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

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A P P E N D I X B Examples of Identifying Feasible Preservation TreatmentsThis appendix presents two example exercises intended to illustrate how the feasibility matrices in Tables 3.2 through 3.5 can be used to identify feasible preservation treatments for a particular project. The first example is for treatment of an existing HMA-surfaced pavement, while the second is for treatment of an existing PCC-surfaced pavement. Each exam- ple includes a description of the project, presentation of the pavement condition and other relevant project information, and a discussion of the analyses performed to arrive at a final list of feasible treatments. Example 1: Rural, HMA Roadway Project Description The project featured in this example is set in a rural, deep- freeze environment and involves a four-lane interstate facil- ity. The roadway is 8.4 mi long and has an ADT of 14,000 vpd, with 11% trucks. The posted speed limit is 65 mph and access is controlled through three distantly spaced interchanges. The project terrain is flat to mildly rolling, and there are no signif- icant horizontal curves. The existing pavement structure was built as a reconstructed pavement in 2001 and was designed for a 20-year period. The pavement consists of 8.5 in. of HMA (1.5 in. surface course, 2.0-in. intermediate course, and 5.0-in. base course) on top of 8 in. of dense-graded aggregate base and a lime-stabilized sub- grade. Since construction, the pavement has undergone three condition surveys and two tests each for smoothness and fric- tion. The results of these surveys/tests, which are based on an evaluation of the outside/driving lane, are summarized in Table B-1. The agency thinking is that either some form of preserva- tion can be performed in 2010 or that a more significant reha- bilitation can be done in the 2013–2015 time frame. Funding for a 2010 preservation activity is largely available and, if47preservation is deemed appropriate, the agency’s goal is for the treatment to perform adequately for at least 4 years. The agency perceives no constraints regarding the availability of locally qualified contractors and good quality materials. And, finally, traffic conditions are such that lane closure durations longer than 1 day are acceptable. Preliminary Feasibility Analysis The existing pavement condition data listed in Table B-1 indi- cate that there is little structural deterioration and that the vast majority of the deficiencies can be treated through preservation techniques. The overall condition levels—PCR in the low- to mid-80s—are such that preventive maintenance techniques and some minor rehabilitation techniques would be appropri- ate, even after factoring in the reduction expected to occur between 2009 and 2010. The most prevalent deficiencies are low- and medium- severity raveling, medium- and high-severity transverse ther- mal cracking, low-severity longitudinal cold-joint cracking, and low- and high-severity stable rutting. Smoothness levels have gradually decreased, but are still reasonably high. Fric- tion along the project has remained at satisfactory levels. Evaluating the condition data in the backdrop of the prelim- inary feasibility matrix given in Table 3.2, it can be seen that the following treatments are generally or highly recommended for treating the above distresses: • Raveling. Slurry seal, single- and double-course micro- surfacing, single-course conventional chip seal, ultra-thin bonded wearing course, ultrathin HMA overlay, and thin HMA overlay. • Transverse thermal cracking. Crack sealing, slurry seal, single- and double-course microsurfacing, single- and dou- ble-course conventional chip seal, single- and double- course polymerized chip seal, ultra-thin bonded wearing course, ultrathin HMA overlay, thin HMA overlay, mill

48Existing Pavement Condition Parameters Condition Survey Year Smoothness Testing Year Friction Testing Year 2005 2007 2009 2007 2009 2007 2009 PCR Eastbound (EB) 95 90 81 Westbound (WB) 96 92 84 Raveling, LS (% area) EB 3.0 11.2 18.4 WB 1.1 3.5 6.8 Raveling, MS (% area) EB 1.3 4.7 7.3 WB 0.0 0.0 1.5 Segregation, LS (% area) EB 0.0 0.0 0.0 WB 6.5 4.5 3.2 Segregation, MS (% area) EB 0.0 0.0 0.0 WB 0.5 3.2 4.7 Trans-thermal cracking, LS (cracks/mi) EB 60 92 87 WB 45 96 102 Trans-thermal cracking, MS (cracks/mi) EB 6 35 49 WB 11 52 64 Long cold-joint cracking, LS (ft/mi) EB 120 967 2,412 WB 75 624 1,798 Long cold-joint cracking, MS (ft/mi) EB 0 54 367 WB 0 24 165 Stable rutting, LS (0.125 to 0.375 in.) (ft/mi) EB 110 1,256 5,868 WB 45 735 3,987 Stable rutting, MS (0.5 to 1.0 in.) (ft/mi) EB 0 151 1,268 WB 0 54 862 Fatigue cracking, LS (% wheel path area) EB 0.2 1.0 2.2 WB 0.0 0.3 1.5 IRI (Average ± Std Dev) (in./mi) EB 96.4 ± 9.7 112.5 ± 12.0 WB 88.5 ± 6.2 105.7 ± 10.3 FN40S (Average ± Std Dev) EB 45.4 ± 3.2 43.6 ± 2.6 WB 47.1 ± 4.5 43.8 ± 4.9 Table B.1. Summary of Pavement Condition Data

49and HMA overlay, HIR remixing and HMA overlay, HIR repaving, and CIR. • Longitudinal cold-joint cracking. Crack filling, slurry seal, single- and double-course microsurfacing, single- and double-course conventional chip seal, single- and double- course polymerized chip seal, ultra-thin bonded wearing course, ultrathin HMA overlay, thin HMA overlay, HIR recycling and HMA overlay, HIR remixing and HMA overlay, HIR repaving, and CIR. • Stable rutting. Double microsurfacing, single- and double- course conventional chip seal, single- and double-course polymerized chip seal, thin HMA overlay, cold mill and thin HMA overlay, HIR surface recycling and HMA overlay, HIR remixing and HMA overlay, HIR repaving, and CIR. Treatments appropriate for all four distress types include double microsurfacing, single-course conventional chip seal, ultrathin HMA overlay, and thin HMA overlay. Final Feasibility Analysis Evaluating these four treatments using the feasibility matrix in Table 3.4, it can be seen that one treatment—ultra-thin HMA overlay—probably lacks the durability for a deep-freeze cli- mate. Also, the expected performance lives of the double microsurfacing and single-course conventional chip seal in a deep-freeze climate are probably such that they barely meet the agency’s performance goal of 4 years. From the results of this analysis, it is reasonable to proceed with a cost-effectiveness analysis that includes double micro- surfacing, single-course conventional chip seal, and thin HMA overlay as the treatment alternatives. If agency experi- ence has indicated that the durability of ultra-thin HMA overlays is not significantly affected by the harsh climate, then this treatment could also be evaluated for cost-effectiveness. Example 2: Urban, PCC Roadway Project Description The project featured in this example is set in an urban, mod- erate-freeze environment and involves a six-lane freeway that is 4.3 mi long. The existing pavement structure is a 9.5-in. doweled jointed plain concrete (JPC) pavement (15-ft joint spacing) resting on a 4-in. asphalt-treated base (ATB) and a lime-stabilized subgrade. The pavement was built in 1996 with a 25-year design life. Current traffic consists of a 55,000 ADT and 16.8% trucks. The posted speed limit is 55 mph and there are four interchanges along the length of the project. The terrain is flat and there are no horizontal curves. Automated pavement-condition surveys (including smooth- ness) have been performed on the outside/driving lane every third year since construction. Friction tests for this same lanewere performed in 2000, 2004, and 2008. The results of the condition, smoothness, and friction surveys are summarized in Table B-2. In addition to these results, on-board sound intensity (OBSI) testing performed in 2008 indicated that the pavement–tire noise levels generated by the transversely tined concrete ranged from 106 to 108 dB(A). Agency funding for some form of preservation is available for the 2010 construction season. The agency’s goal for preser- vation treatment performance is 8 years. Traffic conditions are such that lane closure durations longer than a 2-day weekend are unacceptable. Also, there are no perceived availability constraints regarding locally qualified contractors and good- quality materials. Preliminary Feasibility Analysis The existing pavement condition data listed in Table B-2 indicate that there is no need for major rehabilitation in the near future. Only a few slabs have structural cracks and the rate at which these cracks have developed is low. The table also indicates that the deficiencies are mostly functional and that the overall condition and smoothness levels are in the proper ranges for preservation, even after factoring in the condition changes expected to occur between 2008 and 2010. The most prevalent deficiencies are transverse and longi- tudinal joint seal damage, transverse and longitudinal joint spalling, and polished aggregate. Friction trends have con- firmed the polishing problem and current friction levels are either in or are approaching the marginal zone. Agency review of wet-weather accident rates has indicated a possible concern with the friction levels. Evaluating the condition data in the backdrop of the pre- liminary feasibility matrix given in Table 3.3, it can be seen that the following treatments are generally or highly recom- mended for treating the above distresses: • Polishing. Diamond grinding, ultra-thin bonded wearing course, and thin HMA overlay. • Joint seal damage. Joint resealing. • Joint spalling. Partial-depth patching. • Corner cracking. Crack sealing, full-depth patching. • Transverse cracking. Crack sealing. • Friction. Diamond grinding, diamond grooving, ultra- thin bonded wearing course, and thin HMA overlay. Although none of these treatments address all six deficien- cies, some combination treatments can be formed that will collectively address them. Possible combinations include the following: • Diamond grinding, crack sealing, and joint resealing; • Limited partial- and full-depth patching, diamond grind- ing, and joint resealing;

50Existing Pavement Condition Parameters Condition Survey/Smoothness Testing Year Friction Testing Year 1999 2002 2005 2008 2000 2004 2008 PCR Northbound (NB) 95 92 89 84 Southbound (SB) 98 96 93 88 Polishing (% wheel path area) NB 1.8 5.2 22.4 63.0 SB 0.9 4.5 24.8 58.4 Trans-joint seal damage, LS (joints/mi)a NB 56 102 123 103 SB 45 110 145 122 Trans-joint seal damage, MS (joints/mi)a NB 5 63 93 143 SB 2 48 85 156 Trans-joint seal damage, HS (joints/mi)a NB 0 8 15 38 SB 0 2 21 30 Long joint seal damage, (ft/mi)b NB 0 56 287 784 SB 0 108 402 1,026 Trans-joint spalling, LS (joints/mi)a NB 2 9 23 42 SB 0 4 15 21 Trans-joint spalling, MS (joints/mi)a NB 0 1 5 22 SB 0 0 1 11 Long joint spalling, LS (ft/mi)b NB 14 25 54 130 SB 10 24 48 164 Long joint spalling, MS (ft/mi)b NB 0 2 38 116 SB 0 0 29 84 Corner cracking, LS (slabs/mi) NB 0 2 3 5 SB 0 1 1 3 Corner cracking, MS (slabs/mi) NB 0 0 1 3 SB 0 0 1 2 Transverse cracking, LS (slabs/mi) NB 0 2 3 5 SB 0 0 0 2 IRI (Average ± Std Dev) (in./mi) NB 88 ± 7 106 ± 5 113 ± 6 120 ± 5 SB 86 ± 6 97 ± 5 106 ± 8 114 ± 5 FN40S (Average ± Std Dev) NB 35.2 ± 4.6 32.4 ± 3.9 28.8 ± 2.0 SB 36.1 ± 5.5 35.0 ± 4.5 31.4 ± 3.6 a Out of 352 total transverse joints/mi. b Out of 10,560 ft/mi (longitudinal lane-shoulder joint and longitudinal lane-lane joint). Table B.2. Summary of Pavement Condition Data

51• Limited partial- and full-depth patching, ultra-thin bonded wearing course; and • Limited partial- and full-depth patching, thin HMA overlay. Final Feasibility Analysis Evaluating these four combination treatments using the fea- sibility matrix in Table 3.5, it can be seen that none are suf-ficiently impacted by the climate in terms of durability. Also, the treatment performance and closure duration require- ments appear to be satisfied by all four treatments. Hence, based on this analysis, it is reasonable to proceed with a cost- effectiveness analysis that includes all four combination treatments.