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Standard Definitions for Common Types of Pavement Cracking (2020)

Chapter: Appendix A. Summary of Cracking Protocols

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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Suggested Citation:"Appendix A. Summary of Cracking Protocols." National Academies of Sciences, Engineering, and Medicine. 2020. Standard Definitions for Common Types of Pavement Cracking. Washington, DC: The National Academies Press. doi: 10.17226/25928.
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Appendix A. Summary of Cracking Protocols A 1

Summary of Cracking Protocols PROCTOCOLS AT THE NATIONAL LEVEL Pavement distress protocols were developed at the national level for various purposes. Table 1 summarizes the pavement cracking information for these protocols. The AASHTO protocols, NPS protocol, and SCANNER protocol can be implemented for automated cracking data collection while the ASTM protocols and LTPP protocol are developed for traditional manual or windshield surveys. The protocols suitable for automation technology specify fewer cracking categories whereas the protocols for manual survey report more cracking types on different pavement surface types (AC or PCC). Table 1 Summary of Crack Protocols at the National Level Protocols Automation Pavement Types No. of Cracking Types AASHTO R 85-18 Yes AC 4 AASHTO R 55-10 Yes AC 4 ASTM D6433–16 for Highway No AC & PCC 9 ASTM D5340–12 for Airfield No AC & PCC 9 FHWA LTPP No AC & JPCP & CRCP 13 FHWA NPS Yes Any Type 3 UK SCANNER Yes Any Type 2 AASHTO Protocols AASHTO Designation R 85-18, “Standard Practice for Quantifying Cracks in Asphalt Pavement Surfaces from Collected Images Utilizing Automated Methods”, outlines the procedures for quantifying cracking distress at the network level in asphalt pavement surfaces utilizing automated methods (AASHTO, 2018). Only cracks which are detected in pavement image with dimensions bigger than 1 mm (0.04”) in width and 25 mm (1") in length are reported in this protocol. The definitions for longitudinal, transverse, pattern, and other cracks are provided in Table 2. A 2

Table 2 AASHTO R 85-18 Cracking Protocol Crack Type Definitions Longitudinal Crack A crack at least 0.3 m (12”) long and with a crack orientation between and including +20 and -20 degrees relative to the lane centerline. Transverse Crack A crack at least 0.3 m (12”) long and with a crack orientation between and including 70 and 110 degrees relative to the lane centerline. Pattern Crack A crack that is part of a network of cracks that form an identifiable area or grouping of cracks. Other Crack All cracks not identified as longitudinal, pattern, or transverse. Figure 1 Wheel Path Definition in AASHTO R 85-18 (AASHTO R 85-18, 2018) The wheel path definition in AASHTO R 85-18 is shown in Figure 1. Five measurement zones across a full lane are included in the definition. The sum of the length in meters (feet) and the average width in millimeters (inches) for each cracking category are summarized and reported for each measurement zone and summary section (0.015 km (0.01 mi) or less). Any increase in the extent and severity of cracking located in Zones 2 and 4 above that in Zone 3 is expected to typically reflect the impact of traffic loading. AASHTO Designation R 55-10, “Standard Practice for Quantifying Cracks in Asphalt Pavement Surfaces”, covers the procedures to quantify cracking in asphalt pavement surfaces for automated or manual data collection surveys, both in wheel path and non-wheel path areas, for network-level pavement management applications (AASHTO, 2013). Only the cracks with dimensions bigger than 1 mm (0.04”) in width and 25 mm (1") in length are reported and summarized in AASHTO R 55-10. The intent of this standard is to quantify and differentiate between load-associated (fatigue) and non-load-associated (environmental, reflective, etc.) pavement cracking. Increased cracking intensity in the wheel path as compared with that in the non-wheel path areas is assumed to be load-associated cracking. Non-load-associated cracking is quantified by the cracking measured in the non-wheel path areas. A 3

The wheel path definition in AASHTO R 55-10 is shown in Figure 2. Wheel path cracking is determined in both the inside and outside wheel paths while non-wheel path cracking is the area between the wheel paths, as shown in Figure 2. Cracks with dimensions ≤ 3 mm (1/8”) width are defined as Level 1 severity, cracks with dimensions > 3 mm (1/8”) and ≤ 6 mm (1/4”) width are defined as Level 2 severity, and cracks with dimensions > 6 mm (1/4”) width are defined as Level 3 severity. The intensity of cracking at each severity level is defined as the total length of cracking per unit area (m/m2 or ft/ft2) for each defined survey strip as shown in Figure 2. Figure 2 Wheel path Definition in AASHTO R 55-10 (AASHTO R 55-10, 2013) The AASHTO protocols were developed to be suitable for automatic asphalt pavement crack detection and classification at network level. The crack information summarized in the AASHTO protocols may not be sufficient for decision making at project level which requires more details on cracking type and extent. Furthermore, crack quantification for concrete pavement at the project and network level should be developed for automated imaging systems. ASTM Protocols ASTM Designation D6433–16, “Standard Practice for Roads and Parking Lots Pavement Condition Index Surveys”, illustrates the procedure to evaluate pavement crack data as part of the Pavement Condition Index (PCI) calculation to quantify roads and parking lots pavement condition (ASTM, 2016). Alligator (fatigue) cracking, block cracking, edge cracking, joint reflection cracking, longitudinal and transverse cracking are the major distress types for asphalt pavements. Corner break, durability “D” cracking, linear cracking and shrinkage cracking are rated for concrete pavements. This protocol was designed to manually assess pavement cracking based on visual inspection which is labor-intensive and time-consuming. The definitions of severity levels for these crack categories are not consistent throughout the protocol. For example, the severity level for block cracking is determined by crack width, but the severity definition of alligator/edge cracking is descriptive and not related to crack width. In A 4

addition, the thresholds of crack width over various severity levels for block cracking are different from those for joint reflection cracking. Detailed crack information in this ASTM manual are separately summarized for asphalt and concrete pavement in Table 3. Table 3 ASTM D6433-16 Cracking Protocol Crack Type Severity Levels Low Medium High Asphalt Pavement Alligator Cracking Fine, longitudinal hairline cracks without spalling. Light alligator cracks with lightly spalling. Well defined cracks with spalling. Block Cracking Width ≤ 13 mm (½”) 13 mm (1/2”) < Width ≤ 50 mm (2”) Width > 50 mm (2”) Edge Cracking Cracking with no breakup Cracking with some breakup Considerable breakup Joint Reflection Cracking Width ≤ 10 mm (3/8”) 10 mm (3/8”) < Width ≤ 75 mm (3”) Width > 75 mm (3”) Longitudinal/ Transverse Cracking Width ≤ 10 mm (3/8”) 10 mm (3/8”) < Width ≤ 75 mm (3”) Width > 75 mm (3”) Slippage Cracking No degree of severity Concrete Pavement Corner Break Width ≤ 13 mm (½”) without faulting. 13 mm (1/2”) < Width ≤ 50 mm (2”); or any filled crack with faulting < 10 mm (3/8”). Width > 50 mm (2”); or any crack with faulting > 10 mm (3/8”). Durability (“D”) Cracking “D” cracks cover less than 15% of slab area. Most of the cracks are tight, but a few pieces may be loose and or missing. “D” cracks cover less than 15% of slab area and most of the pieces are loose or missing; or “D” cracks cover more than 15% of the area. “D” cracks cover more than 15% of the area and most of the pieces have come out or could be removed easily. Linear (longitudinal, transverse, and diagonal) on non- reinforced slabs Width ≤ 13 mm (½”) 13 mm (1/2”) < Width ≤ 50 mm (2”) Width > 50 mm (2”) Linear (longitudinal, transverse, and diagonal) on reinforced slabs Width ≤ 3 mm (1/8”) 13 mm (1/2”) < Width ≤ 25 mm (1”) Width > 25 mm (1”) A 5

Crack Type Severity Levels Low Medium High Shrinkage Cracking No degree of severity Divided Slab Low severity of the majority of cracks with 4~8 cracked slabs; or medium severity of the majority of cracks with 4~5 cracked slabs. Low severity of the majority of cracks with more than 8 cracked slabs; or medium severity of the majority of cracks with 6~8 cracked slabs, or high severity of the majority of cracks with 4~5 cracked slabs. Medium severity of the majority of cracks with more than 8 cracked slabs, or high severity of the majority of cracks with more than 6 cracked slabs. ASTM Designation D5340–12, “Standard Test Method for Airport Pavement Condition Index Surveys”, illustrates how to determine airport pavement condition through visual surveys of both asphalt-surfaced pavements and plain or reinforced jointed Portland cement concrete pavements (ASTM, 2012). Alligator cracking, block cracking, joint reflection cracking, longitudinal and transverse cracking, and slippage cracking are collected for asphalt concrete surfaces. Corner break, cracks, durability “D” cracking, shattered slab/intersecting cracks, and shrinkage cracking are rated for concrete-surfaced airfields. Detailed crack information in ASTM D5340-12 are summarized in Table 4. Table 4 ASTM D5340-12 Cracking Protocol Crack Type Severity Levels Low Medium High Asphalt Concrete Airfield Alligator Cracking Fine, longitudinal hairline cracks are not spalled Light alligator cracks are lightly spalled Cracks are well defined and spalled Block Cracking Blocks are defined by cracks that are nonspalled or lightly spalled, causing no Foreign Object Debris (FOD) potential. Nonfilled cracks have 6 mm (1/4”) or less mean width and filled cracks have filler in satisfactory condition. Filled or nonfilled cracks are moderately spalled; nonfilled cracks have a mean width greater than 6 mm (1/4”); or filled cracks greater than 6 mm (1/4”) that are not spalled or have only minor spalling. Blocks are well defined by cracks that are severely spalled, causing a definite FOD potential. Joint Reflection Cracks have only light spalling or no Cracks are moderately spalled; filled cracks are Cracks are severely spalled with pieces A 6

Crack Type Severity Levels Low Medium High Cracking or Longitudinal/ Transverse Cracking spalling, and can be filled or nonfilled. If nonfilled, the cracks have a mean width of 6 mm (1/4”) or less. not spalled or lightly spalled, but filler is in unsatisfactory condition; nonfilled cracks are not spalled or lightly spalled, but the mean crack width is greater than 6 mm (1/4”). loose or missing causing definite FOD potential. Cracks can be either filled or nonfilled of any width. Slippage Cracking Width ≤ 10 mm (3/8”) 10 mm (3/8”) < Width ≤ 40 mm (3/2”) Width > 40 mm (3/2”) Concrete Pavement Corner Break Cracks have little or minor spalling. If nonfilled, it has a mean width ≤ 3 mm (1/8”). A filled crack can be of any width, but the filler material must be in satisfactory condition. Filled or nonfilled crack is moderately spalled; or a nonfilled crack has a mean width between 3 mm (1/8”) and 25 mm (1”); or a filled crack is not spalled or only slightly spalled, but the filler is in unsatisfactory condition; or the area between the corner break and the joints is lightly cracked. Filled or nonfilled crack is severely spalled, causing definite FOD potential; or a nonfilled crack has a mean width greater than 25 mm (1”); or the area between the corner break and the joints is severely cracked. Cracks (longitudinal, transverse, and diagonal) Cracks has little or minor spalling. If nonfilled, it has a mean width ≤ 3 mm (1/8”). A filled crack can be of any width, but the filler material must be in satisfactory condition; or the slab is divided into three pieces by low-severity cracks. Filled or nonfilled crack is moderately spalled; or a nonfilled crack has a mean width between 3 mm (1/8”) and 25 mm (1”); or a filled crack is not spalled or only slightly spalled, but the filler is in unsatisfactory condition; or the slab is divided into three pieces by two or more cracks, one of which is at least medium severity. Filled or nonfilled crack is severely spalled, causing definite FOD potential; or a nonfilled crack has a mean width greater than 25 mm (1”), creating a tire damage potential; or the slab is divided into three pieces by two or more cracks, one of which is at least high severity. Durability (“D”) Cracking “D” cracks are defined by hairline cracks occurring in a limited area of the slab. Little or no disintegration has “D” cracks have developed over a considerable amount of slab area with little or no disintegration or FOD potential. Or “D” “D” cracks have developed over a considerable amount of slab area with disintegration or FOD potential. A 7

Crack Type Severity Levels Low Medium High occurred. No FOD potential. cracking has occurred in a limited area of the slab, but pieces are missing and disintegration has occurred. Some FOD potential. Shattered Slab/Intersecting Cracks Slab is broken into four or five pieces predominantly defined by low- severity cracks. Slab is broken into four or five pieces with over 15% of the cracks of medium severity; slab is broken into six or more pieces with over 85% of the cracks of low severity. Slab is broken into four or five pieces with some or all cracks of high severity; or slab is broken into six or more pieces with over 15% of the cracks of medium or high severity. Shrinkage Cracking No degree of severity LTPP Protocol FHWA LTPP protocol, “Distress Identification Manual for the Long-Term Pavement Performance Program (Fifth Revised Edition)”, illustrates the crack survey and measurement for asphalt pavements, jointed (plain and reinforced) Portland cement pavements (JPCP), and continuously reinforced concrete pavements (CRCP) (FHWA, 2014). This protocol was designed for 500-ft LTPP test sections. This manual is widely implemented for pavement distress rating in the U.S. and worldwide, where some SHAs directly adopt it and other SHAs modify it as state- specific pavement distress manuals. The crack definitions and evaluations covered in this protocol were developed for manual surveys. The detailed crack information in this manual are summarized in Table 5 according to pavement types. Wheel path definition is illustrated in Figure 3. A 8

Figure 3 Wheel path Definition in LTPP Protocol (FHWA, 2014) Table 5 LTPP Cracking Protocol Crack Type Severity Levels Low Medium High Asphalt Pavement Fatigue Cracking Cracks with few connection are not spalled Interconnected cracks may be slightly spalled Cracks are severely spalled interconnected Block Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) Edge Cracking Cracking with no breakup Cracking with some breakup Considerable breakup Longitudinal Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) Reflection Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) Transverse Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) JPCP Pavement Corner Breaks Spalled crack < 10% crack length; no faulting Spalled crack > 10% crack length; or faulting ≤ 13 mm (1/2”) Spalled crack > 10% crack length; or Faulting > 13 mm (1/2”) Durability (“D”) Cracking Tight cracks with no loose pieces Well-defined cracks with some loose pieces Well-developed cracks with significant loose piece Longitudinal Cracking Width ≤ 3 mm (1/8”) with no spalling 3 mm (1/8”) < Width ≤ 13 mm (1/2”); or spalling ≤ 75 mm (3”); or faulting ≤ 13 mm (1/2”) Width > 13 mm (1/2”); or spalling > 75 mm (3”); or faulting > 13 mm (1/2”) A 9

Crack Type Severity Levels Low Medium High Transverse Cracking Width ≤ 3 mm (1/8”) with no spalling 3 mm (1/8”) < Width ≤ 6 mm (1/4”); or spalling ≤ 75 mm (3”); or faulting ≤ 6 mm (1/4”) Width > 6 mm (1/4”); or spalling > 75 mm (3”); or faulting > 6 mm (1/4”) CRCP Pavement Durability (“D”) Cracking Tight cracks with no loose pieces Well-defined cracks with some loose pieces Well-developed cracks with significant loose piece Longitudinal Cracking Width ≤ 3 mm (1/8”) with no spalling 3 mm (1/8”) < Width ≤ 13 mm (1/2”); or spalling ≤ 75 mm (3”); or faulting ≤ 13 mm (1/2”) Width > 13 mm (1/2”); or spalling > 75 mm (3”); or faulting > 13 mm (1/2”) Transverse Cracking Crack spalling ≤ 10% of crack length Crack spalling > 10% and ≤ 50% of crack length Crack spalling > 50% of crack length NPS Protocol FHWA developed a distress identification manual for National Park Service (NPS) road inventory named as “Pavement Distress Identification Manual for the NPS Road Inventory Program” (FHWA, 2009). Cracking data is reported at the interval of 0.02 miles. Same as the AASHTO manual, the cracking information in the NPS manual is extracted from digital images collected using automated pavement surface data collection systems. Alligator, longitudinal, and transverse cracking are included for pavement distress evaluation in this manual. It is worth mentioning that the severity levels of alligator cracking are also defined based on crack width. Detailed crack information described in this manual are summarized in Table 6. Table 6 NPS Cracking Protocol Crack Type Severity Levels Low Medium High Alligator Cracking Cracks are ≤ 6 mm (1/4”) in mean width with low pattern Cracks are > 6mm (1/4”) and ≤ 19 mm (3/4”) in mean width with medium pattern Cracks are > 19 mm (3/4”) in mean width with high pattern Longitudinal Cracking Cracks are ≤ 6 mm (1/4”) in mean width Cracks are > 6mm (1/4”) and ≤ 19 mm (3/4”) in mean width Cracks are > 19 mm (3/4”) in mean width Transverse Cracking Cracks are ≤ 6 mm (1/4”) in mean width Cracks are > 6mm (1/4”) and ≤ 19 mm (3/4”) in mean width Cracks are > 19 mm (3/4”) in mean width A 10

UK SCANNER Protocol UK SCANNER protocol was introduced back in 2005 for measuring the condition of local authority principal roads in the United Kingdom (HGL, 2005). Pavement cracking data along with road geometry, longitudinal profile, transverse profile, texture profile are combined and reported as the Best Value Performance Indicator (BV). Carriageway Cracking Intensity is obtained from the crack map in the Survey Data within a 2-dimensional grid of 200 mm in both the transverse and longitudinal directions. The carriageway Cracking Intensity is expressed as the percentage of the surveyed area that contains cracking as shown Figure 4. Figure 4 Scheme for Cracking Intensity Calculation (HGL, 2005) In addition, the Intensity of Wheeltrack Cracking is also calculated according to the position and length of each crack in the wheel track. The wheeltrack is defined as a 0.3 m band area locating 0.85 m away from the center of a survey. Any cracks with 80% of its length within the wheeltrack are classified as a wheeltrack crack, as illustrated in Figure 5. The calculation of A 11

Intensity of Wheeltrack Cracking follows the same mechanism as that of Cracking Intensity and is explained in Figure 6. It should be emphasized that the grid size for the wheeltrack calculation is 0.3 m by 0.5 m by default which is different from the grid dimension for Cracking Intensity calculation. Figure 5 Classification of Wheeltrack Cracks (HGL, 2005) A 12

Figure 6 Scheme for Intensity of Wheeltrack Cracking Calculation (HGL, 2005) PROCTOCOLS BY STATE HIGHWAY AGENCIES (SHAS) Many SHAs implemented state-specific protocols according to their own experiences. A comprehensive literature review is performed for all the 50 SHAs, while only 34 SHAs have cracking protocols available online. In particular, eight SHAs have developed protocols for current or future applications of automated pavement condition survey technologies, including Alabama, California, Delaware, Florida, Idaho, Pennsylvania, Vermont, and Virginia. A small number of SHAs do not have tabulated protocols; therefore, relevant descriptions do not contain any protocol tables. A 13

Alabama Department of Transportation The Alabama Department of Transportation (ALDOT) has used a vendor to perform automated pavement condition survey for the Alabama pavement network since 1997 (McQueen and Timm, 2005). There are two documents available online describing pavement cracking data collection procedures applied by ALDOT, “ALDOT-392, Project Level Pavement Condition Data Collection Procedures” and “ALDOT-414-04, Network-Level Pavement Condition Data Collection Procedure” (ALDOT, 2009 & 2015). For project level, the ALDOT-392 protocol focuses on manual survey and classifies up to 12 cracking categories on different pavement types. For network level, the ALDOT-414-04 protocol addresses automated pavement data collection and proposes only three cracking types (transverse, load related, and non-load related) for pavement survey. Load related cracks are any crack longer than 1 in. (25.4 mm) located in the wheel paths while not previously identified as transverse cracks, as shown in Figure 7. Detailed crack information described in the ALDOT protocols are summarized in Table 7. Figure 7 Wheel path Definition in Protocol of ALDOT (ALDOT, 2015) Table 7 Cracking Protocol for ALDOT Crack Type Severity Levels Low Medium High Project Level - Asphalt Pavements Fatigue Cracking Cracks with few connection are not spalled. Interconnected cracks may be slightly spalled. Cracks are severely spalled interconnected. Block Cracking Width ≤ 3 mm (1/8”) 3 mm (1/8”) < Width ≤ 6 mm (1/4”) Width > 6 mm (1/4”) A 14

Crack Type Severity Levels Low Medium High Edge Cracking Cracking with no breakup Cracking with some breakup Considerable breakup Longitudinal Cracking Width ≤ 3 mm (1/8”) 3 mm (1/8”) < Width ≤ 6 mm (1/4”) Width > 6 mm (1/4”) Transverse Cracking Width ≤ 3 mm (1/8”) 3 mm (1/8”) < Width ≤ 6 mm (1/4”) Width > 6 mm (1/4”) Project Level - JPCP & JRCP Pavements Corner Breaks Spalled crack < 10% crack length; no faulting. Spalled crack > 10% crack length; faulting ≤ 13 mm (1/2”). Spalled crack > 10% crack length; Faulting > 13 mm (1/2”). Durability (“D”) Cracking Tight cracks with no loose pieces. Well-defined cracks with some loose pieces. Well-developed cracks with significant loose piece. Longitudinal Cracking Width ≤ 3 mm (1/8”) with no spalling. 3 mm (1/8”) < Width ≤ 13 mm (1/2”); or spalling < 75 mm (3”); or faulting < 13 mm (1/2”). Width > 13 mm (1/2”); or spalling > 75 mm (3”); or faulting > 13 mm (1/2”). Transverse Cracking Width ≤ 3 mm (1/8”) with no spalling. 3 mm (1/8”) < Width ≤ 13 mm (1/2”); or spalling < 75 mm (3”); or faulting < 13 mm (1/2”). Width > 6 mm (1/2”); or spalling > 75 mm (3”); or faulting > 13 mm (1/2”). Project Level - CRCP Pavements Durability (“D”) Cracking Tight cracks with no loose pieces. Well-defined cracks with some loose pieces. Well-developed cracks with significant loose piece. Longitudinal Cracking Width ≤ 3 mm (1/8”) with no spalling. 3 mm (1/8”) < Width ≤ 13 mm (1/2”); or spalling < 75 mm (3”); or faulting < 13 mm (1/2”). Width > 13 mm (1/2”); or spalling > 75 mm (3”);. or faulting > 13 mm (1/2”). Transverse Cracking Crack spalling ≤ 10% of crack length Crack spalling > 10% and ≤ 50% of crack length Crack spalling > 50% of crack length Network Level Transverse Cracking Width ≤ 3 mm (1/8”) 3 mm (1/8”) < Width ≤ 6 mm (1/4”) Width > 6 mm (1/4”) Load Associated Cracking Width ≤ 3 mm (1/8”) 3 mm (1/8”) < Width ≤ 6 mm (1/4”) Width > 6 mm (1/4”) Non-load Associated Cracking Width ≤ 3 mm (1/8”) 3 mm (1/8”) < Width ≤ 6 mm (1/4”) Width > 6 mm (1/4”) California Department of Transportation The California Department of Transportation (Caltrans) developed “Automated Pavement Condition Survey Manual” to assistant the application of automated pavement condition survey A 15

at network-level pavement data collection (Caltrans, 2015). The wheel path is defined as shown in Figure 8. Cracking on asphalt, JRCP and CRCP pavements are summarized separately in this manual. The average crack width is implemented to define different severity levels. Different from other protocols, two types of alligator cracking, alligator A cracking (single or double unconnected cracks in the wheel path parallel to the centerline) and alligator B cracking (interconnected cracks in the wheel path forming a series of small polygons), are defined in Caltrans to characterize the extent of alligator cracking development. Detailed crack information for Caltrans are listed in Table 8. Figure 8 Wheel path Definition in Protocol of Caltrans (Caltrans, 2015) Table 8 Cracking Protocol for Caltrans Crack Type Severity Levels Low Medium High Asphalt Pavements Alligator A Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 13 mm (1/2”) Width > 13 mm (1/2”) Alligator B Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 13 mm (1/2”) Width > 13 mm (1/2”) Block Cracking Block size > 0.8 m2 (9 ft2) 0.1 m2 (1 ft2) < Block size ≤ 0.8 m2 (9 ft2) Block size < 0.1 m2 (1 ft2) Edge Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 13 mm (1/2”) Width > 13 mm (1/2”) A 16

Crack Type Severity Levels Low Medium High Longitudinal Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 13 mm (1/2”) Width > 13 mm (1/2”) Transverse Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 13 mm (1/2”) Width > 13 mm (1/2”) JPCP Pavements Corner Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) Longitudinal Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) Transverse Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) Third Stage Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) CRCP Pavements Longitudinal Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) Transverse Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) Colorado Department of Transportation The Colorado Department of Transportation (CDOT) developed the “Colorado DOT Distress Manual for HMA and PCC Pavements” to measure pavement distress for statewide uniformity (CDOT, 2004). Cracking information on HMA and PCC pavements are summarized separately which focus on manual field distress survey. The average crack width is implemented to define various severity levels for different cracks. Detailed crack information for CDOT are listed in Table 9. Table 9 Cracking Protocol for CDOT Crack Type Severity Levels Low Medium High HMA Pavements Fatigue Cracking Cracks with few connection are not spalled. Interconnected cracks may be slightly spalled. Cracks are severely spalled interconnected. Block Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) Edge Cracking Cracking with no breakup. Cracking with some breakup and raveling up to 10%. Considerable breakup or raveling more than 10%. Longitudinal Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) A 17

Crack Type Severity Levels Low Medium High Reflective Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) Transverse Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) PCC Pavements Corner Cracking Spalled crack ≤ 10% crack length; no faulting. Spalled crack > 10% crack length; or faulting ≤ 13 mm (1/2”). Spalled crack > 10% crack length; or faulting > 13 mm (1/2”). Durability (“D”) Cracking Tight cracks with no loose pieces. Well-defined cracks with some loose pieces. Well-developed cracks with significant loose material. Longitudinal Cracking Width ≤ 3 mm (1/8”) with no spalling. 3 mm (1/8”) < Width ≤ 13 mm (1/2”); or spalling ≤ 75 mm (3”); or faulting ≤ 13 mm (1/2”). Width > 13 mm (1/2”); or spalling > 75 mm (3”); or faulting > 13 mm (1/2”). Transverse Cracking Width ≤ 3 mm (1/8”) with no spalling. 3 mm (1/8”) < Width ≤ 5 mm (1/5”); or spalling ≤ 75 mm (3”); or faulting ≤ 5 mm (1/5”). Width > 5 mm (1/5”); or spalling > 75 mm (3”); or faulting > 5 mm (1/5”). Delaware Department of Transportation The Delaware Department of Transportation (DelDOT) developed the “DelDOT Pavement Data Dictionary” to define the distress types, severity levels, and methods of measurement for automated road rating data collection for the DelDOT (DelDOT, 2017). Cracking information on asphalt concrete (AC), Portland cement concrete (PCC), composite pavement (AC over PCC, or APC), surface treated (ST) pavements are summarized separately. Crack length and percentage of cracks for AC pavements whereas only crack percentage for PCC pavements should be reported. The wheel path is defined as shown in Figure 9. The average crack width is implemented to define the low, medium, and high severity levels for different cracks. Detailed crack information in DelDOT are listed in Table 10. For joint reflective cracking and transverse cracking, only cracks at least 3 feet in length are counted. A 18

Figure 9 Wheel path Definition in Protocol of DelDOT (DelDOT, 2017) Table 10 Cracking Protocol for DelDOT Crack Type Severity Levels Low Medium High AC Pavements Fatigue Cracking Cracks with few connection are not spalled. Interconnected cracks may be slightly spalled, with individual pieces of dimensions exceeding 305 mm (12”) in length. Cracks are severely spalled interconnected, with individual pieces of dimensions less 305 mm (12”) in length. Block Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”); or spalling ≤ 76 mm (3”). Width > 19 mm (3/4”); or spalling > 76 mm (3”). Non-Wheel Path Longitudinal Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”); or spalling ≤ 76 mm (3”). Width > 19 mm (3/4”); or spalling > 76 mm (3”). Transverse Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”); or spalling ≤ 76 mm (3”). Width > 19 mm (3/4”); or spalling > 76 mm (3”). APC Pavements Fatigue Cracking Cracks with few connection are not spalled. Interconnected cracks may be slightly spalled, with individual pieces of dimensions exceeding 305 mm (12”) in length. Cracks are severely spalled interconnected, with individual pieces of dimensions less 305 mm (12”) in length. Block Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”); or spalling ≤ 76 mm (3”). Width > 19 mm (3/4”); or spalling > 76 mm (3”). A 19

Crack Type Severity Levels Low Medium High Joint Reflective Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”); or spalling ≤ 76 mm (3”). Width > 19 mm (3/4”); or spalling > 76 mm (3”). Non-Wheel Path Longitudinal Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”); or spalling ≤ 76 mm (3”). Width > 19 mm (3/4”); or spalling > 76 mm (3”). PCC Pavements Map Cracking No Severity Levels Slab Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”); or spalling ≤ 76 mm (3”). Width > 19 mm (3/4”); or spalling > 76 mm (3”). ST Pavements Block Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”); or spalling ≤ 76 mm (3”). Width > 19 mm (3/4”); or spalling > 76 mm (3”). Edge Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) Fatigue Cracking Cracks with few connection are not spalled. Interconnected cracks may be slightly spalled, with individual pieces of dimensions exceeding 305 mm (12”) in length. Cracks are severely spalled interconnected, with individual pieces of dimensions less 305 mm (12”) in length. Non-Wheel Path Longitudinal Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”); or spalling ≤ 76 mm (3”). Width > 19 mm (3/4”); or spalling > 76 mm (3”). Transverse Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”); or spalling ≤ 76 mm (3”). Width > 19 mm (3/4”); or spalling > 76 mm (3”). Florida Department of Transportation The Florida Department of Transportation (FDOT) developed the “2017 Flexible Pavement Condition Survey Handbook” and “2017 Rigid Pavement Condition Survey Handbook” for conducting pavement condition survey (FDOT, 2017). These references describe the procedures for visual, mechanical and automated condition evaluations of the FDOT’s pavement system. For flexible pavement, cracking is rated by calculating the total percent affected area including Class IB cracking, Class II cracking, Class III cracking, raveling, and patching. Percentages for confined to wheel paths (CW) and outside of wheel paths (CO) are calculated separately for the predominant cracking class. The wheel path is defined as shown in Figure 10. For rigid pavement, transverse, longitudinal, and corner cracking are included along with other surface A 20

distresses for defect rating. Only cracks longer than 1 foot are recorded. Table 11 describes the detailed crack information for FDOT. Figure 10 Wheel path Definition in Protocol of FDOT (FDOT, 2017) Table 11 Cracking Protocol for FDOT Crack Type Severity Levels Low Medium High Flexible Pavements Class IB Cracking Hairline cracks: width ≤ 3 mm (1/8”) either in longitudinal or transverse direction; few connection without spalling or pumping. Class II Cracking Crack width > 3 mm (1/8”) & ≤ 6 mm (1/4”) either in longitudinal or transverse direction. Also include cracks formed cell ≤ 0.6 m (2’) on the longest side. Class III Cracking Crack width > 6 mm (1/4”) either in longitudinal or transverse direction. These cracks often exhibit moderate to severe spalling and form complete pattern. Rigid Pavements Transverse Cracking Width ≤ 3 mm (1/8”) 3 mm (1/8”) < Width ≤ 6 mm (1/4”); exhibit little or no faulting or debris. Width > 6 mm (1/4”) with loss of aggregate and intrusion of water or debris. Longitudinal Cracking Width ≤ 3 mm (1/8”) 3 mm (1/8”) < Width ≤ 6 mm (1/4”); exhibit little or no faulting or debris. Width > 6 mm (1/4”) with loss of aggregate and intrusion of water or debris. Corner Cracking Width ≤ 3 mm (1/8”) 3 mm (1/8”) < Width ≤ 6 mm (1/4”); exhibit little or no faulting or debris. Width > 6 mm (1/4”) with loss of aggregate and intrusion of water or debris. A 21

Georgia Department of Transportation The Georgia Department of Transportation (GDOT) developed the Pavement Condition Evaluation System (PACES) to standardize the terminologies of defect types on a pavement and the various severity levels of the defects (GDOT, 2005; Tsai and Wang, 2017). It describes a number of distresses which are manually identified and related to the pavement performance for flexible pavement and surface treatment. Load cracking, block/transverse cracking, and reflection cracking along with their corresponding severity levels are illustrated as shown in Table 12. The standard width of wheel path is 3 ft. Table 12 Cracking Protocol for GDOT Crack Type Severity Levels Level 1 Level 2 Level 3 Level 4 Load Cracking Tight single longitudinal cracks in or at the edge of the wheel path. Wider cracks than Level 1 only occur in the wheel path. Alligator cracks with many interconnection in the wheel path. Alligator cracking in the wheel path starts to pop out. Block/ Transverse Cracking Transverse cracking, longitudinal cracking, or a combination of them not in the wheel path. Block pattern appears with wider cracks compared with Level 1. The blocks are smaller and the cracks are wider than in level 2. NA Reflection Cracking Tight and single transverse cracks may or may not go across the entire lane. Underlying joints and cracks have reflected through the surface. Same pattern as level 2 but with wider cracks. NA Idaho Transportation Department The Idaho Transportation Department (ITD) uses “Pavement Rating Manual” to compute Cracking Index from 0.0 to 5.0 in 0.1 increments to evaluate pavement condition based on the size and location of cracks, percentage of the roadway surveyed that shows distress, and type of road surface (ITD, 2011). A 5.0 rating is good pavement with no visible distress and 0.0 indicates total pavement failure requiring reconstruction. Crack severity is determined via the depth, width, and thickness of a crack. Crack extent is quantified via the amount of cracking in a pavement section. Detailed crack severity and extent information for asphalt and concrete pavements are summarized in Table 13. Table 13 Cracking Protocol for ITD Crack Type Slight Moderate Heavy Flexible Pavements – Severity Levels Longitudinal and Transverse Cracking Width ≤ 3 mm (1/8”). 3 mm (1/8”) < Width ≤ 6 mm (1/4”); or a dip 76 Width > 6 mm (1/4”); or a dip 152 mm (6”) – 203 mm A 22

Crack Type Slight Moderate Heavy mm (3”) – 152 mm (6”) wide at the crack. (8”) wide or vegetation exists at the crack. Alligator Cracking Large alligator cracking, 0.9 m (3’) or more in size. Alligator cracking, 0.3 m (1’) to 0.6 m (2’) in size. Alligator cracking smaller than 0.3 m (1’) in size. Block Cracking Barely visible cracks with size 30 m (10’) by 30 m (10’). Cracks break into smaller cracks with block size 15 m (5’) to 30 m (10’). Block edges start to show alligator cracking and may form potholes. Edge Cracking Hairline alligator cracking. Wider crack that are easily visible at high speeds. Edge falls off or the very wide crack making the pavement look broken. Flexible Pavements – Extent Levels Transverse Cracking 1-4 cracks per 152 m (500’). 4-10 cracks per 152 m (500’). More than 10 cracks per 152 m (500’), or less than 150 m (50’) in between cracks. Longitudinal Cracking 30 m (100’) or less of cracking per 152 m (500’). 30 m (100’) – 152 m (500’) of cracking per 152 m (500’). More than 152 m (500’) of racking per 152 m (500’). Alligator, Block, and Edge Cracking 10% of less of the total evaluation section having cracking. 10-40% of the total evaluation section having cracking. More than 40% of the total evaluation section having cracking. Rigid Pavements – Severity Levels Transverse Slab Cracking Width ≤ 3 mm (1/8”). 3 mm (1/8”) < Width ≤ 10 mm (3/8”); or a dip 76 mm (3”) – 152 mm (6”) wide at the crack. Width > 13 mm (1/2”); or vegetation exists at the crack. Corner Cracking Hairline crack within 152 mm (6”) of the joint. Wider cracks without losing pieces. Wider cracks with losing pieces. Meander Cracking Hairline cracks. Meander cracks up to 13 mm (½”) in width and deep. Meander cracks larger than 13 mm (½”) in width and deep. Rigid Pavements – Extent Levels Transverse Slab, Corner, and Meander Cracking No cracking. 1-2 cracks per 10 slabs. More than 2 cracks per 10 slabs. Illinois Department of Transportation The Illinois Department of Transportation (IDOT) developed the “Illinois Highway Information System Roadway Information & Procedure Manual” to define what, why and how road A 23

information is collected, and when and how the information is entered into the Illinois Roadway Information System (IRIS) (IDOT, 2014). The appendix C of this manual, “Pavement Distress Codes”, lists the types of distress collected and reported into the IRIS for concrete and asphalt pavements. Detailed crack information for asphalt and concrete pavements are summarized in Table 14. Table 14 Cracking Protocol for IDOT Crack Type Severity Levels Low Medium High Concrete Pavements Durability (“D”) Cracking Plainly visible cracking pattern with no loose or missing pieces. Well defined cracks with some loose or missing pieces. Severe cracking with loose and/or missing pieces. Transverse Cracking Hairline crack with no spalling or faulting. Crack width ≤ 6 mm (1/4”) exhibiting some spalling and/or faulting. Crack width > 6 mm (1/4”) exhibiting much spalling and/or faulting. Longitudinal Cracking Crack width ≤ 13 mm (1/2”) with little or no spalling and/or faulting. NA Crack width > 13 mm (1/2”) and spalling and/or faulting may be present. Map Cracking and Scaling Low severity of map cracking with no scaling. Map cracking with 10% or less of the section scaled. Map cracking with greater than 10% of the section scaled. Flexible Pavements Alligator Cracking Hairline cracks with no or only a few interconnecting and no spalling. Pattern exists with interconnecting cracks and lightly spalling. Well defined small pieces exist with likely spalling. Block Cracking Hairline cracks with no or only a few interconnecting and no spalling. Pattern exists with interconnecting cracks and lightly spalling. Well defined block pieces exist with spalling at the edges. Transverse / Reflection Cracking Hairline cracks. Crack width ≤ 6 mm (1/4”) with low to moderate levels of associated distress. Crack width > 6 mm (1/4”) with moderate to severe levels of associated distress. longitudinal Cracking Crack width ≤ 6 mm (1/4”) with little or no spalling. 6 mm (1/4”) < Width ≤ 13 mm (1/2”) with minor spalling. Crack width > 13 mm (1/2”) with severe spalling. Edge Cracking Low or moderate cracking with no breakup or raveling. Low or moderate cracking with some breakup and/or raveling. Cracking with considerable breakup and/or raveling. A 24

Indiana Department of Transportation An identification guideline for pavement surface distresses were developed by Indiana Department of Transportation (INDOT) to improve the INDOT pavement preservation practices (Lee and Shields, 2010). The distress identification manual presents the different types of distresses for asphalt pavements, composite pavements, and PCCP. Each distress type is presented with descriptions, causes, measurements, and pictures. The manual is mainly based on the LTPP protocol and the INDOT Design Manual. Detailed crack information for asphalt and concrete pavements are summarized in Table 15. Table 15 Cracking Protocol for INDOT Crack Type Severity Levels Low Moderate High Asphalt or Composite Pavements Fatigue Cracking Cracks with few connection are not spalled or sealed. Interconnected cracks may be slightly spalled. Cracks are severely spalled interconnected forming a pattern. Reflection Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) Longitudinal Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) Thermal / Transverse Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) Width > 19 mm (3/4”) Block Cracking Width ≤ 2 mm (0.06”) 2 mm (0.06”) < Width ≤ 6 mm (1/4”) Width > 6 mm (1/4”) Edge Cracking Cracking with no breakup, deterioration, or loss of material. Cracking with some breakup and deterioration for up to 10% of the crack length. Considerable breakup and material loss for more than 10% of the crack length. Concrete Pavements Corner Breaks Spalled crack < 10% crack length; no faulting. Spalled crack > 10% crack length; or faulting ≤ 13 mm (1/2”). Spalled crack > 10% crack length; or faulting > 13 mm (1/2”). Transverse Cracking Width ≤ 3 mm (1/8”) with no spalling. Width > 3 mm (1/8”) & ≤ 6 mm (1/4”); or spalling ≤ 75 mm (3”); or faulting ≤ 6 mm (1/4”). Width > 6 mm (1/4”); or spalling > 75 mm (3”); or faulting > 6 mm (1/4”). Longitudinal Cracking Width ≤ 3 mm (1/8”) with no spalling or faulting. 3 mm (1/8”) < Width ≤ 6 mm (1/4”); or spalling ≤ 75 mm (3”); or faulting ≤ 6 mm (1/4”). Width > 6 mm (1/4”); or spalling > 75 mm (3”); or faulting > 6 mm (1/4”). Spalling of Joints and Cracks Spalls ≤ 75 mm 75 mm (3”) < Spalls ≤ 150 mm (6”) with loss of material. Spalls > 150 mm (6”) with loss and broken material or patching materials. A 25

Crack Type Severity Levels Low Moderate High (3”) wide with no loss of material or patching. Durability (“D”) Cracking Tight cracks with no loose pieces. Well-defined cracks with some loose pieces. Well-developed crack pattern with significant loose piece. Kansas Department of Transportation Distress information and its severity levels for flexible and rigid pavements are defined by KDOT (KDOT, 2017), where all pavement condition data except for Joint Distress can be collected as intensity and range images using an automated system since 2013. Range images are predominately used for automated cracking algorithms to detect pavement cracks. Intensity images are primarily used for identifying sealed cracks. Detailed crack information are summarized in Table 16. Table 16 Cracking Protocol for KDOT Crack Type Severity Levels 1 2 3 4 Flexible Pavements Fatigue Cracking Hairline alligator cracking, pieces not removable. Alligator cracking, pieces not removable, cracks spalled. Alligator cracking, pieces are loose and removable, pavement may pump. Pavement has shoved forming a ridge of material adjacent to the wheel path. Transverse Cracking Sealed transverse cracks with no roughness. No roughness, 6 mm (1/4”) or wider with no secondary cracking; or any width with secondary cracking less than 1.2 m (4’) per lane. Any width with noticeable roughness due to depression or bump. Also cracks that have greater than 1.2 m (4’) of secondary cracking but no roughness. Any width with significant roughness due to depression or bump. Secondary cracking will be more severe than level 3. Block Cracking Block size greater than 1.2 m (4’) with no secondary cracking. Block size less than 1.2 m (4’) with no secondary cracking. Block size greater than 1.2 m (4’) with secondary cracking. Block size less than 1.2 m (4’) with secondary cracking. Rigid Pavements Joint Distress Minimal cracking at each joint. Hairline cracking with minimum spalling. Significant cracking and spalling. Some Advanced cracking and severe spalling. A 26

Crack Type Severity Levels 1 2 3 4 patching done or necessary. Patching deteriorated and 0.6 m (2’) to 0.9 m (3’) wide along joint. Kentucky Transportation Cabinet Kentucky Transportation Cabinet (KYTC) developed a pavement distress identification manual to foster more uniform and consistent pavement distress evaluations (KYTC, 2009). The manual is intended to be a training aid for pavement raters and a field reference during the manual rating process. It is recommended the pavement condition evaluation should be performed at similar times each year only while the pavement is dry. Only two types of cracks: load related and other cracking, are included, as shown in Table 17. Table 17 Cracking Protocol for KYTC Crack Type Severity Levels Slight Moderate Severe Flexible Pavements Fatigue Cracking Width ≤ 6 mm (1/4”) without adjacent hairline cracking. 6 mm (1/4”) < Width ≤ 10 mm (3/8”) with light spalling and adjacent cracking. Width > 10 mm (3/8”) with severely spalling and possible potholes. Other Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 13 mm (1/2”) with slight secondary cracking. Width > 13 mm (1/2”) with significant secondary cracking. Portland Cement Pavements Other Cracking Width ≤ 3 mm (1/8”) 3 mm (1/8”) < Width ≤ 10 mm (3/8”) with slight secondary cracking. Width > 10 mm (3/8”) with significant secondary cracking. Louisiana Department of Transportation & Development Louisiana Department of Transportation & Development (DOTD) documents pavement surface distresses on asphalt pavements (AP), jointed concrete pavements (JCP), and continuously reinforced concrete pavements (CRCP) in the “Guidelines on the Application of Preventive Maintenance and Rehabilitation Practices for Pavement Preservation” (DOTD, 2010). The methods of evaluating such distresses could be as simple as a visual manual or an auto windshield survey for project level, or a high-speed pavement data collection vehicle for network level. Regarding the cracking data reported to the DOTD’s PMS, alligator cracking, longitudinal cracking, and transverse cracking should be reported for AP; longitudinal cracking and transverse cracking should be collected on JCP; longitudinal cracking, transverse cracking, and map cracking should be measured on CRCP. Unfortunately, the definition of severity level for these cracking distresses are not defined in this manual. A 27

Maryland Department of Transportation The Maryland Department of Transportation (MDOT) detects measures and rates pavement cracks in accordance with the most recent AASHTO R 55, Highway Performance Monitoring System (HPMS) field manual, and state specific requirements for all pavement images. The pavement cracking data is obtained from pavement images collected via an automatic system. The area between the inside edge of left and right pavement markings will be established for cracking detection. The wheel path zones are centered in the rating area with a width of 1 m (3.33 ft) each. The center of each wheel path zone is a distance of 6.0 ft to relate to a standard truck. The total linear footage of transverse and longitudinal cracks in five zones, including Left Edge, Left Wheelpath, Center, Right Wheelpath, and Right Edge, will be reported. For asphalt pavements, the Functional Crack Density (the sum of all unsealed transverse crack lengths and all unsealed longitudinal non-wheelpath crack lengths divided by the rated area) and the Structural Crack Density (the sum of all longitudinal cracks (sealed and unsealed) within each wheelpath divided by the rated area) will be calculated. The rated area is the entire pavement area within the inside edges of the pavement markings. The percent cracking of continuously reinforced concrete is the total area of all concrete patching, asphalt patching, longitudinal cracking, and punchouts divided by the rated pavement area. The percent cracking of jointed concrete surfaces for HPMS reporting is the percentage of total slabs on jointed concrete pavements, which are cracked per the most recent HPMS field manual guidance. Massachusetts Department of Transportation “Pavement Management Instruction Manual” defines pavement defects for determining the Pavement Condition Index as well as providing data that allow agencies to select the appropriate surface treatment depending on the type and severity of individual defects (MassDOT, 2005). Alligator cracking, transverse cracking, and longitudinal cracking are evaluated and recorded by the degree of distress and area affected. Detailed crack information in this manual are summarized in Table 18. Table 18 Cracking Protocol for MassDOT Crack Type Severity Levels Slight Moderate Severe Fatigue Cracking Hairline cracking with no or few interconnection. 6 mm (1/4”) < Distortion ≤ 13 mm (1/2”) with pattern cracking having light spalling. Distortion > 13 mm (1/2”) with well-defined crack pattern having severely spalling and possible potholes. Transverse Cracking Width ≤ 3 mm (1/8”) 3 mm (1/8”) < Width ≤ 13 mm (1/2”) Width > 13 mm (1/2”) Longitudinal Cracking Width ≤ 3 mm (1/8”) 3 mm (1/8”) < Width ≤ 13 mm (1/2”) Width > 13 mm (1/2”) A 28

Michigan Department of Transportation “Chapter 5: Signs of Pavement & Bridge Distress and Fix Selection Guidelines” in the “Project Scoping Manual” provides examples of common distresses and potential fixes for various type of distresses on Michigan’s pavements (MDOT, 2017) with the LTPP protocol being their basis. The cracking on flexible pavements, rigid pavements, and composite pavements are summarized in Table 19. Table 19 Cracking Protocol for MDOT Crack Type Severity Levels Low Medium High Flexible Pavements Fatigue Cracking Cracks with few connection are not spalled. Interconnected cracks may be slightly spalled. Cracks are severely spalled interconnected. Block Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) with low severity cracking. Width > 19 mm (3/4”) with moderate to high severity cracking. Longitudinal Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) with low severity cracking. Width > 19 mm (3/4”) with moderate to high severity cracking. Transverse Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) with low severity cracking. Width > 19 mm (3/4”) with moderate to high severity cracking. Rigid Pavements Longitudinal Cracking Width ≤ 3 mm (1/8”) with no spalling 3 mm (1/8”) < Width ≤ 13 mm (1/2”); or spalling ≤ 75 mm (3”); or faulting ≤ 13 mm (1/2”). Width > 13 mm (1/2”); or spalling > 75 mm (3”); or faulting > 13 mm (1/2”). Transverse Cracking Width ≤ 3 mm (1/8”) with no spalling 3 mm (1/8”) < Width ≤ 6 mm (1/4”); or spalling ≤ 75 mm (3”); or faulting ≤ 6 mm (1/4”). Width > 6 mm (1/4”); or spalling > 75 mm (3”); or faulting > 6 mm (1/4”). Composite Pavements Reflective Cracking and Joints Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 19 mm (3/4”) with low severity cracking. Width > 19 mm (3/4”) with moderate to high severity cracking. Minnesota Department of Transportation “Pavement Distress Identification Manual” describes the pavement rating procedures used by the Minnesota Department of Transportation (MnDOT), the various types of pavement distresses measured by MnDOT, and the pavement rating indices and how they are calculated (MnDOT, 2011). It defines pavement surface distresses which should be collected and reported to MnDOT PMS on bituminous, concrete and composite pavements. The Surface Rating (SR) is the crack A 29

and surface distress index for MnDOT with a 0.0 – 4.0 rating scale. The higher the SR number, the less amount of cracking is present. A new road has a SR of 4.0. The crack information for different pavement surfaces are summarized in Table 20. Different from many other protocols, this manual does not rely on crack width at all to define severity levels. Only the presence of cracking but no severity level is defined for alligator cracking and multiple cracking on asphalt pavements, “D” cracking on JPCP and CRCP pavements, and transverse cracking on CRCP pavements. Table 20 Cracking Protocol for MnDOT Crack Type Severity Levels Low Medium High Asphalt Pavements Alligator Cracking No degree of severity Multiple Cracking No degree of severity Longitudinal Joint Cracking A single crack, at least 0.9 m (3’) long, parallel to the centerline of the roadway, including a crack that has been route and sealed as long as the sealant is in good condition. Any crack running parallel to the centerline of the roadway with adjacent low severity random cracking, less than 0.3 m (12”) apart. There may also be a small amount of patching or popouts. Cracks that have been repaired with hot mix or slurry materials and are in good condition are also rated as medium. Any crack running parallel to the centerline of the roadway with significant adjacent random cracking 0.3 m (12”) or more apart), have large areas of spalling, missing material and/or potholes. Longitudinal Cracking Transverse Cracking Any crack, at least 1.8 m (6’) long, running transverse to the centerline of the roadway, including cracks that jog at a junction with a longitudinal crack, with no random cracking. Any crack running transverse to the centerline of the roadway, with adjacent low severity random cracking, less than 0.3 m (12”) apart. There may also be a small amount of patching or popouts. Cracks that have been repaired with hot mix or slurry materials and are in good condition are also rated as medium severity. Any crack running transverse to the centerline of the roadway with significant adjacent random cracking 0.3 m (12”) or more apart), have large areas of spalling, missing material and/or potholes. JPCP Pavements Durability No degree of severity A 30

Crack Type Severity Levels Low Medium High (“D”) Cracking Transverse & Longitudinal Joint Cracking Spalling occurs a minimum of 50 mm (2”) from the edge of the joint. NA Spalling occurs a minimum of 75 mm (3”) from the edge of the joint. CRCP Pavements Durability (“D”) Cracking No degree of severity Transverse Cracking No degree of severity Montana Department of Transportation Montana Department of Transportation (MDT) has applied its Data Collection Vehicle to collect pavement distress data including rutting, roughness, and cracking since 2011 (MDT, 2014). Alligator cracking and miscellaneous cracking are defined as load and non-load associated cracking, individually. The Alligator Cracking Index and Miscellaneous Cracking Index ranging from 0 to 100 scale are calculated to represent the cracking condition. These two indexes are further combined with the Ride Index and Rut Index into the Overall Performance Index, which is used to describe the “general health” of a route. Nebraska Department of Roads The “Surface Distress Survey Manual” was developed to assist the Nebraska Department of Roads (NDOR) personnel in conducting pavement surface distress evaluation using the windshield survey for the Nebraska State Highway network (NDOR, 2012). Three severity levels are defined to answer the question of “how bad is the problem”, while six extent levels are illustrated to answer the question of “how big is the problem”, separately. Detailed crack information is summarized in Table 21. Table 21 Cracking Protocol for NDOR Crack Type Severity Levels Low Moderate High Flexible Pavements Alligator Cracking Hairline cracks ≤ 3 mm (1/8”) wide with few interconnection. 3 mm (1/8”) < Width ≤ 6 mm (1/4”) forming an alligator pattern. Width > 6 mm (1/4”) may have loose piece and spalled edge. Edge Cracking Hairline cracking ≤ 6 mm (1/4”) wide. 6 mm (1/4”) < Width ≤ 13 mm (1/2”) or with alligator pattern. Width > 13 mm (1/2”) or with alligator pattern and loosing pieces. Longitudinal Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 13 mm (1/2”) Width > 13 mm (1/2”) A 31

Crack Type Severity Levels Low Moderate High Grid Block Cracking Width ≤ 6 mm (1/4”) 6 mm (1/4”) < Width ≤ 13 mm (1/2”) 13 mm (1/2”) < Width ≤ 50 mm (2”) is “High”; Width > 50 mm (2”) is “Extreme”. Transverse Cracking Hairline cracking ≤ 6 mm (1/4”) wide. 6 mm (1/4”) < Width ≤ 13 mm (1/2”) with little or no spalling. 13 mm (1/2”) < Width ≤ 50 mm (2”) is “High”; Width > 50 mm (2”) is “Extreme”. Rigid Pavements Slab Cracking I No degree of severity Slab Cracking II No degree of severity New Jersey Department of Transportation The official pavement distress manual for New Jersey Department of Transportation (NJDOT) is not available online at this time. Vitillo et al. (2009) developed a Pavement Distress Identification Manal for flexible and rigid pavements for automated distress evaluation system for NJDOT. Limited information is provided in this report regarding pavement distresses. Multiple/Alligator cracking, transverse cracking, and longitudinal cracking should be collected and reported for flexible pavements. Only Multiple/Alligator cracking is surveyed on rigid pavements. The severity levels of those cracking distress follows the FHWA LTPP protocol. New Mexico Department of Transportation New Mexico Department of Transportation (NMDOT) lists and classifies the types of distress commonly found in both Portland Cement Concrete Pavements and Asphalt Pavements in the “Pavement Maintenance Manual” (NMDOT, 2007). Longitudinal cracking, transverse cracking, alligator/fatigue cracking, and edge cracking are collected and reported for flexible pavements. Longitudinal cracking, transverse and diagonal cracking are needed for rigid pavements. With the development of automatic pavement distress detection, Bandini et al. (2012) proposed an improved distress data protocol for flexible and rigid pavements to reduce variability in the distress ratings. In the new protocol, alligator cracking includes alligator cracking and longitudinal cracking located within the wheel path. Longitudinal cracking outside the wheel path and edge cracks are classified as longitudinal cracking. For rigid pavements, the distress types remain the same as the old manual and all severity levels are required to represent pavement condition and serviceability. Detailed cracking severity and extent for flexible pavements in the updated manual for NMDOT are summarized in Table 22. The length of the sample section in Table 22 is 0.1 mile. A 32

Table 22 Cracking Protocol for NMDOT Crack Type Severity Levels Extent Alligator/Fatigue Cracking Low: Hairline cracks ≤ 3 mm (1/8”) wide with few interconnection. Medium: Fully developed cracks wider than 3 mm (1/8”), lightly spalled. High: Severely spalled, cells rock, and may pump. Low: 1% to 30% of sample section. Medium: 31% to 60% of sample section. High: 61% or more of sample section. Longitudinal Cracking Low: Width ≤ 6 mm (1/4”) or sealed with sealant in good condition. Medium: 6 mm (1/4”) < Width ≤ 19 mm (3/4”) with some spalling. High: Width > 19 mm (3/4”). Low: 1% to 30% of sample section. Medium: 31% to 60% of sample section. High: 61% or more of sample section. Transverse Cracking Low: Width ≤ 6 mm (1/4”) or sealed with sealant in good condition. Medium: 6 mm (1/4”) < Width ≤ 19 mm (3/4”) with some spalling. High: Width > 19 mm (3/4”). Low: 1% to 30% of sample section. Medium: 31% to 60% of sample section. High: 61% or more of sample section. New York State Department of Transportation New York State Department of Transportation (NYSDOT) developed the “Network Level Pavement Condition Assessment” to standardize the procedures to assess and quantify network level pavement conditions (NYSDOT, 2010). Surface distresses and ride quality are evaluated at network level while structural capacity and friction are limited to project level data collection. Pavement Surface Rating is conducted by region-based crews traveling at the posted speed limit to assign a condition rating from “1” to “10” based on the distresses appearing on pavement surfaces and identify the presence of specific types of distress called Dominant Distresses. Surface Rating and Dominant Distresses are combined with ride quality, rutting and faulting to calculate the Pavement Condition Index to assess pavement conditions. It is important to reiterate that the Surface Rating is based only on the severity and extent of cracking on pavement surfaces. The Surface Rating does not reflect the type of cracking nor its location or orientation. Other types of distress such as flushing, shoving, raveling, rutting or faulting are not included. Table 23 lists the Surface Rating for different pavement conditions. Table 23 Summary of Surface Rating in Protocols of NYSDOT Rating Condition/Description 9-10 Excellent – No surface distress. 7-8 Good – Surface distress beginning to show. 6 Fair – Surface distress is clearly visible. 1-5 Poor – Distress is frequent and severe. U Under Construction – not rated due to ongoing work. A 33

The Dominant Distresses considered in the NYSDOT Rating Procedure are alligator cracking, faulting, spalling and widening dropoff. Alligator cracking on flexible and overlaid pavements is reported in the wheel path. Alligator cracking is classified as “isolated” (Ai) if it occurs on less than 20% of the length of the segment, or “general” (Ag) if it occurs on more than 20% of the length. North Carolina Department of Transportation North Carolina Department of Transportation (NCDOT) developed “Pavement Condition Survey Manual” to assist personnel in conducting condition survey of the paved road network (NCDOT, 2012). Different from other manuals which define multiple cracking categories, only alligator cracking and transverse cracking are collected and reported for flexible pavements. The alligator cracking contains longitudinal cracking and edge cracking while the transverse cracking includes block cracking. The specifications of pavement distresses on rigid pavements are not provided. Detailed crack information in this protocol are summarized in Table 24. Table 24 Cracking Protocol for NCDOT Crack Type Severity Levels Light Moderate Severe Alligator Cracking Hairline cracks ≤ 3 mm (1/8”) wide with few interconnection. 3 mm (1/8”) < Width ≤ 6 mm (1/4”) forming an alligator pattern. Width > 6 mm (1/4”) may have loose piece, spalled edge, or potholes. Transverse Cracking Hairline cracking ≤ 6 mm (1/4”) wide without spalling or block. 6 mm (1/4”) < Width ≤ 13 mm (1/2”) with blocks 1.2 m2 (10 ft2) or larger, little or no spalling. Width > 13 mm (1/2”) with smaller blocks 0.2~1.2 m2 (2~10 ft2). Ohio Department of Transportation Ohio Department of Transportation (ODOT, 2006) developed the “Pavement Condition Rating System” to provide a uniform procedure for identifying and describing pavement distress in terms of severity and extent. Three levels of severity (Low, Medium and High) and three levels of extent (Occasional, Frequent, and Extensive) are defined. The pavement condition rating (PCR) is a comprehensive index reflecting the overall condition of pavements with varying distress types, severity levels, and extents. PCR has a range from 0 to 100: a PCR of 100 represents a perfect pavement with no observable distress and a PCR of 0 represents a pavement with all distresses present with “High” levels of severity and “Extensive” levels of extent. Severity and extent of cracking distresses in this protocol for flexible pavements, composite pavements, jointed concrete pavements and continuous reinforced concrete pavements are summarized in Table 25. A 34

Table 25 Cracking Protocol for ODOT Crack Type Severity Levels Extent Low Medium High Occasional Frequent Extensive Flexible Pavements Wheel Track Cracking Single/multiple cracks < 6 mm (1/4") Multiple cracks > 6 mm (1/4") Alligator > 6 mm (1/4") with spalling < 20% 20 - 50% > 50% Block & Transverse Cracking > 1.8 m × 1.8 m (6’ × 6’) or transverse crack 1.8 m × 1.8 m (6’ × 6’) to 0.9 m × 0.9 m (3’ × 3’) < 0.9 m × 0.9 m (3’ × 3’) < 20% 20 - 50% > 50% Longitudinal Cracking Single, < 6 mm (1/4”), no spalling Single/multiple 6 – 25 mm (1/4 - 1”), some spalling Multiple, > 25 mm (1”), spalling < 15 m (50’) per 30 m (100’) 15 – 45 m (50 – 150’) per 30 m (100’) > 45 m (150’) per 30 m (100’) Edge Cracking Tight, < 6 mm (1/4”) > 6 mm (1/4"), some spalling > 6 mm (1/4"), moderate spalling < 20% 20 - 50% > 50% Thermal Cracking < 6 mm (1/4”) 6 – 25 mm (1/4 - 1”) > 25 mm (1”) CS > 60 m (200’) CS 23 – 60 m (75 - 200’) CS < 23 m (75’) Composite Pavements Transverse Cracking (Unjointed Base) < 6 mm (1/4”), no spalling 6 – 25 mm (1/4 - 1”), > 0.5 spalled > 25 mm (1”), > 0.5 spalled CS > 4.6 m (15’) CS 3– 4.6 m (10 - 15’) CS < 3 m (10’) Joint Reflection Cracking (Jointed Base) < 6 mm (1/4”), no spalling 6 – 25 mm (1/4 - 1”), > 0.5 spalled > 25 mm (1”), > 0.5 spalled < 20% 20 - 50% > 50% Intermediate Transverse Cracking (Jointed Base) < 6 mm (1/4”), no spalling 6 – 25 mm (1/4 - 1”), > 0.5 spalled > 25 mm (1”), > 0.5 spalled < 10% of the slabs 10 – 30% of the slabs > 30% of the slabs Longitudinal Cracking < 6 mm (1/4”), no spalling 6 – 25 mm (1/4 - 1”), > 0.5 spalled > 25 mm (1”), > 0.5 spalled < 15 m (50’) per 30 m (100’) 15 – 45 m (50 – 150’) per > 45 m (150’) per 30 m (100’) A 35

Crack Type Severity Levels Extent Low Medium High Occasional Frequent Extensive 30 m (100’) Jointed Concrete Pavements Transverse Cracking (Plain Concrete) Hairline Hairline – 5 mm (3/16”) > 5 mm (3/16”) < 10% of the slabs 10 – 30% > 30% Transverse Cracking (Reinforced Concrete) No failed cracks 1 failed crack > 1 failed crack 5 - 10% 10 – 30% > 30% slabs Longitudinal Cracking Hairline 6 – 25 mm (1/4 - 1”) > 25 mm (1”) < 5% 5 – 20% > 20% Continuous Reinforced Concrete Pavements Transverse Crack Spacing CS 1– 1.5 m (3 - 5’) CS < 1 m (3’) CS < 1 m (3’) many cracks intersect < 20% 20 – 50% > 50% Longitudinal Cracking Hairline 6 – 25 mm (1/4 - 1”) > 25 mm (1”) < 5% 5 – 15% > 15% Oklahoma Department of Transportation Oklahoma Department of Transportation (ODOT, 2005) developed the “Pavement Management Distress Rating Guide” to provide thorough and clear descriptions of ODOT’s definitions of pavement distresses and guidelines for rating and recording of distress data. The distresses are measured from collected pavement images and recorded according to this manual. Distress on asphalt concrete pavements (AC), jointed concrete pavements (JCP), and continuously reinforced concrete pavements (CRCP) are illustrated to achieve consistent, accurate, and repeatable distress ratings for the pavement management system. Transverse cracking that projects within 45 degree of perpendicular to the pavement centerline and longer than 2 m (6’) are reported. Cracks other than transverse cracking occurring in the 0.75 m (2.5’) wide wheel paths are defined as fatigue cracking. Any crack in the non-wheel path areas and not already identified as transverse crack is classified as miscellaneous cracking. By default, crack information is recorded and reported for every 0.01-mile section. Detailed cracking information in this protocol are summarized in Table 26. A 36

Table 26 Cracking Protocol for ODOT Crack Type Severity Levels AC Pavements Fatigue Cracking Level 1: Longitudinal cracks with few or no intersecting cracks, or polygon crack (> 0.1 m2 or 1 ft2) in the wheel path. Level 2: Interconnected cracks in the wheel path whose crack width ranges from hairline to 6 mm (1/4”). Polygon crack may have some spalling. Level 3: Interconnected cracks in the wheel path whose crack width is larger than 6 mm (1/4”). Polygon crack is spalled with some. Transverse Cracking Level 1: Width ≤ 6 mm (1/4”) or sealed crack in good condition. Level 2: 6 mm (1/4”) < Width ≤ 12 mm (1/2”). Level 3: 12 mm (1/2”) < Width ≤ 25 mm (1”) or spalling crack with interconnected pieces less than 50 mm (2”) wide. Level 4: Width > 25 mm (1”) or spalling crack with interconnected pieces greater than 50 mm (2”) wide. Miscellaneous Cracking Level 1: Non-wheel path longitudinal crack width ≤ 6 mm (1/4”) and without interconnected cracking. Level 2: Non-wheel path longitudinal crack width > 6 mm (1/4”) or interconnected cracking width ≤ 6 mm (1/4”). Level 3: Interconnected cracking width > 6 mm (1/4”) that form polygons. JCP Pavements Corner Break Level 1: Width ≤ 6 mm (1/4”) with no spalling. Level 2: Width > 6 mm (1/4”) with spalling or settlement; or sealed crack unless it is apparent the crack is less than 6 mm (1/4”) wide. Durability (“D”) Cracking Level 1: “D” cracks which are tight with no loose pieces or patches. Level 2: “D” cracks with loose pieces or missing pieces that have been displaced or patched. Longitudinal or Transverse Cracking Level 1: Width ≤ 6 mm (1/4”) with no spalling. Level 2: Width > 6 mm (1/4”); or sealed crack unless it is apparent the crack is less than 6 mm (1/4”) wide. CRCP Pavements Longitudinal Cracking Level 1: Width ≤ 6 mm (1/4”) with no spalling. Level 2: Width > 6 mm (1/4”) or spalled. Oregon Department of Transportation Oregon Department of Transportation (ODOT, 2010) applies the “Pavement Distress Survey Manual” to identify and quantify the amount and severity of surface distress in a given pavement segment. The distress types and procedures for rating state highway network on Asphalt Concrete Pavements (AC), Jointed Portland Cement Concrete Pavements (JCP), and Continuously Reinforced Portland Cement Concrete Pavements (CRCP) are presented in this manual. Two-person trained crews will conduct condition surveys according to the distress identification procedures in a slow-moving vehicle operating on the adjacent shoulder. Detailed cracking information in this protocol are summarized in Table 27. A 37

Table 27 Cracking Protocol for ODOT Crack Type Severity Levels Low Medium High AC Pavements Fatigue Cracking Cracks with few connection are not spalled. Interconnected cracks may be slightly spalled. Cracks are severely spalled and interconnected. Transverse and Block Cracking Width ≤ 6 mm (1/4”) or sealed crack in good condition. 6 mm (1/4”) < Width ≤ 19 mm (3/4”) and adjacent low severity random cracking. Width > 19 mm (3/4”) and moderate to high severity random cracking. Longitudinal Cracking Width ≤ 6 mm (1/4”) or sealed crack in good condition. 6 mm (1/4”) < Width ≤ 19 mm (3/4”) and adjacent low severity random cracking. Width > 19 mm (3/4”) and moderate to high severity random cracking. JCP Pavements Corner Break Width ≤ 3 mm (1/8”) with no spalling. 3 mm (1/8”) < Width ≤ 13 mm (1/2”); or spalling ≤ 75 mm (3”); or faulting ≤ 13 mm (1/2”). Width > 13 mm (1/2”); or spalling > 75 mm (3”); or faulting > 13 mm (1/2”). Corner Crack Tight cracks with no loose pieces. Well-defined cracks with some loose pieces. Well-developed cracks with significant loose piece. Longitudinal Cracking Width ≤ 3 mm (1/8”) with no spalling. 3 mm (1/8”) < Width ≤ 13 mm (1/2”); or spalling ≤ 75 mm (3”); or faulting ≤ 13 mm (1/2”). Width > 13 mm (1/2”); or spalling > 75 mm (3”); or faulting > 13 mm (1/2”). Transverse Cracking Width ≤ 3 mm (1/8”) with no spalling. 3 mm (1/8”) < Width ≤ 6 mm (1/4”); or spalling ≤ 75 mm (3”); or faulting ≤ 6 mm (1/4”). Width > 6 mm (1/4”); or spalling > 75 mm (3”); or faulting > 6 mm (1/4”). CRCP Pavements Longitudinal Cracking Width ≤ 3 mm (1/8”) with no spalling. 3 mm (1/8”) < Width ≤ 13 mm (1/2”); or spalling ≤ 75 mm (3”); or faulting ≤ 13 mm (1/2”). Width > 13 mm (1/2”); or spalling > 75 mm (3”); or faulting > 13 mm (1/2”). Transverse Cracking Crack spalling ≤ 10% of crack length. Crack spalling > 10% and ≤ 50% of crack length. Crack spalling > 50% of crack length. Pennsylvania Department of Transportation Pennsylvania Department of Transportation (PennDOT, 2017) recently issued the “Automated Pavement Condition Survey Field Manual” with the purpose of providing quantified and location-specific condition data on Pennsylvania's state highway network. Distresses on Bituminous surfaced pavements and rigid pavements are defined individually. Wheel path definitions are illustrated in Figure 11, which vary slightly with different lane widths. Fatigue A 38

cracking, transverse cracking, and miscellaneous cracking are reported for bituminous surface pavements. Transverse cracking and longitudinal cracking are collected and reported for rigid pavements. Detailed cracking information are summarized in Table 28. Figure 11 Wheel path Definition in Protocol of PennDOT (PennDOT, 2017) Table 28 Cracking Protocol for PennDOT Crack Type Severity Levels Low Medium High Bituminous Pavements Fatigue Cracking Average crack width ≤ hairline Hairline < Width ≤ 6 mm (1/4") Alligator > 6 mm (1/4") Transverse Cracking Hairline < Width ≤ 6 mm (1/4") 6 mm (1/4") < Width ≤ 13 mm (1/2") Width > 13 mm (1/2”) Miscellaneous Cracking Hairline < Width ≤ 6 mm (1/4") 6 mm (1/4") < Width ≤ 13 mm (1/2") Width > 13 mm (1/2”) Rigid Pavements Longitudinal Cracking Hairline < Width ≤ 6 mm (1/4") Width ≤ 6 mm (1/4”); spalling ≥ 50 mm (2”) for ≤ 50% length. Width > 6 mm (1/4”); spalling ≥ 50 mm (2”) for > 50% length. Transverse Cracking Width ≤ hairline with no spalling. Hairline < Width ≤ 6 mm (1/4”); or spalling ≥ 50 mm (2”); or faulting ≥ 6 mm (1/4”). Width > 6 mm (1/4”) or spalling ≥ 50 mm (2”) or faulting ≥ 13 mm (1/2”). A 39

South Dakota Department of Transportation South Dakota Department of Transportation (SDDOT) developed the “Pavement Management Visual Distress Survey Manual” to elaborate the distress survey to better evaluate the condition of pavements (SDDOT, 2017). The survey is conducted via windshield methodology with two- person team driving along shoulders. The extents and severity levels for each distress are defined primarily based upon those given in the LTPP manual. Detailed cracking information in this protocol are summarized in Table 29. Table 29 Cracking Protocol for SDDOT Crack Type Severity Levels Low Medium High Flexible Pavements Fatigue Cracking Fine parallel cracks in the wheel path. Alligator pattern clearly developed. Alligator pattern clearly developed with spalling and distortion. Block Cracking Random longitudinal cracks between the wheel paths, or blocks > 1.8 m (6’) per side. Blocks 0.9 m ~ 1.8 m (3’ ~ 6’) per side. Blocks < 0.9 m (3’) per side. Transverse Cracking Width ≤ 6 mm (1/4”), or sealed crack < 13 mm (1/2"). 6 mm (1/4”) < Width ≤ 25 mm (1”) and/or <6 mm (1/4”) depressions. Width > 25 mm (1”) or crack width & depression > 6 mm (1/4”). Rigid Pavements Corner Cracking Crack not spalled with no faulting & piece not broken. Crack spalled slightly; or faulting ≤ 13 mm (1/2”). Spalled crack; or faulting > 13 mm (1/2”). Durability (“D”) Cracking Light cracks with no loose or missing pieces. Well-defined cracks with some loose or missing pieces. Well-developed cracks with significant loose piece. CRCP Block Cracking Closely spaced Transverse shrinkage cracks with occasional interconnected Longitudinal cracks occurring perpendicular to the parent Transverse cracks. The pattern between the Longitudinal and Transverse cracks create a “block” or rectangular pattern. The pattern between the Longitudinal and Transverse cracks create a “block” or rectangular pattern. The cracking pattern is distorted and spalls are present in cracks. Longitudinal Cracking No degree of severity South Carolina Department of Transportation The “Rating Bituminous Pavement Distresses at SCDOT” and “Rating Concrete Pavement Distresses at SCDOT” define the rating methods to identify and record distresses observed on A 40

Bituminous and Concrete pavement segments (SCDOT, 2018). Fatigue cracking, longitudinal cracking, and transverse cracking are defined for asphalt pavements and summarized in Table 30. Table 30 Cracking Protocol for SCDOT Crack Type Severity Levels Low Moderate High Flexible Pavements Fatigue Cracking Fine cracks in the wheel path. 6 mm (1/4”) < Width ≤ 13 mm (1/2”) with alligator pattern. Crack width > 13 mm (1/2”) with separate, spalled, and breaking up alligator pattern. Longitudinal Cracking Crack width ≤ 6 mm (1/4”) with little or no spalling. 6 mm (1/4”) < Width ≤ 13 mm (1/2”) with spalling. Crack width > 13 mm (1/2”) with severe spalling or multiple severity cracking. Transverse Cracking Crack width ≤ 6 mm (1/4”) with little or no spalling. 6 mm (1/4”) < Width ≤ 13 mm (1/2”) with spalling. Crack width > 13 mm (1/2”) with severe spalling or multiple severity cracking. Concrete Pavements Spalled Cracks No degree of severity Shattered Slabs No degree of severity Slabs with Longitudinal Cracking No degree of severity Texas Department of Transportation The “Pavement Management Information System (PMIS) Rater’s Manual for Fiscal Year 2016” defines the methods for visual pavement evaluation of Flexible Pavements, Continuously Reinforced Concrete Pavements (CRCP), and Jointed Concrete Pavements (JCP) sections (TxDOT, 2015). The purpose of the visual survey is to provide pavement condition data which can be used by itself or in combination with ride quality, structural adequacy, skid resistance, climate, and traffic data to assist in describing the overall condition of the State-maintained highway system. Most of the PMIS sections are 0.5 mile in length. If any section is under construction for more than half its length, it is not rated and marked as “under construction”. Windshield survey is performed by two raters traveling along the side of the road at no more than 24 KPH (15 MPH). On flexible pavement, all block cracking and alligator cracking, regardless of width, are rated and the percent block cracking area are determined. All longitudinal cracks at least 3 mm (1/8”) wide are measured as the feet of longitudinal cracking per station. All transverse cracking at least 3 mm (1/8”) wide are measured as the number of transverse cracking per station. A 41

On CRCP pavement, transverse cracking that have spalled is rated and the total number of spalled cracking reported. The average cracking spacing should be calculated to obtain the percentage of spalled transvers cracking as a measure of whether the CRCP slab is behaving as designed. For JCP pavement, slabs with longitudinal cracking travel from one transverse joint to the next transverse joint, or from one transverse joint to an edge joint and is over half the slabs length should be rated and the total number of slabs observed with longitudinal cracking should be reported. Utah Department of Transportation The Utah Department of Transportation (UDOT, 2002) describes the visual distress evaluation methods for flexible and jointed concrete pavements in the “Maintenance and Pavement Management”. The survey procedures observe and record the presence of specific types, severity, and extent of defects or distresses on pavement surfaces. Wheel paths are defined typically 0.6 m (2’) wide and are centered in a lane. For flexible pavements, average crack widths of 10 mm (3/8”) and 19 mm (3/4") are implemented to rate the severity levels for longitudinal, transverse, and block cracking. Only the transverse cracks with a minimum length of 1.2 m (4’) are recorded. For rigid pavements, average crack widths of 3 mm (1/8”) and 13 mm (1/2") are implemented to rate the severity levels for longitudinal, transverse, and block cracking. Detailed crack information described in this protocol are listed in Table 31. Table 31 Cracking Protocol for UDOT Crack Type Severity Levels Low Medium High Flexible Pavements Wheel Path Cracking Longitudinal cracks with no or few secondary cracks. Interconnected cracks starting to form an alligator pattern, dimensions > 305 mm (12”) length. Alligator pattern with dimensions < 305 mm (12”) length, or pumping of soil or pieces missing. Longitudinal Cracking (Non Wheel Path) Transverse Cracking Block Cracking Sealed cracks or unsealed cracks ≤ 10 mm (3/8”). 10 mm (3/8”) < Width ≤ 19 mm (3/4”); or secondary crack widths ≤ 10 mm (3/8”). Width > 19 mm (3/4”); or secondary crack widths > 10 mm (3/8”). Rigid Pavements Longitudinal Cracking Crack widths ≤ 3 mm (1/8”) without spalling or faulting. 3 mm (1/8”) < Width ≤ 13 mm (1/2”); or faulting ≤ 13 mm (1/2”); or spalling ≤ 75 mm (3”). Width > 13 mm (1/2”); or faulting > 13 mm (1/2”); or spalling > 75 mm (3”). A 42

Crack Type Severity Levels Low Medium High Transverse Cracking Crack widths ≤ 3 mm (1/8”) without spalling or faulting. 3 mm (1/8”) < Width ≤ 6 mm (1/4”); or faulting ≤ 6 mm (1/4”); or spalling ≤ 75 mm (3”). Width > 6 mm (1/4”); or faulting > 6 mm (1/4”); or spalling > 75 mm (3”). Corner Breaks One piece and no spalling or faulting. One piece and spalling ≤ 76 mm (3”) or faulting ≤ 13 mm (1/2”). Two or more pieces or spalling > 76 mm (3”) or faulting > 13 mm (1/2”). Vermont Agency of Transportation At the Vermont Agency of Transportation (VTrans), the “Asset Management and Performance Bureau Roadway Condition Assessment Collection Scope of Work” describes the condition assessment details used to analyze the pavement condition and provide input into the agency’s PMS for condition forecasting, budgeting and project programming (VTrans, 2017). Pavement cracking, roughness, and rutting are collected and reported by the consultant. Figure 12 Wheel path Definition (VTrans, 2017) Cracking distress is collected in terms of severity and extent, and aggregated into 0.05 mile sections. Automated identification and classification of cracks should be performed with the collected pavement images. Minimum crack detection resolution shall be 1 mm. Transverse cracking longer than 0.3 m (1’) should be reported. For a given section, the length of transverse cracking in each severity level should be recorded and reported. Wheel path cracking shall be reported separately for the left and right wheel paths. Miscellaneous non-wheel path cracking shall be reported separately for the left edge of lane, the center, and the right edge of lane. The wheel path definition is illustrated in Figure 12. Table 32 summarizes the detailed cracking information in this protocol. A 43

Table 32 Cracking Protocol for VTrans Crack Type Severity Levels Low Medium High Transverse Cracking Width ≤ 3 mm (1/8”) 3 mm (1/8”) < Width ≤ 6 mm (1/4”) Width > 6 mm (1/4”) Wheel Path Cracking Width ≤ 3 mm (1/8”) or few interconnected cracks with no developed pattern. 3 mm (1/8”) < Width ≤ 6 mm (1/4”) or interconnected cracks forming a pattern < 50% of the wheel path width. Width > 6 mm (1/4”) or interconnected cracks forming a pattern > 50% of the wheel path width. Miscellaneous Non-Wheel path Cracking Width ≤ 3 mm (1/8”) or few interconnected cracks with no developed pattern. 3 mm (1/8”) < Width ≤ 6 mm (1/4”) or interconnected cracks forming a pattern < 50% of the appropriate edge or lane center width. Width > 6 mm (1/4”) or interconnected cracks forming a pattern > 50% of the appropriate edge or lane center width. Virginia Department of Transportation The Virginia Department of Transportation (VDOT) implements the “Guide to Evaluating Pavement Distress Through the Use of Digital Images” for pavement distress definitions as well as how distress data are collected and evaluated by both contractors and state personnel (VDOT, 2012). This manual is updated to accommodate data collection through digital images, and for automated/semi-automated distress interpretation with digital images. The locations and sizes of the left and right wheel path as well as the center lane are defined in Figure 13, which vary slightly with different lane width. On roadways without pavement markings, rate a 10 foot width of pavement, beginning at the right edge. (1) Lane Width 12 ft or higher A 44

(2) 8.0 ft ≤ Lane Width ≤ 11.5 ft (3) 7.0 ft ≤ Lane Width ≤ 8.0 ft A 45

(4) Lane Width < 7.0 ft Figure 13 Wheel path Definition in Protocols of VDOT (VDOT, 2012) Distress on Bituminous concrete pavements (BIT, BOJ, BOC), overlays of PCC pavements (BOJ, BOC), jointed PCC pavements (JCP), and continuous reinforced concrete pavements (CRC) are summarized in this manual. Cracking equal to or less than 6 mm (1/4") wide is considered "closed" and those more than 6 mm (1/4") wide is considered "open". The length of transverse, longitudinal, and longitudinal lane joint cracking at each severity level should be recorded. The minimum length of longitudinal cracking and longitudinal lane joint cracking is 1 foot. The square feet of alligator cracking by severity level in the left and right wheel paths should be reported. For reflection cracking, all cracks appearing due to the movement at one joint should be reported as a single reflective cracking. For JCP pavements, the number of slabs affected by each distress type and the total number of joints are recorded. For CRC pavements, average transverse cracking spacing should be reported for the entire section. Table 33 summarizes the cracking types and corresponding severity levels in this protocol. Table 33 Cracking Protocol for VDOT Crack Type Severity Levels Asphalt Pavements Transverse Cracking Longitudinal Cracking Level 1: A crack with the sealant in good condition, or a closed, unsealed crack. Level 2: An open, unsealed crack, or any crack (sealed or unsealed) with adjacent random cracking. Longitudinal Lane Joint Cracking Level 1: A longitudinal paving joint with the sealant in good condition or an open, unsealed joint. Level 2: The longitudinal paving joint must be cracked with severe spalling, or adjacent random cracking. Alligator Cracking Level 1: A single sealed or unsealed longitudinal crack in the wheel path, or an area of cracks with no or few interconnecting cracks with no spalling. Level 2: An area of interconnecting cracks forming the characteristic alligator pattern; may have slight spalling. Level 3: An area of moderately, or severely spalled cracks forming the characteristics alligator pattern. Bituminous Overlays PCC Pavements Reflection Cracking Level 1: A crack with the sealant in good condition, or a closed, unsealed crack. Level 2: A crack with width more than or equal to 6mm (1/4”) but less than 19 mm (3/4"), or a crack with width less than 19 mm (3/4") and with adjacent random cracking and Level 1 or Level 2 crack with an adjacent Level-1 crack is rated as one crack of Level 2. Level 3: A crack with width ≥ 19 mm (3/4”), or a crack with width more than 6mm (1/4”) and with deterioration for a width greater than 150 mm (6”) and two adjacent Level 2 and/or Level 3 cracks are rated as one crack of Level 3. A 46

Crack Type Severity Levels JCP Pavements Corner Breaks Level 1: The crack is spalled for no more than ¼ of its length and the corner break is in one piece. Level 2: The crack is spalled for more than ¼ of its length or the corner break is in two or more pieces. Transverse Cracking Longitudinal Cracking Level 1: A crack that is well sealed so the width cannot be determined, or a closed crack that has no spalling. Level 2: An open crack, or any spalled crack. CRC Pavements Transverse Cracking Level 1: A closed transverse crack with no spalling. Level 2: An open transverse crack with no spalling. Level 3: Any transverse crack with spalling. Cluster Cracking Level 1: Clusters of three or more transverse cracks having an average spacing greater than 1 ft or less than or equal to 2 ft. Level 2: Clustered cracks with an average spacing of less than or equal to 1 ft. Longitudinal Cracking Level 1: A longitudinal crack with no spalling. Level 2: A longitudinal crack with less than or equal to ¼ of the crack length containing spalling. Level 3: A longitudinal crack with greater than ¼ of the crack length containing spalling. Washington State Department of Transportation Pavement distress data are collected using the Washington State Department of Transportation WSDOT's Pavement Distress Identification Van, which is equipped to record pavement profile (ride, faulting, and rutting) and video images of pavement surfaces. The data sets can be collected at highway speeds. WSDOT's “Pavement Surface Condition Rating Manual” was developed as a training aid and a field reference for pavement raters (WSDOT, 1992). It includes description, severity levels, and quantification process for each distress type. The distresses are categorized by pavement type (flexible or rigid) as either Core Program defects or optional defects. For flexible pavements, rutting and wear, alligator cracking, longitudinal cracking, transverse cracking, raveling, flushing, and patching are Core Program defects. For rigid pavements, cracking, joint and crack spalling, pumping and blowing, faulting and settlement, patching, and wear are Core Program defects. For flexible pavements, alligator cracking is measured and recorded as the percentage of the wheel path length. Percentage of the length of the surveyed segment is recorded for longitudinal cracking. Transverse cracking is counted for those that cut across most of at least one full wheel path in the rated lane (2 ft minimum crack length). The extent of transverse cracking is quantified as the frequency of occurrence, expressed as count per 100 ft of lane length. For rigid pavements, the extent of cracking (transversely, longitudinally, or diagonally) is quantified as the A 47

percentage of panels in the segment with cracking. Table 34 summarizes the cracking types for asphalt and concrete pavements. Table 34 Cracking Protocol for WSDOT Crack Type Severity Levels Asphalt Pavements Alligator Cracking Low: Branched, longitudinal, discontinuous thin cracks are beginning to interconnect and form the typical alligator pattern. There is no spalling along the cracks. A single, continuous crack may appear, usually along the wheel path, with frequent, intermittent smaller cracks running at angles to the primary crack. Medium: Cracking is completely interconnected and has fully developed an alligator pattern. Spalling appears at the edges of cracks. The pieces formed by the cracking may be predominantly large (305 mm (12”) or more in the longest dimension). The cracks may be greater than 6 mm (¼”) wide, but the pavement pieces are still in place. High: The pattern of cracking is well developed, with predominantly small pieces (less than 305 mm (12”) in the longest length). Spalling is very apparent at the crack. Individual pieces may be loosened and may rock under traffic. Pieces may be missing. Pumping of fines up through the cracks may be evident. Longitudinal Cracking Transverse Cracking Low: The cracks have very little or no spalling along the edges and are less than 6 mm (¼”) wide. If the cracks are sealed and the width of the crack before sealing is invisible, they should be classified as Low Severity. Medium: The cracks have little or no spalling, but they are greater than 6 mm (¼”) wide. There may be a few randomly spaced low severity connecting cracks near the main crack or at the corners of intersecting cracks. High: Cracks are spalled and there may be several randomly spaced cracks near the main crack or at the corners of intersecting cracks. Pieces are visibly missing along the crack, or the two sides of the crack do not match. At some point, this longitudinal cracking becomes alligator cracking. Block Cracking Low: Block size 3.7 m (12’) by 3.7 m (12’) and crack width less than 6 mm (¼”). Medium: Block size 1.8 m (6’) by 1.8 m (6’) and crack width over 6 mm (¼”). High: Block size 0.9 m (3’) by 0.9 m 3’ and crack is spalled. Portland Cement Concrete Pavements Cracking Low: 1 crack per panel. Medium: 2 or 3 cracks per panel. High: 4 or more cracks per panel. Wisconsin Department of Transportation Wisconsin Department of Transportation (WisDOT, 2002) developed the “Pavement Surface Evaluation and Rating (PASER) Manual for Asphalt Roads” and “Pavement Surface Evaluation and Rating (PASER) Manual for Concrete Roads” to assist local officials in understanding and rating surface conditions of asphalt and concrete pavements. The manuals define distress types A 48

and the causes of distresses, and provide a system to visually rate conditions. The rating data are further used for WisDOT local road inventory and as part of a computerized pavement management system named PASERWARE. In the Asphalt PASER Manual, transverse, reflection, slippage, longitudinal, block, and alligator cracking are defined to demonstrate different cracking conditions. Cracking is combined with surface defects, deformation, patches and potholes to evaluate and rate asphalt pavement surfaces with rating scale ranging from 10 – excellent condition to 1 – failed. In the Concrete PASER Manual, transverse slab cracking, D-cracking, corner cracking, and meander cracking are recorded with severity and extent levels. Surface defects, joints, pavement cracking, and pavement deformation are combined into a rating scale ranging from 10 to 1. A 49

References 1) Alabama Department of Transportation (ALDOT). 2009. Project Level Pavement Condition Data Collection Procedure. ALDOT-392. Montgomery, Alabama. 2) Alabama Department of Transportation (ALDOT). 2015. Network-Level Pavement Condition Data Collection Procedure. ALDOT-414-04. Montgomery, Alabama. 3) American Association of State Highway and Transportation Officials (AASHTO). 2013. Standard Practice for Quantifying Cracks in Asphalt Pavement Surfaces. AASHTO Designation: R 55-10. Washington, DC. 4) American Association of State Highway and Transportation Officials (AASHTO). 2018. Standard Practice for Quantifying Cracks in Asphalt Pavement Surfaces from Collected Pavement Images Utilizing Automated Methods, AASHTO Designation: R 85-18, Washington, DC. 5) ASTM Designation D5340−12. 2012. Standard Test Method for Airport Pavement Condition Index Surveys. West Conshohocken, PA, 2012, DOI: 10.1520/D5340-12. 6) ASTM Designation D6433−16. 2016. Standard Practice for Roads and Parking Lots Pavement Condition Index Surveys. West Conshohocken, PA, 2016, DOI: 10.1520/D6433-16. 7) Bandini et al. 2012. Improving NMDOT’s Pavement Distress Survey Methodology and Developing Correlations between FHWA’s HPMS Distress Data and PMS Data. New Mexico State University, Las Cruces, NM. 8) California Department of Transportation (Caltrans). 2015. Automated Pavement Condition Survey Manual. Sacramento, CA. 9) Colorado Department of Transportation (CDOT). 2004. Colorado DOT Distress Manual for HMA and PCC Pavements. Denver, CO. 10) Delaware Department of Transportation (DelDOT). 2017. DelDOT Pavement Data Dictionary. Dover, DE. 11) Federal Highway Administration (FHWA). 2009. Pavement Distress Identification Manual for the NPS Road Inventory Program (Cycle 4, 2006-2009). Washington, D.C. 12) Federal Highway Administration (FHWA). 2014. Distress Identification Manual for the Long-Term Pavement Performance Program (Fifth Revised Edition). FHWA-HRT-13- 092, Washington, D.C. A 50

13) Florida Department of Transportation (FDOT). 2017. 2017 Flexible Pavement Condition Survey Handbook. Tallahassee, FL. 14) Florida Department of Transportation (FDOT). 2017. 2017 Rigid Pavement Condition Survey Handbook. Tallahassee, FL. 15) Georgia Department of Transportation (GDOT). 2005. Pavement Design Manual. Atlanta, GA. 16) Halcrow Group Limited (HGL). 2005. SCANNER Surveys for Local Roads - Specification Volume 2 Specification for Services. Red Hill House 227, London, UK. 17) Idaho Transportation Department (ITD). 2011. Pavement Rating Manual. Boise, ID. 18) Illinois Department of Transportation (IDOT). 2014. Illinois Highway Information System Roadway Information & Procedure Manual. Springfield, IL. 19) Kansas Department of Transportation (KDOT). 2017. 2017 Kansas NOS Condition Survey Report. Topeka, KS. 20) Kentucky Transportation Cabinet (KYTC). 2009. KYTC Pavement Distress Identification Manual. Frankfort, KY. 21) Lee, H., and J. Kim. Development of a Crack Type Index. 2005. In Transportation Research Record: Journal of the Transportation Research Board, No. 1940, Washington, D.C., pp. 99–109. 22) Louisiana Department of Transportation & Development (DOTD). 2010. Guidelines on the Application of Preventive Maintenance and Rehabilitation Practices for Pavement Preservation. Baton Rouge, LA. 23) Massachusetts Department of Transportation (MassDOT). 2005. Pavement Management Instruction Manual. Boston, MA. 24) McQueen, J. M., and D. H. Timm. 2005. Statistical Analysis of Automated Versus Manual Pavement Condition Surveys. In Transportation Research Record: Journal of the Transportation Research Board, No. 1940, Washington, D.C., pp. 55-62. 25) Michigan Department of Transportation (MDOT). 2017. Project Scoping Manual. Lansing, MI. 26) Minnesota Department of Transportation (MnDOT). 2011. Pavement Distress Identification Manual. St. Paul, MN. 27) Montana Department of Transportation (MDT). 2014. Pavement Condition and Treatment Report. Helena, MT. A 51

28) Nebraska Department of Roads (DNOR). 2012. Surface Distress Survey Manual. Lincoln, NE. 29) New Mexico Department of Transportation (NMDOT). 2007. Pavement Maintenance Manual. Santa Fe, NM. 30) New York State Department of Transportation (NYSDOT). 2010. Network Level Pavement Condition Assessment. Albany, NY. 31) North Carolina Department of Transportation (NCDOT). 2012. Pavement Condition Survey Manual. Raleigh, NC. 32) Ohio Department of Transportation (ODOT). 2006. Pavement Condition Rating System. Columbus, OH. 33) Oklahoma Department of Transportation (ODOT). 2005. Pavement Management Distress Rating Guide. Oklahoma City, OK. 34) Oregon Department of Transportation (ODOT). 2010. Pavement Distress Survey Manual. Salem, OR. 35) Pennsylvania Department of Transportation (PennDOT). 2017. Automated Pavement Condition Survey Field Manual. Publication 336. Harrisburg, PA. 36) South Dakota Department of Transportation (SDDOT). 2017. Pavement Management Visual Distress Survey Manual. Pierre, SD. 37) South Carolina Department of Transportation (SCDOT). 2018. Rating Bituminous Pavement Distresses at SCDOT. Columbia, SC. 38) South Carolina Department of Transportation (SCDOT). 2018. Rating Concrete Pavement Distresses at SCDOT. Columbia, SC. 39) Texas Department of Transportation (TxDOT). 2015. Pavement Management Information System Rater’s Manual for Fiscal Year 2016. Austin, TX. 40) Utah Department of Transportation (UDOT). 2002. FY 2003 UDOT Distress Manual. Taylorsville, UT. 41) Vitillo, N. et al. 2009. Evaluation of the Automated Distress Survey Equipment. FHWA NJ–2009-007. Rutgers University, Piscataway, NJ. 42) Vermont Agency of Transportation (VTrans). 2017. Asset Management and Performance Bureau Roadway Condition Assessment Collection Scope of Work. Montpelier, VT. 43) Virginia Department of Transportation (VDOT). 2012. A Guide to Evaluating Pavement Distress Through The Use of Digital Images. Richmond, VA. A 52

44) Washington State Department of Transportation (WSDOT). 1992. Pavement Surface Condition Rating Manual. Olympia, WA. 45) Wisconsin Department of Transportation (WisDOT). 2002. Pavement Surface Evaluation and Rating Manual for Asphalt Roads. Madison, WI. 46) Wisconsin Department of Transportation (WisDOT). 2002. Pavement Surface Evaluation and Rating Manual for Concrete Roads. Madison, WI. A 53

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Standard Definitions for Common Types of Pavement Cracking Get This Book
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New definitions will help pavement cracking survey providers and pavement engineers at state highway administrations conduct objective cracking measurements and encourage continuing technological innovations by researchers and vendors.

The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 288: Standard Definitions for Common Types of Pavement Cracking helps develop standard, discrete definitions for common cracking types for asphalt and concrete pavements.

The standard definitions would be used to facilitate comparable measurement and interpretation of pavement cracking.

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