some examples in which overall pavement condition is eval- uated in conjunction with detailed distress data in order to identify candidate preservation treatments. It also presents general guidelines for establishing condition-based windows of opportunity for preservation treatments on high-traffic- volume facilities. Two important considerations in the identification of treatments based on windows of opportunity are the rate of deterioration and the gap between when a treatment is selected and when it formally gets constructed. Pavements showing abnormally high reductions in condition (say more than 4 to 5 PCI/PCR points per year or more than 7 to 8 in./mi (0.11 to 0.13 mm/m) of IRI per year) are likely being affected by structural or subsurface material issues that could greatly limit the effectiveness of a preservation treatment. If the gap between treatment selection and construction is expected to be 1 year or more, the conditions of the pavement will likely have changed enough to warrant the reevaluation of treatments. 35 Table 3.1. Recommended RSL Criteria for PM Treatments in Colorado Flexible Pavements Rigid Pavements Minimum RSL Minimum RSL Treatment (years) Treatment (years) Crack filling 9 Crack sealing 10 Crack sealing 10 Joint resealing 10 Sand seals 9 Diamond grinding 8 Chip seals 8 Partial-depth spall repair 10 Microsurfacing (single course) 12 Dowel bar retrofit 10 Microsurfacing (multiple course) 8 Full-depth concrete repair 7 Ultra-thin bonded wearing course 8 Thin HMA overlay 6 Mill and thin HMA overlay 6 Source: Galehouse 2004. Overall Condition, Serviceability, or Roughness Time Condition-Based Windows of Opportunity Appropriate Condition/ Serviceability Range Condition/Serviceability Trendline Roughness Trendline Appropriate Roughness Range Figure 3.3. Windows of opportunity based on age and overall condition.

This is particularly true if the condition data upon which a treatment was selected did not fully reflect the conditions at the time of selection (i.e., the condition survey data were collected or processed several months before the evaluation or selection process). Windows of Opportunity Ohio, New York, and Alberta represent agencies that use overall pavement condition in conjunction with detailed distress data to identify candidate preservation treatments. As seen in Table 3.2, the Ohio DOT uses PCR ranges as criterion for identifying candidate PM treatments for HMA-surfaced pavements. The PCR ranges for five of the six treatments span the same condition range defined by ODOT as good (75 to 90), while the range for the sixth treatment, crack sealing, extends partly into the very good condition category (90 to 100). As dis- cussed later, additional criteria, including detailed distress data and traffic levels, are also used by Ohio in identifying candidate treatments. The New York State DOT uses a 1-to-10 surface condi- tion rating along with pavement roughness (IRI) to identify candidate treatments (preventive and rehabilitation) for high- traffic-volume roads. The performance curve and windows of opportunity shown in Figure 3.4 provide a general basis for the treatment selection matrix, which is shown in Figure 3.5. Generally speaking, non-paving-type PM (i.e., crack sealing) is prescribed for pavements with surface ratings between 7.5 and 8.5 and any level of roughness. Paving-type PM, such as ultra-thin and thin HMA overlays, are candidates for pave- ments with condition ratings between 6.5 and 7.5 and with IRI ≤ 95 in./mi (≤ 1.5 mm/m). Multicourse treatments that entail light to moderate forms of rehabilitation are candidates for pavements with (a) condition ratings between 5.5 and 6.5 and IRI ≤ 95 in./mi (≤ 1.5 mm/m) or (b) condition ratings between 6.5 and 7.5 and 96 ≤ IRI ≤ 170 in./mi (1.51 ≤ IRI ≤ 2.7 mm/m). The Alberta Ministry of Transportation (MOT) uses pave- ment smoothness as the first level in the hierarchy of assessing and selecting preservation treatments (Alberta MOT 2006). Rural highway pavements smoother than the following IRI levels are analyzed according to individual distress types, 36 Table 3.2. Ohio DOT Condition Criteria for PM Treatments Pavement Condition Rating (PCR) Rangea Flexible Composite PM Treatment Pavements Pavements Crack sealing 75 to 95 75 to 95 Chip seal 75 to 90 75 to 90 Microsurfacing 75 to 90 75 to 90 (single course) Microsurfacing 75 to 90 75 to 90 (double course) PMAC overlay 75 to 90 75 to 90 Thin HMA overlay 75 to 90 75 to 90 Source: ODOT 2001. Note: PMAC = Polymer-modified asphalt concrete. a Condition categories listed in ODOT Pavement Condition Rating Manual: 90–100, very good; 75–90, good; 65–75, fair; 55–65, fair to poor; 40–55, poor; 0–40, very poor. Source: NYSDOT 2008. Condition Rating Time 10 9 8 7 6 5 Do Nothing Nonpaving PM PM Paving Multicourse Major Rehab/ Recon Pavement Performance Curve and Windows of Opportunity Figure 3.4. Condition rating windows of opportunity for various forms of pavement preservation for New York highways.

37 9+ D D D D D D Flexible Overlay 8 1 1 1 1 1 1 1 Crack seal 8 CIPR (not used on high volume) 7 5 5A 9 9 11 11 3 Thin overlay 9 Mill and fill 6 9 9 9 11 12 12 5 6.3 mm asphalt 11 Mill and fill w/underlying pvt repairs Surf Rating 5 9 9 11 12 12 13 5A 6.3 mm asphalt mill and fill 12 Major rehab: 2-course OL w/repairs 60 61–95 96–135 136–170 171–220 >220 6 1.5 in. hot-mix overlay 13 Reconstruction: 3-course OL w/repairs Ride Quality (IRI, in./mi) D Defer treatment Pavement Surface Rating Based on Frequency and Severity Descriptions Severity Frequency None Slight Minor Moderate Moderateto Severe Severe Very Severe Travel Is Impaired Impassable No distress is present. A single random defect per 0.10 mi is allowed. None 10/9 - - - - - - - - Most of pavement is free of distress. One or two cracks or distresses are visible for the next 0.10 mi. Infrequent - 8 8 8 7 7 - - - Much of pavement is free of cracking. Large blocks of distress- free pavement are present. Infrequent to occasional - 8 7 7 7 6 6 - - Much (<0.5) to most (>0.5) of the pavement is cracked. Uncracked or undistressed blocks of pavement range from 20 to 30 ft/lane to 12 ft/lane. Occasional to frequent - 7 7 6 6 5 5 - - Nearly all the pavement is cracked. Uncracked or undistressed blocks of pavement are 12 ft2 or less. Frequent - 7 6 6 5 4 3 2 1 Mostly cracked. Cracks or distress are continuous and spaced only a few feet apart. Very frequent - 6 6 5 5 4 3 2 1 Source: NYSDOT 2008. Slight: Cracks are tight, single, and only a few feet long. Tight, single longitudinal joint cracks, partial or continuous, are included. Minor: Cracks are generally <0.125 in. wide, some with minor secondary cracks, no or very few connected cracks. May have a few small spalls (<1 ft2). Moderate: Cracks are generally >0.125 in. wide, secondary cracking is common, some cracks connected; may have some minor popouts or small (1 to 2 ft) to medium (3 to 4 f hing. Moderate to Severe: Distresses vary from “moderate” to “severe.” Severe: Cracks are wide and/or have extensive interconnected secondary cracking; holes, loose material, and/or patching are common; patches may have patches. Very Severe: Cracks are very wide; holes and/or patching is extensive; patches extend across the full lane or extend several feet along the lane; patches on patches are common. Travel Is Impaired: Holes in pavement are large and/or pavement has so many layers of patches that the section can be traveled only at reduced speed. Impassible: Travel by ordinary car would risk damage to the vehicle. t) patc Figure 3.5. Treatment selection matrix used for high-traffic-volume (AADT > 20,000 vpd) HMA-surfaced Interstates and highways in New York.

severities, and extents to determine candidate preservation treatments: AADT, vpd IRI Trigger, in./mi (mm/m) <400 190 (3.0) 400 to 1,500 165 (2.6) 1,501 to 6,000 145 (2.3) 6,001 to 8,000 132.5 (2.1) >8,000 120 (1.9) Pavements rougher than these levels are analyzed for struc- tural capacity to determine treatment thickness requirements. Candidate treatments are then identified based on detailed assessments of individual distress types, severities, and extents. Depending on the structural needs and specific deficiencies to be addressed, the candidate treatments may range from low- cost preventive treatments to expensive major rehabilitation activities. Figure 3.6 illustrates the process used by Alberta. Guidelines for Condition-Based Windows of Opportunity Although overall condition, serviceability, and roughness indicators are not indicators of the specific forms of distress that are present, they can effectively serve as preliminary identifiers of candidate preservation treatments. This is because for an adequately designed and constructed pavement, there is a fairly consistent pattern to distress development and to the sequence of treatments intended to address the distresses at various points in the deterioration cycle. The pattern is as follows: • Within the first few years of HMA construction, various environment-related distresses often begin to develop at the pavement surface, causing the overall condition to reduce slightly. Preventive treatments, like crack sealing and thin surface seals, are best applied at this time in order to slow or reduce the severity of these distresses. • As environment-related distresses continue to develop and other non-load-related distresses emerge, a further reduction in overall condition occurs and some roughness becomes apparent. Consequently, more significant treatments, like chip seals and thin overlays, become more suitable for use. • Further distress development (and possibly the initial onset of some load-related distresses) reduces the overall condition and increases roughness even more, making restorative treat- ments, such as mill-and-overlay and in-place recycling, the more appropriate preservation treatment options. • As load-related distresses become more significant, mod- erate to major forms of pavement rehabilitation become appropriate. Using the information just presented and the following categories of PCI (USACE et al. 2004) and IRI (FHWA 2002), 38 Source: Alberta MOT 2006. Segm ent sm oother than tri gg er value IRI (ride level) Segm ent rougher than tri gg er value 20-year structural overlay re q uirem en t — OL ( 20 y r ) OL (20 yr) > 40 mm OL (20 yr) 90 mm OL (20 yr) 70 mm < OL (20 yr) < 90 mm HIR Mill and inlay OL (10 yr) IL (20 yr) 40 mm < OL (20 yr) < 70 mm Preventive ma intenance Thin OL HIR Mill and inlay OL (10 yr) IL (20 yr) OL (20 yr) < 40 mm Preventive ma intenance Thin OL HIR Mill and inlay Two-lift OL Environ m ental/construction distresses Traffic/load distresses Potholes, dips, heaves, and local distortion Transverse cracks Longitudinal centerline cracks Segregation Ravel Rutting Longitudinal wheelpath fati g ue cracks Wheelpath flushi n g /bleedin g Figure 3.6. Alberta guidelines for assessing pavement preservation treatments and strategies.

some basic guidelines for condition-based windows of oppor- tunity have been developed and are presented in Table 3.3: Condition Description PCI Good 86 to 100 Satisfactory 71 to 85 Fair 56 to 70 IRI, in./mi (mm/m) Condition Description <95 (<1.5) Good ride quality and good condition 95 to 119 (1.5 to 1.88) Acceptable ride quality, fair condition 120 to 170 (1.9) Acceptable ride quality, mediocre condition The windows of opportunity listed in Table 3.3 can be considered as starting points or reference values for agencies that have not developed formal criteria for preservation treatment selection. Agency practices and experiences will generally dictate any adjustments or refinements that need to be made. Detailed Assessment of Treatments and Deficiencies Because preservation treatments address pavement deficien- cies to varying degrees and no one treatment is best suited to all conditions, a detailed assessment is needed that matches treatment capabilities with existing deficiencies. Ideally, this assessment should consider not only the specific distress types present and their causes but also the severity and extent of each observed distress. Moreover, it should consider important functional performance attributes, such as friction, splash- spray, and pavement-tire noise. Two approaches for identifying feasible preservation treat- ments based on existing pavement deficiencies are decision sup- port matrices and decision support trees. Both approaches rely 39 Table 3.3. Recommended PCI Windows of Opportunity for Pavement Preservation Treatments HMA-Surfaced Pavements PCC-Surfaced Pavements Treatment PCI Window Treatment PCI Window Crack fill 75 to 90 Concrete joint resealing 75 to 90 Crack seal 80 to 95 Concrete crack sealing 70 to 90 Slurry seal (Type III) 70 to 85 Diamond grinding 70 to 90 Microsurfacing, single 70 to 85 Diamond grooving 70 to 90 Microsurfacing, double 70 to 85 Partial-depth concrete patching 65 to 85 Chip seal, single Conventional 70 to 85 Full-depth concrete patching 65 to 85 Polymer modified 70 to 85 Chip seal, double Conventional 70 to 85 Dowel bar retrofitting 65 to 85 Polymer modified 70 to 85 Ultra-thin bonded wearing course 65 to 85 Ultra-thin bonded wearing course 70 to 90 Ultra-thin HMAOL 65 to 85 Thin HMA overlay 70 to 90 Thin HMAOL 60 to 80 Cold milling and thin HMAOL 60 to 75 Hot in-place recycling Surf recycle and HMAOL 70 to 85 Remixing and HMAOL 60 to 75 Repaving 60 to 75 Cold in-place recycling and HMAOL 60 to 75 Profile milling 80 to 90 Ultra-thin whitetopping 60 to 80 Note: HMAOL = Hot-mix asphalt overlay.

on a set of rules and criteria to identify appropriate preservation treatments; the former uses a tabular structure like the one shown in Table 3.4 and the latter, a more systematic graphical approach like the one illustrated in Figure 3.7 (Peshkin and Hoerner 2005). The benefits and limitations of these approaches were previously identified by Hicks et al. (2000) as follows: Benefits • Make use of existing experience; • Work well for local conditions; • Good as project-level tools; • Reflect decision processes normally used by an agency; • Flexible in modifying both the decision criteria and the associated treatments; • Generate consistent treatment recommendations; and • Explain and program selection process with relative ease. Limitations • Not always transferrable from agency to agency; • May be more difficult to innovate or introduce new treatments; • Hard to incorporate all important factors (e.g., competing projects, functional classification, remaining life); • Difficult to develop matrix that can incorporate multiple pavement distress types (i.e., do not always address the actual distress conditions); • Generally only designed to focus attention on one or two treatments that have worked well in the past and tend to ignore or overlook new or improved treatments that may be more effective; • Do not include more comprehensive evaluation of various feasible alternatives and life-cycle cost analysis (LCCA) to determine the most cost-effective strategy; and • Not good for network evaluation. The last two limitations listed are not relevant in the present study because the treatment selection framework and method- ology developed and presented in this report are intended for use at the project level and include a cost-effectiveness analysis component. The rules and criteria behind decision support matrixes or trees are based on an understanding (from past experience or historical performance data) of the ability of individual treatments to fix or mitigate specific distresses. As illustrated in Figure 3.8, a key step in developing rules and criteria is to evaluate the primary purposes and functions of treatments in relation to the factors and causes of individual distresses, the 40 Table 3.4. Example Decision Support Matrix for Identifying Flexible Pavement PM Strategies Seal Coat Slurry Seal Microsurfacing 1. Traffic ADT < 2000 R R R 2000 > ADT < 5000 Ma Ma R ADT > 5000 NR NR R 2. Bleeding R R R 3. Rutting NR R R 4. Raveling R R R 5. Cracking Few tight cracks R R R Extensive cracking R NR NR 6. Improving friction Yes Yes Yesb 7. Snowplow Most Moderately Least damage susceptible susceptible Susceptible Source: Jahren et al. 2000. Courtesy of Center for Transportation Research and Education, Iowa State University. Note: R = Recommended; NR = Not recommended; M = Marginal. a There is a greater likelihood of success when used in lower-speed traffic. b Microsurfacing reportedly retains high friction for a longer period of time. c As recommended by International Slurry Seal Association. d Current practice in Iowa. e Sometimes successful (anecdotal evidence). Treatment <0.25 in. 0.25 to 0.5 to 1 in. >1 in. 0.5 in. Microsurfacingc One course Scratch Rut box and Multiple course final surface placement and final with rut surface box Slurry seald One course One course Microsurfacing See note e scratch course and final surface Rut Depth

41 Source: Hicks et al. 1999. M&R Treatment Surface Wear Severity Environmental Cracking Extent Structural Deterioration Fatigue Cracking Extent Rutting Severity M&R Treatment Crack Seal Surface Treatment Crack Seal and 40-mm OL Crack Seal Crack Seal and 40-mm OL Mill/Fill 50 mm Mill/Fill 50 mm Mill/Fill 50 mm Mill/Fill 50 mm Mill/Fill 40 mm Mill/Fill 50 mm Mill/Fill 75 mm Mill 50 mm 75-mm OL Mill 75 mm 100-mm OL Mill 100 mm 125-mm OL Mill 100 mm 150-mm OL Rem HMA, Repl Base, Repave Total Reconstruct Low Moderate High Low Moderate High Low Moderate High Low Moderate High Low Moderate High Low Moderate High Low Moderate High Low Moderate High No Yes Figure 3.7. Example decision support tree for identifying flexible pavement preservation and rehabilitation strategies. Distresses Subgrade Causes/Factors Material deficiencies (design/construction related) Causes/Factors Environmental effects (temp, moisture, UV) Causes/Factors Traffic loading effects (frequency, intensity, type) Causes/Factors Structural inadequacies (design related) Treatment Types Treatment Purposes/Functions Prevent/delay distress development Slow/reduce rate of distress development Restore integrity and functionality of pavement Figure 3.8. Matching of treatments with distress types through evaluation of treatment purposes/functions and distress causes/factors.

locations of the distresses within the pavement structure, and the operational impacts (functional or structural) of the dis- tresses. For instance, a treatment whose primary purpose is to seal surface cracks and rejuvenate the HMA surface layer, would be a good candidate for a pavement that has become oxidized and has consequently developed considerable amounts of low- to medium-severity cracks. A number of decision support matrices and trees were iden- tified in the literature, ranging from simple routines involv- ing a few treatments and several key distress types to complex algorithms featuring many treatments and an array of distress types, severity levels, and extents. As noted by Hicks et al. (2000), both tools can be used effectively in the selection and identification of suitable preservation and rehabilitation treatments. For the guidelines produced in this study, it was determined that a decision support matrix should be used as the basis for identifying candidate preservation treatments based on pave- ment condition. A decision support matrix provides users with a more systematic and understandable approach; however, decision trees could also be easily constructed from the formu- lated decision matrix. Decision Support Matrixes for HMA-Surfaced Pavements Three of the more comprehensive decision support matrixes prepared for HMA-surfaced pavements are illustrated in Tables 3.5 through 3.7 (pp. 43–46). Each of these tables provides an indication of treatment suitability for different types of distress. In addition, Tables 3.5 and 3.6 give indications of treatment suitability corresponding to different distress severity levels. These and other similar matrixes and trees have served as a basis for the development of preservation guidelines in various states and provinces, including California, Illinois, Ohio, Montana, Nebraska, New York, Virginia, Alberta, and Ontario. Tables 3.8 through 3.10 (pp. 48–53) show the decision support matrixes developed by the California and Illinois DOTs. Tables 3.11 and 3.12 (pp. 54–55) illustrate the Ohio DOT’s matrixes for flexible and composite pavements, respectively. Decision Support Matrixes for PCC-Surfaced Pavements The FHWA’s Concrete Pavement Preservation Workshop Reference Manual (Smith et al. 2008) provides detailed guidance on the application of preservation and rehabilita- tion treatments for PCC-surfaced pavements. Table 3.13 (p. 56) presents examples of both general trigger and limit values for different distress and performance indicators and different traffic volume categories. The trigger values define the point when preservation may be appropriate, while the limit values define the point at which the pavement is in need of major structural improvements. Table 3.14 (p. 58) shows the basic decision support matrix (treatment–distress matches) presented in the preservation workshop manual. It is supplemented with more specific information regarding the suitability of some treatments for different distress severity levels. It should be pointed out that the unshaded columns in this table depict the preserva- tion treatments covered in the SHRP 2 Renewal Project R26 study, whereas the shaded columns represent rehabilitation treatments. Survey Results on Treatments and Deficiencies Tables 3.15 and 3.16 (pp. 60–61) reflect the state of the practice for treatment use by transportation agencies based on exist- ing pavement surface conditions. In these tables, “extensive” use means that two-thirds or more of the highway agencies reported using a particular treatment to address a certain pavement deficiency. “Moderate” represents use by between one-third and two-thirds of the agencies, whereas “limited” represents use by less than one-third of the agencies. Guideline Decision-Support Matrixes The treatment application information presented above, representing both best and current practices, was used to formulate decision-support matrixes for identifying feasible treatments based on existing pavement condition. Tables 3.17 and 3.18 (pp. 62–65) show the guideline matrixes developed for HMA- and PCC-surfaced pavements, respectively. These matrixes are a key part of the treatment selection framework and process presented in Guidelines for the Preservation of High-Traffic-Volume Roadways. Final Analysis of Treatment Feasibility: Consideration of Project Needs and Constraints Once a preliminary list of feasible treatments has been developed based on existing pavement conditions, further evaluation is needed to determine which of the treatments largely satisfies the needs and constraints of the project. The needs center on the targeted or required performance of the preservation activity and the impacts that various project and site location factors can have on the performance of the identified feasible treatments. The constraints center on fund- ing limitations for the preservation work and various other factors that can affect the constructability of the identified feasible treatments. Detailed discussions of these two feasibility aspects are pro- vided in the sections that follow. Included in these discussions 42 (text continues on page 46)

43 Table 3.5. Guidelines for Effective Maintenance Treatments (Based on SHRP Southern Region Review of SPS-3 Test Sites) Treatmentsa Thin Slurry Crack Rout and Rout and Chip Seal: Chip Seal: Pavement Conditions Parameters Overlay Seal Seal Sealb Fillb Finec Coarsec Microsurface Fog Traffic ADT/laned <1000 E E E E E E E E E 1000 < ADT < 4000 E E E E E E-Q E-Q E E-Q >4000 E E E E E E-N-Q E-N-Q E E-Q Rutse <3⁄8 in. E E E E E E E E E 3⁄8 in. < R < 1 in. E M-N E E E M-N-Q M-N-Q E T >1 in. E T E E E T T M-C T Cracking Fatigue Low E E E E E E E E M Moderate E M M M M E E M T High M T T T T E E T T Longitudinal Low E E E E E E E E M Moderate E M E E E E E M T High M T M E E M M T T Transverse Low E E E E E E E E M Moderate E M E E E E E M T High M T M E E M M T T Asphalt Surface Dry E E T T T E E E E surface appearance Flushing E E T T T M-Q E-Q E T condition Bleeding E E T T T N-Q N-Q E T Variable E E T T T M-Q E-Q E Mf Raveling Low E E T T T E E E E Moderate E E T T T E E E M High E M T T T E-Q E-Q E M Potholes Low E E T T T E E E T Moderate E M M T T E E M T High M M M T T M M M T Existing pavement texture is rough E E T T T M-Q M-Q E T Poor ride E E T T T T T M T Rural (minimum turning movements) E T T T T E E E E Urban (maximum turning movements) E E E E E E-Q E-Q E E Subsurface moisture High snowplow usage E E E E E E-Q E-Q E E Low frictional resistance E E T T T E E E T Source: Hicks et al. 2000. Note: E = Effective; M = Marginally effective; N = Not recommended; Q = Requires a higher degree of expertise and quality control; T = Not effective. a The chart provides general guidance only. Engineering judgment and experience should be used to select the proper treatment. b Typically requires routine retreatment at 2-year intervals. c For ADT in excess of 50,000 (total) and/or truck volumes in excess of 20%, this treatment can be effective but is not recommended. d Higher percentages of trucks have a significant effect on performance. e Rutting has occurred over an extended period of time. f Spot treatments on dry conditions only.

44 45 Table 3.6. FHWA/FP2 Guidelines for Pavement Treatment Selection Treatments Ultra- Full-Depth evitcefleRnoitamalceR nihT kcarC ralunarG toH dloCdelcyceRdednoB-hgiH.doM .dtS feileR esaB nihT ecalP-nI ecalP-nI tlahpsAgniraeWyrrulSecnamrofreP pihCpihCdnaSkcarC goF tnemevaP yalretnInoitazilibatSyalrevOgnilcyceRgnilcyceRtnemevaPesruoCgnicafrusorciMlaeSlaeS pihClaeSlaeSlaeSlaeSlaeSsretemaraPsnoitidnoC er ***************0001< )TDA( cfifarT (% trucks should *****?*********0004–0001 also be ***?*?******X*?0004>)deredisnoc <stuR 3⁄8 ***************.ni 3⁄8 ?*???*X*??????X.ni 1– ?*XX??X?XXXXXXX.ni 1> ********X*****?woLeugitaf gnikcarC *****???X*?*??XetaredoM *???*?XXXXXXXXXhgiH **************?woL gnikcarC *****????***?*XetaredoMlanidutignol **??*XXXXXXXX?XhgiH **************?woLesrevsnart gnikcarC *****????*?*?*XetaredoM **??*XXXXXXXX?XhgiH ********?****X*yrDnoitidnoc ecafruS ?*******X***?XXgnihsulF ?**********?XXXgnideelB ?***********?X?elbairaV *X*XX?*******?XCCP *************X*woLgnilevaR *************X?etaredoM ********?****X?hgiH **************XwoLselohtoP ******X???????XetaredoM ***?*?X??XXXX?XhgiH X?XX?XXXXXXXXXXegamaD .tsioMgnippirtS *********????XXhguoRerutxeT *******?*XXXXXXrooPediR ********X******gninrut .niMlaruR ************?**gninrut .xaMnabrU ?XXX?XXXXXXXXXXrooPeganiarD ***********?***hgiHesu wolpwonS *?***********XXwoLecnatsiser dikS ??????*??*XXX??woLesioN ***************woLnrecnoc tsoc laitinI ???*?*XX?*?**?*hgiH ?*?***?***?****woLnrecnoc tsoc efiL **?*****?**??*?hgiH ?X?*X?**X*?XX?XwoLytilauq .tsnoc lacoL ***************hgiH *??*??**?*?????hgiH$ yaled-resU Source: FHWA and FP2 2005. Notes: These are broad assumptions. Assessment of a given road should take precedence, with special attention to distress course(s) and needed repairs before treatment. Recommendations in top chart assume good-quality design and construction. Multipliers from the bottom chart should be used. This information is meant to be fed into a decision matrix. X = Not recommended; ? = May be recommended; * = Recommended.

Table 3.7. Guidelines for Preliminary Selection of Candidate Rehabilitation Techniques for HMA-Surfaced Pavements Candidate Rehabilitation Treatments Pavement Distress Cold HIR Surface HIR HIR Thin Thick Combination Mode Mill Recycle Remixing Repaving CIR HMA HMA Treatments Raveling Potholes Bleeding Skid resistance Shoulder drop-off Rutting Corrugations Shoving Fatigue cracking Edge cracking Slippage cracking Block cracking Longitudinal cracking Transverse cracking Reflection cracking Discontinuity cracking Swells Bumps Sags Depressions Ride quality Strength Source: Modified from Dunn and Cross 2001. Courtesy of Asphalt Recycling and Reclaiming Association. Most appropriate Least appropriate 46 is information on the best and current practices that are used in developing the guidelines featured in Guidelines for the Preservation of High-Traffic-Volume Roadways. Performance Needs Performance Definition The term “performance” takes on many connotations when used in reference to pavements. It normally refers to the deterioration of pavement condition over time, as gauged by an overall condition indicator (PCI/PCR), a serviceability indicator (PSI/PSR), a roughness parameter (IRI), or a variety of individual distress indicators (rutting, fatigue cracking, and so on). It is also used to refer to the service life of a pavement, as defined by the time until the pavement needs a major or structural rehabilitation (which can be determined in a variety of ways using time-series condition data or historical pavement construction and rehabilitation event data). The meaning of “performance” is further complicated when applied to a preservation treatment. This is because both the performance of the treatment itself and the influence of the (continued from page 42)

treatment on the performance of the existing pavement are of interest. In addition, the term “effectiveness” is often used when referring to the immediate, short-term, or long-term effects of the treatment application (Kuennen 2006c). For the purposes of this study, performance has been defined as the length of time that a treatment serves the purpose for which it was placed (i.e., provides a benefit). It is the exten- sion in service life imparted to the existing pavement by the preservation treatment. This designation of performance is most compatible with the procedures needed to evaluate the cost-effectiveness of preservation treatments as part of a project-level treatment selection process. Performance Targets and Requirements In addressing treatment feasibility, the user should identify targeted or required levels of performance for the planned preservation activity. This performance goal may be based on a nominal assessment of (a) the expected performance capa- bilities of the alternative treatments for the conditions at hand, (b) the long-term planning and programming impacts for the subject project, and (c) the importance of minimizing delays associated with future maintenance and rehabilitation (M&R) activities. Expected Treatment Performance As a starting point for establishing expected treatment perfor- mance, the project literature was reexamined for information on general treatment performance (and not specifically on high- traffic-volume roadways). Although the type of performance data sought was pavement life extension, the availability of such data was limited. Hence, treatment life data were also sought and compiled. A collective summary of the performance information for treatments applied to HMA- and PCC-surfaced pavements is presented in Tables 3.19 and 3.20 (p. 66), respectively. These ranges are based on information reported by various sources, representing a variety of conditions and using different per- formance measures. As such, these reported ranges may be based as much (or more) on perception instead of on well- designed, quantitative experimental analyses. The literature review discussion in Chapter 2 demonstrated that preservation treatment performance is affected by the conditions in which the treatment is installed and must function. Specifically, treatment effectiveness is influenced by the condition of the pavement upon which it is placed, and treatment durability is influenced by the level of traffic and the type of climate to which it is exposed. An investigation of how these factors—pavement condition, traffic, and climate—affect the general performance ranges listed in the previous tables was made by reexamining the project literature. The results are summarized in the following sections. IMPACT OF PAVEMENT CONDITION ON TREATMENT PERFORMANCE Pavement survival analysis of the performance of SPS-3 PM treatments in the southern long-term pavement performance (LTPP) region revealed quantifiable effects of existing pave- ment condition on treatment performance (Eltahan et al. 1999). Using a failure criterion defined by severities and quantities of cracking, patching, and bleeding, the median survival time (time until 50% of sections reach failure) of thin HMA over- lay, slurry seal, chip seal, and crack seal treatments at 28 SPS-3 sites were computed. The results are summarized in Table 3.21 (p. 67). A recent study of Ohio DOT PM treatments examined the effect of existing pavement condition on treatment performance (Rao et al. 2008). Using historical data on hundreds of pave- ment sections on different facility types throughout the state, the study showed that there is generally an increase in the exten- sion in life of 1 to 2 years corresponding to treatments placed on pavements in good condition (PCR between 80 and 90) ver- sus those placed on pavements in fair condition (PCR between 70 and 80). This effect is illustrated in Table 3.22 (p. 67). The evaluation of preservation treatment performance data by Caltrans indicated significant reductions in performance corresponding to lower overall pavement conditions at the time of treatment application. Table 3.23 (p. 67) shows the estimated lives of five different treatments when applied at three differ- ent pavement condition levels. As can be seen, there are sig- nificant increases in treatment performance (4 to 5 years) for chip seals, slurry seals, microsurfacing, and thin HMA over- lays when they are placed on pavements in good condition rather than on those in fair condition. IMPACT OF TRAFFIC ON TREATMENT PERFORMANCE Satisfactory treatment performance in part depends upon the ability of the treatment to withstand the stresses placed upon it by traffic. These stresses include not only the vertical shear stresses and abrasive forces of repeated traffic applications but also the horizontal shear stresses of turning or braking vehicles and, in certain environments, the abrasive forces of studded tires and snowplows. There is little published information on a quantitative assessment of the impact of traffic level on preservation treat- ment performance. Although the LTPP SPS-3 and SPS-4 studies included sections of varying traffic levels, the various published reports covering treatment performance provided no indication of the effect of traffic level on performance. A 1998 national study of the longevity and performance of diamond-ground PCC pavements (Rao et al. 1999) illustrated the general effect of traffic on surface texture wear following grinding, but age and climate were established as the key vari- ables in a texture deterioration model (traffic and snowplow 47 (text continues on page 57)

48 49 Table 3.8. Caltrans Flexible Pavement Maintenance Treatment Matrix Treatment Costs Traffic Volume Cost: $/sq yd (Treatment Only) Rutting Climate Preventive Treatments Crack/joint seal Emulsion N N N N N GGGGNNGGGGGGG 8,000 0.50–0.65 0.60–0.75 0.70–0.85 +0.15–0.20 +0.60–1.00 Modified (rubber) N N N N N GGGGGGGGGGGGG 8,000 0.55–0.70 0.65–0.80 0.75–0.90 +0.15–0.20 +0.60–1.00 Seal coats Fog seal (see note a FGGFPNNFFGGGGNNNGF) 13,000 0.15–0.30 0.15–0.30 0.15–0.30 +0.05 +0.10 Rejuvenator (see note a FGGNNNNFGGGGGNNNGG) 15,000 0.20–0.50 0.20–0.50 0.20–0.50 +0.10 +0.20 Scrub seal (see note d PGFNGNNFGGGGGNNNGG) 17,000 2.15 2.15 2.15 NA NA Slurry seals Type II (See note a AN06.2–09.104.2–57.102.2–06.1000,32PGGGNNGGGFGGGNNNGF) +0.30 AN06.2–09.104.2–57.102.2–06.1000,42PGGGNNGGGFGGGNFNGGIII epyT +0.30 AN08.1–02.108.1–02.108.1–02.1PGGGNNGGGFGGGNFNGGSAER +0.30 Microsurfacing FGNGGII epyT PGGGNGGGGGGGG 31,000 2.00–2.80 2.10–2.90 2.25–3.00 +0.10–0.20 NA NGGIII epyT PGGGNGGGGGGGGGG 31,000 2.00–2.80 2.10–2.90 2.25–3.00 +0.10–0.20 NA Chip seals AN05.3–00.357.2–52.200.2–08.1000,72PGPPNNNGGFFGGNFNGG enfi .deM :EMP +0.50–1.00 (see note d) AN05.3–00.357.2–52.200.2–08.1000,72FGPPNNNNGFFGGNFNGG muideM :EMP +0.50–1.00 (see note d) PMA: Medium G G N F N FGPPGNNGGGGGG AN000,42 (see note c) PMA: Coarse (see note c GGPPGNNNGGGGGNFNGG) AN000,42 AR: Medium G G N F N FGPPGGNGGGGGG 65,000 3.75–4.55 4.00–4.75 4.25–5.00 NA +0.50–1.00 AR: Coarse G G N F N GGPPGGNNGGGGG 65,000 3.75–4.55 4.00–4.75 4.25–5.00 NA +0.50–1.00 Cape seals NFNGGyrrulS PGGGNNGGGGGGG FGNGGorciM PGGGNNGGGGGGG PM alternative to a seal coat >30,000 ADT PGGGFFGGGGGGGNFPGGO-ABP 65,000 8–12 8–14 10–16 +1.20–4.00 PGGGPFGGGGGGGNFPGGO-CAR 60,000 10–14 10–14 +1.50–3.50 RAC-O high binder (HB) G G P F N PGGGPFGGGGGGG 65,000 10–14 10–14 +1.50–3.50 FGPGGG-CAR GGGGFFGGGGGGG 65,000 10–14 10–14 +1.50–3.50 GGGGFFGGGGGGGNPPGGG-ABP 60,000 8–12 8–14 10–16 +1.20–4.00 Thin bonded wearing G G P F N GGGGFFGGGGGGG 85,000 10–14 10–14 +1.50–3.50 course (BWC) Thin bonded wearing G G P F N GGGGFFGGGGGGG 85,000 10–14 10–14 +1.50–3.50 course rubber (BWC-RAC-O/G) Maintenance treatments Thin lift overlays Conventional G G P GGGGGGGGGGGGGGG 45,000 8–12 8–14 10–16 +1.20–4.00 GGGGGGGGGGGGGGGPGGABP 60,000 8–12 8–14 10–16 +1.20–4.00 GGGGFFGGGGGGGFGPGGCAR 65,000 10–14 10–14 +1.50–3.50 Digouts GGGGGGGGGGGGGGNGPP 125,000 Source: Caltrans 2008a. Note: G = Good performance; F = Fair performance; P = Poor performance; N = Not recommended. a Usually limited to shoulders, low-volume roads, and parking areas. b Generally used on shoulders, parking areas, and locations where less-aggressive surface is desired. c Under evaluation. Please consider other strategy at this time. d Use of pass rejuvenating seal under evaluation. Please consider other PME strategy at this time. R av el in g O xi d at io n B le ed in g < 1 ⁄2 in . > 1 ⁄2 in . D es er t V al le y C o as ta l M o un ta in s A D T < 5 ,0 00 A D T > 5 ,0 00 < 3 0, 00 0 A D T > 3 0, 00 0 N ig ht C o ld S to p P o in ts U rb an R ur al H ig h S no w p lo w U se La rg e P ro je ct s M ed iu m P ro je ct s S m al l P ro je ct s A d d it io na l P re m iu m fo r N ig ht W o rk , $/ sq y d A d d it io na l P re m iu m fo r S ho rt W o rk P er io d s o r W o rk Z o ne s, $ /s q y d . C o st p er L an e- M ile (t o ta l p ro je ct c o st in cl ud es t ra ffi c co nt ro l)

Table 3.9. Caltrans Treatment Guidelines for Effective Maintenance of Cracking in Bituminous Pavements Type of Cracking egdEesrevsnarT/lanidutignoLC rotagillAB rotagillAA rotagillA hgiHmuideMwoLhgiHmuideMwoLhgiHmuideMwoLhgiHmuideMwoLhgiHmuideMwoLairetirC 4/1<htdiW ″ >1/4″, <1/2″ >1/2″ <1/4″ >1/4″, <1/2″ >1/2″ <1/4″ >1/4″, <1/2″ >1/2″ <1/4″ >1/4″, <1/2″ >1/2″ No >0%, <10% >10% rororororororororo Material Material Material %03< ,%02>%02< ,%01>%01<%03< ,%02>%02< ,%01>%01<%03< ,%02>%02< ,%01>%01<aerA Loss Loss Loss Preventive treatments Crack/joint seal (see note e) PPGNFGNNNNPNNFNnoislumE PPPFGPNPNNPNPGN)rebbur( defiidoM Seal coats Fog seal (see note a PPFNNFNNFNNGNPG) Rejuvenator (see note a PPFNNFNNFNNGNNG) eton ees( FGNFGslaes burcS d eton ees( FGN) d) N P N N F P P Slurry seals Type II (see note a PPFNNFNNFNNFNNF) PPFNPFNPFNPFNPFIII epyT Microsurfacing Type II (see note b PPPNNFNPFNPFNNG) PPPNNFNPFNPFNPGIII epyT Chip seal eton ees( FGNPGenfi .deM :EMP d eton ees( PGN) d ) N P P N P P P eton ees( FGNPGmuideM :EMP d eton ees( PGN) d ) N P P N P P P PMA: Medium (see note c eton ees( FGPPG) d eton ees( PGP) d ) P P P N P P P PMA: Coarse (see note c eton ees( FGPPG) d eton ees( PGP) d ) P P P N P P P eton ees( FGFGGFGGmuideM :RA d ) F P F F P P P eton ees( FGFGGFGGesraoC :RA d ) F P F F P P P PM alternative >30,000 ADT Conventional eton ees( FGNFGCAGO ABP d eton ees( FGN) d ) N G F P P P P eton ees( FGGFGGO-CAR d PPPPFGFGG) eton ees( FGGFGG)BH( rednib hgih O-CAR d FFFPFGFGG) eton ees( FGGGGGG-CAR d GGGPFGGGG) Thin bonded wearing course rubber (BWCR) G G G G F (see note d) F (see note d eton ees( FG) d ) F F F P P P P Maintenance treatments eton ees( GGFGGlanoitnevnoC d) P (see note d FFNFFPFGG) eton ees( GGGGGABP d) P (see note d FFNFFPGGG) eton ees( PGPGGCAR d FFNFPPPFGP) eton ees( FGGGGCWB d) F (see note d eton ees( FG) d ) F F F P P P P Digouts GFNFFNGNNGNNFNN Source: Caltrans 2008a. Note: G = Good performance; F = Fair performance: P = Poor performance: N = Not recommended. a Usually limited to shoulders, low-volume roads, and parking areas. b Generally used on shoulders, parking areas, and locations where less-aggressive surface is desired. c Under evaluation. Please consider other strategy at this time. d Effective when proper prep work has been performed. e Per maintenance manual: For cracks <1⁄4 in., crack seal not recommended. 50 51

52 Table 3.10. Illinois DOT Flexible Pavement PM Treatment Matrix Crack Crack Fog Sand Scrub Slurry Pavement Conditions Severity Levels Filling Sealing Seal Seal Seal Rejuvenator Seal Microsurfacing Alligator/fatigue crackinga L1 F F NR NR NR NR F F L2, L3, L4 NR NR NR NR NR NR NR NR Block cracking M1 R R F R R F R R M2 R R NR NR F NR F NR M3, M4 F F NR NR NR NR NR NR “Stable” ruttingb N1, N2 NR NR NR NR NR NR F R N3 NR NR NR NR NR NR NR F Joint reflection and transverse O1 NR NR F R R NR F R crackingc O2, O3 R R NR NR NR NR NR F O4, O5 F F NR NR NR NR NR NR Overlayed patch reflective P1, P2, P3, P4, P5 F* F* F* F* F* F* F* F* cracking Longitudinal/center of lane Q1 R R F F F NR F F cracking Q2, Q3 R F NR NR F NR NR F Q4, Q5 NR NR NR NR NR NR NR NR Reflective widening crack R1 R R F F F NR F F R2, R3 F F NR NR NR NR F F R4, R5 NR NR NR NR NR NR NR NR Centerline deterioration S1, S2, S3, S4 F* F* F* F* F* F* F* F* Edge cracking T1 F F F R R NR F F T2 F F NR NR NR NR NR F T3, T4 NR NR NR NR NR NR NR NR Permanent patch deterioration U1, U2, U3, U4 F* F* F* F* F* F* F* F* Shoving, bumps, sags, and V1 NR NR NR NR NR NR NR F corrugation V2, V3 NR NR NR NR NR NR NR NR Weathering/raveling W1, W2 NR NR F F F F R R W3, W4 NR NR NR NR NR NR F F Reflective D-cracking X1, X2, X3 NR NR NR NR NR NR NR NR Friction Poor NR NR NR R R NR R R ADT <5,000 R R R R R R R R 5,000–10,000 R R F F F R F R >10,000 R R NR NR NR NR NR F Relative cost ($ to $$$$) $ $ $ $$ $$ $$ $$ $$ Source: IDOT 2009. Notes: ADT = Average daily traffic. CIR = Cold in-place recycling. HIR = Hot in-place recycling. HMA = Hot-mix asphalt. UTW = Ultra-thin whitetopping. R: Recommended treatment for the specified pavement condition. Care must be taken in making sure that all critical distress types are addressed by the selected treatment. R*: Recommended treatment when used with milling prior to treatment. R**: Used in combination with crack sealing. F: Feasible treatment, but depends on other project constraints, including other existing distresses. F*: This is a localized distress and should be treated locally, while other distress types present should dictate choice of global treatment. NR: Treatment is not recommended to correct the specified pavement condition. a Preservation treatments do not correct alligator cracking. Of the treatments, chip seals are most appropriate at addressing alligator cracking. b If stable rutting is present without other distresses, microsurfacing or mill and overlay is the recommended treatment. c If cracking is joint reflection related, the preservation treatments will not correct the distress. (continued on next page)

53 Table 3.10 (continued) Ultra-Thin Thin Bonded Chip Cape HMA Wearing Cold Drainage Pavement Conditions Seal Seal CIR HIR Overlay Course UTW Mill Preservation Alligator/fatigue crackinga F F F F F F F NR R NR NR NR NR NR NR NR NR F Block cracking R R R R F F R F NR F F F F NR NR NR NR NR NR NR F F NR NR NR NR NR “Stable” ruttingb F F R R R* F R* F R NR NR R R R* NR R* F F Joint reflection and transverse R R F F R** F NR F NR crackingc F F F F F NR NR NR NR NR NR NR NR NR NR NR NR NR Overlayed patch reflective F* F* F* F* F* F* F* F* F* cracking Longitudinal/center of lane F F F F F F F F NR cracking F F F F F F F F NR NR NR F F NR NR NR NR NR Reflective widening crack F F F F F F F F NR F F F F F NR F NR NR NR NR NR NR NR NR NR NR NR Centerline deterioration F* F* F* F* F* F* F* F* F* Edge cracking R F R R R** F F F R F F F F F NR F NR R NR NR NR NR NR NR NR NR F Permanent patch deterioration F* F* F* F* F* F* F* F* F* Shoving, bumps, sags, and F F R R R F F R F corrugation NR NR R R R NR F R F Weathering/raveling R R F F F F F F NR F F R R R* NR NR NR NR Reflective D-cracking NR NR F F NR F NR F NR Friction R R F F R R F F NR ADT R R R R R R R R R R R F R R R R R R F F NR R R R R R R Relative cost $$ $$ $$$ $$$ $$$ $$$ $$$$ $ Varies

54 Table 3.11. Ohio DOT’s GQL Logic Summary for Selecting Candidate PM Projects on Flexible Pavements Crack Single Double PMAC Thin HMAC Sealing Chip Seal Microsurfacing Microsurfacing Overlay Overlay Raveling L: OFE L: OFE L: OFE L: OFE L: OFE L: NA M: O M: – M: – M: OFE M: OFE M: NA H: – H: – H: – H: – H: – H: NA Bleeding L: – L: – L: – L: – L: – L: NA M: – M: – M: O M: OFE M: O M: NA H: – H: – H: – H: – H: – H: NA Patching L: O L: – L: – L: – L: O L: O M: O M: – M: – M: – M: O M: O H: O H: – H: – H: – H: O H: O Debonding L: O L: – L: – L: – L: O L: O M: – M: – M: – M: – M: O M: O H: – H: – H: – H: – H: O H: O Crack seal deficiency L: E L: NA L: NA L: NA L: NA L: NA M: E M: NA M: NA M: NA M: NA M: NA H: E H: NA H: NA H: NA H: NA H: NA Rutting L: OFE L: OFE L: OFE L: OFE L: OFE L: OFE M: O M: – M: – M: O M: – M: O H: – H: – H: – H: H: – H: – Settlement L: NA L: NA L: NA L: NA L: NA L: NA M: NA M: NA M: NA M: NA M: NA M: NA H: NA H: NA H: NA H: NA H: NA H: NA Potholes L: NA L: – L: – L: – L: O L: O M: NA M: – M: – M: – M: O M: O H: NA H: – H: – H: – H: O H: O Wheel track cracking L: OFE L: OFE L: OF L: OF L: OF L: OF M: O M: – M: O M: O M: O M: O H: – H: – H: – H: – H: – H: – Block and transverse cracking L: OFE L: OF L: OFE L: OFE L: OFE L: OFE M: O M: O M: O M: OF M: OF M: OF H: – H: – H: – H: – H: – H: – Longitudinal cracking L: OFE L: OFE L: OFE L: OFE L: OFE L: OFE M: O M: OFE M: OFE M: OFE M: OFE M: OFE H: – H: – H: – H: – H: – H: – Edge cracking L: OFE L: OF L: OF L: OFE L: OF L: OF M: O M: O M: O M: O M: O M: O H: – H: O H: O H: O H: O H: O Thermal cracking L: OFE L: OFE L: OFE L: OFE L: OFE L: OFE M: O M: O M: O M: O M: OF M: OF H: – H: – H: – H: – H: – H: – Sources: Rao et al. 2008; ODOT 2001. Notes: PMAC = Polymer-modified asphalt concrete. L, M, H: Low, medium, and high severity, respectively. O, F, E: Occasional, frequent, and extensive, respectively. – = Not suitable for distress severity level. NA = Particular distress is not considered in the logical decision.

55 Table 3.12. Ohio DOT’s GQL Logic Summary for Selecting Candidate PM Projects on Composite Pavements Crack Single Double PMAC Thin HMAC Sealing Chip Seal Microsurfacing Microsurfacing Overlay Overlay Raveling L: OFE L: OFE L: OFE L: OFE L: OFE L: NA M: O M: – M: – M: OFE M: OFE M: NA H: – H: – H: – H: – H: – H: NA Bleeding L: – L: – L: – L: – L: – L: NA M: – M: – M: O M: OFE M: O M: NA H: – H: – H: – H: – H: – H: NA Patching L: O L: – L: – L: – L: O L: O M: O M: – M: – M: – M: O M: O H: O H: – H: – H: – H: O H: O Disintegration/debonding L: O L: – L: – L: – L: O L: O M: – M: – M: – M: – M: O M: O H: – H: – H: – H: – H: O H: O Rutting L: OFE L: OFE L: OFE L: OFE L: OFE L: OFE M: O M: – M: – M: O M: – M: O H: – H: – H: – H: – H: – H: – Pumping L: O L: – L: – L: – L: – L: – M: O M: – M: – M: – M: – M: – H: – H: – H: – H: – H: – H: – Shattered slab L: NA L: – L: – L: – L: – L: – M: NA M: – M: – M: – M: – M: – H: NA H: – H: – H: – H: – H: – Settlement L: NA L: NA L: NA L: NA L: NA L: NA M: NA M: NA M: NA M: NA M: NA M: NA H: NA H: NA H: NA H: NA H: NA H: NA Transverse cracks L: OFE L: OFE L: OFE L: OFE L: OFE L: OFE M: OFE M: – M: – M: O M: OF M: OF H: – H: – H: – H: – H: – H: – Joint reflection cracking L: OFE L: OFE L: OFE L: OFE L: OFE L: OFE M: OFE M: – M: – M: O M: OF M: OF H: – H: – H: – H: – H: – H: – Intermediate transverse cracking L: OFE L: O L: O L: O L: O L: O M: OFE M: – M: – M: – M: O M: O H: – H: – H: – H: – H: – H: – Longitudinal cracking L: OFE L: OFE L: OFE L: OFE L: OFE L: OFE M: O M: O M: O M: OFE M: OFE M: OFE H: – H: – H: – H: – H: – H: – Pressure damage/upheaval L: NA L: O L: O L: O L: O L: O M: NA M: – M: – M: – M: – M: – H: NA H: – H: – H: – H: – H: – Crack seal deficiency L: FE L: NA L: NA L: NA L: NA L: NA M: FE M: NA M: NA M: NA M: NA M: NA H: FE H: NA H: NA H: NA H: NA H: NA Corner breaks L: NA L: O L: O L: O L: O L: O M: NA M: – M: – M: – M: – M: – H: NA H: – H: – H: – H: – H: – Punchouts L: – L: – L: – L: – L: – L: – M: – M: – M: – M: – M: – M: – H: – H: – H: – H: – H: – H: – Sources: Rao et al. 2008; ODOT 2001. Notes: PMAC = Polymer-modified asphalt concrete. L, M, H: Low, medium, and high severity, respectively. O, F, E: Occasional, frequent, and extensive, respectively. – = Not suitable for distress severity level. NA = Particular distress is not considered in the logical decision.

Table 3.13. Example Critical Trigger and Limit Values for PCC Pavement Distress and Performance Indicators First Value  Trigger Value/Second Value  Limit Valuea Medium Pavement Type and Performance Measure High (ADT > 10,000) (3,000 < ADT < 10,000) Low (ADT < 3,000) Jointed Plain Concrete Pavement (Joint Space < 20 ft)b Structural Measurements Low-high severity fatigue cracking (% of slabs) 1.5/5.0 2.0/10.0 2.5/15.0 Deteriorated joints (% of joints) 1.5/15.0 2.0/17.5 2.5/20.0 Corner breaks (% of joints) 1.0/8.0 1.5/10.0 2.0/12.0 Average transverse joint faulting (in.) 0.10/0.50 0.10/0.60 0.10/0.70 Durability distress (severity) Medium-high Joint seal damage (% of joints) >25/— Load transfer (%) <50/— Skid resistance Minimum local acceptable level/— Functional Measurement IRI (in./mi) 63/158 76/190 89/222 PSR 3.8/3.0 3.6/2.5 3.4/2.0 California profilograph (in./mi) 12/60 15/80 18/100 Jointed Reinforced Concrete Pavement (Joint Space < 20 ft)c Structural Measurements Medium-high severity trans. cracking (% of slabs) 2.0/30.0 3.0/40.0 4.0/50.0 Deteriorated joints (% of joints) 2.0/10.0 3.0/20.0 4.0/30.0 Corner breaks (% of joints) 1.0/10.0 2.0/20.0 3.0/30.0 Average transverse joint faulting (in.) 0.16/0.50 0.16/0.60 0.16/0.70 Durability distress (severity) Medium-high Joint seal damage (% of joints) >25/— Load transfer (%) <50/— Skid resistance Minimum local acceptable level/— Functional Measurement IRI (in./mi) 63/158 76/190 89/222 PSR 3.8/3.0 3.6/2.5 3.4/2.0 California profilograph (in./mi) 12/60 15/80 18/100 Continuously Reinforced Concrete Pavement Structural Measurements Failures (punchouts, full-depth repairs) (no./mi) 3/10 5/24 6/39 Durability distress (severity) Medium-high Skid resistance Minimum local acceptable level/— Functional Measurement IRI (in./mi) 63/158 76/190 89/222 PSR 3.8/3.0 3.6/2.5 3.4/2.0 California profilograph (in./mi) 12/60 15/80 18/100 Source: Smith et al. 2008. Note: 1 mi = 1.609 km; 1 m = 3.281 ft; 1 in. = 25.4 mm. a Values should be adjusted for local conditions. Actual percentage repaired may be much higher if the pavement is restored several times. b Assumed slab length = 15 ft. c Assumed slab length = 33 ft.

wear were acknowledged as key components of the age and climate variables). An evaluation of thin HMA overlays in Ohio indicated dif- ferences in both treatment life and extensions in pavement service life, when placed on facilities with different traffic levels (Chou et al. 2008). Based on an analysis of 820 sections placed on the state’s priority system (Interstates and other higher-volume, four-lane divided highways) and 2,870 sections placed on the general system (two-lane undivided highways), average treatment service lives of 6.6 and 9.1 years, respec- tively, were observed, based on actual section terminations (i.e., rehabilitation of the overlaid pavement). Additional analysis revealed service lives of 8.0 and 6.0 years for overlays placed on priority-system flexible and composite pavements, respectively, and 8.5 and 8.4 years for overlays placed on general- system flexible and composite pavements, respectively. Chou et al. (2008) also analyzed thin overlay service life, based on the time until a threshold condition level (PCR = 65 for priority system, PCR = 60 for general system) is achieved. As, illustrated in Figure 3.9 (p. 68), average service lives of 9.0 and 13.0 years for applications on the priority and general sys- tems, respectively, were observed. Had the same threshold PCR level been used for both systems, overlay life on the pri- ority system would still have been at least 2 years shorter than the life on the general system. Additional analysis of the data was performed to determine the life extension of thin over- lays. These results indicated an average extension of 7.5 years on the priority system and 10.7 years on the general sys- tem, a 3.2-year difference between the two systems. Based on this study, although no traffic levels were reported for the two highway systems, it appears that higher traffic levels decrease the performance of HMA overlays by 2 or more years. In a recent evaluation of Colorado’s PM program, guide- lines for the application of various preservation treatments were drafted based on subjective discussions of performance with DOT staff (Galehouse 2004). The guidelines included expected pavement service life extensions corresponding to different truck traffic levels. A summary of these expected life extensions is provided in Table 3.24 (p. 68). Although the val- ues listed are subjective, they show that the durability of treat- ments is perceived to be affected by increasingly heavier traffic loads, the impact being between 1 and 3 years when moving from the moderate to heavy truck traffic category. In considering the impact of traffic, there is a tendency to want to also introduce equivalent single-axle loads (ESALs) or some other measure of loading. This was seen even in the survey responses, where one agency categorized high versus low traffic by ESALs and another used a traffic index rather than ADT or AADT. The assumption in focusing on traffic rather than on loads is that the pavement is adequately designed and constructed for the loads it is carrying. If it is not, then it is probably not a good candidate for preservation anyway. IMPACT OF CLIMATE ON TREATMENT PERFORMANCE Satisfactory treatment performance is also a function of the treatment’s ability to withstand stresses associated with climate and environment (temperature, moisture, and the interaction of the two). In some snow and icy climates, the treatment must also withstand the effects of snowplows and deicing salts (and in some states, studded tire use). Little published information was available that involved a quantitative assessment of the impact of climate on preservation treatment performance. The main bodies of work involved the 1998 national study on diamond grinding of PCC pavements (Rao et al. 1999) and the same-year evaluation of LTPP SPS-3 PM test sites (Morian et al. 1998). As mentioned previously, in the case of the former study, age and climate were established as the key variables in a surface texture deterioration model. Plotted trends for freeze and nonfreeze climates suggested an average difference of nearly 0.005 in. (0.125 mm) of reduced texture depth after a 10-year period, with the freeze climate experiencing greater reduction. Evaluation by Morian et al. (1998) of pavement rating score (PRS) data collected on PM test sections at 58 SPS-3 sites throughout the United States and Canada resulted in estimates of treatment performance across four climatic zones. Using a threshold PRS of 50, performance lives were computed, indicating (for the most part) a few years reduction in life associated with use in freeze environments (Table 3.25, p. 69). ADJUSTMENTS TO GENERAL EXPECTATIONS OF TREATMENT PERFORMANCE The evaluations described above indicate that small to moder- ate reductions in treatment performance can be expected to occur as a result of any of the following circumstances: • Existing pavement condition is rated in the fair category instead of the satisfactory/good category. • Traffic level is more characteristic of a high-volume road- way facility than a low-volume facility. • Climate is more characteristic of a freezing climate than a nonfreezing one, with significant snow and ice removal operations necessary for winter precipitation events. Whereas it was beyond the ability and scope of this study to develop estimates of treatment performance that account for various combinations of pavement condition, traffic level, and climatic conditions, it was deemed appropriate to adjust the general expected performance ranges so that they account for the high-traffic-volume levels defined in the study (rural ADT > 5,000 vpd, urban ADT > 10,000 vpd). A conservative approach was taken in making the adjustments, using the findings of the Ohio thin HMA overlay study. A performance reduction value of 2.6 years (the average of the two values [2.0 and 3.2 years] reported) was divided by the midpoint 57 (text continues on page 61) (continued from page 47)

58 Table 3.14. Concrete Pavement Preservation and Rehabilitation Treatments Best Suited for Distresses in PCC-Surfaced Pavements Concrete Pavement Preservation and Rehabilitation Treatments Partial-Depth Full-Depth Dowel Bar Diamond Diamond Joint Crack Asphalt Distress Repair Repair Retrofitting Grinding Grooving Resealing Sealing Overlay Corner breaks LS LSe MS MSe HS Linear cracking (transverse, MS LSe longitudinal, diagonal) HS MSe Punchouts LS MS HS D-cracking (at joints/cracks) MS  HS Map cracking/scaling (non-AAR) LSa  MSa HSa Map cracking/scaling (AAR) MS  HS Joint seal damage d Joint spalling LSa MS MSa HS HSa Blowups LS MS HS Pumping b Joint faulting b c  Bumps, settlements, heaves MS   HS Polishing    Source: Modified from Smith et al. 2008. Notes: AAR = Alkali-aggregate reaction. LS = Low severity; MS = Medium severity; HS = High severity. a Deterioration confined to top one-third of slab. b Joint/crack deflection load transfer ≤ 60%, faulting greater than 0.10 in. but less than 0.25 in., and differential deflection of 0.01 in. c Faulting > 0.125 in. d Existing joint sealant no longer performing intended function of preventing intrusion of incompressibles and infiltration of water into the joints. e Crack widths ≤ 0.5 in. (continued on next page)

59 Table 3.14 (continued) Concrete Pavement Preservation and Rehabilitation Treatments Asphalt Retrofitted Pressure Overlay of Bonded Unbonded Slab Edge Relief Fractured Concrete Concrete Distress Stabilization Drains Joints Slab Overlay Overlay Reconstruction Corner breaks    Linear cracking (transverse,    longitudinal, diagonal) Punchouts    D-cracking (at joints/cracks)    Map cracking/scaling (non-AAR) Map cracking/scaling (AAR)     Joint seal damage Joint spalling    Blowups    Pumping   Joint faulting    Bumps, settlements, heaves     Polishing 

60 Table 3.15. Highway Agency Treatment Usage on HMA-Surfaced Roadways According to Pavement Condition Pavement Distress Surface Distressa Treatment Raveling Oxidation Bleeding Smoothness Friction Noise Light Moderate Heavy Crack filling NA NA NA Limited NA Limited Extensive Moderate Limited Crack sealing NA NA NA Limited NA Limited Extensive Moderate Limited Slurry seal Extensive Extensive Limited Limited Limited None Moderate Limited None Microsurfacing Moderate Moderate Limited Moderate Moderate Limited Extensive Moderate Limited Chip seals Moderate Extensive Limited Limited Moderate None Extensive Extensive Limited Ultra-thin bonded wearing course Moderate Moderate Limited Moderate Extensive Limited Extensive Moderate Limited Thin HMA overlay Extensive Moderate Moderate Extensive Moderate Limited Extensive Extensive Limited Cold milling and overlay Extensive Moderate Moderate Extensive Moderate Limited Extensive Extensive Moderate Ultra-thin HMA overlay Moderate Moderate Moderate Moderate Moderate Limited Extensive Moderate Limited Hot in-place HMA recycling Moderate Moderate Limited Moderate Moderate Limited Extensive Moderate Moderate Cold in-place recycling Limited Limited Limited Moderate Limited Limited Moderate Extensive Extensive Profile milling None None Limited Extensive Moderate Limited Moderate Limited None Ultra-thin whitetopping Limited Limited Limited Moderate Limited Limited Moderate Moderate Limited Note: Extensive = Used by ≥66% of respondents; Moderate = 33% to 66% usage; Limited = <33% usage. a Various forms of cracking.

61 Table 3.16. Highway Agency Treatment Usage on PCC-Surfaced Roadways According to Pavement Condition Pavement Distress Surface Distressa Treatment Smoothness Friction Noise Light Moderate Heavy Concrete joint resealing Limited None Limited Extensive Moderate Limited Concrete crack sealing Limited None Limited Extensive Moderate Limited Diamond grinding Extensive Moderate Moderate Limited Limited Limited Diamond grooving Moderate Extensive Limited Limited Limited Limited Partial-depth concrete patching Moderate None Limited Moderate Extensive Moderate Full-depth concrete patching Moderate Limited Limited Limited Extensive Extensive Dowel bar retrofit Moderate Limited Limited Limited Moderate Moderate Ultra-thin bonded wearing course Extensive Moderate Limited Moderate Moderate Limited Thin HMA overlay Moderate Moderate Limited Moderate Moderate Limited Note: Extensive = Used by ≥66% of respondents; Moderate = 33% to 66% usage; Limited = <33% usage. a Spalling, various forms of cracking. (8.5 years) of the expected performance range (5 to 12 years) of the thin overlay treatment. This resulted in a reduction of 30%. The lower and upper limits of each treatment’s general expected performance range were then reduced by this percentage. The adjusted ranges are listed in Tables 3.26 (p. 69) and 3.27 (p. 70) and were incorporated into the preser- vation guidelines document. To ensure that the effects of existing pavement condition and climate are properly accounted for, the preservation guide- lines suggest using values near the lower limit of the perfor- mance range for treatments to be applied on pavements in fair condition and located in severe-freeze environments. On the other hand, it is suggested that values near the upper limit of the range be used for treatments applied to pavements in good condition and located in nonfreeze environments. For the purposes of this study, three climatic regions were identified based on the LTPP test site classifications established by Jackson and Puccinelli (2006). These regions consist of the following: • Deep freeze (northern-tier states, freezing index [FI] > 400); • Moderate freeze (middle-tier states, 50 < FI ≤ 400); and • Nonfreeze (southern-tier states and portions of coastline, FI ≤ 50). An approximate delineation of the climate zone boundaries is presented in Figure 3.10 (p. 70). One final consideration in assessing treatment performance is the potential for substandard construction and performance due to agency or contractor inexperience or limitations in the quality of locally available materials. One approach to account for construction quality risk is to apply a confidence factor to the expected performance range, with a factor of 1.0 representing 100% confidence, 0.75 representing 75% confidence, and so on. Thus, if the expected performance of a treatment ranged from 4.0 to 6.0 years and the level of confidence was 75% (reflecting some shortcomings in agency or contractor experience or materials quality), then the range would be reduced to between 3.0 and 4.5 years. Construction Constraints There are several construction factors that affect the feasibility of a preservation treatment, including the following: • The anticipated or targeted time frame (i.e., time of year) for construction. Each candidate treatment must be examined in terms of the weather patterns (temperature, precipitation) for which they are most suitable for application and of the various weather-related effects (e.g., moisture left in pavement structure, salt or sand from winter maintenance operations remaining in cracks and joints). Table 3.28 (p. 71) provides an illustration of one agency’s recommen- dations for treatment timing restrictions. • Work zone duration restrictions. Depending on agency policies and practices and a variety of other factors (traffic volume and speed, driving difficulty, facility setting, and so on), there may be a need to restrict the duration of work zone setups so as to minimize congestion and maximize (continued from page 57) (text continues on page 69)

62 Table 3.17. Guideline Decision-Support Matrix for Preliminary Identification of Candidate Treatments for HMA-Surfaced Pavements Distress Types and Severity Levels (L  Low, M Medium, H  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     ● Crack seal 80–95 2–5d   ● ●  Slurry seal (Type III) 70–85 5–8 ●      ●    Microsurfacing: Single 70–85 5–8 ●   ●   ●    Microsurfacing: Double 70–85 5–8 ●   ●   ● ● ● ● Chip seal: Single Conventional 70–85 5–8 ●  ● ●   ● ● ●  Polymer modified 70–85 5–8   ●    ● ● ●  Chip seal: Double Conventional 70–85 5–8       ● ● ● ● Polymer modified 70–85 5–8      ● ●● ●● ●● ● Ultra-thin bonded 65–85 5–10 ●  ●        wearing course Ultra-thin HMAOL 65–85 5–10 ●  ●        Thin HMAOL 60–80 6–12 ●  ●   ● ●● ● ● ● Cold milling and 60–75 7–12 ●   ●    ● ● ● thin HMAOL Hot in-place recycling Surf recycle/HMAOL 70–85 5–8 ●   ●   ● ● ●  Remixing/HMAOL 60–75 7–12      ● ● ● ● ● Repaving 60–75 7–12      ● ● ● ● ● Cold in-place recycling 60–75 7–12      ● ● ● ● ● and HMAOL Profile milling 80–90 3–6           Ultra-thin whitetopping 60–80 6–12          ● Note: ● = Highly Recommended;  = Generally Recommended;  = 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. (continued on next page) Water Fatigue/ Ravel/ Bleed/ Segre- Bleed/ Long WP/ Trans Joint Long/ Weather Flush Polish gation Pumpa Slippage Block Therm Reflect Edge

63 Distress 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)        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/HMAOL ●       Remixing/HMAOL ●● ●● ●  ●   Repaving ●● ●● ●  ●   Cold in-place recycling ●● ●● ●  ●   and HMAOL Profile milling ●  e e    Ultra-thin whitetopping        Surface Characteristics Issues Table 3.17 (continued)

64 Table 3.18. Guideline Decision-Support Matrix for Preliminary Identification of Candidate 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)

65 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 Table 3.18 (continued)

66 Table 3.19. General Expected Performance of Preservation Treatments Applied to HMA-Surfaced Pavements Expected Performance Expected Performance Treatment (Treatment Life) (yr) (Pavement Life Extension) (yr) Crack filling 2 to 4 NA Crack sealing 3 to 8 2 to 5 Slurry seal 3 to 5 4 to 5 Microsurfacing Single course 3 to 6 3 to 5 Double course 4 to 7 4 to 6 Chip seal Single course 3 to 7 5 to 6 Double course 5 to 10 8 to 10 Ultra-thin bonded wearing course 7 to 12 NA Thin HMA overlay Dense graded 5 to 12 NA Open graded (OGFC) 6 to 12 NA Gap graded (SMA) NAa NA Cold milling and thin HMA overlay 5 to 12 NA Ultra-thin HMA overlay 4 to 8 NA Hot in-place recycling Surface recycle and thin HMA overlay 6 to 10b NA Remixing and thin HMA overlay 7 to 15c NA Repaving 6 to 15 NA Cold in-place recycling and thin HMA overlay Between 6 to 8 and 7 to 15d NA Profile milling 2 to 5 NA Ultra-thin whitetopping NA NA Sources: Peshkin et al. 1999; Lamptey et al. 2005; Peshkin and Hoerner 2005; Dunn and Cross 2001; Newcomb 2009; Cuelho et al. 2006; Okpala et al. 1999; Caltrans 2008a; NDOR 2002. Note: NA = Not available. a Current indications are that SMA overlays perform the same or slightly better than dense-graded overlays. b Range based on reported performance of surface recycle and subsequent surface treatment. c Range based on reported performance of remixing and subsequent HMA overlay of unspecified thickness. d Range based on reported performance of CIR and subsequent surface treatment (6 to 8 years) and CIR and subsequent HMA overlay of unspecified thickness (7 to 15 years). Table 3.20. General Expected Performance of Preservation Treatments Applied to PCC-Surfaced Pavements Expected Performance Expected Performance Treatment (Treatment Life) (yr) (Pavement Life Extension) (yr) Concrete joint resealing 2 to 8 5 to 6 Concrete crack sealing 4 to 7 NA Diamond grinding 8 to 15 NA Diamond grooving 10 to 15 NA Partial-depth concrete patching 5 to 15 NA Full-depth concrete patching 5 to 15 NA Dowel bar retrofit 10 to 15 NA Ultra-thin bonded wearing course 6 to 10 NA Thin HMA overlay 6 to 10 NA Sources: Peshkin et al. 1999; Smith et al. 2008; Peshkin et al. 2007; Caltrans 2008a; Caltrans 2008b; NDOR 2002.

67 Table 3.21. Median Survival Time of PM Treatments Pretreatment Pavement Thin HMA Chip Slurry Crack Condition Overlay Seal Seal Seal Good 7.5 yr NA 6.5 yr 6.5 yr Fair 7.3 yr NA 5.0 yr 7.2 yr Poor 2.2 yr NA 2.5 yr 0.75 yr Source: Eltahan et al. 1999. Table 3.22. Performance of PM Treatments in Ohio PCR Range at Existing Primary Applications Time of Pavement with Respect to PM Treatment Treatment Type Highway Classa 80 75 70 65 Chip seals 70 to 80 Flexible General 6.0 9.0 12.0 80 to 90 Flexible General 6.5 9.0 12.0 All All All 6.25 9.0 12.0 Single-course microsurfacing 70 to 80 Flexible General and urban 3.75 5.75 7.5 9.5 80 to 90 Flexible General and urban 5.0 7.0 8.5 10.5 70 to 80 Composite Urban and priority 2.25 4.0 6.25 8.5 80 to 90 Composite Urban and priority All All All 3.75 5.5 7.25 9.25 Double-course microsurfacing 70 to 80 Flexible Priority and urban 3.75 5.25 7.0 9.0 80 to 90 Flexible Priority and urban 70 to 80 Composite Priority and urban 80 to 90 Composite Priority and urban 6.5 8.5 10.5 12.0 All All All 5.0 6.5 8.25 10.0 Ultra-thin bonded wearing courseb 70 to 80 All Priority 6.0 8.0 10.0 11.5 80 to 90 All Priority 6.0 8.0 10.25 12.0 All All All 6.0 8.0 10.0 11.5 PMAC overlaysc 70 to 80 Flexible Priority and urban 6.5 8.25 10.25 12.0 80 to 90 Flexible Priority and urban 7.0 8.25 10.25 12.0 70 to 80 Composite Priority and urban 6.0 8.25 10.75 12.0 80 to 90 Composite Priority and urban All All All 6.5 8.25 10.25 12.0 Thin HMA overlays (without repairs) 70 to 80 Flexible General, urban, and priority 8.5 11.0 14.0 80 to 90 Flexible General, urban, and priority 10.25 12.0 15.0 70 to 80 Composite Priority and urban 7.0 9.25 12.0 80 to 90 Composite Priority and urban 10.0 12.0 15.0 All All All 8.5 11.0 14.0 Thin HMA overlays (with repairs) 70 to 80 Flexible Urban and general 11.0 12.0 15.0 80 to 90 Flexible Urban and general 70 to 80 Composite General, urban, and priority 11.0 12.0 15.0 80 to 90 Composite General, urban, and priority All All All 11.0 12.0 15.0 Source: Rao et al. 2008. Note: PMAC = Polymer-modified asphalt concrete. a ODOT Highway Classification: Priority = Interstates and four-lane NHS highways outside urban area; Urban = Nonpriority state routes in urban areas; General = All remaining state routes (mostly two-lane highways). b Proprietary product NovaChip. c Proprietary product SmoothSeal. Pavement Life Extension, Based on Projected Treatment Age (yr) at Terminal PCR of: Table 3.23. Projected Performance of Preservation Treatments in California Good Fair Poor Condition Condition Condition (PCI  80) (PCI  60) (PCI  40) Treatment (yr) (yr) (yr) Fog seal 3 to 5 1 to 3 1 to 2 Chip seal 7 to 10 3 to 5 1 to 3 Slurry seal 7 to 10 3 to 5 1 to 3 Microsurfacing 8 to 12 5 to 7 2 to 4 Thin HMA overlay 10 to 12 5 to 7 2 to 4 Source: Hicks and Marsh 2005.

68 Table 3.24. Expected Pavement Service Life Extensions Affected by Pavement Preservation Treatments in Colorado, Corresponding to Truck Traffic Levels Pavement Expected Pavement Life Extension (yr) for: Treatment Type AADTT < 400 tpd 400 ≤ AADTT ≤ 6,000 tpd AADTT > 6,000 tpd Crack filling Flexible ≤4 ≤2 ≤2 Crack sealing Flexible ≤4 ≤3 ≤2 Sand seals Flexible ≤3 Not advised Not advised Chip seals Flexible 6 to 9 3 to 6 2 to 3 Microsurfacing (single course) Flexible 6 to 9 3 to 5 2 to 3 Microsurfacing (multiple course) Flexible 8 to 9 4 to 6 2 to 4 Ultra-thin bonded wearing course Flexible ≤9 ≤7 ≤5 Thin HMA overlay Flexible 10 to 11 5 to 9 3 to 5 Mill and thin HMA overlay Flexible 10 to 11 5 to 10 3 to 5 Crack sealing Rigid ≤6 ≤3 ≤2 Joint resealing Rigid 4 to 6 3 to 5 2 to 3 Diamond grinding Rigid 6 3 2 to 3 Partial-depth spall repair Rigid 4 to 6 2 to 3 ≤3 Dowel bar retrofitting Rigid 4 to 6 2 to 3 ≤3 Full-depth concrete repair Rigid 6 to 11 3 to 10 ≤5 Source: Galehouse 2004. Note: AADTT = average annual daily truck traffic; tpd = trucks per day. Source: Chou et al. 2008. Figure 3.9. Average performance trends of thin HMA overlay on Ohio priority-system and general-system pavements.

69 Table 3.26. Expected Performance of Preservation Treatments Applied to HMA-Surfaced Pavements on High-Traffic-Volume Roads Expected Performance Expected Performance Treatment (Treatment Life) (yr) (Pavement Life Extension) (yr) Crack filling 1.5 to 3 NA Crack sealing 2.0 to 5.5 2 to 5 Slurry seal 2.0 to 3.5 4 to 5 Microsurfacing Single course 2.0 to 4.0 3 to 5 Double course 3.0 to 5.0 4 to 6 Chip seal Single course 2.0 to 5.0 5 to 6 Double course 3.5 to 7.0 8 to 10 Ultra-thin bonded wearing course 5.0 to 8.5 NA Thin HMA overlay Dense graded 3.5 to 8.5 NA Open graded (OGFC) 4.5 to 8.5 NA Gap graded (SMA) NA NA Cold milling and thin HMA overlay 3.5 to 8.5 NA Ultra-thin HMA overlay 2.5 to 5.5 NA Hot in-place recycling Surface recycle and thin HMA overlay 4.0 to 7.0 NA Remixing and thin HMA overlay 5.0 to 10.5 NA Repaving 4.0 to 10.5 NA Cold in-place recycling and thin HMA overlay 5.0 to 7.5 NA Profile milling 1.5 to 3.5 NA Ultra-thin whitetopping NA NA Note: NA = Not available. Table 3.25. Estimates of Treatment Performance in Four Climatic Zones Thin HMA Chip Slurry Crack Climate Zone Overlay Seal Seal Seal Dry nonfreeze >12 yr 7 yr >12 yr 9–10 yr Dry freeze 6–7 yr 11 yr 5 yr 6 yr Wet nonfreeze >12 yr >12 yr >12 yr 7 yr Wet freeze 7 yr 6–7 yr 5 yr 3–4 yr Source: Morian et al. 1998. safety. Such restrictions could be tight, entailing that work be performed in a single daytime or overnight shift, or more moderate, allowing work to take place over a weekend, for example. The impact of work zone duration restrictions must be evaluated against the time-to-opening requirements of each candidate treatment. The preservation survey results indicated that most treatments can satisfy the tightest restriction of a single daytime or overnight shift. For treat- ments applied to HMA-surfaced pavements, only ultra- thin whitetopping was reported as not being able to meet this restriction; longer closure time is needed in order for the PCC to cure and reach an acceptable strength level. For PCC-surfaced pavements, longer closure times are gener- ally required for partial-depth and full-depth repairs and for dowel bar retrofitting. Although the use of high early strength PCC mixes and fast-track proprietary repair materials (and precast full-depth repair panels) do enable these treatments to be used in single-shift or overnight closures, the costs are often significantly greater than the conventional cementitious materials used and their dura- bility is more variable. • Roadway geometrics. Every project consists of a unique set of geometric conditions or circumstances. The presence of features such as significant horizontal or vertical curves, intersections or interchanges, overhead bridges or sign structures, paved shoulders, and curb-and-gutter could be problematic to the construction of certain preservation (continued from page 61)

70 Table 3.27. Expected Performance of Preservation Treatments Applied to PCC-Surfaced Pavements on High-Traffic-Volume Roadways Expected Performance Expected Performance Treatment (Treatment Life) (yr) (Pavement Life Extension) (yr) Concrete joint resealing 1.5 to 5.5 5 to 6 Concrete crack sealing 3.5 to 4.0 NA Diamond grinding 5.5 to 7.0 NA Diamond grooving 7.0+ NA Partial-depth concrete patching 3.5 to 10.5 NA Full-depth concrete patching 3.5 to 10.5 NA Dowel bar retrofitting 7.0 to 10.5 NA Ultra-thin bonded wearing course 4.0 to 6.5 NA Thin HMA overlay 4.0 to 6.5 NA Source: Adapted from Jackson and Puccinelli 2006. Deep Freeze Moderate Freeze Nonfreeze Figure 3.10. Deep freeze, moderate freeze, and nonfreeze climatic regions. treatments. Likewise, how each candidate treatment would deal with existing pavement markers and striping must be determined. • Availability of experienced contractors and quality materials. Certain treatments, like microsurfacing, in-place re- cycling, and diamond grinding, require specialized equipment and materials that may not be locally available. Others may require a level of expertise or high-quality materials that may also not be locally available. Each can- didate treatment must be evaluated for shortcomings in these regards. • Traffic accommodation and safety issues. Some projects may include geometrics or other features that could be problem- atic from the standpoint of accommodating or controlling traffic during treatment construction. Each candidate treat- ment must be evaluated for shortcomings in these regards. • Environmental considerations. In some agencies and for certain locations (generally urban areas), a special emphasis is placed on using construction activities that are sensitive to the environment. Techniques that involve reduced carbon emissions and recycling of materials or that fit well with pavement sustainability concepts are viewed as desirable.

Selection of the Preferred Preservation Treatment Cost is an important consideration in treatment selec- tion. While the cost of a treatment does not have a direct bearing on the effectiveness of a treatment, costs are an obvious consideration in what an agency can afford. How- ever, agencies are strongly encouraged to look beyond the first costs or treatment initial construction costs and instead consider both the life-cycle costs and the benefit of the treatment. Approaches for doing this are described in greater detail here. Treatment Cost-Effectiveness Analysis Cost-effectiveness analysis is an economic evaluation technique for comparing that which is sacrificed (cost) to that which is gained (performance benefit) for the purpose of evaluating alternatives (Lamptey et al. 2005). Cost-effectiveness can be measured in the short term (i.e., for one or more treatments administered at a given time) or in the long term (i.e., for sev- eral treatments carried out over an extended period of time) using analysis procedures that range from detailed and com- plex to less detailed and simple. In simple terms, the alterna- tive that provides the greatest benefits for the least costs is the “best.” This section presents two 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). EAC is simpler to conduct and requires only basic information regarding cost and performance. It measures cost-effectiveness in the short term for alternatives that are assumed to provide similar benefit (for example, a chip seal and a slurry that are both applied to improve surface texture). The second approach, BCR, requires much more data and computational 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. Historical bid prices are an excellent source for developing treatment cost estimates, but these data must be adjusted to current-day values to account for the effects of inflation. To the extent possible, care should be exercised in developing estimated costs so that they account for project-specific factors, such as size (quantity of treatment needed), site-specific surface preparation requirements (such as material removal, patching, and cleaning), special traffic control requirements, and various contingencies (e.g., striping and pavement marker removal and replacement and associated shoulder work), that may have affected 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 $/yd2 ($/m2) or $/lane-mi ($/lane-km). 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) and, more recently, from maintenance management systems. However, very few PMS databases include information on preservation treatment performance 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 71 Table 3.28. Recommended Time Periods for Constructing Pavement Preservation Treatments in Colorado Asphalt Pavement Treatments Application Timinga Concrete Pavement Treatments Application Timinga Crack filling Early fall Crack sealing Early fall Crack sealing Sand seals Elev ≥ 10,000 ft: 7/4 to 8/1 Joint resealing — Chip seals 8,000 ≤ Elev < 10,000 ft: 6/15 to 8/15 Diamond grinding Microsurfacing 6,000 ≤ Elev < 8,000 ft: 6/1 to 9/1 Partial-depth repair 4,000 ≤ Elev < 6,000 ft: 5/15 to 9/1 Dowel bar retrofitting Elev < 4,000 ft: 5/1 to 9/1 Full-depth repair Ultra-thin bonded wearing course — Thin HMAOL Mill and thin HMAOL Source: Galehouse 2004. Notes: HMAOL = Hot-mix asphalt overlay; 1 ft = 0.305 m. a Exclusive of weather limitations placed on treatments.

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” concept. Although pavement survival analysis techniques (i.e., time until treatment failure or until a specific threshold condition is reached) can be used, estimates of treatment performance are more easily achieved using pavement performance mod- eling techniques (i.e., time-series trends of overall condition, serviceability, and individual distress development). And, since pretreatment pavement condition can have a significant impact on treatment life, 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 insufficient for analysis, then performance information should be sought from other sources. These may include agencies that have utilized the candidate treatments in similar condi- tions 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 “bang for the buck” concept. It involves a simple cal- culation of the treatment unit cost (inclusive of supplemental preparation work and maintenance of traffic) divided by the expected treatment performance, as shown in Equation 1. EAC Treatment Unit Cost Expected Performance, ye = ars ( )1 In this analysis method, the expected treatment performance is the extension in service life of the pavement generated by the preservation treatment. Although this extension may be easily identified as (a) the time taken for the pavement condition or serviceability/smoothness to return to the level it was at imme- diately 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 3.11. Benefit-Cost Ratio The BCR method of cost-effectiveness combines the results of individual evaluations of treatment benefits and treat- ment 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 characteristics of the existing pavement (whether the original structure or the last significant rehabilitation treatment) and all future projected preservation and rehabilitation treatments associ- ated with a given preservation strategy must be estimated. In the BCR method, the benefits associated with a particular 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 by 72 Approach 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 3.11. Estimation of preservation treatment life.

the 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 3.12 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 highway 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 shown in Equation 2. NPV IC M R i SV ijj k dis n dis j = + × + ⎡ ⎣⎢ ⎤ ⎦⎥ − × +=∑ &1 1 1 1 1 ⎡ ⎣⎢ ⎤ ⎦⎥ AP ( )2 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 activity 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 activity; SV = Salvage value, $; and AP = Analysis period length, years. The bottom portion of Figure 3.12 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 pavement and apply the subsequent preservation and rehabilitation treatments. Although most state highway agencies have a standardized procedure for conducting LCCA, state-of-the-practice guidance 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 spreadsheet program, RealCost, has also been developed and is available for public use at www.fhwa.dot.gov/infrastructure/asstmgmt/ lccasoft.cfm. 73 Pavement 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 3.12. Illustration of benefits and costs associated with a pavement preservation treatment strategy.

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 analysis by the “cost” obtained from the LCCA: As stated previously, the treatment with the highest B/C ratio is deemed the most cost-effective. Treatment Costs Although treatment costs do not affect treatment perfor- mance, certain cost considerations are inevitably a crucial part of the treatment selection process. The costs of interest are (a) the direct costs incurred by the highway agency as a result of constructing the treatment and (b) the indirect costs borne by the highway users as a result of the disruptions created by treatment construction work zones. DIRECT AGENCY COSTS The direct agency costs primarily consist of the in-place cost of the treatment (typically, the product of the awarded con- tractor’s unit cost for the treatment and the estimated treatment quantity, supplemented by surface preparation costs and main- tenance of traffic costs). In some instances, a percentage of B C Benefit NPV= ( )3 this cost (5% to 10%) may be added to reflect the engineering (design and construction), administrative, and traffic control costs anticipated with the treatment’s construction. Treatment unit costs depend on several factors, the most notable of which include the size and location of the project, severity and quantity of distresses, and the quality of a treat- ment’s constituent materials. In this study, unit cost infor- mation was gleaned from the literature to serve as a general resource in the absence of agency estimates derived from historical bid tabulations. Tables 3.29 and 3.30 show the unit costs obtained for treatments applied to HMA- and PCC- surfaced roadways, respectively, along with a relative cost indicator. The costs represent the in-place costs of the treat- ments, exclusive of traffic control costs and any associated surface preparation costs. The use of these relative or comparative costs is introduced because the recent volatility of materials prices, as well as variations in prices by region, project location, contractor availability, project size, and so on highlight the perils of report- ing costs that will most certainly change. What is less likely to change is the comparative relationship between these costs, although even that is not an absolute. INDIRECT USER COSTS User costs are defined as nonagency costs that are borne by the users of a pavement facility (Peshkin et al. 2004). User 74 Table 3.29. Estimated and Relative Treatment Costs for Preservation Treatments on HMA-Surfaced Pavements Treatment Relative Cost ($ to $$$$) Estimated Unit Cost Crack filling $ $0.10 to $1.20/ft Crack sealing $ $0.75 to $1.50/ft Slurry seal $$ $0.75 to $1.00/yd2 Microsurfacing (single course) $$ $1.50 to $3.00/yd2 Chip seal (single course) $$ (conventional) $1.50 to $2.00/yd2 (conventional) $$$ (polymer modified) $2.00 to $4.00/yd2 (polymer modified) Ultra-thin bonded wearing course $$$ $4.00 to $6.00/yd2 Thin HMA overlay (dense graded) $$$ $3.00 to $6.00/yd2 Cold milling and thin HMA overlay $$$ $5.00 to $10.00/yd2 Ultra-thin HMA overlay $$ $2.00 to $3.00/yd2 Hot in-place recycling (excluding thin HMA overlay $$/$$$ $2.00 to $7.00/yd2 for surface recycle and remixing types) Cold in-place recycling (excluding thin HMA overlay) $$ $1.25 to $3.00/yd2 Profile milling $ $0.35 to $0.75/yd2 Ultra-thin whitetopping $$$$ $15.00 to $25.00/yd2 Note: $ = low cost; $$ = moderate cost; $$$ = high cost; $$$$ = very high cost.

costs are 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 activities. 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 or significantly rough roads. VOCs typically 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 costs are primarily composed of the costs of human fatalities, 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 work zone construction equipment. 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 main- tenance, rehabilitation, or construction operations are taking place that impinge on the number of lanes available to moving 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 operating 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. Less than a quarter of the survey respondents reported that they account for user costs when evaluating preservation treatments. However, on high-traffic-volume roadways, user costs can represent a significant portion of the total cost. Current FHWA-recommended practice is to consider including in the economic analysis only the time-delay and VOC components associated with work zones. These com- ponents can be estimated reasonably well and make up a large portion of the total user costs. Other work zone user cost components are either too difficult to collect and reasonably quantify or do not factor to an appreciable amount. Further, for most pavement facilities in fair or good condition (e.g., pave- ments with a PSR of 2.5 or greater), user costs during normal operating conditions are minimal (Peshkin et al. 2004). 75 Table 3.30. Estimated and Relative Treatment Costs for Preservation Treatments on PCC-Surfaced Pavements Treatment Relative Cost ($ to $$$$) Estimated Unit Cost Joint resealing Crack sealing Diamond grinding Diamond grooving Partial-depth patching Full-depth patching Dowel bar retrofit Ultra-thin bonded wearing course Thin HMA overlay Note: $ = low cost; $$ = moderate cost; $$$ = high cost; $$$$ = very high cost. $ $ $$ $$ $$/$$$ $$/$$$ $$$ $$$ $$$ $1.00 to $2.50/ft $0.75 to $2.00/ft $1.75 to $5.50/yd2 $1.25 to $3.00/yd2 $75 to $150/yd2 (patched area) (equivalent $2.25 to $4.50/yd2, based on 3% surface area patched) $75 to $150/yd2 (patched area) (equivalent $2.25 to $4.50/yd2, based on 3% surface area patched) $25 to $35/bar (equivalent $3.75 to $5.25/yd2, based on 6 bars per 12-ft crack/ joint and crack/joint retrofits every 30 ft) $4.00 to $6.00/yd2 $3.00 to $6.00/yd2

For projects in which time-delay and VOC user costs are likely to occur as a result of performing preservation or reha- bilitation 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 the computations. A some- what simplified approach for computing 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 PM can be used to perform the computations. The following are brief descriptions of how user costs can be incorporated 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 and curing times, and other construction factors, the delays experi- enced as a result of the different work zone requirements 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 preservation 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 3.13. • In the BCR method, the user costs of all future preservation and rehabilitation treatments associated with each preser- vation strategy can be computed as part of the LCCA. Al- though the user cost NPV results may be combined with the agency cost NPV results, it is generally recommended that they be examined separately because of the possibility that they will overwhelm the agency costs. Evaluation of Economic and Noneconomic Factors 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 process is 76 Condition 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 3.13. Effect of preservation treatment life on discounted rehabilitation user costs.

77 that many other factors (economic and noneconomic) 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 consid- eration in the final selection. Examples include the availability of qualified (and properly equipped) contractors and quality materials, the anticipated level of traffic 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: • Substantially lower cost-effectiveness compared with 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 negative 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 eval- uate the different factors and identify the preferred treatment is a 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 multi- plied by rating scores given to each treatment alternative, based on how well the treatment satisfies 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 treatment with the highest score is then recognized as the preferred treatment. A fairly complete list of factors that are appropriate for inclusion in the final selection process follows. 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 BCR);  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/visibility); 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 3.31.

78 Table 3.31. 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.

Next: Chapter 4 - Implementation of Preservation Guidelines »
Preservation Approaches for High-Traffic-Volume Roadways Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

TRB’s second Strategic Highway Research Program (SHRP 2) Report S2-R26-RR-1: Preservation Approaches for High-Traffic-Volume Roadways documents the state of the practice of preservation treatment on asphalt and concrete pavements. The report focuses on treatments suitable for application on high-traffic-volume roadways but also discusses current practices for low-volume roadways.

The same project that produced SHRP 2 Report S2-R26-RR-1 also produced SHRP 2 Report S2-R26-RR-2: Guidelines for the Preservation of High-Traffic-Volume Roadways. The report provides suggested guidelines for the application of preservation treatments on high-traffic-volume roadways and considers traffic volume, pavement condition, work-zone requirements, environmental conditions, and expected performance.

An e-book version of this report is available for purchase at Google, iTunes, and Amazon.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!