22 - UFC 3-260-16 O-M Manual Standard Practice For Airfield Pavement Condition Surveys.pdf

UFC 3-260-16

3 February 2019

UNIFIED FACILITIES CRITERIA (UFC)

O&M MANUAL:

STANDARD PRACTICE FOR

AIRFIELD PAVEMENT CONDITION

SURVEYS

APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED

O&M MANUAL: STANDARD PRACTICE FOR AIRFIELD PAVEMENT CONDITION

SURVEYS

Any copyrighted material included in this UFC is identified at its point of use.

Use of the copyrighted material apart from this UFC must have the permission of the copyright holder.

U.S. ARMY CORPS OF ENGINEERS

NAVAL FACILITIES ENGINEERING COMMAND

AIR FORCE CIVIL ENGINEER CENTER (Preparing Activity)

Record of Changes (changes are indicated by \1\ ... /1/)

Change No. Date Location

This UFC supersedes UFC 3-260-16FA, Airfield Pavement Condition Survey Procedures Pavements, dated 16 January 2004, UFC 3-270-05, Paver Concrete Surfaced Airfields Pavement Condition Index (PCI), dated 15 March 2001, and UFC 3-270-06, Paver Asphalt Surfaced Airfields Pavement Condition Index (PCI), dated 15 March 2001.

FOREWORD

The Unified Facilities Criteria (UFC) system is prescribed by MIL-STD 3007 and provides planning, design, construction, sustainment, restoration, and modernization criteria, and applies to the Military Departments, the Defense Agencies, and DOD Field Activities in accordance with USD (AT&L) Memorandum dated 29 May 2002. UFC will be used for all DOD projects and work for other customers where appropriate. All construction outside of the United States is also governed by Status of Forces Agreements (SOFA), Host Nation Funded Construction Agreements (HNFA), and, in some instances, Bilateral Infrastructure Agreements (BIA).

Therefore, the acquisition team must ensure compliance with the more stringent of the UFC, the SOFA, the HNFA, and the BIA, as applicable.

UFC are living documents and will be periodically reviewed, updated, and made available to users as part of the Services’ responsibility for providing technical criteria for military construction. Headquarters, U.S. Army Corps of Engineers (HQUSACE), Naval Facilities Engineering Command (NAVFAC), and the Air Force Civil Engineer Center (AFCEC) are responsible for administration of the UFC system. Military Departments, the Defense Agencies, and DOD Field Activities should contact the preparing Service for document interpretation and improvements. Technical content of UFC is the responsibility of the cognizant DOD working group. Recommended changes with supporting rationale should be sent to the respective Service proponent office by the following electronic form: Criteria Change Request. The form is also accessible from the Internet site listed below.

• UFC are effective upon issuance and are distributed only in electronic media from the following source: Whole Building Design Guide web site http://dod.wbdg.org/.

Refer to UFC 1-200-01, DoD Building Code (General Building Requirements), for implementation of new issuances on projects.

AUTHORIZED BY:

LARRY D. McCALLISTER, PhD, PE, PMP, SES

JOSEPH E. GOTT, P.E.

Chief Engineer Naval Facilities Engineering Command Chief, Engineering and Construction

Directorate of Civil Works U.S. Army Corps of Engineers

NANCY J. BALKUS, P.E., SES, DAF MICHAEL McANDREW Deputy Director of Civil Engineers DCS Logistics, Engineering and Force Protection (HAF/A4C) HQ, United States Air Force

Deputy Assistant Secretary of Defense (Facilities Investment and Management) Office of the Assistant Secretary of Defense (Energy, Installations, and Environment) http://www.wbdg.org/pdfs/ufc_implementation.pdf http://www.wbdg.org/ccb/browse_cat.php?o=29&c=4 http://dod.wbdg.org/

REVISION SUMMARY SHEET

Document: UFC 3-260-16, O&M Manual: Standard Practice for Airfield Pavement Condition Surveys

Superseding: This UFC supersedes UFC 3-260-16FA, Airfield Pavement Condition Survey Procedures Pavements, dated 16 January 2004, UFC 3-270-05, Paver Concrete Surfaced Airfields Pavement Condition Index (PCI), dated 15 March 2001, and UFC 3- 270-06, Paver Asphalt Surfaced Airfields Pavement Condition Index (PCI), dated 15 March 2001.

Description: This UFC provides procedures for performing a pavement condition survey at all airfields with DOD missions. This UFC is intended for use by all personnel responsible for such surveys.

Reasons for Document: This revision addresses unification issues and the latest airfield pavement condition survey methodologies.

Impact: This document does not impact design cost, initial cost, energy savings, or life cycle costs.

Unification Issues: None i

TABLE OF CONTENTS

CHAPTER 1 INTRODUCTION

1-1 PURPOSE AND SCOPE

1-2 APPLICABILITY

1-3 GLOSSARY

1-4 REFERENCES

CHAPTER 2 INSPECTION PROCEDURE

2-1 PAVEMENT SECTIONING

2-2 SAMPLE UNITS

2-2.1 Definition

2-2.2 Sample Unit Sizes

2-2.3 Examples

2-3 NETWORK-LEVEL INSPECTION

2-3.1 Determining the Number of Sample Units to be Inspected

2-3.2 Selecting Sample Units to Inspect

2-4 PROJECT-LEVEL INSPECTION

2-4.1 Determining the Number of Sample Units to be Inspected

2-4.2 Selecting Sample Units to Inspect

2-5 SELECTION OF ADDITIONAL SAMPLE UNITS

2-6 PAVEMENT DISTRESS RECORDING

2-6.1 Example PCI Survey Sheets: Airfield Pavements

CHAPTER 3 PCI CALCULATION PROCEDURE

3-1 INTRODUCTION

3-2 CALCULATION OF A SAMPLE UNIT PCI FOR ASPHALT-SURFACED

PAVEMENTS

3-2.1 Step 1: Determine Deduct Values ii

3-2.2 Step 2: Determine the Maximum Allowable Number of Deducts (m). . 15

3-2.3 Step 3: Determine the Maximum Corrected Deduct Value (CDV)

3-2.4 Step 4: Calculate PCI by Subtracting the Maximum CDV from 100

3-3 CALCULATION OF A SAMPLE UNIT PCI FOR CONCRETE-

SURFACED PAVEMENTS

3-3.1 Step 1: Determine Deduct Values

3-3.2 Step 2: Determine the Maximum Allowable Number of Deducts (m). . 20

3-3.3 Step 3: Determine the Maximum CDV

3-3.4 Step 4: Calculate the PCI by Subtracting the Maximum CDV from 100. ..

3-4 CALCULATION OF THE PCI FOR A PAVEMENT SECTION

3-5 EXTRAPOLATING DISTRESS QUANTITIES FOR A PAVEMENT

SECTION

APPENDIX A PAVEMENT CONDITION INDEX (PCI) DISTRESS DEFINITIONS -

ASPHALT-SURFACED AIRFIELDS

APPENDIX B PAVEMENT CONDITION INDEX (PCI) DISTRESS DEFINITIONS -

CONCRETE-SURFACED AIRFIELDS

APPENDIX C PAVEMENT CONDITION INDEX (PCI) DISTRESS DEDUCT CURVES

FOR ASPHALT (BITUMINOUS) AIRFIELD PAVEMENTS

APPENDIX D PAVEMENT CONDITION INDEX (PCI) DISTRESS DEDUCT CURVES

FOR CONCRETE AIRFIELD PAVEMENTS

APPENDIX E BLANK FORMS

APPENDIX D GLOSSARY

APPENDIX E REFERENCES

iii

FIGURES

Figure 2-1 Example Division of a Jointed Rigid Pavement Section into Sample Units of 20 Slabs

Figure 2-2 Example Division of a Flexible Pavement Section into Sample Units

Figure 2-3 Selection of the Minimum Number of Sample Units

Figure 2-4 Example of Systematic Random Sampling

Figure 2-5 Asphalt-Surfaced Airfield Pavements Example PCI Survey Sheet

Figure 2-6 Concrete-Surfaced Airfield Pavements Example PCI Survey Sheet

Figure 3-1 Asphalt-Surfaced Airfield PCI Survey Data Sheet Example

Figure 3-2 PCI Calculation Steps for Sample Unit

Figure 3-3 AC Pavement Deduct Curve for Alligator Cracking Distress

Figure 3-4 Determination of Maximum Allowable Deducts (m) for Airfield Pavements ...

Figure 3-5 PCI Calculation Sheet for Example Sample Unit Shown in Figure 3-1

Figure 3-6 Correction Curves for AC-Surfaced Airfield Pavements

Figure 3-7 Concrete-Surfaced Airfield PCI Survey Data Sheet Example

Figure 3-8 PCI Calculation Sheet for the Example Sample Unit Shown in Figure 3-7 21

Figure A-1 Low-Severity Alligator Cracking

Figure A-2 Medium-Severity Alligator Cracking

Figure A-3 High-Severity Alligator Cracking

Figure A-4 Bleeding

Figure A-5 Bleeding

Figure A-6 Low-Severity Block Cracking

Figure A-7 Low-Severity Block Cracking

Figure A-8 Medium-Severity Block Cracking

Figure A-9 Medium-Severity Block Cracking

Figure A-10 High-Severity Block Cracking iv

Figure A-11 High-Severity Block Cracking

Figure A-12 Corrugation

Figure A-13 Low-Severity Corrugation

Figure A-14 Medium-Severity Corrugation

Figure A-15 High-Severity Corrugation

Figure A-16 Low-Severity Depression

Figure A-17 Medium-Severity Depression

Figure A-18 High-Severity Depression

Figure A-19 High-Severity Depression

Figure A-20 Jet Blast Erosion

Figure A-21 Low-Severity Joint Reflection Cracking

Figure A-22 Medium-Severity Joint Reflection Cracking

Figure A-23 High-Severity Joint Reflection Cracking

Figure A-24 Low-Severity L&T Cracking

Figure A-25 Medium-Severity L&T Cracking

Figure A-26 High-Severity L&T Cracking

Figure A-27 Low-Severity PFC L&T Cracking

Figure A-28 Medium-Severity PFC L&T Cracking

Figure A-29 Medium-Severity PFC L&T Cracking

Figure A-30 High-Severity PFC L&T Cracking

Figure A-31 Oil Spill

Figure A-32 Low-Severity Patching

Figure A-33 Medium-Severity Patching

Figure A-34 High-Severity Patching

Figure A-35 Polished Aggregate

Figure A-36 Low-Severity Raveling (Dense Mix) v

Figure A-37 Medium-Severity Raveling (Dense Mix)

Figure A-38 High-Severity Raveling (Dense Mix)

Figure A-39 Low-Severity Raveling (Slurry Seal/Coal Tar Over Dense Mix)

Figure A-40 Medium-Severity Raveling (Slurry Seal/Coal Tar Over Dense Mix)

Figure A-41 High-Severity Raveling (Slurry Seal/Coal Tar Over Dense Mix)

Figure A-42 Low-Severity Raveling (PFC)

Figure A-43 Medium-Severity Raveling (PFC)

Figure A-44 Medium-Severity Raveling (PFC)

Figure A-45 High-Severity Raveling (PFC)

Figure A-46 Rutting

Figure A-47 Low-Severity Shoving

Figure A-48 Medium-Severity Shoving

Figure A-49 High-Severity Shoving

Figure A-50 Slippage Cracking

Figure A-51 Low-Severity Swell

Figure A-52 Medium-Severity Swell

Figure A-53 High-Severity Swell

Figure A-54 Low-Severity Weathering

Figure A-55 Medium-Severity Weathering

Figure A-56 High-Severity Weathering

Figure B-1 Low-Severity Blowup

Figure B-2 Low-Severity Blowup

Figure B-3 Medium-Severity Blowup

Figure B-4 High-Severity Blowup

Figure B-5 Low-Severity Corner Break

Figure B-6 Medium-Severity Corner Break vi

Figure B-7 High-Severity Corner Break

Figure B-8 Low-Severity Linear Cracks

Figure B-9 Medium-Severity Linear Cracks

Figure B-10 High-Severity Linear Cracks

Figure B-11 Cracks (Reinforced PCC)

Figure B-12 Low-Severity “D” Cracking

Figure B-13 Medium-Severity “D” Cracking

Figure B-14 High-Severity “D” Cracking

Figure B-15 Low-Severity Joint Seal Damage

Figure B-16 Medium-Severity Joint Seal Damage

Figure B-17 High-Severity Joint Seal Damage

Figure B-18 Low-Severity Small Patch

Figure B-19 Medium-Severity Small Patch

Figure B-20 High-Severity Small Patch

Figure B-21 Low-Severity Large Patch

Figure B-22 Medium-Severity Large Patch

Figure B-23 High Severity Large Patch

Figure B-24 Popouts

Figure B-25 Pumping

Figure B-26 Pumping

Figure B-27 Low-Severity Scaling

Figure B-28 Medium-Severity Scaling

Figure B-29 High-Severity Scaling

Figure B-30 Low-Severity Settlement or Faulting

Figure B-31 Low-Severity Settlement or Faulting

Figure B-32 High-Severity Settlement or Faulting vii

Figure B-33 Low-Severity Shattered Slab/Intersecting Cracks

Figure B-34 Medium-Severity Shattered Slab/Intersecting Cracks

Figure B-35 High-Severity Shattered Slab/Intersecting Cracks

Figure B-36 Shrinkage Cracks

Figure B-37 Low-Severity Joint Spall

Figure B-38 Medium-Severity Joint Spall

Figure B-39 High-Severity Joint Spall

Figure B-40 High-Severity Joint Spall

Figure B-41 Low-Severity Corner Spall

Figure B-42 Medium-Severity Corner Spall

Figure B-43 High-Severity Corner Spall

Figure B-44 Low-Severity ASR

Figure B-45 Medium-Severity ASR

Figure B-46 High-Severity ASR

Figure C-1 Deduct Curves for Alligator Cracking (41) {1}

Figure C-2 Deduct Curve for Bleeding (42) {2}

Figure C-3 Deduct Curves for Block Cracking (43) {3}

Figure C-4 Deduct Curves for Corrugation (44) {4}

Figure C-5 Deduct Curves for Depression (45) {5}

Figure C-6 Deduct Curve for Jet Blast Erosion (46) {6}

Figure C-7 Deduct Curves for Joint Reflection Cracking (47- English Units) {7}

Figure C-8 Deduct Curves for Joint Reflection Cracking (47- Metric Units) {7}

Figure C-9 Deduct Curves for Longitudinal/Transverse (48- English Units) {8}

Figure C-10 Deduct Curves for Longitudinal/Transverse (48- Metric Units) {8}

Figure C-11 Deduct Curve for Oil Spillage (49) {9}

Figure C-12 Deduct Curves for Patching/Utility Cut (50) {10} viii

Figure C-13 Deduct Curve for Polished Aggregate (51) {11}

Figure C-14 Deduct Curves for Raveling (52) {12}

Figure C-15 Deduct Curves for Rutting (53) {13}

Figure C-16 Deduct Curves for Shoving (54) {14}

Figure C-17 Deduct Curve for Slippage Cracking (55) {15}

Figure C-18 Deduct Curves for Swell (56) {16}

Figure C-19 Deduct Curves for Weathering (57) {17}

Figure C-20 Correct Deduct Curves for Asphalt Airfields

Figure D-1 Deduct Curves for Blowup (61) {1}

Figure D-2 Deduct Curves for Corner Break (62) {2}

Figure D-3 Deduct Curves for Cracking (63) {3}

Figure D-4 Deduct Curves for Durability Cracking (64) {4}

Figure D-5 Deduct Values for Joint Seal Damage (65) {5}

Figure D-6 Deduct Curves for Small Patch (66) {6}

Figure D-7 Deduct Curves for Patching/Utility Cut (67) {7}

Figure D-8 Deduct Curve for Popouts (68) {8}

Figure D-9 Deduct Curve for Pumping (69) {9}

Figure D-10 Deduct Curves for Scaling (70) {10}

Figure D-11 Deduct Curves for Settlement (71) {11}

Figure D-12 Deduct Curves for Shattered Slab (72) {12}

Figure D-13 Distress Curve for Shrinkage Cracks (73) {13}

Figure D-14 Deduct Curves for Joint Spall (74) {14}

Figure D-15 Deduct Curves for Corner Spalling (75) {15}

Figure D-16 Deduct Curves for ASR (76) {16}

Figure D-17 Corrected Deduct Value Curves for Concrete

Figure E-1 Airfield Asphalt Pavement Condition Data Survey Sheet (Manual) ix

Figure E-2 Airfield Concrete Pavement Condition Data Survey Sheet (Manual)

Figure E-3 AC Airfield Pavement Condition Survey Data Sheet (Automated)

Figure E-4 PCC Airfield Pavement Condition Survey Data Sheet (Automated)

Figure E-5 PCI Calculation Form

Figure E-6 Section/Branch Report Form

Figure F-1 Pavement Condition Index (PCI) and Simplified PCI Rating Scales

TABLES

Table 2-1 Example of Network-Level Sampling Criteria Used by Some Agencies

Table 3-1 Calculation of Deduct Values for Distresses Shown in Figure 3-1

Table 3-2 Calculation of Deduct Values for Distresses Shown in Figure 3-7

Table 3-3 Medium-Severity Alligator Cracking in Five Surveyed Sample Units

Table 3-4 Medium-Severity Alligator Cracking in an Additional Sample Unit

Table A-1 Frequently Occurring Problems in Asphalt Pavement Distress Identification

Table A-2 Corrugation Measurement Criteria

Table A-3 Maximum Depth of Depression

Table A-4. Mean Rut Depth Criteria

Table A-5. Shoving Criteria

Table A-6. Swell Criteria

Table B-1 Frequently Occurring Problems In Pavement Distress Identification

Table B-2. Difference in Elevation

Table B-3 Severity Levels of Spalling

EQUATIONS

Equation 2-1 Minimum Sample Units

Equation 3-1 Allowable Number of Deducts for Airfields x

Equation 3-2 Area Weighted Averaging for Unequally Sized Sample Units

Equation 3-3 Area Weighted Average PCI for Additional Sample Units

Equation 3-4 Section PCI for Additional Sample Units

CHAPTER 1 INTRODUCTION

1-1 PURPOSE AND SCOPE.

1-1.1 This Unified Facilities Criteria (UFC) provides the procedure for performing a pavement condition survey at all airfields with present or potential DOD missions. This UFC is intended for use by all personnel responsible for such surveys.

1-1.2 The objectives of a pavement condition survey are to determine the present condition of the pavement in terms of apparent structural integrity and operational surface condition, to provide a common index for comparing the condition and performance of pavements at all air stations along with a rational basis for justification of pavement repair projects, and to provide feedback on pavement performance for validating and improving current pavement design, evaluation, and maintenance procedures.

1-1.3 The airfield pavement condition survey is a visual inspection of both rigid and flexible pavement for signs of pavement distress. The pavement condition index (PCI) is a numerical rating that indicates the type and severity of the inspected distress.

The airfield condition survey and the resulting PCI are the primary means of obtaining and recording important airfield pavement performance data. This UFC describes the condition survey of both flexible pavements (all pavements with conventional bituminous concrete surfaces) and rigid pavements (jointed portland cement concrete [PCC] pavements) and the procedure for determining the PCI of the inspected pavement.

1-1.4 The pavement network is divided into branches that are in turn divided into sections. Each section is divided into sample units. The type and severity of pavement distress is assessed by visual inspection of the pavement sample units. The quantity of the distress is measured as described in Appendix A (flexible pavement) and Appendix B (rigid pavement). The distress data are used to calculate the PCI for each sample unit. The PCI of the pavement section is determined based on the PCI of the inspected sample units within the section. The distresses can be numbered using several conventions. Within this UFC, two numbering conventions are presented. One uses the convention adopted within the PAVER software, which starts the numbering of flexible distresses at 41 and continues through 57. For rigid pavement, the distresses start with 61 and continue through 76. This is done to ensure the distresses for the flexible and rigid airfield distresses have unique numerical identifiers and to allow for separate distresses for flexible and rigid roadways to have unique numerical identifiers from 1 to

39. The second convention provided in Appendix A and Appendix B is consistent with ASTM D5340 and is contained in braces: {#}. This numbering convention produces multiple distresses for the same numerical identifier and should be used with caution.

For additional information on performing pavement condition surveys for NATO countries, refer to STANAG 7181.

1-2 APPLICABILITY.

This UFC applies to all Service elements and contractors performing airfield pavement condition surveys.

1-3 GLOSSARY.

Appendix F contains a list of acronyms, abbreviations, and definitions.

1-4 REFERENCES.

Appendix G contains a list of references used in this document. The publication date of the code or standard is not included in this document. Unless otherwise specified, the most recent edition of the referenced publication applies.

CHAPTER 2 INSPECTION PROCEDURE

2-1 PAVEMENT SECTIONING.

The first step in the condition survey is the designation of pavement sections. Each branch, such as a runway or taxiway, is divided into sections that are definable in terms of the same design, the same construction history, the same traffic area, and generally the same overall condition. Generally, sections are determined from pavement design and construction records and can be further subdivided as deemed necessary based on a preliminary survey. It is important that all pavement in a given section be such that it is considered uniform. For example, the center portion of some runways in the traffic lanes are separate sections from the portion outside the traffic lanes.

2-2 SAMPLE UNITS.

2-2.1 Definition.

A sample unit is a defined portion of a pavement section designated only for the purpose of pavement inspection.

2-2.2 Sample Unit Sizes.

2-2.2.1 Asphalt-Surfaced Airfields.

For asphalt-surfaced airfields, each sample unit area is defined as 5,000 ± 2,000 square feet (465 ± 186 square meters). Note that sample unit sizes close to the recommended mean are preferred for accuracy.

2-2.2.2 Concrete-Surfaced Airfields.

For concrete airfields with joints spaced less than or equal to 25 feet (7.6 meters), the recommended sample unit size is 20 ± 8 slabs. For slabs with joints spaced greater than 25 feet (7.6 meters), imaginary joints less than or equal to 25 feet (7.6 meters) apart and in perfect condition are assumed. For example, if slabs have joints spaced 60 feet (18.3 meters) apart, imaginary joints are assumed at 20 feet (6.1 meters). Thus, each slab is counted as three slabs for the purpose of pavement inspection. This is needed because the deduct values were developed for jointed concrete slabs less than or equal to 25 feet (7.6 meters).

2-2.3 Examples.

Figures 2-1 and 2-2, respectively, illustrate the division of a jointed rigid pavement and flexible pavement section into sample units. Each sample unit is numbered where it is identifiable for future inspections, maintenance needs, or statistical sample purposes.

Inspect each of the selected sample units and determine its PCI. The PCI of a pavement section is determined by the size-weighted average of the PCI of each sample unit inspected within the section.

Figure 2-1 Example Division of a Jointed Rigid Pavement Section into Sample Units of 20 Slabs

Figure 2-2 Example Division of a Flexible Pavement Section into Sample Units

2-3 NETWORK-LEVEL INSPECTION.

2-3.1 Determining the Number of Sample Units to be Inspected.

A network-level survey is conducted by surveying a few sample units per section. Table 2-1 provides an example of criteria used by some agencies for determining the number of sample units to survey at the network level. The number of units to be inspected (n) is increased by 1 for every increase of five units in section (N) until N equals 15. When N equals 16 to 40, the value of n is set at 4. When the value of N is greater than 40, n is set at 10 percent of N and rounded up to the next whole sample unit. For example, if N = 52 then n = 6 (rounded up from 5.2).

Table 2-1 Example of Network-Level Sampling Criteria Used by Some Agencies

No. of Sample Units in Section (N)

No. of Units to be Inspected (n)

1 to 5 1

6 to 10 2

11 to 15 3

16 to 40 4

Over 40 10 percent of N (round up to next whole sample unit)

2-3.2 Selecting Sample Units to Inspect.

When selecting sample units to inspect as recommended in Table 2-1, ensure the sample units are representative (not random) of the overall condition of the section. The main objective for budget estimating and network condition assessment is to obtain a meaningful rating with the least cost.

2-4 PROJECT-LEVEL INSPECTION.

2-4.1 Determining the Number of Sample Units to be Inspected.

Management at the project level requires accurate data for the preparation of work plans and contracts; therefore, more sample units are inspected than are usually sampled for network-level management. The first step in sampling is to determine the minimum number of sample units (n) to survey to obtain an adequate estimate of the section’s PCI. This number is determined for a project-level evaluation by using the curves shown in Figure 2-3. Using this number, a reasonable estimate of the true mean PCI of the section is obtained. There is a 95 percent probability that the estimate is within ±5 points of the true mean PCI (the PCI obtained if all the sample units were inspected).

The curves in Figure 2-3 were constructed using Equation 2-1:

Equation 2-1 Minimum Sample Units 𝑛𝑛 =

𝑁𝑁(𝑠𝑠2)

𝑒𝑒2

4 (𝑁𝑁 − 1) + 𝑠𝑠2

where:

n = minimum number of sample units N = total number of sample units in the pavement section e = allowable error in the estimate of the section PCI (The value e was set equal to 5 when constructing the curves of Figure 2-3.)

s = standard deviation of the PCI between sample units in the section

The curves in Figure 2-3 are based on the PCI standard deviation among sample units or PCI range (i.e., lowest sample unit PCI subtracted from the highest sample unit PCI).

For the initial inspection, the PCI standard deviation for a pavement section is assumed to be 10 for asphalt concrete (AC) -surfaced pavements (or a PCI range of 25) and 15 for PCC-surfaced pavements (or a PCI range of 35). These values are based on field data obtained from many surveys; however, if local experience is different, use the average standard deviation reflecting local conditions for the initial inspection. For subsequent inspections, use the actual PCI standard deviation or range (determined from the previous inspection) to determine the minimum number of sample units to be surveyed. When the total number of samples within a section is less than five, survey all of the sample units.

Figure 2-3 Selection of the Minimum Number of Sample Units1

1 Shahin et al., 1976-1977

2-4.2 Selecting Sample Units to Inspect.

Space the sample units to be inspected equally throughout the section, with the first unit chosen at random. This technique, known as “systematic random,” is illustrated in Figure 2-4 and described by the following three steps:

1. The sample interval (i) is determined by i = N ÷ n, where N equals the total number of available sample units and n equals the minimum number of sample units to be surveyed. The sampling interval (i) is rounded to the smaller whole number (for example, 3.6 is rounded to 3.0).

2. Random starts are selected between sample unit 1 and the sampling interval (i). For example, if i = 3, the random start would be a number from 1 to 3.

3. The sample units to be surveyed are identified as S, S+i, S+2i, and so forth. If the selected start is 3 and the sampling interval is 3 then the sample units to be surveyed are 3, 6, 9, 12, and so forth.

Figure 2-4 Example of Systematic Random Sampling

2-5 SELECTION OF ADDITIONAL SAMPLE UNITS.

One of the major drawbacks to both systematic random sampling at the project level and representative sampling at the network level is that sample units in exceptionally bad condition may not necessarily be included in the survey. At the same time, sample units that have a one-time-occurrence type of distress (for example, utility cut patching) may be included inappropriately as a random sample.

To overcome these drawbacks, identify any unusual sample units and inspect them as additional units rather than as random or representative units. When additional sample units are included in the survey, the calculation of the section PCI is altered to prevent extrapolation of the unusual conditions across the entire section. This procedure is described in more detail in Chapter 3.

2-6 PAVEMENT DISTRESS RECORDING.

2-6.1 Example PCI Survey Sheets: Airfield Pavements.

Figures 2-5 and 2-6 are sample PCI survey sheets. Blank forms are in Appendix E.

Figure 2-5 Asphalt-Surfaced Airfield Pavements Example PCI Survey Sheet

AC Airfield Pavement Condition Survey Data Sheet (Automated)

PID Delta_R1230_B01 INSPECTOR S. Smith

NAME

FROM RW 12 End BRANCH Runway

USE

DATE 06/20/2018

INSPECTED

TO TW A SECTION 100 FT

WIDTH

SECTION 2000 FT

LENGTH

AC Surfaced Distress Codes

41. Alligator Cracking {1} 46. Jet Blast {6} 51. Polished Aggregate {11} 56. Swell {16}

42. Bleeding {2} 47. JT. Reflection (PCC) {7} 52. Raveling {12} 57. Weathering {17}

43. Block Cracking {3} 48. Long. & Trans. Cracking {8} 53. Rutting {13}

44. Corrugation {4} 49. Oil Spillage {9} 54. Shoving From PCC {14}

45. Depression {5} 50. Patching {10} 55. Slippage Cracking {15}

SAMPLE

NUMBER

SAMPLE

AREA

SKETCH/COMMENTS

DISTRESS

CODE L M H

48 47 FT 16 FT

41 53 FT

45 75 FT

53 28 SF

Figure 2-6 Concrete-Surfaced Airfield Pavements Example PCI Survey Sheet

PCC AIRFIELD PAVEMENT CONDITION SURVEY DATA SHEET (Automated) PID Delta_R1230_B03 INSPECTOR S. Smith

NAME

FROM TW F

BRANCH USE Runway DATE

INSPECTED

06/20/201

TO RW 30 END

SECTION WIDTH 100 FT

SECTION

LENGTH

2000 FT

SLAB WIDTH 25 FT

SLAB LENGTH 25

FT

NUMBER OF 320

SLABS

PCC Surfaced Distress Codes

61. Blowup {1} 65. Joint Seal Damage {5} 69. Pumping {9} 73. Shrinkage Cracks {13}

62. Corner Break {2} 66. Patching, Small < 1.5 m (< 5

ft) {6} 70. Scaling {10} 74. Spalling, Joints {14}

63. Cracks {3} 67. Patching, Large/ Utility Cut {7}

71.

Settlement/Faulting {11}

75. Spalling, Corner {15}

64. Durability Cracking {4} 68. Popouts {8} 72. Shattered Slab

{12} 76. ASR {16}

SAMPLE NUMBER 005 SLABS IN SAMPLE

CODE

L M H

63 5 2

74 3

72 1

75 6

CHAPTER 3 PCI CALCULATION PROCEDURE

3-1 INTRODUCTION.

The PCI is calculated for each inspected sample unit. The PCI cannot be computed for the entire pavement section without computing the PCI for the sample units first. The PCI calculation is based on the deduct values, which are weighting factors from 0 to 100 that indicate the impact each distress has on pavement condition. A deduct value of 0 indicates that a distress has no effect on either pavement structural integrity or surface operational condition, whereas a value of 100 indicates an extremely serious distress.

3-2 CALCULATION OF A SAMPLE UNIT PCI FOR ASPHALT-SURFACED

PAVEMENTS.

The PCI calculation procedure is illustrated for the sample unit example shown in Figure 3-1. The calculation steps are summarized in Figure 3-2 and paragraphs 3-2.1 through 3-2.4.

Figure 3-1 Asphalt-Surfaced Airfield PCI Survey Data Sheet Example

AC Airfield Pavement Condition Survey Data Sheet (Automated)

PID Delta_R1230_B01 INSPECTOR S. Smith

NAME

FROM RW 12 End BRANCH Runway

USE

DATE 06/20/2018

INSPECTED

TO TW A SECTION 100 FT

WIDTH

SECTION 2000 FT

LENGTH

AC Surfaced Distress Codes

41. Alligator Cracking {1} 46. Jet Blast {6} 51. Polished Aggregate {11} 56. Swell {16}

42. Bleeding {2} 47. JT. Reflection (PCC) {7} 52. Raveling {12} 57. Weathering {17}

43. Block Cracking {3} 48. Long. & Trans. Cracking {8} 53. Rutting {13}

44. Corrugation {4} 49. Oil Spillage {9} 54. Shoving From PCC {14}

45. Depression {5} 50. Patching {10} 55. Slippage Cracking {15}

SAMPLE

NUMBER 008 SAMPLE

AREA

5000 SF

CODE L M H

48 47 FT 16 FT

41 53 FT

45 75 FT

53 28 SF

Figure 3-2 PCI Calculation Steps for Sample Unit

3-2.1 Step 1: Determine Deduct Values.

Table 3-1 shows the results of the calculation of the deduct values for the distresses shown in Figure 3-1.

1a. Add the totals for each distress type at each severity level and record them as shown in Table 3-1. Distress quantities are measured in square feet (square meters), linear feet (meters), or number of occurrences, depending on the distress type.

1b. Divide the quantity of each distress type at each severity level by the total area of the sample unit then multiply by 100 to obtain the percentage of density per sample unit for each distress type and severity.

1c. Determine the deduct value for each distress type and severity level combination from the distress deduct value curves. Figure 3-3 shows an example of a deduct curve for distress type 41, alligator cracking, for asphalt-surfaced airfield pavements. Deduct curves for all asphalt airfield distresses are provided in Appendix C.

Table 3-1 Calculation of Deduct Values for Distresses Shown in Figure 3-1

Paver Distress

ASTM

Distress Description Severity Qty

(ft/ft2) Qty

(m/m2) Density Deduct

(41) {1} Alligator cracking L 53 ft2 4.9 m2 1.06 21.0

(45) {5} Depression L 75 ft2 7.0 m2 1.5 9.2

(48) {8} Longitudinal and transverse cracking

L 47 ft 14.3 m 0.94 4.8

(48) {8} Longitudinal and transverse cracking

M 16 ft 4.9 m 0.32 6.7

(53) {13} Rutting M 25 ft2 2.3 m2 0.5 20.2 ft2 (m2) = square feet (square meters) ft (m) = feet (meters)

Figure 3-3 AC Pavement Deduct Curve for Alligator Cracking Distress

3-2.2 Step 2: Determine the Maximum Allowable Number of Deducts (m).

The maximum allowable number of deducts is calculated as shown in Figure 3-4 or using Equation 3-1.

Figure 3-4 Determination of Maximum Allowable Deducts (m) for Airfield Pavements

Equation 3-1 Allowable Number of Deducts for Airfields 𝑚𝑚𝑖𝑖= 1+ �

� (100 − 𝐻𝐻𝐻𝐻𝑉𝑉𝑖𝑖)

where:

mi = allowable number of deducts, including fractions, for sample unit i HDVi = highest individual deduct value for sample unit i

For example, in Table 3-1 (calculated from Figure 3-1) the allowable number of deducts is calculated as:

𝑚𝑚𝑖𝑖= 1+ �

� (100 − 21.02) = 8.48

The number of individual deduct values is reduced to m, including the fractional part. If fewer than m deduct values are available then all the deduct values are used. For the example in Figure 3-1, all the deduct values are used since they are less than m.

3-2.3 Step 3: Determine the Maximum Corrected Deduct Value (CDV).

The maximum CDV is determined iteratively as described in these five steps:

3a. List the individual deduct values in descending order as shown in Figure 3-5, row 1. For example, the values in Table 3-1, which were calculated from the example shown in Figure 3-1, are sorted as follows:

21, 20.2, 9.2, 6.7, and 4.8.

3b. Determine the total deduct value by adding all individual deduct values. In the current example, the total deduct value is 61.9.

3c. Determine the CDV from q (number of deduct values over 5) and the total deduct value by looking up the appropriate correction curve. Figure 3-6 shows the correction curve for asphalt-surfaced airfield pavements. The CDV for row 1 is calculated as 31.

3d. Reduce to 5.0 the smallest individual deduct value that is greater than 5.0, as shown in row number 2 in Figure 3-5. Repeat steps 3b and 3c until q is equal to 1.

3e. The maximum CDV is the largest of the CDVs determined.

Figure 3-5 PCI Calculation Sheet for Example Sample Unit Shown in Figure 3-1

PCI CALCULATION FORM

BRANCH Runway SECTION B01 SAMPLE UNIT 008

CALCULATED BY S. Smith DATE 06/20/2018

Adjustment of the Number of Deduct Values (1 Minimum, 10 Maximum):

ITERATION

NUMBER

DEDUCT VALUES (Arrange Values from Highest Value to Lowest Value)

DEDUCT

TOTAL

Number of Deduct

Values Greater than (but not equal

to) 5.0 q

Corrected Deduct Value

CDV

* Do not list more values than the Adjustment Number of Deduct Values (round to the next higher integer if a fraction/decimal) ** The last (lowest) value listed may be a fraction of one of the DEDUCT VALUES in the Condition Survey Data Sheet

1 21.0 20.2 9.2 6.7 4.8 61.9 4 31

2 21.0 20.2 9.2 5.0 4.8 60.2 3 36

3 21.0 20.2 5.0 5.0 4.8 56.0 2 37

4 21.0 5.0 5.0 5.0 4.8 40.8 1 41

MAXIMUM CDV = 41

Corrected Pavement Condition Index (PCI) = 100 - MAXIMUM CDV = 59

AC m = 8.48 > 5

Figure 3-6 Correction Curves for AC-Surfaced Airfield Pavements

3-2.4 Step 4: Calculate PCI by Subtracting the Maximum CDV from 100.

For the example, the PCI equals 100 - 41 = 59.

3-3 CALCULATION OF A SAMPLE UNIT PCI FOR CONCRETE-

SURFACED PAVEMENTS.

3-3.1 Step 1: Determine Deduct Values.

Table 3-2 shows the results of the calculation of the deduct values for the distresses shown in Figure 3-7.

1a. For each unique combination of distress type and severity level, add the number of slabs in which they occur. For example, Figure 3-7 lists three slabs with low-severity joint spalling.

1b. Divide the number of slabs from step 1a by the total number of slabs in the sample unit then multiply by 100 to obtain the percentage of density per sample unit for each distress type and severity combination.

1c. Determine the deduct values for each distress type and severity level combination using the appropriate deduct curve in Appendix D for concrete airfields.

Figure 3-7 Concrete-Surfaced Airfield PCI Survey Data Sheet Example

PCC AIRFIELD PAVEMENT CONDITION SURVEY DATA SHEET (Automated)

PID Delta_R1230_B03 INSPECTOR S. Smith

NAME

FROM TW F

BRANCH USE Runway DATE INSPECTED 06/20/2018

TO RW 30 END

SECTION WIDTH 100 FT

SECTION LENGTH

2000 FT

SLAB WIDTH 25 FT

SLAB LENGTH 25 FT

NUMBER OF 320

SLABS

PCC Surfaced Distress Codes

61. Blowup {1} 65. Joint Seal Damage {5} 69. Pumping {9} 73. Shrinkage Cracks {13}

62. Corner Break {2} 66. Patching, Small < 1.5 m (< 5 ft) {6} 70. Scaling {10} 74. Spalling, Joints {14}

63. Cracks {3} 67. Patching, Large/ Utility Cut {7} 71. Settlement/Faulting {11} 75. Spalling, Corner {15}

64. Durability Cracking {4} 68. Popouts {8} 72. Shattered Slab {12} 76. ASR {16}

SAMPLE NUMBER 005 SLABS IN SAMPLE 20 SKETCH/COMMENTS

DISTRESS CODE L M H

63 5 2

74 3

72 1

75 6

Table 3-2 Calculation of Deduct Values for Distresses Shown in Figure 3-7

Paver Distress

ASTM

Distress Description Severity Quantity Units Density Deduct

(63) {4} Linear cracking M 2 Slabs 10 18.7

(63) {4} Linear cracking L 5 Slabs 25 15.4

(72) {13} Shattered slab L 1 Slabs 5 11.0

(74) {15} Joint spall L 3 Slabs 15 4.8

(75) {16} Corner spall L 6 Slabs 30 9.6

3-3.2 Step 2: Determine the Maximum Allowable Number of Deducts (m).

This step is the same as the comparable step for asphalt-surfaced pavements described in paragraph 3-2.2. For the example in Figure 3-7, based on a highest deduct value (HDV) of 18.66, m is calculated using Equation 3-1:

𝑚𝑚𝑖𝑖= 1+ � 9 � (100 − 18.66) = 8.71

The maximum allowable number of deducts, m, was calculated to be 8.71. There are only five deduct values (18.66, 15.43, 11.02, 4.78, and 9.62) so taking a percentage of one of the deduct values is not necessary; however, if in the sample unit m was calculated to be 3.4, it would be necessary to take the three highest deduct values and 40 percent of the fourth-highest deduct value.

3-3.3 Step 3: Determine the Maximum CDV.

Determine the maximum CDV by following the procedures in paragraph 3-2.3 but using the appropriate correction curve in Appendix D for concrete airfields.

3-3.4 Step 4: Calculate the PCI by Subtracting the Maximum CDV from 100.

Figure 3-8 summarizes the PCI calculation for the example of PCC pavement data shown in Figure 3-7.

Figure 3-8 PCI Calculation Sheet for the Example Sample Unit Shown in Figure 3-7

PCI CALCULATION FORM

BRANCH Runway SECTION B03 SAMPLE UNIT 005

CALCULATED BY S. Smith DATE 06/20/2018

Adjustment of the Number of Deduct Values (1 Minimum, 10 Maximum):

ITERATION

NUMBER

DEDUCT VALUES (Arrange Values from Highest Value to Lowest Value)

DEDUCT

TOTAL

Number of

Deduct Values Greater than (but not equal to) 5.0 q

Corrected Deduct Value

CDV

* Do not list more values than the Adjustment Number of Deduct Values (round to the next higher integer if a fraction/decimal) ** The last (lowest) value listed may be a fraction of one of the DEDUCT VALUES in the Condition Survey Data Sheet

1 18.7 15.4 11.0 9.6 4.8 59.5 4 38

2 18.7 15.4 11.0 5.0 4.8 54.9 3 38

3 18.7 15.4 5.0 5.0 4.8 48.9 2 42

4 18.7 5.0 5.0 5.0 4.8 38.5 1 38

MAXIMUM CDV = 42

Corrected Pavement Condition Index (PCI) = 100 - MAXIMUM CDV = 58

PCC m = 8.8 > 5

3-4 CALCULATION OF THE PCI FOR A PAVEMENT SECTION.

If all surveyed sample units are selected either by using the systematic random technique or on the basis of being representative of the section and are equal in size, the PCI of the section is determined by averaging the PCIs of the inspected sample units. If the inspected sample units are not equal in size, use area-weighted averaging as shown in Equation 3-2.

Equation 3-2 Area Weighted Averaging for Unequally Sized Sample Units

PCIs = PCI of pavement section PCIr = area-weighted average PCI of random (or representative) sample units PCIr i = PCI of random sample unit number i Ari = area of the random sample unit i R = total number of inspected random sample units

If additional sample units are inspected in addition to the random or representative units, the section PCI is computed using Equations 3-3 and 3-4:

Equation 3-3 Area Weighted Average PCI for Additional Sample Units

𝑷𝑷𝑷𝑷𝑷𝑷𝒂𝒂 =

∑ ( 𝑷𝑷𝑷𝑷𝑷𝑷𝒂𝒂𝒂𝒂 × 𝑨𝑨𝒂𝒂𝒂𝒂)𝑨𝑨

𝒂𝒂=𝟏𝟏

∑ (𝑨𝑨𝒂𝒂𝒂𝒂)𝑹𝑹

𝒂𝒂=𝟏𝟏

Equation 3-4 Section PCI for Additional Sample Units

𝑃𝑃𝑃𝑃𝑃𝑃𝑠𝑠 =

𝑃𝑃𝑃𝑃𝑃𝑃𝑟𝑟�𝐴𝐴𝑠𝑠 − ∑ 𝐴𝐴𝑎𝑎𝑖𝑖𝐴𝐴

𝑖𝑖=1 � + 𝑃𝑃𝑃𝑃𝑃𝑃𝑎𝑎 × ∑ 𝐴𝐴𝑎𝑎𝑖𝑖𝐴𝐴

𝑖𝑖=1

𝐴𝐴𝑠𝑠

PCIa = area weighted average PCI of additional sample units PCIai = PCI of additional sample unit number i Aai = area of additional sample unit I As = total section area

PCIs = PCIr = ∑ (PCIr i Ari

)𝑅𝑅

𝑖𝑖=1 ∑ Ari

𝑅𝑅

𝑖𝑖=1

For example, if in a section of 60,000 square feet (5,574 square meters), five random sample units were inspected and determined to have PCIs of 56 (5,000 square feet [465 square meters]), 72 (5,000 square feet [465 square meters]), 65 (5,000 square feet [465 square meters]), 69 (4,000 square feet [372 square meters]), and 61 (4,000 square feet [372 square meters]), and two additional sample units with PCIs of 42 (3,500 square feet [325 square meters]) and 39 (3,500 square feet [325 square meters]) were included, the PCI of the section would be:

𝑃𝑃𝑃𝑃𝑃𝑃𝑟𝑟 =

(56 × 5,000) + (72 × 5,000) + (65 × 5,000) + (69 × 4,000) + (61 × 4,000)

5,000 + 5,000 + 5,000 + 4,000 + 4,000

𝑃𝑃𝑃𝑃𝑃𝑃𝑟𝑟 = 64.57

𝑃𝑃𝑃𝑃𝑃𝑃𝑎𝑎 =

(42 × 3,500) + (39 × 3,500)

3,500 + 3,500

𝑃𝑃𝑃𝑃𝑃𝑃𝑎𝑎 = 40.5

𝑃𝑃𝑃𝑃𝑃𝑃𝑠𝑠 =

64.57(60,000 − 7,000) + 40.5 × 6,500

60,000

𝑃𝑃𝑃𝑃𝑃𝑃𝑠𝑠 = 61

3-5 EXTRAPOLATING DISTRESS QUANTITIES FOR A PAVEMENT

SECTION.

3-5.1 When a pavement has been inspected by sampling, it is necessary to extrapolate the quantities and densities of distress over the entire pavement section to determine total quantities for the section. If all sample units surveyed were selected at random, the extrapolated quantity of a given distress at a given severity level is determined as shown in the following example for an asphalt-surfaced airfield with medium-severity alligator cracking:

Surface type: AC

Section area: 49,000 square feet (4,552 square meters)

Total number of sample units in section: 10

3-5.2 Five sample units were surveyed at random and the amount of medium-severity alligator cracking was determined as shown in Table 3-3:

Table 3-3 Medium-Severity Alligator Cracking in Five Surveyed Sample Units

Sample Unit ID Number

Sample Unit Area ft2

(m2) Medium-Severity

Alligator Cracking ft2 (m2)

02 5,000 (465) 200 (18.6)

04 5,000 (465) 400 (37.2)

06 5,000 (465) 300 (27.9)

08 5,000 (465) 100 (9.3)

10 4,000 (372) 200 (18.6)

Total Random 24,000 (2230) 1,200 (111.5)

3-5.3 The average density for medium-severity alligator cracking then is 1,200 divided by 24,000, or 0.05. The extrapolated quantity is determined by multiplying density by section area (0.05 × 49,000 = 2,450 square feet [227.6 square meters]). If additional sample units were included in the survey, the extrapolation process is slightly different. In the above example, assume that sample unit number 01 was surveyed as an additional unit and that the amount of medium-severity alligator cracking was measured as shown in Table 3-4:

Table 3-4 Medium-Severity Alligator Cracking in an Additional Sample Unit

Additional Sample Unit ID Number

Sample Unit Area ft2 (m2)

Medium-Severity Alligator Cracking ft2 (m2)

01 5,000 (465) 2,000 (186)

Total Additional 5,000 (465) 2,000 (186)

3-5.4 Since 5,000 square feet (465 square meters) were surveyed as additional in this example, the section’s randomly represented area is 49,000 - 5,000 square feet (4,552 – 465 square meters) or 44,000 square feet (4087 square meters). The extrapolated distress quantity is obtained by multiplying the distress density by the section’s randomly represented area then adding the amount of additional distress. In this example, the extrapolated distress quantity equals (0.05 × 44,000 square feet (4,087 square meters) + 2,000 square feet (186 square meters) or 4,200 square feet (390 square meters).

APPENDIX A DISTRESS DEFINITIONS - ASPHALT-SURFACED AIRFIELDS.

A-1 INTRODUCTION.

This appendix contains distress definitions and measurement methods for asphalt-surfaced airfields. This information is used to determine the PCI.

Note: Each distress definition is followed by a number in parentheses, indicating the PAVER distress code, and a number in braces, indicating the ASTM D5340 distress code, i.e., “Distress (#) {#}.” See Table 3-5.

Table A-1 Frequently Occurring Problems in Asphalt Pavement Distress Identification

Situation Action Remarks

Alligator cracking and rutting in same area

Record each separately at respective severity level

Bleeding counted in area Polished aggregate is not counted in same area

Polished aggregate in very small amount Do not count

Polished aggregate is only counted when there is a significant amount

Any distress (including cracking) in a patched area

Do not record Effect of distress is considered in patch severity level

Block cracking is recorded

For asphalt pavements, not including AC over PCC, if block cracking is recorded, do not record longitudinal and transverse cracking in the same area

Asphalt overlay over concrete

Block cracking and joint reflection cracking are recorded separately

AC over PCC could have, for example, 100 percent block cracking and 100 feet of joint reflection cracking

Weathering (surface wear) and raveling in the same sample area

Weathering (surface wear) is not recorded if medium-or high-severity raveling is recorded

Raveling is always recorded

A-2 ALLIGATOR (FATIGUE) CRACKING (41) {1}.

A-2.1 Description.

Alligator (or fatigue) cracking is a series of interconnecting cracks caused by fatigue failure of the asphalt surface under repeated traffic loading. The cracking initiates at the bottom of the asphalt surface (or stabilized base) where tensile stress and strain is highest under a wheel load. The cracks propagate to the surface initially as a series of parallel cracks. After repeated traffic loading, the cracks connect and form multi-sided, sharp-angled pieces that develop a pattern resembling chicken wire or the skin of an alligator. The pieces are less than 2 feet (0.6 meter) on the longest side. Alligator cracking occurs only in areas subjected to repeated traffic loadings, such as wheel paths; therefore, it would not occur over an entire area unless the entire area was subjected to traffic loading. (Pattern-type cracking that occurs over an entire area that is not subject to loading is rated as block cracking, which is not a load-associated distress.) Alligator cracking is considered a major structural distress.

A-2.2 Severity Levels.

L Fine, longitudinal hairline cracks running parallel to each other with no or only a few interconnecting cracks. The cracks are not spalled.

M Further development of light alligator cracking into a pattern or network of cracks that may be lightly spalled. Medium-severity alligator cracking is defined by a well-defined pattern of interconnecting cracks, where all pieces are securely held in place (i.e., good aggregate interlock between pieces).

H Network or pattern cracking progresses so that pieces are well-defined and spalled at the edges; some of the pieces rock under traffic and may cause foreign object damage (FOD) potential.

A-2.3 How to Measure.

Alligator cracking is measured in square feet (square meters) of surface area. The major difficulty in measuring this type of distress is that often two or three levels of severity exist within one distressed area. If these portions can be easily distinguished from each other, measure and record separately; however, if the different levels of severity cannot be easily divided, rate the entire area at the highest severity level present. If alligator cracking and rutting occur in the same area, each is recorded separately at its respective severity level.

Figure A-1 Low-Severity Alligator Cracking

Figure A-2 Medium-Severity Alligator Cracking

Figure A-3 High-Severity Alligator Cracking

A-3 BLEEDING (42) {2}.

A-3.1 Description.

Bleeding is a film of bituminous material on the pavement surface that creates a shiny, glass-like, reflecting surface that usually becomes quite sticky. Bleeding is caused by excessive amounts of asphalt cement or tars in the mix and/or low air-void content.

Bleeding occurs when asphalt fills the voids of the mix during hot weather and then expands onto the surface of the pavement. Since the bleeding process is not reversible during cold weather, asphalt or tar will accumulate on the surface.

A-3.2 Severity Levels.

No degrees of severity are defined. Note bleeding when it is extensive enough to cause a reduction in skid resistance.

A-3.3 How to Measure.

Bleeding is measured in square feet (square meters) of surface area. If bleeding is counted, polished aggregate is not counted in the same area.

Figure A-4 Bleeding

Figure A-5 Bleeding

A-4 BLOCK CRACKING (43) {3}.

A-4.1 Description.

Block cracks are interconnected cracks that divide the pavement into roughly rectangular pieces. The blocks may range in size from approximately 1 by 1 foot to 10 by 10 feet (0.3 by 0.3 meter to 3 by 3 meters). Block cracking is caused mainly by shrinkage of the AC and daily temperature cycling (which results in daily stress/strain cycling); it is not load-associated. The occurrence of block cracking usually indicates that the asphalt has significantly hardened. Block cracking typically occurs over a large proportion of pavement area but sometimes will occur in non-traffic areas. This type of distress differs from alligator cracking in that alligator cracks form smaller, multi-sided pieces with sharp angles. Also, unlike block cracks, alligator cracks are caused by repeated traffic loadings and therefore are located only in traffic areas (i.e., wheel paths).

A-4.2 Severity Levels.

L Blocks are defined by cracks that are non-spalled (sides of the crack are vertical) or only lightly spalled, causing no FOD potential. Non-filled cracks have 0.25 inch (6 millimeters) or less mean width and filled cracks have filler in satisfactory condition.

M Blocks are defined by either (1) filled or non-filled cracks that are moderately spalled (some FOD potential); (2) non-filled cracks that are not spalled or have only minor spalling (some FOD potential) but have a mean width greater than approximately

0.25 inch (6 millimeters); or (3) filled cracks that are not spalled or have only minor spalling (some FOD potential) but have filler in unsatisfactory condition.

H Blocks are well defined by cracks that are severely spalled, causing a definite FOD potential.

A-4.3 How to Measure.

Block cracking is measured in square feet (square meters) of surface area. It usually occurs at one severity level in a given pavement section; however, measure and record separately any areas of the pavement section having distinctly different levels of severity. For asphalt pavements, not including AC over PCC, if block cracking is recorded, do not record longitudinal and transverse (L&T) cracking in the same area.

For asphalt overlay over concrete, separately record block cracking, joint reflection cracking, and L&T cracking reflected from old concrete.

Figure A-6 Low-Severity Block Cracking

Figure A-7 Low-Severity Block Cracking

Figure A-8 Medium-Severity Block Cracking

Figure A-9 Medium-Severity Block Cracking

Figure A-10 High-Severity Block Cracking

Figure A-11 High-Severity Block Cracking

A-5 CORRUGATION (44) {4}.

A-5.1 Description.

Corrugation is a series of closely spaced ridges and valleys (ripples) occurring at fairly regular intervals, usually less than 5 feet (1.5 meters) along the pavement. The ridges are perpendicular to the traffic direction. Traffic action combined with an unstable pavement surface or base usually causes this type of distress.

A-5.2 Severity Levels.

L Corrugations are minor and do not significantly affect ride quality (see measurement criteria below).

M Corrugations are noticeable and significantly affect ride quality (see measurement criteria below).

H Corrugations are easily noticed and severely affect ride quality (see measurement criteria below).

A-5.3 How to Measure.

Corrugation is measured in square feet (square meters) of…