Pavement Patching Practices (2014)

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34 This chapter presents the findings of surveys and communi- cations with local agencies in the United States, as well as agencies outside the United States, relative to their pavement patching practices. The states’ practices are compared with those of the local agencies and international organizations. The agencies responding to the surveys included: • Twenty local agencies in eight U.S. states; • Thirty-three highway authorities at the national and local levels in the United Kingdom and Ireland, plus three maintenance contractors; and • Five Canadian agencies, including three provinces and two large cities. For ease of comparison, the responses from the U.S. states, U.S. local agencies, and the United Kingdom and Ireland are included on the same graphs in the following section, “Patch- ing Practices in U.S. Local Agencies.” The discussion of the comparison of practices in the United Kingdom and Ireland to the U.S. state and local practices follows in “Patching Prac- tices in the United Kingdom and Ireland.” Canadian responses are not graphed since there were so few; discussion of these responses can be found in “Patching Practices in Canada.” PATCHING PRACTICES IN U.S. LOCAL AGENCIES As mentioned previously, a total of 20 respondents, repre- senting local agencies in eight states, provided answers to the questionnaire. The local agency responses are summarized here and compared with the responses from the state agen- cies. Because of the small sample size, these results may not be representative of all local agencies. As with the state agencies, the local agencies also believe patching is an important part of their maintenance program, with 19 of 20 respondents indicating so. As shown in Fig- ure 26, local agencies place slightly higher importance on patching than the states (95% vs. 90%). Estimates of the per- centage of the maintenance budget used for patching range from a low of 5% in Arapahoe County, Colorado (which includes parts of suburban Denver), in the dry-freeze region, to a high of 80% in the city of Akron, Ohio, an industrial city in the wet-freeze region. A higher percentage of local agencies reported having an established methodology for determining where patching is needed; 81% of locals vs. 57% of states, as shown in Fig- ure 27. It could be speculated that this may be, in part, the result of typically smaller networks that may allow closer monitoring of performance. Some local agencies do report patrolling their networks to identify problems. The triggers that call for patching are fairly similar for the local and state agencies (see Figure 28). Cracking appears to be of somewhat more concern to the local agencies (71% vs. 55%). The width of joints and extent of scaling or spalling are less important to locals than states (33% and 38% for locals vs. 43% and 55% for states, respectively). This may be because greater proportions of the local networks tend to be asphalt surfaces rather than concrete. The distress types addressed by patching are also quite sim- ilar between the local agencies and states, although again most of the concrete-related distress types (or composite pavement problems) appear less frequently for local agencies; the com- mon distress patched include deterioration of the asphalt sur- face over a joint (composite pavements), spalling, joint failure, faulting, and punch-outs (see Figure 29). Fatigue cracking was cited by two agencies; thinner pavements that are more prone to fatigue cracking tend to be more frequently associated with local agencies with typically lower budgets. A total of 14 local agencies reported reacting to sudden problems within 1 to 7 days (reactive patching); the other six did not respond. More locals reported responding to planned patches more quickly than the states, with six of 14 respond- ing within 1 to 7 days; the comparison is shown in terms of percent of responses in Figure 30. This may be partly a ques- tion of interpreting Time Zero and partly because fewer con- tracts for maintenance are let by locals, meaning more of the patching is done in-house. When patching is needed, local agencies rely on their own workforces to a greater extent than the states do. In other words, the local agencies reported using paving or specialty contractors less often than the states, as shown in Figure 31. This may be a reflection of typically smaller budgets for the local agencies. In terms of traffic control measures, local agencies report using arrow boards, barriers, and flashing lights on equipment less often than the state agencies for both reactive and planned chapter four COMPARISON OF U.S. STATE PRACTICES wITH OTHER AGENCIES

35 patching operations (see Figure 32). States tend to use traffic signals more often on planned patching projects. Two local agencies admitted to performing patching without traffic con- trol in some cases; this typically involves the “throw-and-go” patching technique under adverse conditions. In general, the states use plans, specifications, or guidelines for patching more frequently than local agencies, as shown in Figure 33. Many local agencies adopt the state requirements for patching. Perhaps surprisingly, a higher percentage of local agen- cies reported having QC/QA procedures for patching, 43% versus 32% of states, as shown in Figure 34. This may be a reflection of potential bias in the pool of agencies respond- ing, which may have been skewed toward those agencies 82% 81% 57% 18% 19% 43% 0% 20% 40% 60% 80% 100% UK/Ireland US Local US State Survey response Yes No FIGURE 27 Comparison of U.S. state, local, and U.K. responses on having a method to determine need for patching (Source: survey responses.) 92% 95% 90% 8% 10% 0% 20% 40% 60% 80% 100% UK/Ireland US Local US State Survey response Yes No 5% FIGURE 26 Comparison of U.S. state, local, and U.K. responses to importance of patching (Source: survey responses.) 0% 20% 40% 60% 80% 100% UK/Ireland US Local US State Survey response Visual identification Sudden safety problems Public complaints Area or depth of pothole Poor ride quality Extent of scaling or spalling Extent of cracking Depth of rutting Roughness/ravelling Width of joint FIGURE 28 Comparison of U.S. state, local, and U.K. responses to “Is there a trigger that calls for patching?” (Source: survey responses.)

0% 20% 40% 60% 80% 100% UK/Ireland US Local US State Survey response Potholes Deterioration at paving joint Deterioration at previous patch Deterioration around cracks Joint failure Rutting Spalling Delamination Material distress Blowups Raveling Corner Breaks Punchouts Segregation Faulting FIGURE 29 Comparison of U.S. state, local, and U.K. responses to “What distresses require patching?” (Source: survey responses.) 0% 20% 40% 60% 80% 100% 1-7 8-14 15-21 22-30 >30 1-7 8-14 15-21 22-30 >30 1-7 8-14 15-21 22-30 >30 UK /Ir el an d US Lo ca l US S ta te Survey response El ap se d ti m e, d ay s Planned patching Reactive patching FIGURE 30 Comparison of U.S. state, local, and U.K. responses to “Typical time needed to complete patching?” (Source: survey responses.)

0% 20% 40% 60% 80% 100% State forces Paving contractor Specialty contractor Other State forces Paving contractor Specialty contractor Other State forces Paving contractor Specialty contractor Other UK /Ir el an d US Lo ca l US S ta te Survey response Planned patching Reactive patching FIGURE 31 Comparison of U.S. state, local, and U.K. responses to “Who places patches?” (Source: survey responses.) 0% 20% 40% 60% 80% 100% Stop/Go Static lane closure Mobile lane closure Flashing lights and arrows on… Portable traffic lights Priority boarding Give/Take "Stop Works" sign None Other Flaggers Lane closure with cones Lane closure with arrow boards Lane closure with barriers Flashing lights and arrows on… Traffic signals None Other Flaggers Lane closure with cones Lane closure with arrow boards Lane closure with barriers Flashing lights and arrows on… Traffic signals None Other UK /Ir el an d US L oc al US st at e Survey response Planned Reactive FIGURE 32 Comparison of U.S. state, local, and U.K. responses to “What traffic control measures are used?” (Source: survey responses.)

38 with a greater level of interest in patching or may depend on how they interpret the term QC/QA. The procedures used to assess quality are reported to include measuring density, concrete strength, survival of the patch, thickness, quality of materials, and smoothness. A higher percentage of local agencies also reported monitor- ing the performance of both reactive and planned patches than the states; about 67% vs. 38% and 71% vs. 51%, respectively, as shown in Figure 35. States report tracking the location of planned patches to a greater extent than the locals do (55% vs. 38%), but the results are closer for reactive patches (40% of states and 38% of locals); see Figure 36. The use of automated equipment is fairly similar, in terms of percentage of responses (see Figure 37). About 62% of the local agencies and 59% of state agencies report using automated equipment. Two local agencies (out of 20) also reported using automated equipment only on contract work; of these two agencies, both report using paving contractors for planned patching and one also uses specialty contractors. This automated equipment is usually a spray patcher. In one state, several local agencies reportedly have a specialty con- tractor do infrared heating patching. Comparisons of the materials used by local and state agen- cies are shown in Figures 38 and 39. It can be seen from Fig- ure 38 that a higher percentage of state agencies use generic and proprietary stockpile materials, spray injection, and poly- mers. The discrepancies are even greater with the materials for patching concrete pavements. The local agencies use cementitious materials much less frequently than the states (Figure 39), in large part because several of the responding local agencies reported having little to no exposed concrete surfaces in their jurisdictions. 74% 77% 68% 78% 31% 62% 38% 54% 67% 62% 52% 70% 3% 13% 8% 11% 8% 2% 27% 2% 19% 23% 10% 24% 11% 54% 23% 62% 23% 31% 11% 45% 12% 8% 15% 23% 0% 20% 40% 60% 80% 100% Reactive Planned Temporary Permanent Reactive Planned Temporary Permanent Reactive Planned Temporary Permanent U K/ Ire la nd U S Lo ca l U S St at e Survey response Yes Yes, but only for patching by contract No FIGURE 33 Comparison of U.S. state, local, and U.K. responses to “Do you have plans, specifications, or guidelines for patching?” (Source: survey responses.) 0% 20% 40% 60% 80% 100% UK/Ireland US Local US State Survey response Yes No 28% 43% 32% 72% 57% 68% FIGURE 34 Comparison of U.S. state, local, and U.K. responses to “Do you have any QC/QA requirements at placement?” (Source: survey responses.)

39 FIGURE 35 Comparison of U.S. state, local, and U.K. responses to “Do you monitor patch performance?” (Source: survey responses.) 63% 63% 67% 71% 38% 51% 11% 10% 6% 13% 32% 24% 29% 24% 53% 36% 0% 20% 40% 60% 80% 100% Reactive Planned Reactive Planned Reactive Planned U K/ Ire la nd U S Lo ca l U S St at e Survey response Yes Yes, but only for patching by contract FIGURE 36 Comparison of U.S. state, local, and U.K. responses to “Do you have a method for tracking patch locations?” (Source: survey responses.) 54% 62% 38% 38% 40% 55% 44% 38% 62% 57% 60% 45% 0% 20% 40% 60% 80% 100% Reactive Planned Reactive Planned Reactive Planned U K/ Ire la nd U S Lo ca l U S St at e Survey response Yes No FIGURE 37 Comparison of U.S. state, local, and U.K. responses to “Do you use automated patching equipment?” (Source: survey responses.) 38% 62% 58% 14% 10% 7% 49% 29% 36% 0% 50% 100% UK/Ireland US Local US State Survey response Yes Yes, but only for patching by contract No

40 0% 20% 40% 60% 80% 100% UK/Ireland US Local US State Survey response Hot asphalt mix Generic stockpile mix Spray emulsion and aggregate Proprietary asphalt mix Warm mix asphalt Polymeric materials Crumb rubber mastic Other FIGURE 38 Comparison of U.S. state, local, and U.K. responses to “What materials are used to patch asphalt pavements?” (Source: survey responses.) 0% 20% 40% 60% 80% 100% UK/Ireland US Local US State Survey response Asphalt patching material Rapid strength hydraulic cement Normal hydraulic cement mixtures Epoxy mixtures Other rapid setting cement mixtures Latex or polymer-modified concrete FIGURE 39 Comparison of U.S. state, local, and U.K. responses to “What materials are used to patch concrete pavements?” (Source: survey responses).

41 As there was variability between the states, there was also variability found among the local agencies responding to the survey. There were also differences between the responses from local agencies compared with the state agencies. Many of these differences could be attributed to the different scale of operations and budgets between local and state agencies. The typically smaller roadway networks for the locals allow a greater familiarity with the status and performance of the pavements. Conversely, the typically smaller budgets may limit what local agencies can do themselves and what they must contract out, if funding allows. PATCHING PRACTICES IN THE UNITED KINGDOM AND IRELAND In the United Kingdom and Ireland, recent severe winter condi- tions have caused significant damage to the roadway networks, and roads are deteriorating more rapidly than usual (74). Thus the need to maintain roads is a growing concern (75). A version of the U.S. screening survey was distributed to organizations dealing with roadways in the United Kingdom and Ireland to assess the current practices regarding pavement patch- ing. A total of 36 survey responses were received from these agencies, including the national Department for Regional Development in Northern Ireland, almost 30 city and county councils, and three private contractors. (The responding agen- cies are listed in Appendix B.) The survey findings and dif- ferences between the various road authorities are explored in more detail in Pollock (75). When asked if patching is a major part of their maintenance operations, 33 of 36 responses (92%) indicated that it was, as shown in Figure 26. This response rate was similar to the U.S. state response level of 90%. One respondent who said no represented a borough council and indicated that if patch- ing amounts to more than about 10% to 15% of an area, that agency considers resurfacing as an option; they have found that even if the patches in such an area are of high quality, the area around the patch soon deteriorates, making resurfacing a more cost-effective approach. The reported percentages of patching as a portion of the total maintenance program varied from about 8% in Scotland to nearly 50% in Northern Ireland and England, when motorways (similar to U.S. interstates) were excluded. Motorways were generally built to and are maintained at higher standards than the remainder of the road- way networks. The Department of Transport has published patching guide- lines in Well-Maintained Highway: Code of Practice for High- way Maintenance Management (76). This code recommends creating a specific inspection frequency and a severity rating system to determine and rate maintenance needs. Many of the agencies that reported having an established methodology for determining where patching is needed (82%) have based their system on these guidelines, as can be seen in Figure 27. The six agencies that did not have a method cited budgetary constraints, the relative unimportance of patching in their operations, and a limited network as the main reasons. In Northern Ireland, the road authority determines where maintenance is needed and alerts maintenance contractors to that need. Similar to the U.K./Ireland data, 81% of respondents from U.S. local agen- cies reported having an established methodology for determin- ing where patching is needed. This contrasts sharply with U.S. state agencies, where only 57% of respondents reported that they have established methods. As in the United States, visual identification is the most common trigger for patching, as shown in Figure 28. The advantages of this method are that it requires no equipment and only requires one person to assess the need (75). Safety was the second most common trigger, again similar to the United States. In contrast, public complaints in the United Kingdom and Ireland were notably lower than the United States, pos- sibly indicting less promotion or awareness of related com- munications channels between the public and road owner. The most notable contrast relative to the United States was the low occurrence of scaling, spalling, or cracking as a trigger for patching. This difference most likely reflects the limited quan- tity of concrete pavements in the United Kingdom and Ireland. The distress types addressed by patching are also simi- lar in the United States and U.K./Ireland (see Figure 29). Potholes are the most common distress that is patched. The least common distresses were punch-outs, faulting, and blowups—again because of the limited extent of concrete pavements in the area (about 5% of the network in the United Kingdom). In terms of the amount of time elapsing between patch- ing awareness or planning and actual completion, the U.K./ Ireland trends again closely followed those in the United States (see Figure 30). The majority of respondents (74%) reported reactive patching to be completed within 1 to 7 days. Nota- bly, some respondents reported completion times for reactive patches of 15 to 21, 22 to 30, and >30 days (10%, 8%, and 3% of respondents, respectively). This contrasts with U.S. findings where all local agencies reported 1 to 7 days for patching and no state agencies reported delays greater than 15 to 21 days. This may reflect smaller available budgets, networks, and workforces. With regard to planned patching, the U.K./Ireland data contrasts with the U.S. findings to some degree. While relatively high percentages of U.S. local and state agencies reported patching being undertaken within 1 to 14 days (50% and 26%, respectively), the corresponding value for the U.K./ Ireland was only 14%. Similar to the United States, a large proportion of respondents (55%) indicated planned patching in the U.K./Ireland required time periods of >30 days. The use of paving and specialty contractors to perform reactive and planned patching is more prevalent in the United Kingdom and Ireland than in the United States, as shown in Figure 31. Only about 72% of the responses indicated that patching is performed by the road authorities themselves in the U.K./Ireland. This is compared with 88% and 92% of

42 responses for U.S. state and local agencies, respectively. Of the remainder, the use of paving and specialty contractors appears to be roughly equal (35% and 38% of responses, respectively). One agency commented that its small roadway network did not justify investing in a crew and equipment to perform patching. In other cases, specialty contractors were used for specific materials and skilled contractors used where high-quality patching is needed, such as on motorways. The terminology and practices used for traffic control in the United Kingdom and Ireland differ from those in the United States, as shown in Figure 32. This is one of the sur- vey questions that required the most “translation” from U.S. terminology. One conclusion that can be drawn from this fig- ure is that the use of traffic signals is much more prevalent in the U.K. and Ireland than in the United States; portable traffic lights are used in more than 70% of the organizations reporting. Figure 33 shows that the agencies in the U.K. and Ireland make more use of specifications, plans, or guidelines than the states of local agencies in the United States for both reactive and planned patching as well as temporary and permanent. The majority of the U.K./Ireland respondents (72%) reported that they do not implement any QC/QA proce- dures at the time of placement (see Figure 34), although they do check the material quality before placement. A supplier accreditation system that helps to monitor material quality is reportedly used in some cases. For those agencies that do have some form of QC/QA at placement, the parameters evaluated include strength, smoothness, depth, and density (voids). Inter- estingly, it was noted that most of the QC/QA testing occurs in the regions with smaller network extents. For both planned and reactive patches in the United King- dom and Ireland, 63% of respondents reported monitoring installed patch performance as a standard activity (see Fig- ure 35). This compares closely with U.S. local agency feedback, where 67% and 71% of respondents reported monitoring for reactive and planned patches, respectively. For U.S. state agencies, however, performance monitor- ing appears to be less frequent, with only 38% and 51% of respondents reporting its use for reactive and planned patches, respectively. In terms of tracking patches, 54% and 62% of U.K./ Ireland respondents reported the operation as standard for reactive and planned patches, respectively (see Figure 36). This was slightly higher than for the United States, with cor- responding values of 40% and 55% for U.S. state agencies and 38% for U.S. local agencies. In the United Kingdom and Ireland, a contractor reported the use of a laptop tracking sys- tem with GPS. In addition to the specific location, the patch size, date, and material are also tracked. Another maintenance contractor uses a similar system based on tracking the loca- tion of their equipment. Automated equipment is used by about half of the respon- dents, similar to the use in the United States (see Fig ure 37). Spray injection equipment and infrared heaters are used in some jurisdictions. A maintenance contractor reported using planers and other automated equipment to increase produc- tion. One reason cited for not using automated equipment is that it is not cost-effective to mobilize the equipment for isolated repairs. As in the United States, the reported costs vary widely depending on a number of factors, which makes it hard to draw any valid comparisons. In terms of materials typically used for patching asphalt pavements in the United Kingdom and Ireland, as shown in Figure 38, the trend noted was very similar to that for U.S. agencies, with hot asphalt mix being most commonly used (82%). As with the U.S. local agency data, proprietary asphalt mixes and spray emulsion and aggregate were the next most commonly reported options (39% and 33%, respectively). Polymeric materials are rarely used and, unlike the United States, the use of crumb rubber mastic was not reported by any of the U.K./Ireland agencies. For concrete pavements, as shown in Figure 39, similar trends were again noted, with asphalt and rapid strength hydraulic cements being the first and second most reported materials (54% and 42%, respectively). Clearly, with these options, the speed with which the roadway can be reopened to traffic is the primary benefit. Calcium sulfate and epoxy were not used. In general, it appears the experiences of national and local roadway authorities in the United Kingdom and Ireland are quite similar to those of the state and local agencies in the United States. There are some differences, especially regard- ing the use of contractors for performing patching operations; however, in general similar materials, methods, and manage- ment techniques are used. PATCHING PRACTICES IN CANADA Only five responses were received from Canadian provinces and cities; therefore, this small sample size may not be repre- sentative of the country as a whole. Because of the small size of this sample, the results are summarized in this section but not graphed because they could be misleading. • As in the United States, the responding Canadian agen- cies generally believe patching is a major activity within their maintenance programs, with four of five reporting it as important. • The same triggers are important in Canada as in the United States. The most commonly cited triggers include visual identification and safety issues (four of five responses); public complaints, size of the distressed area, rut depth, and poor ride (each three of five).

43 • As in the United States, there was little consistency in how the costs of patching were tracked and reported. • The same distresses were deemed suitable for repair by patching as in the United States. The most common dis- tresses were potholes (four); and rutting, raveling, and crack deterioration (three each). Concrete pavement dis- tresses such as scaling and spalling were less frequently mentioned by the responding agencies, which generally reported having relatively little exposed concrete pave- ment. Agencies also reported patching dips over culverts and permafrost. • The time to respond to a patching need also showed trends similar to those in the United States. Reactive patching is typically addressed within 1 to 7 or 8 to 14 days. Planned patching takes longer, on average more than 30 days. • Two of the responding agencies reported having spec- ifications for reactive patching, and four of five have them for planned patching. • Just two of the five responding agencies have QC/QA procedures for patching. • The materials used for patching by the responding agen- cies were somewhat more limited than that revealed in the U.S. surveys of state and local agencies. This is likely because of the small sample size. Patches on asphalt pavements are reportedly done using hot mix asphalt, proprietary asphalt mixes, and spray patch- ing (four of five). One agency reported using generic stockpile mix. For concrete pavements, asphalt mixes are used by four of five agencies and rapid-set hydraulic cement by one. Again, these agencies have relatively little exposed concrete. • Automated equipment for patching is used by all five agencies. Spray injection patchers are the most common automated equipment in use. • Patching is performed by both agency and contract personnel. • Similar traffic control measures are used. • Two of the five agencies reported monitoring of perfor- mance and two have a method to track patch locations; however, they are not the same two. Only one agency reported having a method to track locations and moni- tor performance. • One of the needs cited by the responding agencies was for training of maintenance personnel.