Research, Development, and Technology

Turner-Fairbank Highway Research Center

6300 Georgetown Pike

McLean, VA 22101-2296

PUBLICATION NO. FHWA-HRT-20-070 NOVEMBER 2020 

Long-Term Pavement Performance 

Data Analysis Program: Effect of Dowel 

Misalignment on Concrete Pavement 

Performance
FOREWORD

This report documents the analysis of data collected through the Long-Term Pavement 

Performance (LTPP) program to characterize the effects of dowel misalignment on concrete 

pavement performance. The objective of this research was to measure the alignment of dowels at 

the transverse joints of in-service pavements. This report documents this information on a 

State-by-State basis. Data were used to evaluate typical distribution of various types of 

misalignment and analyze how misalignment relates to pavement performance factors such as

cracking, faulting, and spalling. 

A majority of dowels in LTPP studies had good alignment with regard to horizontal skew, 

vertical tilt, longitudinal translation, and vertical translation. To characterize the entire transverse 

joint, rather than just the individual dowels, the joint score and equivalent dowel diameter

measures were used for each pavement section. The researchers found that, while dowel 

misalignment may be a contributing factor, its effects were secondary, as there are many other 

factors that affect pavement performance. The biggest contribution of dowel misalignment was 

in terms of its effect on load transfer at the transverse joints, which may translate to poor faulting 

performance, depending on other factors that impact faulting. 

Cheryl Allen Richter, Ph.D., P.E. 

Director, Office of Infrastructure

Research and Development 

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation 

(USDOT) in the interest of information exchange. The U.S. Government assumes no liability for 

the use of the information contained in this document. 

The U.S. Government does not endorse products or manufacturers. Trademarks or 

manufacturers’ names appear in this report only because they are considered essential to the 

objective of the document. 

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve 

Government, industry, and the public in a manner that promotes public understanding. Standards 

and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its 

information. FHWA periodically reviews quality issues and adjusts its programs and processes to 

ensure continuous quality improvement.
TECHNICAL REPORT DOCUMENTATION PAGE

1. Report No.

FHWA-HRT-20-070

2. Government Accession No. 3. Recipient’s Catalog No.

4. Title and Subtitle

Long-Term Pavement Performance Data Analysis Program: 

Effect of Dowel Misalignment on Concrete Pavement 

Performance

5. Report Date

November 2020

6. Performing Organization Code

7. Author(s)

Shreenath Rao, Ph.D., P.E., and Lax Premkumar, P.E.

8. Performing Organization Report No.

9. Performing Organization Name and Address

Applied Research Associates, Inc.

100 Trade Centre Drive, Suite 200

Champaign, IL 61820

10. Work Unit No.

11. Contract or Grant No.

DTFH61-14-C-00017

12. Sponsoring Agency Name and Address

Office of Infrastructure

Federal Highway Administration

6300 Georgetown Pike

McLean, VA 22101

13. Type of Report and Period Covered

Final Report; May 2014–September 2018

14. Sponsoring Agency Code

HRDI-30

15. Supplementary Notes

The Federal Highway Administration Contracting Officer’s Representative was Jack Springer (retired). 

16. Abstract

Magnetic imaging tomography (MIT) scanning is a nondestructive method for measuring the alignment of 

dowels placed at transverse joints of jointed plain concrete pavements (JPCPs). Several highway agencies across 

the United States have adopted specifications for dowel alignment, with many using the joint score measure. 

However, this measure was developed intuitively and not based on any laboratory or field tests. National 

Cooperative Highway Research Program (NCHRP) Report 637 provides a methodology to determine an 

equivalent dowel diameter measure based on dowel misalignment (Khazanovich et al. 2009). This procedure was 

developed from laboratory tests and with limited field validation. The relationship between dowel misalignment 

and the performance of JPCP is unclear, but understanding it is imperative for developing construction

guidelines. This report presents results of MIT scanning data collected on Long-Term Pavement Performance 

(LTPP) test sections and data analysis to assess the effects of dowel misalignment on JPCP performance. As part 

of this study, MIT scanning was performed on 121 Specific Pavement Studies-2 and 3 General Pavement 

Studies-3 test sections. Dowel alignment parameters, joint score, and equivalent dowel diameter were calculated 

as part of the analysis. Statistical analysis was performed to determine any relationship between the joint score 

and cracking and between the joint score and spalling. The analysis did not indicate any definitive relationship 

between the joint score and cracking or the joint score and spalling within the analysis range for most States, 

although some effect was observed for three States. This lack of relationship does not mean severely misaligned 

dowels have no effect on pavement performance, particularly localized distresses. Analysis of the equivalent 

dowel diameter as a measure of dowel misalignment for use with AASHTOWare® Pavement ME Design 

software suggests that using the equivalent dowel diameter is a less-biased estimator of long-term load-transfer 

efficiency (LTE), as modeled using AASHTOWare Pavement ME Design, than using the actual dowel diameter, 

suggesting a relationship between dowel misalignment and long-term LTE (AASHTO 2014). However, there is

considerable scatter in the LTE modeled using AASHTOWare Pavement ME Design versus actual LTE. The 

remaining bias and scatter suggests that the models (i.e., equivalent dowel diameter and LTE in AASHTOWare 

Pavement ME Design) could potentially be improved using data collected as part of this study.

17. Key Words

Long-term pavement performance, LTPP, 

concrete pavement performance, dowel 

misalignment, dowel alignment, MIT scanning, 

equivalent dowel diameter, dowel specifications

18. Distribution Statement

No restrictions. This document is available to the public 

through the National Technical Information Service, 

Springfield, VA 22161.

http://www.ntis.gov

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

116 

22. Price

N/A

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized.
ii

SI* (MODERN METRIC) CONVERSION FACTORS

APPROXIMATE CONVERSIONS TO SI UNITS

Symbol When You Know Multiply By To Find Symbol

LENGTH

in inches 25.4 millimeters mm

ft feet 0.305 meters m

yd yards 0.914 meters m

mi miles 1.61 kilometers km

AREA

in2 square inches 645.2 square millimeters mm2

ft2 square feet 0.093 square meters m2

yd2 square yard 0.836 square meters m2

ac acres 0.405 hectares ha

mi2 square miles 2.59 square kilometers km2

VOLUME

fl oz fluid ounces 29.57 milliliters mL

gal gallons 3.785 liters L

ft3 cubic feet 0.028 cubic meters m3

yd3 cubic yards 0.765 cubic meters m3

NOTE: volumes greater than 1,000 L shall be shown in m3

MASS

oz ounces 28.35 grams g

lb pounds 0.454 kilograms kg

T short tons (2,000 lb) 0.907 megagrams (or “metric ton”) Mg (or “t”)

TEMPERATURE (exact degrees)

°F Fahrenheit 5 (F-32)/9 Celsius °C or (F-32)/1.8

ILLUMINATION

fc foot-candles 10.76 lux lx

fl foot-Lamberts 3.426 candela/m2 cd/m2

FORCE and PRESSURE or STRESS

lbf poundforce 4.45 newtons N

lbf/in2 poundforce per square inch 6.89 kilopascals kPa

APPROXIMATE CONVERSIONS FROM SI UNITS

Symbol When You Know Multiply By To Find Symbol

LENGTH

mm millimeters 0.039 inches in

m meters 3.28 feet ft

m meters 1.09 yards yd

km kilometers 0.621 miles mi

AREA

mm2 square millimeters 0.0016 square inches in2

m2 square meters 10.764 square feet ft2

m2 square meters 1.195 square yards yd2

ha hectares 2.47 acres ac

km2 square kilometers 0.386 square miles mi2

VOLUME

mL milliliters 0.034 fluid ounces fl oz

L liters 0.264 gallons gal

m3 cubic meters 35.314 cubic feet ft3

m3 cubic meters 1.307 cubic yards yd3

MASS

g grams 0.035 ounces oz

kg kilograms 2.202 pounds lb

Mg (or “t”) megagrams (or “metric ton”) 1.103 short tons (2,000 lb) T

TEMPERATURE (exact degrees)

°C Celsius 1.8C+32 Fahrenheit °F

ILLUMINATION

lx lux 0.0929 foot-candles fc

cd/m2 candela/m2 0.2919 foot-Lamberts fl

FORCE and PRESSURE or STRESS

N newtons 2.225 poundforce lbf

kPa kilopascals 0.145 poundforce per square inch lbf/in2

*SI is the symbol for International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. 

(Revised March 2003)
iii

TABLE OF CONTENTS

CHAPTER 1. BACKGROUND AND LITERATURE REVIEW ............................................ 1

CHAPTER 2. SELECTION OF LTPP TEST SECTIONS ...................................................... 7

CHAPTER 3. MIT SCANNING .................................................................................................. 9

CHAPTER 4. DOWEL ALIGNMENT DATA ANALYSES .................................................. 13

DOWEL ALIGNMENT ANALYSES ................................................................................. 13

JOINT SCORE ANALYSES ............................................................................................... 19

EQUIVALENT DOWEL DIAMETER ANALYSES ........................................................ 21

CHAPTER 5. MIT SCANNING ANALYSES BY STATE ..................................................... 23

ARIZONA .............................................................................................................................. 23

ARKANSAS........................................................................................................................... 27

CALIFORNIA ....................................................................................................................... 31

COLORADO ......................................................................................................................... 36

DELAWARE ......................................................................................................................... 40

IOWA ..................................................................................................................................... 45

KANSAS ................................................................................................................................ 49

NORTH CAROLINA ........................................................................................................... 54

NORTH DAKOTA ............................................................................................................... 58

SOUTH DAKOTA ................................................................................................................ 63

WISCONSIN ......................................................................................................................... 67

CHAPTER 6. JOINT SCORE ANALYSES ............................................................................. 73

CHAPTER 7. JOINT-OPENING ANALYSES ....................................................................... 87

CHAPTER 8. AASHTOWARE PAVEMENT ME DESIGN ANALYSES USING 

EQUIVALENT DOWEL DIAMETER .................................................................................... 89

CHAPTER 9. CONCLUSIONS AND RECOMMENDATIONS ......................................... 103

REFERENCES .......................................................................................................................... 105
iv

LIST OF FIGURES

Figure 1. Illustration. Types of dowel misalignment (adapted from Tayabji 1986). ...................... 2

Figure 2. Chart. Percentage of analysis pavement test sections with respect to

PCC thickness. .......................................................................................................................... 8

Figure 3. Chart. Percentage of analysis pavement test sections with respect to 

construction year. ...................................................................................................................... 8

Figure 4. Photo. Testing a pavement transverse joint using an MIT scanning device. .................. 9

Figure 5. Photo. MIT scanning of North Carolina LTPP test section 37_0207. .......................... 11

Figure 6. Photo. Cracking and spalling on Arkansas LTPP test section 05_0217........................ 11

Figure 7. Photo. Full-width spray patching on Delaware LTPP test section 10_0208. ................ 12

Figure 8. Photo. Skewed transverse joints on Iowa LTPP test section 19_0259. ......................... 12

Figure 9. Chart. Horizontal skew distribution of dowels (23,300 1.5-inch-diameter dowels 

from 1,997 transverse joints and 21,240 1.25-inch-diameter dowels from 1,824 

transverse joints). .................................................................................................................... 14

Figure 10. Chart. Vertical tilt distribution of dowels (23,300 1.5-inch-diameter dowels 

from 1,997 transverse joints and 21,240 1.25-inch-diameter dowels from 1,824 

transverse joints). .................................................................................................................... 14

Figure 11. Chart. Longitudinal translation distribution of dowels (23,300 1.5-inch-diameter 

dowels from 1,997 transverse joints and 21,240 1.25-inch-diameter dowels from 

1,824 transverse joints). .......................................................................................................... 15

Figure 12. Chart. Vertical translation distribution of dowels (23,300 1.5-inch-diameter 

dowels from 1,997 transverse joints and 21,240 1.25-inch-diameter dowels from 

1,824 transverse joints). .......................................................................................................... 15

Figure 13. Chart. Cumulative horizontal skew distribution of 21,240 1.25-inch-diameter 

dowels from 1,824 transverse joints. ...................................................................................... 16

Figure 14. Chart. Cumulative vertical tilt distribution of 21,240 1.25-inch-diameter dowels 

from 1,824 transverse joints. ................................................................................................... 16

Figure 15. Chart. Cumulative longitudinal translation distribution of 

21,240 1.25-inch-diameter dowels from 1,824 transverse joints. ........................................... 17

Figure 16. Chart. Cumulative vertical translation distribution of 21,240 1.25-inch-diameter 

dowels from 1,824 transverse joints. ...................................................................................... 17

Figure 17. Chart. Cumulative horizontal skew distribution of 23,300 1.5-inch-diameter 

dowels from 1,997 transverse joints. ...................................................................................... 18

Figure 18. Chart. Cumulative vertical tilt distribution of 23,300 1.5-inch-diameter dowels 

from 1,997 transverse joints. ................................................................................................... 18

Figure 19. Chart. Cumulative longitudinal translation distribution of 

23,300 1.5-inch-diameter dowels from 1,997 transverse joints. ............................................. 19

Figure 20. Chart. Cumulative vertical translation distribution of 23,300 1.5-inch-diameter 

dowels from 1,997 transverse joints. ...................................................................................... 19

Figure 21. Chart. Joint score distribution for 1.25- and 1.5-inch-diameter dowels from 

3,821 transverse joints (23,300 1.5-inch-diameter dowels from 1,997 transverse joints 

and 21,240 1.25-inch-diameter dowels from 1,824 transverse joints). ................................... 21

Figure 22. Chart. Horizontal skew distribution for LTPP test sections in Arizona. ..................... 24

Figure 23. Chart. Vertical tilt distribution for LTPP test sections in Arizona. ............................. 24

Figure 24. Chart. Longitudinal translation distribution for LTPP test sections in Arizona. ......... 24
v 

Figure 25. Chart. Vertical translation distribution for LTPP test sections in Arizona.................. 25

Figure 26. Chart. Joint score distribution for LTPP test sections in Arizona. .............................. 26

Figure 27. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in Arizona. ................................................................................................................. 27

Figure 28. Chart. Horizontal skew distribution for LTPP test sections in Arkansas. ................... 28

Figure 29. Chart. Vertical tilt distribution for LTPP test sections in Arkansas. ........................... 28

Figure 30. Chart. Longitudinal translation distribution for LTPP test sections in Arkansas. ....... 29

Figure 31. Chart. Vertical translation distribution for LTPP test sections in Arkansas................ 29

Figure 32. Chart. Joint score distribution for LTPP test sections in Arkansas. ............................ 30

Figure 33. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in Arkansas. ............................................................................................................... 31

Figure 34. Chart. Horizontal skew distribution for LTPP test sections in California. .................. 32

Figure 35. Chart. Vertical tilt distribution for LTPP test sections in California. .......................... 33

Figure 36. Chart. Longitudinal translation distribution for LTPP test sections in California. ..... 33

Figure 37. Chart. Vertical translation distribution for LTPP test sections in California. ............. 34

Figure 38. Chart. Joint score distribution for LTPP test sections in California. ........................... 35

Figure 39. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in California. ............................................................................................................. 36

Figure 40. Chart. Horizontal skew distribution for LTPP test sections in Colorado. ................... 37

Figure 41. Chart. Vertical tilt distribution for LTPP test sections in Colorado. ........................... 37

Figure 42. Chart. Longitudinal translation distribution for LTPP test sections in Colorado. ....... 38

Figure 43. Chart. Vertical translation distribution for LTPP test sections in Colorado................ 38

Figure 44. Chart. Joint score distribution for LTPP test sections in Colorado. ............................ 39

Figure 45. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in Colorado. ............................................................................................................... 40

Figure 46. Chart. Horizontal skew distribution for LTPP test sections in Delaware. ................... 41

Figure 47. Chart. Vertical tilt distribution for LTPP test sections in Delaware. .......................... 42

Figure 48. Chart. Longitudinal translation distribution for LTPP test sections in Delaware. ...... 42

Figure 49. Chart. Vertical translation distribution for LTPP test sections in Delaware. .............. 43

Figure 50. Chart. Joint score distribution for LTPP test sections in Delaware. ............................ 44

Figure 51. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in Delaware. .............................................................................................................. 45

Figure 52. Chart. Horizontal skew distribution for LTPP test sections in Iowa. .......................... 46

Figure 53. Chart. Vertical tilt distribution for LTPP test sections in Iowa. .................................. 46

Figure 54. Chart. Longitudinal translation distribution for LTPP test sections in Iowa. .............. 47

Figure 55. Chart. Vertical translation distribution for LTPP test sections in Iowa. ..................... 47

Figure 56. Chart. Joint score distribution for LTPP test sections in Iowa. ................................... 48

Figure 57. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in Iowa....................................................................................................................... 49

Figure 58. Chart. Horizontal skew distribution for LTPP test sections in Kansas. ...................... 50

Figure 59. Chart. Vertical tilt distribution for LTPP test sections in Kansas. .............................. 51

Figure 60. Chart. Longitudinal translation distribution for LTPP test sections in Kansas. .......... 51

Figure 61. Chart. Vertical translation distribution for LTPP test sections in Kansas. .................. 52

Figure 62. Chart. Joint score distribution for LTPP test sections in Kansas. ............................... 53

Figure 63. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in Kansas. .................................................................................................................. 54
vi 

Figure 64. Chart. Horizontal skew distribution for LTPP test sections in North Carolina. .......... 55

Figure 65. Chart. Vertical tilt distribution for LTPP test sections in North Carolina. .................. 55

Figure 66. Chart. Longitudinal translation distribution for LTPP test sections in 

North Carolina. ....................................................................................................................... 56

Figure 67. Chart. Vertical translation distribution for LTPP test sections in North Carolina. ..... 56

Figure 68. Chart. Joint score distribution for LTPP test sections in North Carolina. ................... 57

Figure 69. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in North Carolina. ..................................................................................................... 58

Figure 70. Chart. Horizontal skew distribution for LTPP test sections in North Dakota. ............ 59

Figure 71. Chart. Vertical tilt distribution for LTPP test sections in North Dakota. .................... 60

Figure 72. Chart. Longitudinal translation distribution for LTPP test sections in 

North Dakota. .......................................................................................................................... 60

Figure 73. Chart. Vertical translation distribution for LTPP test sections in North Dakota......... 61

Figure 74. Chart. Joint score distribution for LTPP test sections in North Dakota. ..................... 62

Figure 75. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in North Dakota. ........................................................................................................ 63

Figure 76. Chart. Horizontal skew distribution for the LTPP test section in South Dakota. ........ 64

Figure 77. Chart. Vertical tilt distribution for the LTPP test section in South Dakota. ................ 64

Figure 78. Chart. Longitudinal translation distribution for the LTPP test section in 

South Dakota. .......................................................................................................................... 65

Figure 79. Chart. Vertical translation distribution for the LTPP test section in 

South Dakota. .......................................................................................................................... 65

Figure 80. Chart Joint score distribution for the LTPP test section in South Dakota. .................. 66

Figure 81. Chart. Joint score versus effective reduction in dowel diameter for the LTPP test 

section in South Dakota. ......................................................................................................... 67

Figure 82. Chart. Horizontal skew distribution for LTPP test sections in Wisconsin. ................. 68

Figure 83. Chart. Vertical tilt distribution for LTPP test sections in Wisconsin. ......................... 68

Figure 84. Chart. Longitudinal translation distribution for LTPP test sections in Wisconsin. ..... 69

Figure 85. Chart. Vertical translation distribution for LTPP test sections in Wisconsin.............. 69

Figure 86. Chart. Joint score distribution for LTPP test sections in Wisconsin. .......................... 70

Figure 87. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in Wisconsin. ............................................................................................................. 71

Figure 88. Chart. Joint score and presence of cracking for LTPP test sections in Arizona. ......... 74

Figure 89. Chart. Joint score and presence of spalling for LTPP test sections in Arizona. .......... 75

Figure 90. Chart. Joint score and presence of cracking for LTPP test sections in Arkansas. ....... 75

Figure 91. Chart. Joint score and presence of spalling for LTPP test sections in Arkansas. ........ 76

Figure 92. Chart. Joint score and presence of cracking for LTPP test sections in California. ..... 76

Figure 93. Chart. Joint score and presence of spalling for LTPP test sections in California. ...... 77

Figure 94. Chart. Joint score and presence of cracking for LTPP test sections in Colorado. ....... 77

Figure 95. Chart. Joint score and presence of spalling for LTPP test sections in Colorado. ........ 78

Figure 96. Chart. Joint score and presence of cracking for LTPP test sections in Delaware. ...... 78

Figure 97. Chart. Joint score and presence of spalling for LTPP test sections in Delaware. ....... 79

Figure 98. Chart. Joint score and presence of cracking for LTPP test sections in Iowa............... 79

Figure 99. Chart. Joint score and presence of spalling for LTPP test sections in Iowa. ............... 80

Figure 100. Chart. Joint score and presence of cracking for LTPP test sections in Kansas. ........ 80

Figure 101. Chart. Joint score and presence of spalling for LTPP test sections in Kansas. ......... 81
vii 

Figure 102. Chart. Joint score and presence of cracking for LTPP test sections in 

North Carolina. ....................................................................................................................... 81

Figure 103. Chart. Joint score and presence of spalling for LTPP test sections in 

North Carolina. ....................................................................................................................... 82

Figure 104. Chart. Joint score and presence of cracking for LTPP test sections in 

North Dakota. .......................................................................................................................... 82

Figure 105. Chart. Joint score and presence of spalling for LTPP test sections in 

North Dakota. .......................................................................................................................... 83

Figure 106. Chart. Joint score and presence of cracking for the LTPP test section in 

South Dakota. .......................................................................................................................... 83

Figure 107. Chart. Joint score and presence of spalling for the LTPP test section in 

South Dakota. .......................................................................................................................... 84

Figure 108. Chart. Joint score and presence of cracking for LTPP test sections in 

Wisconsin. ............................................................................................................................... 84

Figure 109. Chart. Joint score and presence of spalling for LTPP test sections in 

Wisconsin. ............................................................................................................................... 85

Figure 110. Chart. Joint-opening data from five instrumented transverse joints at Arizona 

LTPP test section 4_0215. ...................................................................................................... 88

Figure 111. Chart. Predicted and actual LTE Using AASHTOWare Pavement ME Design 

from the LTPP database for 117 test sections using the actual and average equivalent 

dowel diameter. ..................................................................................................................... 102

Figure 112. Chart. Predicted and actual LTE Using AASHTOWare-Pavement ME Design 

from the LTPP database for 117 test sections using the actual and average equivalent 

dowel diameter. ..................................................................................................................... 102
viii

LIST OF TABLES

Table 1. Number of LTPP test sections by State for MIT scanning and analyses. ......................... 7

Table 2. MIT scanning field input. ............................................................................................... 10

Table 3. Weighting factors used to determine the joint score (Yu and Khazanovich 2005). ....... 20

Table 4. Average joint score for States with LTPP test sections. ................................................. 21

Table 5. Equivalent dowel diameter and effective percent reduction in dowel diameter for 

States with LTPP test sections. ............................................................................................... 22

Table 6. Details of LTPP test sections in Arizona. ....................................................................... 23

Table 7. Dowel misalignment summary for LTPP test sections in Arizona. ................................ 25

Table 8. Joint score and equivalent dowel diameter for LTPP test sections in Arizona. .............. 26

Table 9. Details of LTPP test sections in Arkansas. ..................................................................... 27

Table 10. Dowel misalignment summary for LTPP test sections in Arkansas. ............................ 30

Table 11. Joint score and equivalent dowel diameter for LTPP test sections in Arkansas........... 31

Table 12. Details of LTPP test sections in California. .................................................................. 32

Table 13. Dowel misalignment summary for LTPP test sections in California. .......................... 34

Table 14. Joint score and equivalent dowel diameter for LTPP test sections in California. ........ 35

Table 15. Details of LTPP test sections in Colorado. ................................................................... 36

Table 16. Dowel misalignment summary for LTPP test sections in Colorado. ............................ 39

Table 17. Joint score and equivalent dowel diameter for LTPP test sections in Colorado........... 40

Table 18. Details of LTPP test sections in Delaware.................................................................... 41

Table 19. Dowel misalignment summary for LTPP test sections in Delaware. ........................... 43

Table 20. Joint score and equivalent dowel diameter for LTPP test sections in Delaware. ......... 44

Table 21. Details of LTPP test sections in Iowa. .......................................................................... 45

Table 22. Dowel misalignment summary for LTPP test sections in Iowa.................................... 48

Table 23. Joint score and equivalent dowel diameter for LTPP test sections in Iowa. ................ 49

Table 24. Details of LTPP test sections in Kansas. ...................................................................... 50

Table 25. Dowel misalignment summary for LTPP test sections in Kansas. ............................... 52

Table 26. Chart. Joint score and equivalent dowel diameter for LTPP test sections in 

Kansas. .................................................................................................................................... 53

Table 27. Details of LTPP test sections in North Carolina. .......................................................... 54

Table 28. Dowel misalignment summary for LTPP test sections in North Carolina. .................. 57

Table 29. Joint score and equivalent dowel diameter for LTPP test sections in 

North Carolina. ....................................................................................................................... 58

Table 30. Details of LTPP test sections in North Dakota. ............................................................ 59

Table 31. Dowel misalignment summary for LTPP test sections in North Dakota. ..................... 61

Table 32. Joint score and equivalent dowel diameter for LTPP test sections in 

North Dakota. .......................................................................................................................... 62

Table 33. Details of the LTPP test section in South Dakota. ........................................................ 63

Table 34. Dowel misalignment summary for the LTPP test section in South Dakota. ................ 65

Table 35. Joint score and equivalent dowel diameter for the LTPP test section in 

South Dakota. .......................................................................................................................... 66

Table 36. Details of LTPP test sections in Wisconsin. ................................................................. 67

Table 37. Dowel misalignment summary for LTPP test sections in Wisconsin. .......................... 70

Table 38. Joint score and equivalent dowel diameter for LTPP test sections in Wisconsin......... 71

Table 39. Joint score category. ..................................................................................................... 73
ix

Table 40. Summary results of statistical analyses. ....................................................................... 74

Table 41. Maximum joint opening, dowel alignment data, and joint score for five 

instrumented transverse joints with joint-opening data at Arizona LTPP test section 

4_0215..................................................................................................................................... 88

Table 42. Comparison of AASHTOWare Pavement ME Design analyses results with 

actual LTPP distress data using the average equivalent and actual dowel diameter for 

LTPP test sections in Arizona. ................................................................................................ 91

Table 43. Comparison of AASHTOWare Pavement ME Design analyses results with 

actual LTPP distress data using the average equivalent and actual dowel diameter for 

LTPP test sections in Arkansas. .............................................................................................. 92

Table 44. Comparison of AASHTOWare Pavement ME Design analyses results with 

actual LTPP distress data using the average equivalent and actual dowel diameter for 

LTPP test sites in Colorado..................................................................................................... 93

Table 45. Comparison of AASHTOWare Pavement ME Design analyses results with 

actual LTPP distress data using the average equivalent and actual dowel diameter for 

LTPP test sections in California. ............................................................................................ 94

Table 46. Comparison of AASHTOWare Pavement ME Design analyses results with 

actual LTPP distress data using the average equivalent and actual dowel diameter for 

LTPP test section in Delaware. ............................................................................................... 95

Table 47. Comparison of AASHTOWare Pavement ME Design analyses results with 

actual LTPP distress data using the average equivalent and actual dowel diameter for 

LTPP test sections in Iowa. ..................................................................................................... 96

Table 48. Comparison of AASHTOWare Pavement ME Design analyses results with 

actual LTPP distress data using the average equivalent and actual dowel diameter for 

LTPP test sections in Kansas. ................................................................................................. 97

Table 49. Comparison of AASHTOWare Pavement ME Design analyses results with 

actual LTPP distress data using the average equivalent and actual dowel diameter for 

LTPP test sections in North Carolina...................................................................................... 98

Table 50. Comparison of AASHTOWare Pavement ME Design analyses results with 

actual LTPP distress data using the average equivalent and actual dowel diameter for 

LTPP test sections in North Dakota. ....................................................................................... 99

Table 51. Comparison of AASHTOWare Pavement ME Design analysis results with actual 

LTPP distress data using the average equivalent and actual dowel diameter for the 

LTPP test section in South Dakota. ...................................................................................... 100

Table 52. Comparison of AASHTOWare Pavement ME Design analyses results with 

actual LTPP distress data using the average equivalent and actual dowel diameter for 

LTPP test sections in Wisconsin. .......................................................................................... 100

Table 53. Summary of AASHTOWare Pavement ME Design analyses results with actual 

LTPP distress data using the average equivalent and actual dowel diameter. ...................... 101
x 

LIST OF ABBREVIATIONS

ACPA American Concrete Pavement Association

DBI dowel bar inserter 

FHWA Federal Highway Administration

GPS General Pavement Studies

JPCP jointed plain concrete pavement 

LTE load-transfer efficiency

LTPP Long-Term Pavement Performance

MIT magnetic imaging tomography 

NCHRP National Cooperative Highway Research Program 

PCC portland cement concrete

SMP Seasonal Monitoring Program 

SPS Specific Pavement Studies
1 

CHAPTER 1. BACKGROUND AND LITERATURE REVIEW

Transverse joints are essential features of jointed plain concrete pavements (JPCPs) that help 

relieve thermal- and moisture-induced stresses. At the same time, they are the weakest aspects of 

JPCPs, experiencing higher stresses and deflections compared to interior parts of the slab under 

the same loading conditions. With modern JPCPs, dowels are placed across transverse joints to 

allow for wheel-load shear transfer across slabs while also allowing unrestricted slab expansion 

and contraction due to changes in temperature and moisture. When compared to JPCPs with 

undoweled transverse joints, slab corner deflections in JPCPs with doweled transverse joints are 

reduced by the improved wheel-load shear transfer. Dowels help increase pavement life by 

providing greater smoothness and reducing the potential for pumping, base erosion, and faulting. 

These pavement-life-extending benefits have been demonstrated by several pavement studies 

(Yu et al. 1998; Khazanovich et al. 1998; Hoerner et al. 2000). Some researchers consider 

pumping and transverse joint faulting issues largely resolved if properly sized and aligned 

dowels are used at the transverse joints (Khazanovich et al. 1998; Lechner 2005). 

To be effective, dowels must be parallel to both the centerline and surface of the pavement, 

placed with sufficient cover, and centered across the transverse joint. Any deviation from such 

positioning is considered dowel misalignment. Some engineers and researchers only consider 

rotation as misalignment and consider translation as mislocation, but for convenience and 

consistency, all deviations (e.g., rotational and translational) in this study are considered

misalignments. 

The major categories of dowel misalignment are translational—which includes horizontal, 

longitudinal, and vertical translation—and rotational—which includes horizontal skew and 

vertical tilt—as illustrated in figure 1 (Tayabji 1986; Rao 2009). Horizontal translation is often 

disregarded as a misalignment parameter because properly positioning dowels at regular spacing 

(typically 12 inches) along the transverse joint is not an issue and not considered a key factor 

affecting transverse joint performance.
2 

© 2009 Shreenath Rao.

Figure 1. Illustration. Types of dowel misalignment (adapted from Tayabji 1986). 

Potential adverse effects of dowel misalignment include the following: 

• Reduced load-transfer efficiency (LTE), resulting in increased long-term faulting and, in 

some situations, increased corner cracking. 

• Transverse joint spalling from excessive steel/concrete bearing stresses.

• Slab cracking from transverse joint lockup or restraint. 

Dowels are placed in concrete using dowel baskets or dowel bar inserters (DBIs). Dowel baskets 

are carriages designed to support or link dowels and hold them at the desired alignment during 

paving operations. DBIs place dowels into fresh concrete as the concrete is laid, eliminating the 

need to manually place dowels in baskets prior to paving operations. 

In the past two decades, highway agencies and paving contractors have increasingly used 

magnetic imaging tomography (MIT) scanning to evaluate dowel alignment in JPCPs. Numerous 

evaluations of the accuracy of MIT scanning have shown such devices are reliable tools for 

measuring dowel alignment with high accuracy for dowels inserted with dowel baskets with cut 

transport-tie wires or DBIs (Yu and Khazanovich 2005). Studies by Hossain and Elfino (2006) 

and Leong et al. (2006), respectively, confirmed the accuracy of MIT scanning devices. 

Researchers found MIT scanning devices to be robust and versatile for investigations requiring 

large numbers of measurements in a wide range of environments (Yu and Tayabji 2007). The 

robustness and versatility of the devices prompted the Federal Highway Administration’s 

(FHWA) Concrete Pavement Technology Program to initiate a loan program encouraging the 

implementation of MIT technology. FHWA identified MIT scanning devices as practical, 

implementation-ready products with the potential to improve the quality of concrete pavements 

(Yu 2005).

The increased use of MIT scanning has exposed the issue of how much dowel misalignment is 

acceptable to an agency. Many agency’s dowel alignment tolerances were established prior to a 
3 

clear understanding of field-achievable tolerances and a real-world understanding of the effects 

of dowel misalignment on pavement performance. These once-acceptable dowel alignment 

tolerances are under scrutiny, launching renewed interest in dowel misalignment research, 

including laboratory and field studies by Khazanovich et al. (2009), Rao et al. (2009), Leong 

et al. (2006), Milind et al. (2006), and the American Concrete Pavement Association ((ACPA) 

2006). These studies contributed significantly to the understanding of how dowel misalignment

impacts transverse joint movements and the long-term performance of JPCPs. 

In NCHRP Report 637, the effect of dowel misalignment on the performance of JPCP was

evaluated through laboratory testing, analytical modeling, and limited field testing (Khazanovich 

et al. 2009). A procedure was developed to compute an equivalent dowel diameter for a 

transverse joint based on alignment of all dowels at that joint. Key results from Khazanovich 

et al. (2009) include the following: 

• Extreme longitudinal and vertical translation can cause significant reductions in shear 

capacity.

• A combination of low concrete cover and low embedment length (resulting from vertical 

and longitudinal translation) has a more adverse effect on dowel performance than either 

of the two rotational misalignments. 

• Dowel rotational misalignments of up to 2 inches have a negligible effect on pullout and 

shear performance measures.

The researchers concluded that rotational dowel misalignment is not a sufficient cause for 

transverse joint lockup and does not cause significant additional longitudinal stresses. The 

researchers developed a procedure to compute the equivalent dowel diameter for a transverse 

joint based on dowel misalignment that considers the effects of longitudinal translation, vertical 

translation, horizontal skew, and vertical tilt of all dowels within the joint. The equivalent dowel 

diameter calculated using this procedure can be used in mechanistic–empirical pavement design

procedures, such as those used with AASHTOWare® Pavement ME Design software, to model 

the long-term performance of the pavement, primarily LTE and faulting, and the resulting 

International Roughness Index, but was shown to have minimal effect on transverse joint locking 

and slab cracking (AASHTO 2014). 

Field studies show that slab or transverse joint distress may not always occur from rotational 

dowel misalignments (i.e., horizontal skews or vertical tilts). Khazanovich et al. (2009) observed 

that, within the nonextreme limits of rotational dowel misalignments measured in their study, 

there were no differences in the amount of transverse cracking and transverse joint spalling 

observed from rotational dowel misalignments. ACPA (2006) observed that projects with a 

significant number of rotationally misaligned dowels performed well without showing any signs 

of distress after 8 yr or more of service under heavy traffic, suggesting a limited number of 

rotationally misaligned dowels in JPCP transverse joints may be tolerable. A project constructed 

in 1977 that was surveyed and cored by Fowler and Gulden (1983) performed well under 

moderately high interstate traffic without any signs of increased distresses for over 25 yr despite 

the prevalence of severely rotationally misaligned dowels. 

Some researchers conducted slab pullout tests to model the effects of severely rotationally 

misaligned dowels on transverse joint behavior during joint movement (Tayabji 1986; Prabhu 
4 

et al. 2006; Khazanovich et al. 2009). Although the exact test configurations varied, in some 

cases, multiple dowels were tested together to represent a transverse joint. General observations 

from these tests were that the force required to displace a dowel increased with increasing 

rotational misalignment. When the dowels were nonuniformly rotationally misaligned, a greater 

amount of pullout force was required and showed a greater amount of cracking than transverse 

joints with dowels that were uniformly rotationally misaligned. Slabs developed cracking only at 

significant misalignment levels (greater than 0.75 inches) when the rotational misalignment of 

dowels along the transverse joint was nonuniform and excessive levels of joint opening were 

present (greater than 0.5 inches). Minor spalling around dowels was observed in slabs with 

severe rotational misalignment. Khazanovich et al. (2009) observed that rotational dowel 

misalignments of up to 2 inches have a negligible effect on pullout and shear performance 

measures.

One of the earliest methods to categorize dowel misalignment and consider the combined effects 

of all dowels at a transverse joint was developed by Yu and Khazanovich (2005) and calculates 

the rotational misalignment of all dowels within the transverse joint into a joint score. Transverse 

joints with a higher joint score correspond to more dowels with higher levels of rotational 

misalignment than transverse joints with a lower joint score. The joint score does not consider 

longitudinal and vertical translations, and the weight factors based on the extent of rotational 

misalignment for any individual dowel were developed intuitively and not based on any 

laboratory or field tests. Because of this limitation, the joint score measure was discussed in an 

FHWA Technical Brief as only a quick first step toward identifying transverse joints for further 

investigation with regard to lockup potential, but not necessarily as a measure for acceptance by 

highway agencies (Yu and Tayabji 2007). 

Despite that stipulation, many highway agencies are adopting the joint score measure in their 

specifications for establishing acceptance criteria primarily because of its simplicity

(CDOT 2015; Gancarz et al. 2015). A typical specification requires the joint score to be less 

than 10, above which corrective action is often specified. Corrective actions range from cutting 

misaligned dowels (to effectively reduce the joint score to less than 10 by eliminating any chance 

of the misaligned dowel contributing to transverse joint lockup) to removal and replacement of 

the transverse joint by performing full-depth repairs. 

However, there is no evidence, empirical or otherwise, to support the aforementioned criterion 

for corrective action based on transverse joint lockup since it is inconsistent with the results from 

NCHRP Report 637 and limited transverse joint-opening and -closing studies conducted by 

Mallela et al. (2012). They measured joint openings and closings over a 48-hour period of 

transverse joints with a joint score ranging from 1 to 40 and found that all transverse joints 

tested, including those with the highest number and degree of dowel misalignment (i.e., joint 

scores ranging from 30 to 40), experienced transverse joint opening and closing as a function of 

temperature change, suggesting there were no transverse joint lockups. 

Due to the limited scope of laboratory and field studies completed to date, there is still a 

significant lack of guidance for establishing effective construction specifications based on actual 

field performance. Practical questions yet unanswered include the following: 
5 

• Do one or two severely misaligned dowels at a transverse joint have the same impact as 

several dowels with minor misalignment?

• Do misaligned dowels in the wheel path have the same impact as those outside the wheel 

path? 

• Does one out-of-compliance transverse joint warrant corrective action?

• How many consecutive transverse joints need to be misaligned before distress is evident? 

• Are there other factors (e.g., climate, base type, dowel size, pavement thickness) that 

contribute to transverse joint lockup? 

• Are the weighting factors used to compute the joint score representative of actual field 

performance?

• How can relative dowel misalignment (i.e., dowels misaligned in different directions) be 

best account for compared to uniform dowel misalignment (i.e., dowels misaligned in the 

same direction)?

• What are the effects of various types of misalignment on actual field performance? 

The General Pavement Studies (GPS) and Specific Pavement Studies (SPS) test sections 

included in the Long-Term Pavement Performance (LTPP) database (i.e., GPS-3 and SPS-2) 

were used in this current study to evaluate and address some of the aforementioned questions 

(FHWA 2014). Much of the information needed to evaluate performance of these test sections 

vis-à-vis dowel alignment is contained in the LTPP database, including the following: 

• Design, materials, construction, and support data. 

• Climatic data.

• Traffic data.

• Pavement performance data.

• Falling weight deflectometer data.

• Distress data.

• Profile data.

• Transverse joint-opening and -closing data (for select test sections).

The key piece of information needed to evaluate performance of these test sections with regard 

to dowel alignment not included in the LTPP database is alignment data for each of the dowels 

within the transverse joints. This current research effort was conducted to collect MIT scanning 

data on various GPS-3 and SPS-2 test sections for inclusion in the LTPP database. Results of 

MIT scanning and analysis are presented in the following sections. MIT scanning data collected 

as part of this project were used in a preliminary analysis as part of this study and serve as a 

platform for detailed statistical analysis to address unanswered practical questions regarding 

effects of dowel misalignment on actual field performance. While a preliminary analysis was 

performed in this study, a more thorough and detailed statistical analysis and evaluation of the 

data were beyond the scope of this study, the primary purpose of which was to collect and 

document dowel misalignment data at these GPS-3 and SPS-2 test sections.

7 

CHAPTER 2. SELECTION OF LTPP TEST SECTIONS

The LTPP database includes 181 doweled JPCP test sections ranging in thickness from 6.4 to 

13.2 inches. Each test section is a driving lane (i.e., traffic or outside lane), 500 ft in length, with 

approximately 33 transverse joints. Based on scheduling and availability of lane closures for the 

LTPP test sections, a total of 3 GPS-3 and 121 SPS-2 test sections were included in field data 

collection using an MIT scanning device. At some SPS-2 sites, one or two test sections were not 

tested because of scheduling conflicts with lane closures and testing crew travel. 

Five test sections (one each in Iowa and Kentucky and two in both North Dakota and Wisconsin) 

were not included in the analysis because they had skewed transverse joints. One test section 

(Wisconsin) was not included in the analysis because it had only four dowels per transverse joint.

One test section (Arkansas) with 1-inch-diameter dowels was eliminated from analysis due to an 

error with the MIT parameter file. Table 1 represents the breakdown of the numbers of LTPP test 

sections by State. Arkansas included 1 GPS-3 and 12 SPS-2 test sections. The distribution of 

LTPP test sections by portland cement concrete (PCC) thickness and construction year are 

shown in figure 2 and figure 3. 

Table 1. Number of LTPP test sections by State for MIT scanning and analyses. 

State Experiment Type

Number of LTPP Test Sections 

for Field Data Collection

Number of LTPP Test Sections 

Used in Analyses 

Arizona SPS-2 12 12 

Arkansas GPS-3/SPS-2 13 12 

California SPS-2 12 12 

Colorado SPS-2 12 12 

Delaware SPS-2 14 14 

Iowa SPS-2 13 12 

Kansas SPS-2 12 12 

Kentucky GPS-3 1 0 

North Carolina SPS-2 8 8 

North Dakota SPS-2 14 12 

South Dakota GPS-3 1 1 

Wisconsin SPS-2 12 10 

Total GPS-3/SPS-2 124 117 
8 

Source: FHWA.

Figure 2. Chart. Percentage of analysis pavement test sections with respect to 

PCC thickness. 

Source: FHWA.

Figure 3. Chart. Percentage of analysis pavement test sections with respect to 

construction year.
9 

CHAPTER 3. MIT SCANNING

In recent years, highway agencies and paving contractors have increasingly used MIT scanning 

devices, as shown in figure 4, for evaluating dowel alignments in JPCPs. The measuring process 

involves setting rails on the transverse joint to be scanned, entering pavement information into a 

handheld computer, and then pulling the unit along the joint. During scanning, the device emits a 

weak, pulsating magnetic signal and detects the transient magnetic response signal induced in the 

metal dowels. The methods of tomography are then used to determine the position and alignment 

of the dowels. The data analysis process is performed using software provided with such devices. 

© 2005 Shreenath Rao.

Figure 4. Photo. Testing a pavement transverse joint using an MIT scanning device. 

The accuracy of MIT scanning results depends on the position and alignment of the dowels. MIT 

scanning devices are designed to provide the most accurate results under the following 

conditions (Yu and Khazanovich 2005; ACPA 2006): 

• Mean dowel depth of 4 to 8 inches. 

• Maximum rotational misalignment of 0.75 inches. 

• Maximum longitudinal translation of 2 inches. 

When these conditions are satisfied, the accuracy is typically within 0.12 inches on rotational 

misalignment and vertical translation (Yu and Khazanovich 2005). For dowels placed in baskets, 

MIT scanning results are accurate only if the dowels are insulated from the basket by a coating 

(either paint or epoxy) and the transport ties on the basket are cut or removed. Even if the 

transport tie wires are not cut during construction, they eventually break due to cyclic 

movements of the adjacent slabs and the resulting stresses in the tie wires. Thus, older pavements 

originally constructed with uncut transport tie wires reflect MIT scanning signals as if the tie 

wires were cut. MIT scanning results are also sensitive to the lateral placement of the dowel 

basket. The best results are obtained when the dowel basket is centered under the transverse joint 
10 

saw cut. The presence of other sources of metal (e.g., dowels close to tie bars, steel mesh 

reinforcement, metal conduit, and overhead power lines) may cause interference and will induce 

errors in the data.

For the current study, a two-person crew was deployed for field testing. Testing was restricted to 

the LTPP lane (i.e., traffic or outside lane) for all test sections with lane closures provided by 

State highway agencies. The rail assembly was set up along the transverse joint of the outside 

lane to test the joint in one complete scan. For safety reasons due to live traffic in the inside lane, 

the scan was terminated about 6 inches before the centerline longitudinal joint. In most cases, 

data from all dowels in the LTPP lane were collected because the last dowel is typically 6 inches

away from the centerline longitudinal joint and MIT scanning devices can collect alignment data 

as long as the front end of the unit is reasonably close (i.e., within a few inches). 

For each LTPP test section, scanning commenced at the beginning of the test section and 

proceeded along the direction of traffic until the end of the test section. Any notes taken during 

scanning were documented through test logs for every LTPP test section. Each day, upon 

completion of field data collection, data files were saved to a local server and uploaded to a 

secure server for backup purposes. 

To reduce processing errors and for consistency and efficiency during data collection, the 

settings shown in table 2 were used for all LTPP test sections. The raw MIT data files were rerun 

with the appropriate dowel diameter parameter file during post data collection analysis, 

correcting for dowel alignment results to reflect the actual dowel diameter from the LTPP 

database. Based on the PCC thickness of each test section included in the LTPP database, the 

depth deviation parameter was recalculated. This recalculation did not impact the results of the 

analysis as compared to collecting data using the correct inputs for PCC thickness and dowel 

size. Images documented during MIT scanning are shown in figure 5 through figure 8. 

Table 2. MIT scanning field input. 

MIT Input Value

PCC thickness 11.0 inches

Dowel spacing 12.0 inches

Offset of first dowel 6.0 inches

Dowel size (length × diameter) 18.0 inches × 1.5 inches
11 

Source: FHWA.

Figure 5. Photo. MIT scanning of North Carolina LTPP test section 37_0207. 

Source: FHWA.

Figure 6. Photo. Cracking and spalling on Arkansas LTPP test section 05_0217. 
12 

Source: FHWA.

Figure 7. Photo. Full-width spray patching on Delaware LTPP test section 10_0208. 

Source: FHWA.

Figure 8. Photo. Skewed transverse joints on Iowa LTPP test section 19_0259. 
13 

CHAPTER 4. DOWEL ALIGNMENT DATA ANALYSES 

This section discusses the analysis of dowel alignment data collected using an MIT scanning 

device. Major data analysis tasks included the following: 

• Analyzing raw MIT scanning files to generate misalignment data, including vertical 

translation, longitudinal translation, horizontal skew, and vertical tilt, for each dowel at 

each transverse joint.

• Computing a joint score for each transverse joint.

• Computing the equivalent dowel diameter using NCHRP Report 637 methodology for 

each transverse joint.

• Analyzing the effects of joint score on slab cracking and transverse joint spalling.

• Comparing predicted distress from AASHTOWare Pavement ME Design and LTPP field 

distress using both the actual and equivalent dowel diameter for each test section.

DOWEL ALIGNMENT ANALYSES 

MIT scanning data were analyzed using the software provided with the MIT scanning device. 

For each transverse joint successfully analyzed, software provides outputs that include the 

positions and depths of the dowels; horizontal, vertical, and total rotational misalignments; and 

longitudinal translations. The vertical translations are estimates and computed based on the 

average PCC thickness from the LTPP database, dowel diameter, and measured depth of dowels 

from the surface.

Results from the analysis were compared with the field notes to ensure consistency in transverse 

joint numbering. Quality checks were included to eliminate extraneous signals from errant tie 

bars or dowels, other metallic objects, or overhead power lines. These extraneous signals can be 

clearly seen in the software output as aberrations in the contour plots generated by the software. 

In case of potential influence due to tie bars, the affected dowels were eliminated from analysis.

The analysis in this current study was limited to dowels with 1.25- and 1.5-inch diameters 

because almost all test sections surveyed had dowels of one of these two diameters—the two 

most common dowel diameters used in the United States. The only 1-inch-diameter dowel test 

section (Arkansas) was eliminated from analysis due to an error with the MIT parameter file. The 

misalignment distributions for the dowels are shown in figure 9 through figure 20 and are based 

on the MIT scanning results of 23,300 1.5-inch-diameter dowels from 1,997 transverse joints and 

21,240 1.25-inch-diameter dowels from 1,824 transverse joints. The results show that 

approximately 73, 80, and 62 percent of the dowels with horizontal skew, vertical tilt, and 

vertical translation, respectively, have misalignments ranging between 0 and ±0.5 inches. There 

is more variation in the longitudinal translation data, and approximately 29 percent of the dowels 

have greater than 1.5 inches magnitude of longitudinal translation. There was no observed effect 

of PCC thickness on the amount of variation for any of the misalignment parameters. MIT 

scanning results for individual States are shown in the MIT Scanning Analysis by State chapter. 
14 

Source: FHWA.

Figure 9. Chart. Horizontal skew distribution of dowels (23,300 1.5-inch-diameter dowels 

from 1,997 transverse joints and 21,240 1.25-inch-diameter dowels from 1,824 transverse 

joints). 

Source: FHWA.

Figure 10. Chart. Vertical tilt distribution of dowels (23,300 1.5-inch-diameter dowels from 

1,997 transverse joints and 21,240 1.25-inch-diameter dowels from 1,824 transverse joints). 
15 

Source: FHWA.

Figure 11. Chart. Longitudinal translation distribution of dowels (23,300 1.5-inch-diameter 

dowels from 1,997 transverse joints and 21,240 1.25-inch-diameter dowels from 

1,824 transverse joints). 

Source: FHWA.

Figure 12. Chart. Vertical translation distribution of dowels (23,300 1.5-inch-diameter

dowels from 1,997 transverse joints and 21,240 1.25-inch-diameter dowels from 

1,824 transverse joints). 
16 

Source: FHWA.

Figure 13. Chart. Cumulative horizontal skew distribution of 21,240 1.25-inch-diameter

dowels from 1,824 transverse joints.

Source: FHWA.

Figure 14. Chart. Cumulative vertical tilt distribution of 21,240 1.25-inch-diameter dowels 

from 1,824 transverse joints.
17 

Source: FHWA.

Figure 15. Chart. Cumulative longitudinal translation distribution of 

21,240 1.25-inch-diameter dowels from 1,824 transverse joints.

Source: FHWA.

Figure 16. Chart. Cumulative vertical translation distribution of 21,240 1.25-inch-diameter

dowels from 1,824 transverse joints.
18 

Source: FHWA.

Figure 17. Chart. Cumulative horizontal skew distribution of 23,300 1.5-inch-diameter

dowels from 1,997 transverse joints.

Source: FHWA.

Figure 18. Chart. Cumulative vertical tilt distribution of 23,300 1.5-inch-diameter dowels 

from 1,997 transverse joints.
19 

Source: FHWA.

Figure 19. Chart. Cumulative longitudinal translation distribution of 

23,300 1.5-inch-diameter dowels from 1,997 transverse joints.

Source: FHWA.

Figure 20. Chart. Cumulative vertical translation distribution of 23,300 1.5-inch-diameter

dowels from 1,997 transverse joints.

JOINT SCORE ANALYSES 

Many highway agencies specify evaluating dowel alignment following construction at a sample 

number of transverse joints using an MIT scanning device (CDOT 2015; Gancarz et al. 2015). 

Rotational misalignments of individual dowels within a transverse joint are used to compute the 

joint score, and acceptance and rejection decisions are made based on criteria detailed in each 

highway agency’s specification. A joint score is calculated as 1 plus the sum of the product of 

the weights empirically assigned to each degree of misalignment and the number of dowels in 

each misalignment category (Yu and Khazanovich 2005; Yu and Tayabji 2007). Weighting 
20 

factors for determining the joint score are shown in table 3. In table 3, the range of misalignment 

represents the total misalignment, which is calculated as the square root of the sum of squares of 

the horizontal skew and vertical tilt. In general, transverse joints with joint scores greater than 10 

have a higher potential for joint lockup and are recommended for further evaluation and 

monitoring (Yu and Khazanovich 2005). Yu and Khazanovich (2005) developed the joint score 

measure intuitively as a quick first step toward identifying transverse joints for further 

investigation with regard to lockup potential, not as a measure for acceptance by highway 

agencies.

In this study, the original measure for computing the joint score established by Yu and 

Khazanovich (2005) was used. The original measure did not consider the number of dowels at a 

transverse joint or slab width because it was meant as a quick first step toward identifying 

transverse joints for further investigation, not as a measure for acceptance. Since the original 

measure was developed, some practitioners have redefined the joint score measure by scaling it 

to the slab width and the number of dowels at the transverse joint.

Table 3. Weighting factors used to determine the joint score (Yu and Khazanovich 2005). 

Range of Misalignment

(Inches)

Weighting 

Factor 

0.4 < d < 0.6 0 

0.6 < d < 0.8 2 

0.8 < d < 1.0 4 

1.0 < d < 1.5 5 

d > 1.5 10 

d = dowel diameter. 

The joint score was calculated for all transverse joints tested as part of this study. The 

distribution of the joint score for 1,824 1.25-inch-diameter and 1,997 1.5-inch-diameter dowels is 

shown in figure 21. The average and standard deviation of the joint scores for each State is 

shown in table 4. Since two GPS-3 test sections (one each in Kentucky and Arkansas) were not 

included in the analysis, table 4 represents one test site (with one GPS-3 test section 

(South Dakota) or multiple SPS-2 test sections) in each State. Figure 21 shows that 52 percent of 

transverse joints with 1.5-inch-diameter dowels and 47 percent of transverse joints with 

1.25-inch-diameter dowels have joint scores less than 10. However, close to 20 percent of the 

transverse joints indicate high joint scores (i.e., values greater than 30). 
21 

Source: FHWA.

Figure 21. Chart. Joint score distribution for 1.25- and 1.5-inch-diameter dowels from 

3,821 transverse joints (23,300 1.5-inch-diameter dowels from 1,997 transverse joints and 

21,240 1.25-inch-diameter dowels from 1,824 transverse joints).

Table 4. Average joint score for States with LTPP test sections. 

State

Average Joint 

Score

Joint Score 

Standard Deviation

Number of 1.25-InchDiameter Dowel 

Transverse Joints

Number of 1.5-InchDiameter Dowel 

Transverse Joints

Arizona 11 12 197 195 

Arkansas 18 16 169 202 

California 27 20 196 194 

Colorado 11 17 199 198 

Delaware 19 22 228 219 

Iowa 14 17 198 200 

Kansas 18 19 198 203 

North Carolina 11 15 26 232 

North Dakota 11 13 190 194 

South Dakota 18 8 25 0 

Wisconsin 21 21 198 160 

EQUIVALENT DOWEL DIAMETER ANALYSES 

NCHRP Report 637 provided a methodology to calculate an equivalent dowel diameter using 

dowel misalignment (Khazanovich et al. 2009). The equivalent dowel diameter can be used in 

AASHTOWare Pavement ME Design to model the long-term performance of a pavement test 

section and compare it with actual field distresses. 

The equivalent dowel diameter for the various dowel diameters was calculated for the individual 

transverse joints of each LTPP test section, and the values are presented in table 5. The average 

effective percent reduction in dowel diameter from the actual dowel diameter in place is also 

shown in table 5. 
22 

Table 5. Equivalent dowel diameter and effective percent reduction in dowel diameter for 

States with LTPP test sections. 

State

Dowel Diameter 

(Inches) 

Number of 

Transverse 

Joints 

Equivalent

Dowel Diameter 

(Inches) 

Standard 

Deviation 

Equivalent

Dowel Diameter

(Inches) 

Effective 

Reduction in 

Dowel Diameter

(Percent) 

Arizona 1.25 197 1.20 0.05 4.2 

1.50 195 1.40 0.09 6.4 

Arkansas 1.25 169 1.13 0.18 9.3 

1.50 202 1.42 0.11 5.5 

California 1.25 196 0.94 0.26 25.0 

1.50 194 1.25 0.24 17.8 

Colorado 1.25 199 1.18 0.27 8.3 

1.50 198 1.44 0.13 4.1 

Delaware 1.25 228 1.05 0.36 16.8 

1.50 219 1.46 0.11 2.7 

Iowa 1.25 198 1.17 0.18 6.4 

1.50 200 1.43 0.15 4.4 

Kansas 1.25 198 1.14 0.20 8.9 

1.50 203 1.44 0.11 4.3 

North Carolina 1.25 26 1.20 0.14 3.8 

1.50 232 1.42 0.24 6.1 

North Dakota 1.25 190 1.23 0.06 1.8 

1.50 194 1.46 0.07 2.7 

South Dakota 1.25 25 1.21 0.03 3.5 

Wisconsin 1.25 198 1.15 0.17 8.1 

1.50 160 1.39 0.21 7.2 
23 

CHAPTER 5. MIT SCANNING ANALYSES BY STATE

Details of the LTPP test sections in each State, along with results of MIT scanning analyses, are 

described in this section.

ARIZONA

The dowel alignments of 12 SPS-2 test sections in Arizona were evaluated using an MIT 

scanning device as part of this study. All test sections are in the eastbound direction of I–10 and 

were constructed in 1993. Dowels were placed using dowel baskets for all test sections. Other 

details of the test sections are shown in table 6. Results of MIT scanning analyses are shown in 

figure 22 through figure 25 and table 7. 

Table 6. Details of LTPP test sections in Arizona. 

Test Section

PCC Thickness 

(Inches) 

Dowel Diameter 

(Inches) Scan Date

Lane Width 

(ft)

4_0213 7.9 1.25 12/10/2014 14 

4_0214 8.3 1.25 12/09/2014 12 

4_0215 11.0 1.50 12/10/2014 12 

4_0216 11.2 1.50 12/11/2014 14 

4_0217 8.1 1.25 12/10/2014 14 

4_0218 8.3 1.25 12/09/2014 12 

4_0219 10.8 1.50 12/10/2014 12 

4_0220 11.2 1.50 12/09/2014 14 

4_0221 8.1 1.25 12/10/2014 14 

4_0222 8.6 1.25 12/09/2014 12 

4_0223 11.1 1.50 12/11/2014 12 

4_0224 10.6 1.50 12/11/2014 14 

MIT scanning results from Arizona show that approximately 75, 93, and 54 percent of dowels 

have misalignments ranging between 0 and ±0.5 inches for horizontal skew, vertical tilt, and 

vertical translation, respectively. There is more variation in the longitudinal translation data, and 

approximately 45 percent of dowels have greater than 1 inch magnitude of longitudinal 

translation.

The joint score distribution and equivalent dowel diameter are shown in figure 26 and table 8. 

Approximately 63 percent of transverse joints have a joint score less than 10, while 10 percent of 

transverse joints have a joint score greater than 30. Figure 27 shows the relationship between the 

joint score and effective reduction in dowel diameter for each transverse joint tested in Arizona.

Whereas the joint score considers only vertical tilt and horizontal skew, the equivalent dowel 

diameter considers vertical tilt, horizontal skew, vertical translation, and longitudinal translation.
24 

Source: FHWA.

Figure 22. Chart. Horizontal skew distribution for LTPP test sections in Arizona. 

Source: FHWA.

Figure 23. Chart. Vertical tilt distribution for LTPP test sections in Arizona. 

Source: FHWA.

Figure 24. Chart. Longitudinal translation distribution for LTPP test sections in Arizona. 
25 

Source: FHWA.

Figure 25. Chart. Vertical translation distribution for LTPP test sections in Arizona. 

Table 7. Dowel misalignment summary for LTPP test sections in Arizona. 

Test 

Section

Average 

Horizontal 

Skew 

(Inches)

Horizontal 

Skew 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Tilt 

(Inches)

Vertical 

Tilt 

Standard 

Deviation 

(Inches)

Average 

Longitudinal 

Translation 

(Inches)

Longitudinal 

Translation 

Standard 

Deviation 

(Inches)

Average 

Vertical

Translation 

(Inches)

Vertical

Translation 

Standard 

Deviation 

(Inches)

4_0213 0.27 0.29 0.22 0.17 0.97 0.72 0.31 0.25

4_0214 0.44 0.51 0.19 0.22 0.87 0.59 0.42 0.27

4_0215 0.50 0.35 0.29 0.19 1.28 0.75 0.64 0.43

4_0216 0.50 0.49 0.38 0.25 1.56 0.71 0.64 0.46

4_0217 0.24 0.19 0.17 0.22 0.72 0.71 0.22 0.20

4_0218 0.31 0.25 0.15 0.12 0.80 0.54 0.46 0.31

4_0219 0.32 0.24 0.16 0.17 0.77 0.56 0.30 0.26

4_0220 0.27 0.25 0.28 0.20 0.94 0.63 0.91 0.40

4_0221 0.34 0.32 0.22 0.43 0.90 0.69 0.42 0.35

4_0222 0.61 0.34 0.16 0.16 0.66 0.44 0.39 0.29

4_0223 0.40 0.42 0.27 0.28 1.41 0.77 0.52 0.42

4_0224 0.29 0.26 0.27 0.40 1.22 0.69 0.89 0.38
26 

Source: FHWA.

Figure 26. Chart. Joint score distribution for LTPP test sections in Arizona. 

Table 8. Joint score and equivalent dowel diameter for LTPP test sections in Arizona. 

Test 

Section

Average 

Joint Score

Joint Score 

Standard 

Deviation 

Average PCC 

Thickness 

(Inches)

Actual 

Dowel 

Diameter 

(Inches)

Average 

Equivalent

Dowel 

Diameter 

(Inches)

Equivalent

Dowel Diameter 

Standard 

Deviation 

(Inches)

Effective 

Reduction 

in Dowel 

Diameter

(Percent)

4_0213 7 8 7.9 1.25 1.21 0.07 1.5 

4_0214 9 7 8.3 1.25 1.18 0.21 6.6 

4_0215 18 16 11.0 1.50 1.43 0.06 8.6 

4_0216 22 12 11.2 1.50 1.39 0.21 4.8 

4_0217 5 12 8.1 1.25 1.24 0.04 0.5 

4_0218 6 7 8.3 1.25 1.23 0.02 6.4 

4_0219 6 6 10.8 1.50 1.48 0.03 5.6 

4_0220 8 8 11.2 1.50 1.42 0.06 4.3 

4_0221 9 9 8.1 1.25 1.19 0.09 2.6 

4_0222 20 13 8.6 1.25 1.17 0.08 7.9 

4_0223 11 12 11.1 1.50 1.42 0.16 9.0 

4_0224 7 8 10.6 1.50 1.38 0.18 6.5 
27 

Source: FHWA.

Figure 27. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in Arizona.

ARKANSAS

The dowel alignments of 12 SPS-2 test sections in Arkansas were evaluated using an MIT 

scanning device as part of this study. All test sections are in the westbound direction of I–30 and 

were constructed in 1995. Dowels were placed using dowel baskets for all test sections. Other 

details of the test sections are shown in table 9. Results of the MIT scanning analyses are shown 

in figure 28 through figure 31 and table 10. 

Table 9. Details of LTPP test sections in Arkansas. 

Test Section

PCC Thickness 

(Inches)

Dowel Diameter 

(Inches) Scan Date

Lane Width 

(ft)

5_0214 8.4 1.25 09/29/2014 12 

5_0215 11.5 1.50 09/29/2014 12 

5_0216 11.0 1.50 10/01/2014 14 

5_0217 8.3 1.25 09/30/2014 14 

5_0218 8.2 1.25 09/30/2014 12 

5_0219 11.1 1.50 09/30/2014 12 

5_0220 10.7 1.50 09/30/2014 14 

5_0221 8.3 1.25 10/01/2014 14 

5_0222 8.3 1.25 09/29/2014 12 

5_0223 10.9 1.50 09/29/2014 12 

5_0224 10.9 1.50 09/30/2014 14 

MIT scanning results from Arkansas show that approximately 70, 83, and 62 percent of dowels 

have misalignments ranging between 0 and ±0.5 inches for horizontal skew, vertical tilt, and 

vertical translation, respectively. There is more variation in the longitudinal translation data, and 

only approximately 48 percent of dowels have side shift ranging between 0 and ±0.5 inches. 
28 

The joint score distribution and equivalent dowel diameter are shown in figure 32 and table 11. 

Approximately 40 percent of transverse joints have a joint score less than 10, while 17 percent of 

transverse joints have a joint score greater than 30. Figure 33 shows the relationship between the 

joint score and effective reduction in dowel diameter for each transverse joint tested in Arkansas. 

Whereas the joint score considers only vertical tilt and horizontal skew, equivalent dowel 

diameter considers vertical tilt, horizontal skew, vertical translation, and longitudinal translation.

Source: FHWA.

Figure 28. Chart. Horizontal skew distribution for LTPP test sections in Arkansas. 

Source: FHWA.

Figure 29. Chart. Vertical tilt distribution for LTPP test sections in Arkansas. 
29 

Source: FHWA.

Figure 30. Chart. Longitudinal translation distribution for LTPP test sections in Arkansas. 

Source: FHWA.

Figure 31. Chart. Vertical translation distribution for LTPP test sections in Arkansas. 
30 

Table 10. Dowel misalignment summary for LTPP test sections in Arkansas. 

Test 

Section

Average 

Horizontal 

Skew 

(Inches)

Horizontal 

Skew 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Tilt 

(Inches)

Vertical 

Tilt 

Standard 

Deviation 

(Inches)

Average 

Longitudinal 

Translation 

(Inches)

Longitudinal 

Translation 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Translation 

(Inches)

Vertical 

Translation 

Standard 

Deviation 

(Inches)

5_0214 0.53 0.46 0.38 0.36 0.92 0.99 0.50 0.30 

5_0215 0.32 0.35 0.27 0.27 0.75 0.60 0.69 0.37 

5_0216 0.43 0.40 0.35 0.34 0.67 0.59 0.54 0.42 

5_0217 0.56 0.53 0.40 0.61 1.16 1.68 0.44 0.52 

5_0218 0.59 1.01 0.49 0.98 1.19 1.50 0.73 0.58 

5_0219 0.43 0.34 0.32 0.29 0.93 0.83 0.36 0.37 

5_0220 0.36 0.58 0.28 0.58 0.82 0.81 0.55 0.36 

5_0221 0.31 0.26 0.30 0.31 0.40 0.58 0.33 0.25 

5_0222 0.32 0.26 0.22 0.23 0.45 0.65 0.22 0.20 

5_0223 0.32 0.27 0.27 0.31 1.09 1.02 0.44 0.25 

5_0224 0.37 0.30 0.25 0.27 0.81 0.68 0.32 0.28 

Source: FHWA.

Figure 32. Chart. Joint score distribution for LTPP test sections in Arkansas. 
31 

Table 11. Joint score and equivalent dowel diameter for LTPP test sections in Arkansas. 

Test 

Section

Average 

Joint 

Score

Joint Score 

Standard 

Deviation 

Average 

PCC 

Thickness 

(Inches)

Actual 

Dowel 

Diameter 

(Inches)

Average 

Equivalent

Dowel 

Diameter 

(Inches)

Equivalent

Dowel 

Diameter 

Standard 

Deviation 

(Inches)

Effective 

Reduction in 

Dowel 

Diameter 

(Percent)

5_0214 27 15 8.4 1.25 1.14 0.07 8.4 

5_0215 9 10 11.5 1.50 1.40 0.04 6.4 

5_0216 21 15 11.0 1.50 1.42 0.09 5.6 

5_0217 33 18 8.3 1.25 1.15 0.19 8.1 

5_0218 27 24 8.2 1.25 0.97 0.31 22.6 

5_0219 19 12 11.1 1.50 1.41 0.04 5.7 

5_0220 13 14 10.7 1.50 1.39 0.25 7.1 

5_0221 11 11 8.3 1.25 1.22 0.03 2.5 

5_0222 9 11 8.3 1.25 1.18 0.03 5.3 

5_0223 11 9 10.9 1.50 1.41 0.04 6.0 

5_0224 14 9 10.9 1.50 1.47 0.05 2.1 

Source: FHWA.

Figure 33. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in Arkansas. 

CALIFORNIA

The dowel alignments of 12 SPS-2 test sections in California were evaluated using an MIT 

scanning device as part of this study. All test sections are in the northbound direction of SR 99 

and were constructed in 1999. Dowels were placed using dowel baskets for all test sections. 

Other details of the test sections are shown in table 12. Results of the MIT scanning analyses are 

shown in figure 34 through figure 37 and table 13. 
32 

Table 12. Details of LTPP test sections in California. 

Test Section

PCC Thickness 

(Inches)

Dowel Diameter 

(Inches) Scan Date

Lane Width 

(ft)

6_0201 8.3 1.50 10/22/2014 12 

6_0202 8.0 1.25 10/21/2014 13 

6_0203 11.4 1.50 10/20/2014 13 

6_0204 11.1 1.25 10/21/2014 12 

6_0205 8.2 1.50 10/21/2014 12 

6_0206 8.0 1.25 10/20/2014 13 

6_0207 11.0 1.50 10/20/2014 13 

6_0208 10.7 1.25 10/21/2014 12 

6_0209 8.4 1.50 10/21/2014 12 

6_0210 8.6 1.25 10/21/2014 13 

6_0211 12.1 1.50 10/20/2014 13 

6_0212 11.1 1.25 10/21/2014 12 

MIT scanning results from California show that approximately 53, 71, and 23 percent of dowels 

have misalignments ranging between 0 and ±0.5 inches for horizontal skew, vertical tilt, and 

vertical translation, respectively. There is more variation in the longitudinal translation data, and 

approximately 40 percent of dowels have greater than 2 inches (absolute) longitudinal 

translation.

The joint score distribution and equivalent dowel diameter are shown in figure 38 and table 14. 

Approximately 20 percent of transverse joints have a joint score less than 10, while 38 percent of 

transverse joints have a joint score greater than 30. Figure 39 shows the relationship between the 

joint score and effective reduction in dowel diameter for each transverse joint tested in 

California. Whereas the joint score considers only vertical tilt and horizontal skew, equivalent 

dowel diameter considers vertical tilt, horizontal skew, vertical translation, and longitudinal 

translation.

Source: FHWA.

Figure 34. Chart. Horizontal skew distribution for LTPP test sections in California. 
33 

Source: FHWA.

Figure 35. Chart. Vertical tilt distribution for LTPP test sections in California. 

Source: FHWA.

Figure 36. Chart. Longitudinal translation distribution for LTPP test sections in 

California. 
34 

Source: FHWA.

Figure 37. Chart. Vertical translation distribution for LTPP test sections in California. 

Table 13. Dowel misalignment summary for LTPP test sections in California. 

Test 

Section

Average 

Horizontal 

Skew 

(Inches)

Horizontal 

Skew 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Tilt 

(Inches)

Vertical 

Tilt 

Standard 

Deviation 

(Inches)

Average 

Longitudinal 

Translation 

(Inches)

Longitudinal 

Translation 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Translation 

(Inches)

Vertical 

Translation 

Standard 

Deviation 

(Inches)

6_0201 0.90 0.54 0.47 0.68 2.18 1.29 0.78 0.57 

6_0202 0.53 0.30 0.23 0.24 1.69 0.83 1.14 0.42 

6_0203 0.47 0.55 0.48 0.51 1.92 2.20 1.33 0.90 

6_0204 0.59 0.83 0.54 0.51 1.77 1.03 1.13 0.58 

6_0205 0.57 0.43 0.33 0.60 1.60 1.03 0.68 0.49 

6_0206 0.62 0.55 0.40 0.64 1.76 1.07 1.07 0.53 

6_0207 0.38 0.60 0.53 0.45 2.15 1.13 0.84 0.72 

6_0208 0.54 0.82 0.46 0.43 1.98 0.99 1.16 1.43 

6_0209 0.47 0.34 0.36 0.48 1.49 1.56 0.71 1.37 

6_0210 0.53 0.36 0.32 0.30 1.67 1.11 0.80 0.53 

6_0211 0.83 1.64 0.62 0.86 2.00 0.96 1.37 0.68 

6_0212 0.62 0.91 0.53 0.67 1.64 0.87 1.38 0.59 
35 

Source: FHWA.

Figure 38. Chart. Joint score distribution for LTPP test sections in California. 

Table 14. Joint score and equivalent dowel diameter for LTPP test sections in California. 

Test 

Section

Average

Joint 

Score

Joint Score 

Standard 

Deviation 

Average 

PCC 

Thickness 

(Inches)

Actual 

Dowel 

Diameter 

(Inches)

Average 

Equivalent

Dowel 

Diameter 

(Inches)

Equivalent

Dowel 

Diameter 

Standard 

Deviation 

(Inches)

Effective 

Reduction in 

Dowel 

Diameter 

(Percent)

6_0201 44 25 8.3 1.50 1.14 0.23 24.1 

6_0202 20 17 8.0 1.25 0.80 0.27 35.7 

6_0203 28 18 11.4 1.50 1.22 0.13 18.4 

6_0204 27 18 11.1 1.25 1.00 0.16 19.7 

6_0205 23 20 8.2 1.50 1.29 0.22 13.7 

6_0206 29 16 8.0 1.25 0.79 0.36 36.4 

6_0207 23 19 11.0 1.50 1.31 0.15 12.7 

6_0208 22 17 10.7 1.25 1.03 0.16 17.4 

6_0209 21 18 8.4 1.50 1.29 0.20 13.8 

6_0210 23 20 8.6 1.25 1.05 0.13 15.9 

6_0211 37 26 12.1 1.50 1.21 0.38 19.4 

6_0212 27 17 11.1 1.25 0.96 0.24 23.1 
36 

Source: FHWA.

Figure 39. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in California. 

COLORADO

The dowel alignments of 12 SPS-2 test sections in Colorado were evaluated using an MIT 

scanning device as part of this study. All test sections are in the eastbound direction of I–76 and 

were constructed in 1993. Dowels were placed using dowel baskets for all test sections. Other 

details of the test sections are shown in table 15. Results of the MIT scanning analyses are shown 

in figure 40 through figure 43 and table 16. 

Table 15. Details of LTPP test sections in Colorado. 

Test Section

PCC Thickness 

(Inches)

Dowel Diameter 

(Inches) Scan Date

Lane Width 

(ft)

8_0213 8.6 1.25 09/10/2014 14 

8_0214 8.4 1.25 09/10/2014 12 

8_0215 11.5 1.50 09/11/2014 12 

8_0216 11.9 1.50 09/10/2014 14 

8_0217 8.6 1.25 09/11/2014 14 

8_0218 7.6 1.25 09/11/2014 12 

8_0219 9.9 1.50 09/11/2014 12 

8_0220 11.2 1.50 09/12/2014 14 

8_0221 8.3 1.25 09/12/2014 14 

8_0222 8.5 1.25 09/12/2014 12 

8_0223 11.7 1.50 09/12/2014 12 

8_0224 11.6 1.50 09/12/2014 14 
37 

MIT scanning results from Colorado show that approximately 92, 81, and 79 percent of dowels 

have misalignments ranging between 0 and ±0.5 inches for horizontal skew, vertical tilt, and 

vertical translation, respectively. There is more variation in the longitudinal translation data, and 

approximately 41 percent of dowels have longitudinal translation ranging between 0 and 

±0.5 inches. 

The joint score distribution and equivalent dowel diameter are shown in figure 44 and table 17. 

Approximately 65 percent of transverse joints have a joint score less than 10, while 12 percent of 

transverse joints have a joint score greater than 30. Figure 45 shows the relationship between the 

joint score and effective reduction in dowel diameter for each transverse joint tested in Colorado. 

Whereas the joint score considers only vertical tilt and horizontal skew, equivalent dowel 

diameter considers vertical tilt, horizontal skew, vertical translation, and longitudinal translation. 

Source: FHWA.

Figure 40. Chart. Horizontal skew distribution for LTPP test sections in Colorado. 

Source: FHWA.

Figure 41. Chart. Vertical tilt distribution for LTPP test sections in Colorado. 
38 

Source: FHWA.

Figure 42. Chart. Longitudinal translation distribution for LTPP test sections in Colorado. 

Source: FHWA.

Figure 43. Chart. Vertical translation distribution for LTPP test sections in Colorado. 
39 

Table 16. Dowel misalignment summary for LTPP test sections in Colorado. 

Test 

Section

Average 

Horizontal 

Skew 

(Inches)

Horizontal 

Skew 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Tilt 

(Inches)

Vertical 

Tilt 

Standard 

Deviation 

(Inches)

Average 

Longitudinal 

Translation 

(Inches)

Longitudinal 

Translation 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Translation 

(Inches)

Vertical 

Translation 

Standard 

Deviation 

(Inches)

8_0213 0.12 0.09 0.16 0.12 0.36 0.37 0.29 0.26 

8_0214 0.24 0.29 0.29 0.26 0.75 0.62 0.18 0.13 

8_0215 0.30 0.77 0.33 0.61 0.79 0.91 0.32 0.27 

8_0216 0.16 0.25 0.18 0.23 0.55 0.72 0.19 0.15 

8_0217 0.44 0.67 0.61 0.81 1.85 2.08 0.36 0.54 

8_0218 0.32 0.37 0.47 0.72 1.48 1.58 0.35 0.73 

8_0219 0.25 0.40 0.60 0.83 1.81 1.56 0.74 0.60 

8_0220 0.21 0.19 0.25 0.24 1.18 0.93 0.19 0.14 

8_0221 0.21 0.18 0.34 0.30 1.70 1.11 0.42 0.33 

8_0222 0.19 0.15 0.25 0.23 0.63 0.76 0.34 0.19 

8_0223 0.21 0.28 0.36 0.32 1.30 1.14 0.22 0.27 

8_0224 0.16 0.29 0.25 0.50 1.06 1.18 0.62 0.44 

Source: FHWA.

Figure 44. Chart. Joint score distribution for LTPP test sections in Colorado. 
40 

Table 17. Joint score and equivalent dowel diameter for LTPP test sections in Colorado. 

Test 

Section

Average 

Joint 

Score

Joint Score 

Standard 

Deviation 

Average 

PCC 

Thickness 

(Inches)

Actual 

Dowel 

Diameter 

(Inches)

Average 

Equivalent

Dowel 

Diameter 

(Inches)

Equivalent

Dowel 

Diameter 

Standard 

Deviation 

(Inches)

Effective 

Reduction in 

Dowel 

Diameter 

(Percent)

8_0213 1 0 8.6 1.25 1.24 0.21 0.6 

8_0214 9 9 8.4 1.25 1.22 0.05 2.2 

8_0215 12 14 11.5 1.50 1.45 0.12 3.6 

8_0216 5 7 11.9 1.50 1.48 0.07 1.2 

8_0217 29 26 8.6 1.25 1.09 0.42 12.8 

8_0218 21 26 7.6 1.25 1.05 0.42 16.0 

8_0219 23 23 9.9 1.50 1.32 0.21 12.3 

8_0220 6 7 11.2 1.50 1.48 0.04 1.2 

8_0221 11 15 8.3 1.25 1.19 0.07 4.9 

8_0222 4 8 8.5 1.25 1.24 0.02 0.6 

8_0223 10 9 11.7 1.50 1.47 0.07 2.0 

8_0224 9 19 11.6 1.50 1.43 0.12 4.8 

Source: FHWA.

Figure 45. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in Colorado. 

DELAWARE

The dowel alignments of 14 SPS-2 test sections in Delaware were evaluated using an MIT 

scanning device as part of this study. All test sections are in the southbound direction of US 113 

and were constructed in 1992. Dowels were placed using dowel baskets for all test sections. 

Other details of the test sections are shown in table 18. Results of the MIT scanning analyses are 

shown in figure 46 through figure 49 and table 19. 
41 

Table 18. Details of LTPP test sections in Delaware. 

Test Section

PCC Thickness 

(Inches)

Dowel Diameter 

(Inches) Scan Date

Lane Width 

(ft)

10_0201 8.3 1.25 05/28/2015 12 

10_0202 8.8 1.25 05/27/2015 14 

10_0203 11.7 1.50 05/28/2015 14 

10_0204 11.0 1.50 05/26/2015 12 

10_0205 9.2 1.25 05/28/2015 12 

10_0206 8.9 1.25 05/27/2015 14 

10_0207 11.3 1.50 05/27/2015 14 

10_0208 12.1 1.50 05/26/2015 12 

10_0209 8.2 1.25 05/28/2015 12 

10_0210 8.3 1.25 05/27/2015 14 

10_0211 11.8 1.50 05/28/2015 14 

10_0212 12.4 1.50 05/26/2015 12 

10_0259 10.2 1.50 05/26/2015 12 

10_0260 10.2 1.25 05/28/2015 12 

MIT scanning results from Delaware show that approximately 72, 83, and 59 percent of dowels 

have misalignments ranging between 0 and ±0.5 inches for horizontal skew, vertical tilt, and 

vertical translation, respectively. There is more variation in the longitudinal translation data, and 

approximately 59 percent of dowels have longitudinal translation ranging between 0 and 

±0.5 inches. 

The joint score distribution and equivalent dowel diameter are shown in figure 50 and table 20. 

Approximately 50 percent of transverse joints have a joint score less than 10, while 25 percent of 

transverse joints have a joint score greater than 30. Figure 51 shows the relationship between the 

joint score and effective reduction in dowel diameter for each transverse joint tested in Delaware. 

Whereas the joint score considers only vertical tilt and horizontal skew, equivalent dowel 

diameter considers vertical tilt, horizontal skew, vertical translation, and longitudinal translation.

Source: FHWA.

Figure 46. Chart. Horizontal skew distribution for LTPP test sections in Delaware. 
42 

Source: FHWA.

Figure 47. Chart. Vertical tilt distribution for LTPP test sections in Delaware. 

Source: FHWA.

Figure 48. Chart. Longitudinal translation distribution for LTPP test sections in Delaware. 
43 

Source: FHWA.

Figure 49. Chart. Vertical translation distribution for LTPP test sections in Delaware. 

Table 19. Dowel misalignment summary for LTPP test sections in Delaware. 

Test 

Section

Average 

Horizontal 

Skew 

(Inches)

Horizontal 

Skew 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Tilt 

(Inches)

Vertical 

Tilt 

Standard 

Deviation 

(Inches)

Average 

Longitudinal 

Translation 

(Inches)

Longitudinal 

Translation 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Translation 

(Inches)

Vertical 

Translation 

Standard 

Deviation 

(Inches)

10_0201 0.94 0.45 0.25 0.21 0.52 0.42 0.60 0.33 

10_0202 0.56 0.41 0.29 0.30 0.49 0.44 0.47 0.29 

10_0203 0.24 0.19 0.26 0.23 0.45 0.42 0.26 0.23 

10_0204 0.23 0.20 0.27 0.26 0.66 1.13 0.41 0.44 

10_0205 0.43 0.41 0.23 0.30 0.48 0.55 0.26 0.23 

10_0206 0.55 0.45 0.29 0.35 0.43 0.40 0.69 0.38 

10_0207 0.26 0.73 0.26 0.22 0.49 0.49 0.28 0.25 

10_0208 0.27 0.37 0.33 0.42 0.72 0.89 0.55 0.45 

10_0209 0.74 0.95 0.23 0.19 0.50 0.52 0.62 0.33 

10_0210 0.22 0.16 0.19 0.30 0.54 0.52 0.37 0.30 

10_0211 0.34 0.29 0.32 0.25 0.57 0.48 0.26 0.21 

10_0212 0.30 0.26 0.36 0.30 0.71 0.79 0.55 0.34 

10_0259 0.28 0.41 0.32 0.26 0.27 0.44 0.48 0.33 

10_0260 0.74 0.93 2.37 2.71 9.64 12.43 3.95 2.70 
44 

Source: FHWA.

Figure 50. Chart. Joint score distribution for LTPP test sections in Delaware. 

Table 20. Joint score and equivalent dowel diameter for LTPP test sections in Delaware. 

Test 

Section

Average 

Joint 

Score

Joint Score 

Standard 

Deviation 

Average 

PCC 

Thickness 

(Inches)

Actual 

Dowel 

Diameter 

(Inches)

Average 

Equivalent

Dowel 

Diameter 

(Inches)

Equivalent

Dowel 

Diameter 

Standard 

Deviation 

(Inches)

Effective 

Reduction in 

Dowel 

Diameter 

(Percent)

10_0201 47 20 8.3 1.25 1.07 0.11 14.7 

10_0202 24 16 8.8 1.25 1.19 0.06 5.1 

10_0203 7 10 11.7 1.50 1.49 0.02 0.7 

10_0204 8 10 11.0 1.50 1.48 0.03 1.1 

10_0205 9 13 9.2 1.25 1.22 0.06 2.2 

10_0206 26 17 8.9 1.25 1.10 0.17 12.0 

10_0207 7 9 11.3 1.50 1.47 0.07 1.7 

10_0208 11 15 12.1 1.50 1.42 0.17 5.5 

10_0209 30 18 8.2 1.25 1.14 0.10 8.9 

10_0210 4 7 8.3 1.25 1.23 0.05 1.6 

10_0211 13 15 11.8 1.50 1.48 0.04 1.4 

10_0212 13 15 12.4 1.50 1.47 0.05 2.2 

10_0259 9 8 10.2 1.50 1.41 0.19 6.0 

10_0260 68 22 10.2 1.25 0.30 0.43 76.0 
45 

Source: FHWA.

Figure 51. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in Delaware.

IOWA 

The dowel alignments of 12 SPS-2 test sections in Iowa were evaluated using an MIT scanning 

device as part of this study. All test sections are in the northbound direction of US 65 and were 

constructed in 1994. Dowels were placed using dowel baskets for all test sections. Other details 

of the test sections are shown in table 21. Results of the MIT scanning analyses are shown in 

figure 52 through figure 55 and table 22. 

Table 21. Details of LTPP test sections in Iowa. 

Test Section

PCC Thickness 

(Inches)

Dowel Diameter 

(Inches) Scan Date

Lane Width 

(ft)

19_0213 8.9 1.25 11/19/2014 14 

19_0214 8.4 1.25 11/19/2014 12 

19_0215 11.4 1.50 11/18/2014 12 

19_0216 11.4 1.50 11/18/2014 12 

19_0217 8.1 1.25 11/18/2014 14 

19_0218 8.4 1.25 11/18/2014 12 

19_0219 11.5 1.50 11/17/2014 14 

19_0220 11.5 1.50 11/18/2014 14 

19_0221 9.4 1.25 11/20/2014 14 

19_0222 8.3 1.25 11/20/2014 12 

19_0223 12.5 1.50 11/20/2014 12 

19_0224 10.0 1.50 11/20/2014 14 
46 

MIT scanning results from Iowa show that approximately 81, 78, and 76 percent of dowels have 

misalignments ranging between 0 and ± 0.5 inches for horizontal skew, vertical tilt, and vertical 

translation, respectively. There is more variation in the longitudinal translation data, and 

approximately 31 percent of dowels have longitudinal translation ranging between 0 and 

±1.0 inch. 

The joint score distribution and equivalent dowel diameter are shown in figure 56 and table 23. 

Approximately 55 percent of transverse joints have a joint score less than 10, while 14 percent of 

transverse joints have a joint score greater than 30. Figure 57 shows the relationship between the 

joint score and effective reduction in dowel diameter for each transverse joint tested in Iowa. 

Whereas the joint score considers only vertical tilt and horizontal skew, equivalent dowel 

diameter considers vertical tilt, horizontal skew, vertical translation, and longitudinal translation. 

Source: FHWA.

Figure 52. Chart. Horizontal skew distribution for LTPP test sections in Iowa. 

Source: FHWA.

Figure 53. Chart. Vertical tilt distribution for LTPP test sections in Iowa. 
47 

Source: FHWA.

Figure 54. Chart. Longitudinal translation distribution for LTPP test sections in Iowa. 

Source: FHWA.

Figure 55. Chart. Vertical translation distribution for LTPP test sections in Iowa. 
48 

Table 22. Dowel misalignment summary for LTPP test sections in Iowa. 

Test 

Section

Average 

Horizontal 

Skew 

(Inches)

Horizontal 

Skew 

Standard 

Deviation 

(Inches)

Average 

Vertical

Tilt 

(Inches)

Vertical 

Tilt 

Standard 

Deviation 

(Inches)

Average 

Longitudinal 

Translation 

(Inches)

Longitudinal 

Translation 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Translation 

(Inches)

Vertical 

Translation 

Standard 

Deviation 

(Inches)

19_0213 0.32 0.51 0.35 0.34 1.74 1.15 0.31 0.43 

19_0214 0.26 0.22 0.41 0.34 1.82 1.35 0.19 0.27 

19_0215 0.26 0.25 0.19 0.24 0.83 0.85 0.15 0.12 

19_0216 0.22 0.23 0.27 0.36 1.34 1.07 0.20 0.26 

19_0217 0.38 0.61 0.39 0.49 1.32 1.06 0.49 0.62 

19_0218 0.42 0.58 0.35 0.39 1.25 0.94 0.17 0.24 

19_0219 0.33 0.52 0.34 0.44 1.77 1.36 0.47 0.29 

19_0220 0.41 0.33 0.64 0.80 2.79 2.07 0.43 0.97 

19_0221 0.37 0.21 0.22 0.19 0.87 0.82 0.61 0.27 

19_0222 0.41 0.31 0.49 0.48 2.25 1.53 0.26 0.37 

19_0223 0.37 0.36 0.28 0.28 1.57 1.22 0.48 0.23 

19_0224 0.28 0.26 0.28 0.23 1.46 1.08 0.42 0.24 

Source: FHWA.

Figure 56. Chart. Joint score distribution for LTPP test sections in Iowa. 
49 

Table 23. Joint score and equivalent dowel diameter for LTPP test sections in Iowa. 

Test 

Section

Average 

Joint 

Score

Joint Score 

Standard 

Deviation 

Average 

PCC 

Thickness 

(Inches)

Actual 

Dowel 

Diameter 

(Inches)

Average 

Equivalent

Dowel 

Diameter 

(Inches)

Equivalent

Dowel 

Diameter 

Standard 

Deviation 

(Inches)

Effective 

Reduction in 

Dowel 

Diameter 

(Percent)

19_0213 12 12 8.9 1.25 1.21 0.05 3.4 

19_0214 14 14 8.4 1.25 1.21 0.07 3.0 

19_0215 6 10 11.4 1.50 1.48 0.04 1.1 

19_0216 5 5 11.4 1.50 1.46 0.08 2.7 

19_0217 17 21 8.1 1.25 1.05 0.35 15.8 

19_0218 15 13 8.4 1.25 1.17 0.18 6.1 

19_0219 11 13 11.5 1.50 1.42 0.15 5.6 

19_0220 31 25 11.5 1.50 1.31 0.29 12.8 

19_0221 8 9 9.4 1.25 1.21 0.04 2.9 

19_0222 25 23 8.3 1.25 1.15 0.18 8.1 

19_0223 12 14 12.5 1.50 1.47 0.05 1.8 

19_0224 8 9 10.0 1.50 1.47 0.05 2.0 

Source: FHWA.

Figure 57. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in Iowa. 

KANSAS

The dowel alignments of 12 SPS-2 test sections in Kansas were evaluated using an MIT 

scanning device as part of this study. All test sections are in the westbound direction of I–70 and 

were constructed in 1992. Dowels were placed using dowel baskets for all test sections. Other 

details of the test sections are shown in table 24. Results of the MIT scanning analysis are shown 

in figure 58 through figure 61 and table 25. 
50 

Table 24. Details of LTPP test sections in Kansas. 

Test Section

PCC Thickness 

(Inches)

Dowel Diameter 

(Inches) Scan Date

Lane Width 

(ft)

20_0201 7.7 1.25 12/01/2015 12 

20_0202 7.7 1.25 12/01/2015 14 

20_0203 11.1 1.50 12/01/2015 14 

20_0204 11.3 1.50 12/01/2015 12 

20_0205 7.5 1.25 12/02/2015 12 

20_0206 7.5 1.25 12/02/2015 14 

20_0207 11.2 1.50 12/02/2015 14 

20_0208 10.8 1.50 12/02/2015 12 

20_0209 8.6 1.25 12/03/2015 12 

20_0210 8.4 1.25 12/03/2015 14 

20_0211 11.1 1.50 12/02/2015 14 

20_0212 11.1 1.50 12/02/2015 12 

MIT scanning results from Kansas show that approximately 69, 7, and 95 percent of dowels have 

misalignments ranging between 0 and ±0.5 inches for horizontal skew, vertical tilt, and vertical 

translation, respectively. There is more variation in the longitudinal translation data, and 

approximately 29 percent of dowels have longitudinal translation ranging greater than 2 inches. 

The joint score distribution and equivalent dowel diameter are shown in figure 62 and table 26. 

Approximately 47 percent of transverse joints have a joint score less than 10, while 24 percent of 

transverse joints have a joint score greater than 30. Figure 63 shows the relationship between the 

joint score and effective reduction in dowel diameter for each transverse joint tested in Kansas. 

Whereas the joint score considers only vertical tilt and horizontal skew, equivalent dowel 

diameter considers vertical tilt, horizontal skew, vertical translation, and longitudinal translation. 

Source: FHWA.

Figure 58. Chart. Horizontal skew distribution for LTPP test sections in Kansas. 
51 

Source: FHWA.

Figure 59. Chart. Vertical tilt distribution for LTPP test sections in Kansas. 

Source: FHWA.

Figure 60. Chart. Longitudinal translation distribution for LTPP test sections in Kansas. 
52 

Source: FHWA.

Figure 61. Chart. Vertical translation distribution for LTPP test sections in Kansas. 

Table 25. Dowel misalignment summary for LTPP test sections in Kansas. 

Test 

Section

Average 

Horizontal 

Skew 

(Inches)

Horizontal 

Skew 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Tilt 

(Inches)

Vertical 

Tilt 

Standard 

Deviation 

(Inches)

Average 

Longitudinal 

Translation 

(Inches)

Longitudinal 

Translation 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Translation 

(Inches)

Vertical 

Translation 

Standard 

Deviation 

(Inches)

20_0201 0.35 0.79 0.41 0.76 1.30 1.33 0.57 0.50 

20_0202 0.32 0.19 0.26 0.38 0.83 0.71 0.61 0.35 

20_0203 0.38 0.42 0.22 0.19 1.12 0.81 0.36 0.20 

20_0204 0.47 0.28 0.24 0.23 1.05 0.73 0.30 0.17 

20_0205 0.41 0.45 0.45 0.60 1.62 1.28 0.51 0.34 

20_0206 0.31 0.23 0.40 0.42 1.74 1.59 0.56 0.52 

20_0207 0.47 0.37 0.60 0.76 2.48 1.70 0.56 0.32 

20_0208 0.46 0.30 0.30 0.26 1.66 1.25 0.40 0.29 

20_0209 0.41 0.44 0.41 0.42 2.06 3.19 0.32 0.91 

20_0210 0.29 0.24 0.37 0.33 1.77 1.40 0.37 0.24 

20_0211 0.42 0.27 0.39 0.29 1.67 1.30 0.51 0.33 

20_0212 0.58 0.31 0.33 0.38 1.32 1.23 0.46 0.33 
53 

Source: FHWA.

Figure 62. Chart. Joint score distribution for LTPP test sections in Kansas. 

Table 26. Chart. Joint score and equivalent dowel diameter for LTPP test sections in 

Kansas. 

Test 

Section

Average 

Joint 

Score

Joint Score 

Standard 

Deviation 

Average 

PCC 

Thickness 

(Inches)

Actual 

Dowel 

Diameter 

(Inches)

Average 

Equivalent

Dowel 

Diameter 

(Inches)

Equivalent

Dowel 

Diameter 

Standard 

Deviation 

(Inches)

Effective 

Reduction in 

Dowel 

Diameter 

(Percent)

20_0201 16 22 7.7 1.25 1.09 0.22 12.6 

20_0202 7 9 7.7 1.25 1.05 0.27 15.6 

20_0203 10 11 11.1 1.50 1.48 0.03 1.6 

20_0204 16 16 11.3 1.50 1.48 0.04 1.5 

20_0205 21 20 7.5 1.25 1.19 0.11 5.0 

20_0206 17 15 7.5 1.25 1.17 0.11 6.4 

20_0207 28 31 11.2 1.50 1.35 0.17 10.0 

20_0208 19 17 10.8 1.50 1.46 0.05 2.9 

20_0209 22 21 8.6 1.25 1.13 0.18 9.4 

20_0210 16 19 8.4 1.25 1.19 0.08 4.6 

20_0211 20 17 11.1 1.50 1.43 0.07 4.6 

20_0212 27 18 11.1 1.50 1.43 0.15 4.4 
54 

Source: FHWA.

Figure 63. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in Kansas. 

NORTH CAROLINA

The dowel alignments of 8 SPS-2 test sections in North Carolina were evaluated using an MIT 

scanning device as part of this study. All test sections are in the southbound direction of US 52 

and were constructed in 1992. Dowels were placed using a DBI for all test sections. Other details 

of the test sections are shown in table 27. Results of the MIT scanning analyses are shown in 

figure 64 through figure 67 and table 28. 

Table 27. Details of LTPP test sections in North Carolina. 

Test Section

PCC Thickness 

(Inches)

Dowel Diameter 

(Inches) Scan Date

Lane Width 

(ft)

37_0203 11.4 1.50 03/09/2015 14 

37_0204 11.2 1.50 03/12/2015 12 

37_0207 11.6 1.50 03/09/2015 14 

37_0208 11.2 1.50 03/11/2015 12 

37_0211 11.4 1.50 03/10/2015 14 

37_0212 10.9 1.50 03/10/2015 12 

37_0259 10.2 1.25 03/09/2015 12 

37_0260 11.5 1.50 03/10/2015 14 

MIT scanning results from North Carolina show that approximately 78, 89, and 76 percent of 

dowels have misalignments ranging between 0 and ±0.5 inches for horizontal skew, vertical tilt, 

and vertical translation, respectively. There is more variation in the longitudinal translation data, 

and approximately 53 percent of dowels have longitudinal translation ranging between 0 and 

±0.5 inches. 
55 

The joint score distribution and equivalent dowel diameter are shown in figure 68 and table 29. 

Approximately 62 percent of transverse joints have a joint score less than 10, while 9 percent of 

transverse joints have a joint score greater than 30. Figure 69 shows the relationship between the 

joint score and effective reduction in dowel diameter for each transverse joint tested in 

North Carolina. Whereas the joint score considers only vertical tilt and horizontal skew, 

equivalent dowel diameter considers vertical tilt, horizontal skew, vertical translation, and 

longitudinal translation. 

Source: FHWA.

Figure 64. Chart. Horizontal skew distribution for LTPP test sections in North Carolina. 

Source: FHWA.

Figure 65. Chart. Vertical tilt distribution for LTPP test sections in North Carolina. 
56 

Source: FHWA.

Figure 66. Chart. Longitudinal translation distribution for LTPP test sections in 

North Carolina. 

Source: FHWA.

Figure 67. Chart. Vertical translation distribution for LTPP test sections in 

North Carolina. 
57 

Table 28. Dowel misalignment summary for LTPP test sections in North Carolina. 

Test 

Section

Average 

Horizontal 

Skew 

(Inches)

Horizontal 

Skew 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Tilt 

(Inches)

Vertical 

Tilt 

Standard 

Deviation 

(Inches)

Average 

Longitudinal 

Translation 

(Inches)

Longitudinal 

Translation 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Translation 

(Inches)

Vertical 

Translation 

Standard 

Deviation 

(Inches)

37_0203 0.41 0.24 0.23 0.21 1.04 0.91 0.44 0.39 

37_0204 0.58 0.40 0.32 0.43 1.69 4.09 0.30 0.48 

37_0207 0.35 0.43 0.35 0.82 0.59 0.88 0.41 0.43 

37_0208 0.28 1.03 0.40 0.77 0.78 1.06 0.31 0.38 

37_0211 0.35 0.38 0.24 0.54 0.64 0.93 0.45 1.96 

37_0212 0.26 0.19 0.20 0.18 0.52 0.42 0.17 0.13 

37_0259 0.30 0.25 0.26 0.28 0.29 0.52 0.69 0.23 

37_0260 0.40 0.83 0.43 0.84 0.71 1.06 0.32 0.35 

Source: FHWA.

Figure 68. Chart. Joint score distribution for LTPP test sections in North Carolina. 
58 

Table 29. Joint score and equivalent dowel diameter for LTPP test sections in 

North Carolina. 

Test 

Section

Average 

Joint 

Score

Joint Score 

Standard 

Deviation 

Average 

PCC 

Thickness 

(Inches)

Actual 

Dowel 

Diameter 

(Inches)

Average 

Equivalent

Dowel 

Diameter 

(Inches)

Equivalent

Dowel 

Diameter 

Standard 

Deviation 

(Inches)

Effective 

Reduction in 

Dowel 

Diameter 

(Percent)

37_0203 11 11 11.4 1.50 1.45 0.06 3.1 

37_0204 23 19 11.2 1.50 1.39 0.31 7.2 

37_0207 12 14 11.6 1.50 1.39 0.37 7.3 

37_0208 10 22 11.2 1.50 1.44 0.22 4.0 

37_0211 9 9 11.4 1.50 1.42 0.27 5.3 

37_0212 4 4 10.9 1.50 1.50 0.01 0.1 

37_0259 7 10 10.2 1.25 1.20 0.14 3.8 

37_0260 14 12 11.5 1.49 1.31 0.32 12.2 

Source: FHWA.

Figure 69. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in North Carolina. 

NORTH DAKOTA

The dowel alignments of 12 SPS-2 test sections in North Dakota were evaluated using an MIT 

scanning device as part of this study. All test sections are in the eastbound direction of I–94 and 

were constructed in 1994. Dowels were placed using dowel baskets for all test sections. Other 

details of the test sections are shown in table 30. Results of the MIT scanning analyses are shown 

in figure 70 through figure 73 and table 31. 
59 

Table 30. Details of LTPP test sections in North Dakota. 

Test Section

PCC Thickness 

(Inches)

Dowel Diameter 

(Inches) Scan Date

Lane Width 

(ft)

38_0213 7.9 1.25 09/22/2015 14 

38_0214 8.0 1.25 09/21/2015 12 

38_0215 11.1 1.50 09/21/2015 12 

38_0216 11.1 1.50 09/21/2015 14 

38_0217 7.9 1.25 09/23/2015 14 

38_0218 7.9 1.25 09/23/2015 12 

38_0219 10.8 1.50 09/24/2015 12 

38_0220 11.0 1.50 09/23/2015 14 

38_0221 8.1 1.25 09/30/2015 14 

38_0222 8.0 1.25 09/24/2015 12 

38_0223 11.1 1.50 09/24/2015 12 

38_0224 11.0 1.50 09/30/2015 14 

MIT scanning results from North Dakota show that approximately 82, 84, and 72 percent of 

dowels have misalignments ranging between 0 and ±0.5 inches for horizontal skew, vertical tilt, 

and vertical translation, respectively. There is more variation in the longitudinal translation data, 

and approximately 30 percent of dowels have longitudinal translation ranging between 0 and 

±0.5 inches. 

The joint score distribution and equivalent dowel diameter are shown in figure 74 and table 32. 

Approximately 64 percent of transverse joints have a joint score less than 10, while 7 percent of 

transverse joints have a joint score greater than 30. Figure 75 shows the relationship between the 

joint score and effective reduction in dowel diameter for each transverse joint tested in 

North Dakota. Whereas the joint score considers only vertical tilt and horizontal skew, 

equivalent dowel diameter considers vertical tilt, horizontal skew, vertical translation, and 

longitudinal translation. 

Source: FHWA.

Figure 70. Chart. Horizontal skew distribution for LTPP test sections in North Dakota. 
60 

Source: FHWA.

Figure 71. Chart. Vertical tilt distribution for LTPP test sections in North Dakota. 

Source: FHWA.

Figure 72. Chart. Longitudinal translation distribution for LTPP test sections in 

North Dakota. 
61 

Source: FHWA.

Figure 73. Chart. Vertical translation distribution for LTPP test sections in North Dakota. 

Table 31. Dowel misalignment summary for LTPP test sections in North Dakota. 

Test 

Section

Average 

Horizontal 

Skew 

(Inches)

Horizontal 

Skew 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Tilt 

(Inches)

Vertical 

Tilt 

Standard 

Deviation 

(Inches)

Average 

Longitudinal 

Translation 

(Inches)

Longitudinal 

Translation 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Translation 

(Inches)

Vertical 

Translation 

Standard 

Deviation 

(Inches)

38_0213 0.25 0.20 0.25 0.21 1.06 0.75 0.16 0.13 

38_0214 0.29 0.24 0.31 0.25 1.27 1.07 0.21 0.15 

38_0215 0.29 0.27 0.77 0.44 1.96 1.11 0.53 0.29 

38_0216 0.22 0.17 0.29 0.48 0.95 0.77 0.30 0.28 

38_0217 0.34 0.23 0.19 0.17 0.75 0.65 0.50 0.34 

38_0218 0.32 0.21 0.29 0.42 1.06 0.80 0.33 0.20 

38_0219 0.41 0.21 0.20 0.24 1.08 0.79 0.95 0.23 

38_0220 0.23 0.15 0.18 0.16 1.06 0.96 0.58 0.74 

38_0221 0.23 0.18 0.19 0.28 0.90 0.78 0.24 0.18 

38_0222 0.36 0.23 0.25 0.22 0.71 0.63 0.18 0.14 

38_0223 0.40 0.25 0.21 0.18 1.12 1.01 0.22 0.14 

38_0224 0.20 0.15 0.31 0.27 1.37 1.19 0.31 0.25 
62 

Source: FHWA.

Figure 74. Chart. Joint score distribution for LTPP test sections in North Dakota. 

Table 32. Joint score and equivalent dowel diameter for LTPP test sections in 

North Dakota. 

Test 

Section

Average 

Joint 

Score

Joint Score 

Standard 

Deviation 

Average 

PCC 

Thickness 

(Inches)

Actual 

Dowel 

Diameter 

(Inches)

Average 

Equivalent

Dowel 

Diameter 

(Inches)

Equivalent

Dowel 

Diameter 

Standard 

Deviation 

(Inches)

Effective 

Reduction in 

Dowel 

Diameter 

(Percent)

38_0213 7 8 7.9 1.25 1.24 0.13 0.9 

38_0214 12 12 8.0 1.25 1.22 0.05 2.7 

38_0215 39 23 11.1 1.50 1.38 0.10 7.8 

38_0216 6 6 11.1 1.50 1.48 0.04 1.6 

38_0217 7 6 7.9 1.25 1.22 0.04 2.8 

38_0218 10 9 7.9 1.25 1.21 0.13 3.6 

38_0219 9 7 10.8 1.50 1.48 0.03 1.7 

38_0220 3 5 11.0 1.50 1.47 0.05 1.7 

38_0221 4 4 8.1 1.25 1.24 0.02 0.6 

38_0222 11 7 8.0 1.25 1.24 0.01 0.5 

38_0223 12 9 11.1 1.50 1.48 0.05 1.5 

38_0224 9 13 11.0 1.50 1.47 0.07 2.3 
63 

Source: FHWA.

Figure 75. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in North Dakota. 

SOUTH DAKOTA

The dowel alignment of one GPS-3 test section in South Dakota was evaluated using an MIT 

scanning device as part of this study. The test section is in the eastbound direction of US 14 and 

was constructed in 1988. Dowels were placed using dowel baskets. Other details of the test 

section are shown in table 33. Results of the MIT scan analysis are shown in figure 76 through 

figure 79 and table 34. 

Table 33. Details of the LTPP test section in South Dakota. 

Test Section

PCC Thickness 

(Inches)

Dowel Diameter 

(Inches) Scan Date

Lane Width 

(ft)

46_3052 9.0 1.25 10/07/2015 12 

MIT scanning results from South Dakota show that approximately 55, 93, and 97 percent of 

dowels have misalignments ranging between 0 and ±0.5 inches for horizontal skew, vertical tilt, 

and vertical translation, respectively. Approximately 90 percent of dowels have longitudinal 

translation (absolute) less than 1.0 inch. 

The joint score distribution and equivalent dowel diameter are shown in figure 80 and table 35. 

Approximately 8 percent of transverse joints have a joint score less than 10, and 8 percent of 

transverse joints have a joint score greater than 30. Figure 81 shows the relationship between the 

joint score and effective reduction in dowel diameter for each transverse joint tested in 

South Dakota. Whereas the joint score considers only vertical tilt and horizontal skew, 

equivalent dowel diameter considers vertical tilt, horizontal skew, vertical translation, and 

longitudinal translation. 
64 

Source: FHWA.

Figure 76. Chart. Horizontal skew distribution for the LTPP test section in South Dakota. 

Source: FHWA.

Figure 77. Chart. Vertical tilt distribution for the LTPP test section in South Dakota. 
65 

Source: FHWA.

Figure 78. Chart. Longitudinal translation distribution for the LTPP test section in 

South Dakota. 

Source: FHWA.

Figure 79. Chart. Vertical translation distribution for the LTPP test section in 

South Dakota. 

Table 34. Dowel misalignment summary for the LTPP test section in South Dakota. 

Test 

Section

Average 

Horizontal 

Skew 

(Inches)

Horizontal 

Skew 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Tilt 

(Inches)

Vertical 

Tilt 

Standard 

Deviation 

(Inches)

Average 

Longitudinal 

Translation 

(Inches)

Longitudinal 

Translation 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Translation 

(Inches)

Vertical 

Translation 

Standard 

Deviation 

(Inches)

46_3052 0.53 0.37 0.23 0.16 0.20 0.26 0.19 0.13 
66 

Source: FHWA.

Figure 80. Chart Joint score distribution for the LTPP test section in South Dakota. 

Table 35. Joint score and equivalent dowel diameter for the LTPP test section in 

South Dakota. 

Test 

Section

Average 

Joint 

Score

Joint Score 

Standard 

Deviation 

Average 

PCC 

Thickness 

(Inches)

Actual 

Dowel 

Diameter 

(Inches)

Average 

Equivalent

Dowel 

Diameter 

(Inches)

Equivalent

Dowel 

Diameter 

Standard 

Deviation 

(Inches)

Effective 

Reduction in 

Dowel 

Diameter 

(Percent)

46_3052 18 8 9.0 1.25 1.21 0.03 3.45 
67 

Source: FHWA.

Figure 81. Chart. Joint score versus effective reduction in dowel diameter for the LTPP test 

section in South Dakota.

WISCONSIN

The dowel alignments of 11 SPS-2 test sections in Wisconsin were evaluated using an MIT 

scanning device as part of this study. All test sections are in the westbound direction of SR 29 

and were constructed in 1997. Dowels were placed using dowel baskets for all test sections.

Other details of the test sections are shown in table 36. Results of the MIT scanning analyses are 

shown in figure 82 through figure 85 and table 37. 

Table 36. Details of LTPP test sections in Wisconsin. 

Test Section

PCC Thickness 

(Inches)

Dowel Diameter 

(Inches) Scan Date

Lane Width 

(ft)

55_0213 8.5 1.25 11/04/2015 14 

55_0215 10.9 1.50 11/05/2015 12 

55_0217 8.5 1.25 11/04/2015 14 

55_0219 11.8 1.50 11/05/2015 12 

55_0221 8.2 1.25 11/03/2015 14 

55_0223 11.2 1.50 11/04/2015 12 

55_0259 10.6 1.50 11/03/2015 12 

55_0261 8.2 1.25 11/04/2015 12 

55_0262 8.3 1.25 11/05/2015 12 

55_0263 10.0 1.25 11/03/2015 12 

55_0265 10.7 1.50 11/09/2015 12 
68 

MIT scanning results from Wisconsin show that approximately 65, 79, and 66 percent of dowels 

have misalignments ranging between 0 and ±0.5 inches for horizontal skew, vertical tilt, and 

vertical translation, respectively. There is more variation in the longitudinal translation data, and 

approximately 39 percent of dowels have longitudinal translation ranging between 0 and 

±0.5 inches. 

The joint score distribution and equivalent dowel diameter are shown in figure 86 and table 38. 

Approximately 36 percent of transverse joints have a joint score less than 10, and 22 percent of 

transverse joints have a joint score greater than 30. Figure 87 shows the relationship between the 

joint score and effective reduction in dowel diameter for each transverse joint tested in 

Wisconsin. Whereas the joint score considers only vertical tilt and horizontal skew, equivalent 

dowel diameter considers vertical tilt, horizontal skew, vertical translation, and longitudinal 

translation. 

Source: FHWA.

Figure 82. Chart. Horizontal skew distribution for LTPP test sections in Wisconsin. 

Source: FHWA.

Figure 83. Chart. Vertical tilt distribution for LTPP test sections in Wisconsin. 
69 

Source: FHWA.

Figure 84. Chart. Longitudinal translation distribution for LTPP test sections in 

Wisconsin. 

Source: FHWA.

Figure 85. Chart. Vertical translation distribution for LTPP test sections in Wisconsin. 
70 

Table 37. Dowel misalignment summary for LTPP test sections in Wisconsin. 

Test 

Section

Average 

Horizontal 

Skew 

(Inches)

Horizontal 

Skew 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Tilt 

(Inches)

Vertical 

Tilt 

Standard 

Deviation 

(Inches)

Average 

Longitudinal 

Translation 

(Inches)

Longitudinal 

Translation 

Standard 

Deviation 

(Inches)

Average 

Vertical 

Translation 

(Inches)

Vertical 

Translation 

Standard 

Deviation 

(Inches)

55_0213 0.72 0.51 0.30 0.28 0.92 1.13 0.24 0.19 

55_0215 0.39 0.29 0.32 0.25 1.30 1.14 0.28 0.21 

55_0217 0.49 0.31 0.34 0.79 1.00 0.88 0.82 0.26 

55_0219 0.44 0.54 0.63 0.98 1.33 1.34 0.36 0.49 

55_0221 0.32 0.22 0.29 0.20 0.82 0.82 0.31 0.18 

55_0223 0.28 0.46 0.28 0.30 1.08 0.89 0.26 0.19 

55_0259 0.40 0.34 0.31 0.23 0.87 0.71 0.27 0.22 

55_0261 0.38 0.20 0.19 0.20 0.45 0.44 0.34 0.15 

55_0262 0.43 0.34 0.31 0.28 1.46 1.10 0.21 0.19 

55_0263 0.45 0.37 0.25 0.21 0.64 0.57 1.16 0.40 

55_0265 0.64 1.00 1.07 1.13 2.12 2.09 1.25 0.73 

Source: FHWA.

Figure 86. Chart. Joint score distribution for LTPP test sections in Wisconsin. 
71 

Table 38. Joint score and equivalent dowel diameter for LTPP test sections in Wisconsin. 

Test 

Section

Average 

Joint 

Score

Joint Score 

Standard 

Deviation 

Average 

PCC 

Thickness 

(Inches)

Actual 

Dowel 

Diameter 

(Inches)

Average 

Equivalent

Dowel 

Diameter 

(Inches)

Equivalent

Dowel 

Diameter 

Standard 

Deviation 

(Inches)

Effective 

Reduction in 

Dowel 

Diameter 

(Percent)

55_0213 35 24 8.5 1.25 1.17 0.23 6.8 

55_0215 17 12 10.9 1.50 1.45 0.09 3.4 

55_0217 20 15 8.5 1.25 0.99 0.33 20.6 

55_0219 27 29 11.8 1.50 1.37 0.29 8.6 

55_0221 9 9 8.2 1.25 1.24 0.02 1.0 

55_0223 10 11 11.2 1.50 1.48 0.03 1.6 

55_0259 17 15 10.6 1.50 1.47 0.02 2.0 

55_0261 8 8 8.2 1.25 1.24 0.01 0.4 

55_0262 20 12 8.3 1.25 1.20 0.05 4.3 

55_0263 17 8 10.0 1.25 1.05 0.06 16.3 

55_0265 57 27 10.7 1.50 1.18 0.29 21.6 

Source: FHWA.

Figure 87. Chart. Joint score versus effective reduction in dowel diameter for LTPP test 

sections in Wisconsin. 

73 

CHAPTER 6. JOINT SCORE ANALYSES 

The chi-square test of independence was used to determine any potential relationship between 

the joint score and cracking/spalling for the LTPP test sections. The chi-square test of 

independence is considered an appropriate statistical test for analysis of any two categorical 

variables. The presence and absence of cracking or spalling for each slab was determined by 

evaluating available LTPP distress maps and data from the LTPP database. Joint score data were 

divided into three categories for analysis, as shown in table 39. 

Table 39. Joint score category. 

Joint Score Category

≤12 Low

12 < joint score ≤ 30 Medium 

>30 High

The following null and alternative hypotheses, respectively, were assumed:

• H0—joint score and cracking/spalling are independent. 

• HA—joint score and cracking/spalling are dependent. 

The null hypothesis was rejected if the calculated probability (p-value) was less than 0.05. For 

the LTPP test sections analyzed, rejection of H0 implied that the joint score was related to the 

presence of cracking/spalling. Summary results of the analyses are shown in table 40. The 

p-value is broken down by State because each State represents a site with one GPS-3 test section 

or multiple SPS-2 test sections. Thus, breaking down p-values by State are a way to control for 

traffic, climate, and subgrade while maintaining a large enough sample size for the analyses. 

This analysis is not appropriate using the full dataset as the conditions (i.e., traffic, climate, and 

subgrade) change substantially from one location to another. While there are many factors 

responsible for cracking and spalling in PCC pavement, if the joint score has an impact on 

spalling or cracking at any specific site, it can be expected to show up in the analyses results 

shown in table 40 provided a sufficiently large sample size (i.e., number of transverse joints) is 

used. Figure 87 through figure 109 show the number of transverse joints exhibiting 

cracking/spalling compared to the total number of transverse joints for each of the three joint 

score categories.

Summary results of the LTPP test sections analyzed shown in table 40 indicate no definitive 

relationship between the joint score and transverse cracking or spalling of PCC slabs, except for 

three instances. Arizona and Arkansas have a p-value of less than 0.05, indicating a relationship 

between the joint score and slab cracking. Similarly, Iowa has a p-value of less than 0.05, 

indicating a relationship between the joint score and spalling. These results suggest other factors 

have a stronger effect on transverse cracking and spalling, but there may be some 

project-specific situations where dowel alignment (as measured using the joint score) has some 

influence on transverse cracking and spalling. Thus, dowel alignment may be a contributing 

factor, but not necessarily the primary factor, for these distresses. More detailed analyses of the 

data may be required to identify other contributing factors. LTPP test sections in North Carolina, 
74 

South Dakota, and Wisconsin did not exhibit any slab cracking and were eliminated from the 

cracking statistical analyses. 

Table 40. Summary results of statistical analyses. 

State Number of Transverse Joints for Analyses Cracking p-Value Spalling p-Value

Arizona 390 0.015* 0.470 

Arkansas 357 0.035* 0.823 

California 388 0.769 0.589 

Colorado 386 0.128 0.682 

Delaware 449 0.425 0.750 

Iowa 387 0.782 0.001* 

Kansas 390 0.126 0.192 

North Carolina 248 N/A 0.191 

North Dakota 383 0.653 0.451 

South Dakota 25 N/A 0.052 

Wisconsin 346 N/A 0.097 

*Significant at p = 0.05. 

N/A = not applicable. 

Source: FHWA.

Figure 88. Chart. Joint score and presence of cracking for LTPP test sections in Arizona. 
75 

Source: FHWA.

Figure 89. Chart. Joint score and presence of spalling for LTPP test sections in Arizona. 

Source: FHWA.

Figure 90. Chart. Joint score and presence of cracking for LTPP test sections in Arkansas. 
76 

Source: FHWA.

Figure 91. Chart. Joint score and presence of spalling for LTPP test sections in Arkansas. 

Source: FHWA.

Figure 92. Chart. Joint score and presence of cracking for LTPP test sections in California. 
77 

Source: FHWA.

Figure 93. Chart. Joint score and presence of spalling for LTPP test sections in California. 

Source: FHWA.

Figure 94. Chart. Joint score and presence of cracking for LTPP test sections in Colorado. 
78 

Source: FHWA.

Figure 95. Chart. Joint score and presence of spalling for LTPP test sections in Colorado. 

Source: FHWA.

Figure 96. Chart. Joint score and presence of cracking for LTPP test sections in Delaware. 
79 

Source: FHWA.

Figure 97. Chart. Joint score and presence of spalling for LTPP test sections in Delaware. 

Source: FHWA.

Figure 98. Chart. Joint score and presence of cracking for LTPP test sections in Iowa. 
80 

Source: FHWA.

Figure 99. Chart. Joint score and presence of spalling for LTPP test sections in Iowa. 

Source: FHWA.

Figure 100. Chart. Joint score and presence of cracking for LTPP test sections in Kansas. 
81 

Source: FHWA.

Figure 101. Chart. Joint score and presence of spalling for LTPP test sections in Kansas. 

Source: FHWA.

Figure 102. Chart. Joint score and presence of cracking for LTPP test sections in 

North Carolina. 
82 

Source: FHWA.

Figure 103. Chart. Joint score and presence of spalling for LTPP test sections in 

North Carolina. 

Source: FHWA.

Figure 104. Chart. Joint score and presence of cracking for LTPP test sections in 

North Dakota. 
83 

Source: FHWA.

Figure 105. Chart. Joint score and presence of spalling for LTPP test sections in 

North Dakota. 

Source: FHWA.

Figure 106. Chart. Joint score and presence of cracking for the LTPP test section in 

South Dakota. 
84 

Source: FHWA.

Figure 107. Chart. Joint score and presence of spalling for the LTPP test section in 

South Dakota. 

Source: FHWA.

Figure 108. Chart. Joint score and presence of cracking for LTPP test sections in 

Wisconsin. 
85 

Source: FHWA.

Figure 109. Chart. Joint score and presence of spalling for LTPP test sections in Wisconsin. 

87 

CHAPTER 7. JOINT-OPENING ANALYSES 

Arizona LTPP test section 4_0215, which was selected for MIT scanning and analysis, was part 

of the LTPP Seasonal Monitoring Program (SMP). Joint-opening data for five transverse joints 

on Arizona LTPP test section 4_0215 (i.e., joint 29 through joint 33) collected over 

approximately 13 yr were extracted from the LTPP database for analysis. Joint-opening data for 

Arizona LTPP test section 4_0215 are shown in figure 110. Each datapoint represents the 

average gage reading of three locations (i.e., pavement edge, middle of lane, and inside lane 

edge) relative to the smallest average gage reading at the transverse joint. A similar analysis was 

performed for Arizona LTPP test section 4_0215 in NCHRP Report 637 for joint-opening data 

measured over 10 yr.

Figure 110 shows that all transverse joints opened and closed over the analysis period due to 

thermal expansion and contraction of the PCC slabs and were not inhibited from doing so by 

misaligned dowels. Table 41 shows the maximum joint opening, average horizontal skew, 

average vertical tilt, average longitudinal translation, joint score, and effective reduction in 

dowel diameter for the five transverse joints from Arizona LTPP test section 4_0215. Data in 

table 41 do not indicate any correlation between dowel misalignment and joint opening for 

joint 29 through joint 33. The sample size presented in figure 110 and table 41 is limited, and 

analysis of other joint-opening data is needed to further understand the effect of dowel 

misalignment on joint opening and the potential for joint lockup. 
88 

Source: FHWA.

Figure 110. Chart. Joint-opening data from five instrumented transverse joints at Arizona 

LTPP test section 4_0215. 

Table 41. Maximum joint opening, dowel alignment data, and joint score for five

instrumented transverse joints with joint-opening data at Arizona LTPP test section

4_0215. 

Transverse 

Joint 

Number

Maximum Joint 

Opening

(Thousandths of 

Inches) 

Average 

Horizontal 

Skew

(Inches)

Average 

Vertical 

Tilt 

(Inches)

Average 

Longitudinal 

Translation 

(Inches) Joint Score 

Effective 

Reduction in 

Dowel 

Diameter 

(Percent) 

29 293 0.18 0.36 1.33 1 3.5 

30 210 0.36 0.15 0.29 1 0.0 

31 154 0.09 0.29 2.12 1 2.7 

32 182 0.21 0.42 0.86 14 3.0 

33 166 0.21 0.37 1.37 7 0.3 
89 

CHAPTER 8. AASHTOWARE PAVEMENT ME DESIGN ANALYSES USING 

EQUIVALENT DOWEL DIAMETER

To identify any relationship between the equivalent dowel diameter and LTPP field distress data, 

analyses were conducted using data from all test sections. Pavement distress information was 

extracted from the LTPP database and compared with predicted performance from

AASHTOWare Pavement ME Design using both the actual and computed equivalent dowel 

diameter. The goal of these analyses was to consider the effects of dowel misalignment through 

the use of the equivalent dowel diameter in terms of performance criteria, such as faulting and 

cracking, in the context of other compounding factors (e.g., climate, traffic, materials, support 

conditions), which allows data from all sections to be used together as the impact of these factors 

is considered in AASHTOWare Pavement ME Design performance models.

Default global calibration coefficients and actual relevant site information available in the LTPP 

database (e.g., subgrade, materials, traffic, and climate) for each test section were used to 

develop the AASHTOWare Pavement ME Design files for the analyses. Although some States 

developed local calibration coefficients, they were not used for consistency between all LTPP 

test sections analyzed. Results of the analyses for various test sections are shown in table 42

through table 52. The AASHTOWare Pavement ME Design runs were executed from the actual 

construction month to the field-data-collection month as shown in table 42 through table 52. 

Table 53, figure 111, and figure 112 summarize the results of the analyses.

The results of the analyses show that using the average equivalent, instead of actual, dowel 

diameter produces a reduced bias of the in-service LTE as modeled using AASHTOWare 

Pavement ME Design. This result is consistent for both 1.25- and 1.5-inch-diameter dowels, and 

the effect is stronger when LTE is greater than 60 percent. Figure 111 shows that, when the 

actual dowel diameter is used, AASHTOWare Pavement ME Design generally models higher 

LTE than is observed in the field; some of this bias is removed when the average equivalent 

dowel diameter is used. For LTE, table 53 shows lower mean residuals when comparing 

as-predicted distresses versus actual distresses using the average equivalent, as opposed to actual, 

dowel diameter. Thus, using the equivalent dowel diameter is a less-biased estimator of 

long-term pavement LTE as modeled using AASHTOWare Pavement ME Design than using the 

actual dowel diameter.

The results of the analyses are reversed when evaluating faulting. The results of faulting analyses 

show that using the average equivalent, instead of actual, dowel diameter produces a greater bias 

of faulting as modeled using AASHTOWare Pavement ME Design. Figure 112 shows that when 

the actual dowel diameter is used, AASHTOWare Pavement ME Design models are generally 

unbiased; some bias (i.e., asymmetry) is introduced when the average equivalent dowel diameter

is used. For faulting, table 53 shows lower mean residuals when comparing as-predicted 

distresses versus actual distresses using the actual, as opposed to average equivalent dowel 

diameter. Thus, using the actual dowel diameter is a less-biased estimator of faulting as modeled 

using AASHTOWare Pavement ME Design than using the average equivalent dowel diameter. 

The two results of the analyses seem contradictory because faulting correlates with LTE.

However, the results make sense when the following two factors are considered: 
90 

• Faulting correlates with LTE, but low LTE does not always correspond to high faulting. 

• Factors such as traffic, support conditions, climate, and age all affect faulting 

independent of LTE.

The results of the analyses also show the effect of calibration on the faulting models in 

AASHTOWare Pavement ME Design, which was calibrated using LTPP test sections. As such, 

the research team for the current study hypothesize that dowel misalignment in LTPP test 

sections is accounted for in the calibration. The calibration process for faulting may have 

removed some of the bias in faulting models but not necessarily in LTE models because LTE 

models are not calibrated with field-measured LTE data. 

Taken together, the data suggest that dowel misalignment affects long-term LTE of a concrete 

pavement because using the average equivalent, instead of actual, dowel diameter reduces bias in 

the AASHTOWare Pavement ME Design LTE model. This result is consistent with the lab 

results conducted in NCHRP Report 637. However, figure 111 and figure 112 exhibit a 

considerable amount of scatter in LTE and faulting modeled using AASHTOWare Pavement ME

Design versus actual LTE and faulting. The remaining bias and scatter suggests that the two 

models (i.e., the equivalent dowel diameter model from NCHRP Report 637 and the LTE model 

in AASHTOWare Pavement ME Design) can be improved using the data collected as part of this 

study. More thorough analyses and adjustments to the models may be warranted to improve the 

equivalent dowel diameter model and the LTE model in AASHTOWare Pavement ME Design, 

which is beyond the scope of this study. 

Analyses of LTE and faulting as independent variables with the joint score and average 

equivalent dowel diameter as dependent variables were not undertaken in this study. LTE and 

faulting are significantly impacted by other parameters (e.g., traffic, dowel size, base type, 

subgrade type, climate, PCC thickness, and age of pavement). For example, a test section 

experiencing 5 million trucks over 20 yr will have lower LTE and far more faulting than a test 

section experiencing 200,000 trucks over 20 yr with the same extent of misalignment. Likewise, 

a test section with—a heavy clay subgrade and an aggregate base will have lower LTE and more 

faulting than a test section with a sandy gravel subgrade and a treated base for the same average 

joint score. These types of analyses have to be performed on a section-by-section basis by 

comparing the well-aligned transverse joints within a test section to the poorly aligned transverse 

joints within the same test section. However, there is too much inherent variability between slabs 

and transverse joints within any test section to perform this analysis on a section-by-section 

basis. These analyses for each test section were also beyond the scope of this study. As such, in 

this study, a 500-foot LTPP test section was analyzed as a single unit and AASHTOWare 

Pavement ME Design used to account for the effects of other variables by comparing LTE and 

faulting using the actual and average equivalent dowel diameter to the pavement age.

Temperature affects the field-measured LTE but is not considered in the LTE generated by 

AASHTOWare Pavement ME Design using the actual and average equivalent dowel diameter. 

The LTE generated using AASHTOWare Pavement ME Design represents an average LTE at 

the pavement age (corresponding to the date of field data collection) rather than a 

temperature-dependent LTE affected by daily opening and closing of transverse joints due to 

temperature cycling. Because the temperature dependence of LTE cannot be modeled in 

AASHTOWare Pavement ME Design, it is not considered in analyses. It is assumed that, 
91 

because of the large number of transverse joints analyzed in this study, the temperature effects on 

transverse joint LTE average out. 

Table 42. Comparison of AASHTOWare Pavement ME Design analyses results with actual 

LTPP distress data using the average equivalent and actual dowel diameter for LTPP test 

sections in Arizona.

Test 

Section

Dowel Diameter

(Inches)

Predicted 

LTE 

(Percent) 

(12/2014) 

Predicted 

faulting 

(Inches)

(12/2014) 

Predicted 

Slabs 

Cracked 

(Percent) 

(12/2014) 

Actual 

LTE 

(Percent) 

(12/2014) 

Actual 

Faulting 

(Inches)

(12/2014) 

Actual 

Slabs 

Cracked 

(Percent) 

(12/2014) 

213 1.23 (equivalent) 90.1 0.002 51.04 66 0.027 0.0 

1.25 (actual) 90.7 0.001 51.04 66 0.027 0.0 

214 1.17 (equivalent) 86.1 0.804 3.42 61 0.051 3.0 

1.25 (actual) 89.7 0.498 3.42 61 0.051 3.0 

215 1.37 (equivalent) 87.8 0.297 5.28 73 0.023 0.0 

1.50 (actual) 91.6 0.161 5.28 73 0.023 0.0 

216 1.43 (equivalent) 89.1 0.032 0.00 57 0.011 0.0 

1.50 (actual) 91.0 0.017 0.00 57 0.011 0.0 

217 1.24 (equivalent) 91.6 0.026 99.92 53 0.012 63.6 

1.25 (actual) 91.8 0.024 99.92 53 0.012 63.6 

218 1.17 (equivalent) 87.9 0.926 99.93 83 0.009 51.5 

1.25 (actual) 91.1 0.624 99.93 83 0.009 51.5 

219 1.42(equivalent) 92.1 0.152 99.48 48 0.007 57.5 

1.50 (actual) 93.6 0.127 99.48 48 0.007 57.5 

220 1.44 (equivalent) 91.1 0.011 0.00 82 0.006 0.0 

1.50 (actual) 92.4 0.006 0.00 82 0.006 0.0 

221 1.22 (equivalent) 90.6 0.000 1.42 38 0.021 0.0 

1.25 (actual) 91.5 0.000 1.42 38 0.021 0.0 

222 1.15 (equivalent) 85.5 0.511 0.10 39 0.012 21.2 

1.25 (actual) 90.4 0.245 0.10 39 0.012 21.2 

223 1.37 (equivalent) 88.9 0.191 0.08 54 0.013 0.0 

1.50 (actual) 92.4 0.093 0.08 54 0.013 0.0 

224 1.40 (equivalent) 91.0 0.008 0.00 57 0.004 0.0 

1.50 (actual) 93.1 0.003 0.00 57 0.004 0.0 
92 

Table 43. Comparison of AASHTOWare Pavement ME Design analyses results with actual 

LTPP distress data using the average equivalent and actual dowel diameter for LTPP test 

sections in Arkansas. 

Test 

Section

Dowel Diameter

(Inches)

Predicted 

LTE 

(Percent) 

(08/2013) 

Predicted 

Faulting 

(Inches)

(08/2013) 

Predicted 

Slabs 

Cracked 

(Percent) 

(08/2013) 

Actual 

LTE 

(Percent) 

(08/2013) 

Actual 

Faulting 

(Inches)

(08/2013) 

Actual 

Slabs 

Cracked 

(Percent) 

(08/2013) 

214 1.14 (equivalent) 85.1 0.166 32.02 67 0.10 3.03 

1.25 (actual) 90.6 0.097 32.02 67 0.10 3.03 

215 1.40 (equivalent) 95.0 0.012 0.01 93 0.14 0.00 

1.50 (actual) 95.0 0.009 0.01 93 0.14 0.00 

216 1.42 (equivalent) 89.7 0.002 0.00 51 0.04 0.00 

1.50 (actual) 91.7 0.001 0.00 51 0.04 0.00 

217 1.15 (equivalent) 89.4 0.002 11.40 52 0.02 24.20 

1.25 (actual) 92.8 0.000 11.40 52 0.02 24.20 

218 0.97 (equivalent) 53.7 1.030 96.23 44 0.01 100.00 

1.25 (actual) 91.8 0.121 96.23 44 0.01 100.00 

219 1.41 (equivalent) 94.1 0.006 0.01 32 0.01 0.00 

1.50 (actual) 95.0 0.005 0.01 32 0.01 0.00 

220 1.39 (equivalent) 95.0 0.001 0.00 84 0.02 0.00 

1.50 (actual) 95.0 0.001 0.00 84 0.02 0.00 

221 1.22 (equivalent) 95.0 0.000 1.05 81 0.05 6.06 

1.25 (actual) 95.0 0.000 1.05 81 0.05 6.06 

222 1.18 (equivalent) 89.6 0.129 30.62 84 0.09 0.00 

1.25 (actual) 91.9 0.103 30.62 84 0.09 0.00 

223 1.41 (equivalent) 95.0 0.007 0.06 91 0.02 0.00 

1.50 (actual) 95.0 0.006 0.06 91 0.02 0.00 

224 1.47 (equivalent) 94.7 0.001 0.00 39 0.04 0.00 

1.50 (actual) 95.0 0.001 0.00 39 0.04 0.00 
93 

Table 44. Comparison of AASHTOWare Pavement ME Design analyses results with actual 

LTPP distress data using the average equivalent and actual dowel diameter for LTPP test 

sites in Colorado. 

Test 

Section

Dowel Diameter

(Inches)

Predicted 

LTE 

(Percent) 

(09/2013) 

Predicted 

Faulting 

(Inches)

(09/2014) 

Predicted 

Slabs 

Cracked 

(Percent) 

(09/2014) 

Actual LTE 

(Percent) 

(09/2013) 

Actual 

Faulting 

(Inches)

(09/2014) 

Actual 

Slabs 

Cracked 

(Percent) 

(09/2014) 

213 1.24 (equivalent) 91.0 0.005 0.70 79 0.0 0.0 

1.25 (actual) 91.3 0.004 0.70 79 0.0 0.0 

214 1.22 (equivalent) 89.5 0.042 0.00 80 0.0 3.0 

1.25 (actual) 90.5 0.038 0.00 80 0.0 3.0 

215 1.45 (equivalent) 95.0 0.011 0.00 88 0.0 0.0 

1.50 (actual) 95.0 0.009 0.00 88 0.0 0.0 

216 1.48 (equivalent) 93.6 0.002 0.00 95 0.0 18.1 

1.50 (actual) 94.0 0.001 0.00 95 0.0 18.1 

217 1.09 (equivalent) 83.3 0.008 0.00 88 0.1 21.2 

1.25 (actual) 92.9 0.000 0.00 88 0.1 21.2 

218 1.05 (equivalent) 84.9 0.173 12.74 78 0.0 9.1 

1.25 (actual) 93.6 0.098 12.74 78 0.0 9.1 

219 1.32 (equivalent) 95.0 0.012 0.00 89 0.0 0.0 

1.50 (actual) 95.0 0.009 0.00 89 0.0 0.0 

220 1.48 (equivalent) 95.0 0.000 0.00 91 0.1 0.0 

1.50 (actual) 95.0 0.000 0.00 91 0.1 0.0 

221 1.19 (equivalent) 90.4 0.000 0.17 92 0.0 0.0 

1.25 (actual) 92.5 0.000 0.17 92 0.0 0.0 

222 1.24 (equivalent) 90.6 0.022 0.00 89 0.0 0.0 

1.25 (actual) 90.9 0.021 0.00 89 0.0 0.0 

223 1.47 (equivalent) 93.2 0.009 0.00 28 0.0 12.1 

1.50 (actual) 93.7 0.009 0.00 28 0.0 12.1 

224 1.43 (equivalent) 91.0 0.001 0.00 95 0.0 0.0 

1.50 (actual) 92.6 0.001 0.00 95 0.0 0.0 
94 

Table 45. Comparison of AASHTOWare Pavement ME Design analyses results with actual 

LTPP distress data using the average equivalent and actual dowel diameter for LTPP test 

sections in California. 

Test 

Section

Dowel Diameter

(Inches)

Predicted 

LTE 

(Percent) 

(10/2014) 

Predicted 

Faulting 

(Inches)

(10/2014) 

Predicted 

Slabs 

Cracked 

(Percent) 

(10/2014) 

Actual 

LTE 

(Percent) 

(10/2014) 

Actual 

Faulting 

(Inches)

(10/2014) 

Actual 

Slabs 

Cracked 

(Percent) 

(10/2014) 

201 1.14 (equivalent) 84.1 0.061 53.11 78 0.01 75.75 

1.50 (actual) 94.4 0.007 53.11 78 0.01 75.75 

202 0.80 (equivalent) 43.7 0.193 8.50 87 0.01 81.80 

1.25 (actual) 90.9 0.000 8.50 87 0.01 81.80 

203 1.22 (equivalent) 67.9 0.015 1.21 83 0.01 0.00 

1.50 (actual) 90.9 0.000 1.21 83 0.01 0.00 

204 1.00 (equivalent) 44.0 0.169 0.05 94 0.02 0.00 

1.25 (actual) 77.1 0.037 0.05 94 0.02 0.00 

205 1.29 (equivalent) 92.5 0.004 0.00 79 0.03 69.69 

1.50 (actual) 95.0 0.001 0.00 79 0.03 69.69 

206 0.79 (equivalent) 51.2 0.067 0.00 88 0.00 69.69 

1.25 (actual) 92.0 0.000 0.00 88 0.00 69.69 

207 1.31(equivalent) 87.3 0.000 0.00 72 0.04 9.09 

1.50 (actual) 93.4 0.000 0.00 72 0.04 9.09 

208 1.03 (equivalent) 52.0 0.092 0.00 74 0.03 6.06 

1.25 (actual) 82.9 0.013 0.00 74 0.03 6.06 

209 1.29 (equivalent) 91.9 0.011 25.22 85 0.03 3.03 

1.50 (actual) 95.0 0.003 25.22 85 0.03 3.03 

210 1.05 (equivalent) 67.1 0.035 1.24 88 0.01 0.00 

1.25 (actual) 91.5 0.000 1.24 88 0.01 0.00 

211 1.21 (equivalent) 53.0 0.023 0.04 87 0.02 0.00 

1.50 (actual) 91.1 0.000 0.04 87 0.02 0.00 

212 0.96 (equivalent) 51.0 0.115 0.03 96 0.00 0.00 

1.25 (actual) 79.9 0.024 0.03 96 0.00 0.00 
95 

Table 46. Comparison of AASHTOWare Pavement ME Design analyses results with actual 

LTPP distress data using the average equivalent and actual dowel diameter for LTPP test 

section in Delaware.

Test 

Section

Dowel Diameter

(Inches)

Predicted 

LTE 

(Percent) 

(05/2012) 

Predicted 

Faulting 

(Inches)

(05/2012) 

Predicted 

Slabs 

Cracked 

(Percent) 

(05/2012) 

Actual LTE 

(Percent) 

(05/2012) 

Actual 

Faulting 

(Inches)

(05/2012) 

Actual 

Slabs 

Cracked 

(Percent) 

(05/2012) 

201 1.07 (equivalent) 90.1 0.026 0.01 88 0.0 0.0 

1.25 (actual) 93.3 0.009 0.01 88 0.0 0.0 

202 1.19 (equivalent) 89.8 0.001 0.00 85 0.0 0.0 

1.25 (actual) 91.5 0.001 0.00 85 0.0 0.0 

203 1.49 (equivalent) 92.1 0.000 0.00 88 0.0 0.0 

1.50 (actual) 92.3 0.000 0.00 88 0.0 0.0 

204 1.48 (equivalent) 91.2 0.005 0.00 87 0.0 0.0 

1.50 (actual) 91.6 0.004 0.00 87 0.0 0.0 

205 1.22 (equivalent) 88.9 0.005 0.00 80 0.0 12.1 

1.25 (actual) 90.1 0.004 0.00 80 0.0 12.1 

206 1.10 (equivalent) 90.4 0.000 0.00 85 0.0 0.0 

1.25 (actual) 94.0 0.000 0.00 85 0.0 0.0 

207 1.47 (equivalent) 94.2 0.000 0.00 90 0.0 3.0 

1.50 (actual) 94.5 0.000 0.00 90 0.0 3.0 

208 1.42 (equivalent) 91.0 0.001 0.00 91 0.0 0.0 

1.50 (actual) 92.4 0.001 0.00 91 0.0 0.0 

209 1.14 (equivalent) 87.5 0.010 0.00 83 0.0 0.0 

1.25 (actual) 91.8 0.006 0.00 83 0.0 0.0 

210 1.23 (equivalent) 93.4 0.000 0.00 81 0.0 0.0 

1.25 (actual) 93.8 0.000 0.00 81 0.0 0.0 

211 1.48 (equivalent) 93.0 0.000 0.00 70 0.0 0.0 

1.50 (actual) 93.3 0.000 0.00 70 0.0 0.0 

212 1.47 (equivalent) 90.4 0.002 0.00 74 0.0 0.0 

1.50 (actual) 91.2 0.002 0.00 74 0.0 0.0 

259 1.41 (equivalent) 90.8 0.007 0.00 71 0.0 0.0 

1.50 (actual) 92.7 0.006 0.00 71 0.0 0.0 

260 0.30 (equivalent) 46.1 0.055 0.00 77 0.0 0.0 

1.25 (actual) 83.8 0.010 0.00 77 0.0 0.0 
96 

Table 47. Comparison of AASHTOWare Pavement ME Design analyses results with actual 

LTPP distress data using the average equivalent and actual dowel diameter for LTPP test 

sections in Iowa. 

Test 

Section

Dowel Diameter

(Inches)

Predicted 

LTE 

(Percent) 

(11/2014) 

Predicted 

Faulting 

(Inches)

(11/2014) 

Predicted 

Slabs 

Cracked 

(Percent) 

(11/2014) 

Actual LTE 

(Percent) 

(11/2014) 

Actual 

Faulting 

(Inches)

(11/2014) 

Actual 

Slabs 

Cracked 

(Percent) 

(11/2014) 

213 1.21 (equivalent) 89.9 0.000 0.01 73 0.0 0.0 

1.25 (actual) 91.2 0.000 0.01 73 0.0 0.0 

214 1.21 (equivalent) 88.9 0.025 0.01 83 0.0 6.1 

1.25 (actual) 90.2 0.022 0.01 83 0.0 6.1 

215 1.48 (equivalent) 90.9 0.009 0.00 89 0.0 0.0 

1.50 (actual) 91.4 0.008 0.00 89 0.0 0.0 

216 1.46 (equivalent) 90.3 0.012 0.00 88 0.0 0.0 

1.50 (actual) 95.0 0.011 0.00 88 0.0 0.0 

217 1.05 (equivalent) 87.2 0.002 0.07 82 0.0 0.0 

1.25 (actual) 93.9 0.002 0.07 82 0.0 0.0 

218 1.17 (equivalent) 89.7 0.009 0.00 67 0.0 6.1 

1.25 (actual) 92.1 0.007 0.00 67 0.0 6.1 

219 1.42 (equivalent) 94.3 0.000 0.00 86 0.0 0.0 

1.50 (actual) 95.0 0.000 0.00 86 0.0 0.0 

220 1.31 (equivalent) 91.6 0.000 0.00 79 0.0 0.0 

1.50 (actual) 94.2 0.000 0.00 79 0.0 0.0 

221 1.21 (equivalent) 92.0 0.000 0.00 83 0.0 0.0 

1.25 (actual) 92.9 0.000 0.00 83 0.0 0.0 

222 1.15 (equivalent) 88.7 0.014 0.00 87 0.0 0.0 

1.25 (actual) 92.0 0.010 0.00 87 0.0 0.0 

223 1.47 (equivalent) 90.6 0.003 0.00 88 0.0 0.0 

1.50 (actual) 91.4 0.003 0.00 88 0.0 0.0 

224 1.47 (equivalent) 94.6 0.000 0.00 85 0.0 0.0 

1.50 (actual) 94.8 0.000 0.00 85 0.0 0.0 
97 

Table 48. Comparison of AASHTOWare Pavement ME Design analyses results with actual 

LTPP distress data using the average equivalent and actual dowel diameter for LTPP test 

sections in Kansas. 

Test 

Section

Dowel Diameter

(Inches)

Predicted 

LTE 

(Percent) 

(09/2012) 

Predicted 

Faulting 

(Inches)

(09/2012) 

Predicted 

Slabs 

Cracked 

(Percent) 

(09/2012) 

Actual 

LTE 

(Percent) 

(09/2012) 

Actual 

Faulting 

(Inches)

(09/2012) 

Actual 

Slabs 

Cracked 

(Percent) 

(09/2012) 

201 1.09 (equivalent) 84.9 0.136 45.32 95 0.0 15.2 

1.25 (actual) 91.9 0.077 45.32 95 0.0 15.2 

202 1.05 (equivalent) 81.3 0.055 13.42 86 0.0 24.2 

1.25 (actual) 92.2 0.000 13.42 86 0.0 24.2 

203 1.48 (equivalent) 91.6 0.002 0.00 82 0.0 0.0 

1.50 (actual) 92.0 0.002 0.00 82 0.0 0.0 

204 1.48 (equivalent) 90.4 0.072 0.01 71 0.0 3.0 

1.50 (actual) 90.9 0.069 0.01 71 0.0 3.0 

205 1.19 (equivalent) 91.8 0.035 9.50 70 0.0 0.0 

1.25 (actual) 93.2 0.027 9.50 70 0.0 0.0 

206 1.17 (equivalent) 91.0 0.000 0.45 86 0.0 0.0 

1.25 (actual) 93.4 0.000 0.45 86 0.0 0.0 

207 1.35 (equivalent) 91.5 0.002 0.00 89 0.0 0.0 

1.50 (actual) 94.7 0.000 0.00 89 0.0 0.0 

208 1.46 (equivalent) 92.2 0.034 0.00 87 0.0 0.0 

1.50 (actual) 92.9 0.030 0.00 87 0.0 0.0 

209 1.13 (equivalent) 84.2 0.087 0.28 84 0.0 0.0 

1.25 (actual) 90.7 0.052 0.28 84 0.0 0.0 

210 1.19 (equivalent) 88.6 0.004 0.03 86 0.0 0.0 

1.25 (actual) 91.1 0.000 0.03 86 0.0 0.0 

211 1.43 (equivalent) 91.5 0.002 0.00 86 0.0 0.0 

1.50 (actual) 93.0 0.001 0.00 86 0.0 0.0 

212 1.43 (equivalent) 90.7 0.050 0.00 92 0.0 0.0 

1.50 (actual) 92.3 0.041 0.00 92 0.0 0.0 
98 

Table 49. Comparison of AASHTOWare Pavement ME Design analyses results with actual 

LTPP distress data using the average equivalent and actual dowel diameter for LTPP test 

sections in North Carolina. 

Test 

Section

Dowel Diameter

(Inches)

Predicted 

LTE 

(Percent) 

(10/2012) 

Predicted 

Faulting 

(Inches)

(10/2012) 

Predicted 

Slabs 

Cracked 

(Percent) 

(10/2012) 

Actual LTE 

(Percent) 

(10/2012) 

Actual 

Faulting 

(Inches)

(10/2012) 

Actual 

Slabs 

Cracked 

(Percent) 

(10/2012) 

203 1.45 (equivalent) 90.1 0.000 0.0 76 0.0 0.0 

1.50 (actual) 91.3 0.000 0.0 76 0.0 0.0 

204 1.39 (equivalent) 87.6 0.013 0.0 89 0.0 0.0 

1.50 (actual) 90.9 0.009 0.0 89 0.0 0.0 

207 1.39 (equivalent) 91.0 0.000 0.0 96 0.0 0.0 

1.50 (actual) 93.6 0.000 0.0 96 0.0 0.0 

208 1.44 (equivalent) 91.1 0.004 0.0 32 0.0 0.0 

1.50 (actual) 92.5 0.003 0.0 32 0.0 0.0 

211 1.42 (equivalent) 90.3 0.001 0.0 66 0.0 0.0 

1.50 (actual) 92.3 0.001 0.0 66 0.0 0.0 

212 1.50 (equivalent) 92.5 0.004 0.0 59 0.0 0.0 

1.50 (actual) 92.5 0.004 0.0 59 0.0 0.0 

259 1.20 (equivalent) 80.6 0.017 0.0 56 0.0 0.0 

1.25 (actual) 85.4 0.011 0.0 56 0.0 0.0 

260 1.31 (equivalent) 87.2 0.001 0.0 84 0.0 0.0 

1.50 (actual) 92.4 0.000 0.0 84 0.0 0.0 
99 

Table 50. Comparison of AASHTOWare Pavement ME Design analyses results with actual 

LTPP distress data using the average equivalent and actual dowel diameter for LTPP test 

sections in North Dakota. 

Test 

Section

Dowel Diameter

(Inches)

Predicted 

LTE 

(Percent) 

(08/2012) 

Predicted 

Faulting 

(Inches)

(08/2012) 

Predicted 

Slabs 

Cracked 

(Percent) 

(08/2012) 

Actual LTE 

(Percent) 

(08/2012) 

Actual 

Faulting 

(Inches)

(08/2012) 

Actual 

Slabs 

Cracked 

(Percent) 

(08/2012) 

213 1.24 (equivalent) 94.4 0.000 5.86 80 0.0 0.0 

1.25 (actual) 94.5 0.000 5.75 80 0.0 0.0 

214 1.22 (equivalent) 91.0 0.055 1.00 89 0.0 0.0 

1.25 (actual) 91.8 0.051 0.98 89 0.0 0.0 

215 1.38 (equivalent) 95.0 0.023 0.00 92 0.0 0.0 

1.50 (actual) 95.0 0.022 0.00 92 0.0 0.0 

216 1.48 (equivalent) 95.0 0.000 0.00 96 0.0 0.0 

1.50 (actual) 93.9 0.000 0.00 96 0.0 0.0 

217 1.22 (equivalent) 94.7 0.000 0.00 73 0.0 9.1 

1.25 (actual) 95.0 0.000 0.00 73 0.0 9.1 

218 1.21 (equivalent) 93.7 0.021 0.00 87 0.0 0.0 

1.25 (actual) 94.4 0.020 0.00 87 0.0 0.0 

219 1.48 (equivalent) 95.0 0.016 0.00 91 0.1 0.0 

1.50 (actual) 95.0 0.016 0.00 91 0.1 0.0 

220 1.47 (equivalent) 95.0 0.000 0.00 85 0.0 0.0 

1.50 (actual) 95.0 0.000 0.00 85 0.0 0.0 

221 1.24 (equivalent) 93.7 0.000 0.00 83 0.0 0.0 

1.25 (actual) 93.8 0.000 0.00 83 0.0 0.0 

222 1.24 (equivalent) 92.0 0.026 0.01 90 0.0 0.0 

1.25 (actual) 92.2 0.025 0.01 90 0.0 0.0 

223 1.48 (equivalent) 95.0 0.017 0.00 91 0.0 0.0 

1.50 (actual) 95.0 0.017 0.00 91 0.0 0.0 

224 1.47 (equivalent) 94.1 0.000 0.00 92 0.0 0.0 

1.50 (actual) 94.4 0.000 0.00 92 0.0 0.0 
100 

Table 51. Comparison of AASHTOWare Pavement ME Design analysis results with actual 

LTPP distress data using the average equivalent and actual dowel diameter for the LTPP 

test section in South Dakota.

Test 

Section

Dowel Diameter

(Inches)

Predicted 

LTE 

(Percent) 

(05/2011) 

Predicted 

Faulting 

(Inches)

(05/2011) 

Predicted 

Slabs 

Cracked 

(Percent) 

(05/2011) 

Actual LTE 

(Percent) 

(05/2011) 

Actual 

Faulting 

(Inches)

(05/2011) 

Actual 

Slabs 

Cracked 

(Percent) 

(05/2011) 

3052 1.21 (equivalent) 90.5 0.020 0.1 92 0.0 0.0 

1.25 (actual) 91.4 0.018 0.1 92 0.0 0.0 

Table 52. Comparison of AASHTOWare Pavement ME Design analyses results with actual 

LTPP distress data using the average equivalent and actual dowel diameter for LTPP test 

sections in Wisconsin. 

Test 

Section

Dowel Diameter

(Inches)

Predicted 

LTE 

(Percent) 

(07/2012) 

Predicted 

Faulting 

(Inches)

(07/2012) 

Predicted 

Slabs 

Cracked 

(Percent) 

(07/2012) 

Actual LTE 

(Percent) 

(07/2012) 

Actual 

Faulting 

(Inches)

(07/2012) 

Actual 

Slabs 

Cracked 

(Percent) 

(07/2012) 

213 1.17 (equivalent) 93.2 0.000 0.0 90 0.0 0.0 

1.25 (actual) 94.1 0.000 0.0 90 0.0 0.0 

215 1.45 (equivalent) 95.0 0.011 0.0 92 0.0 0.0 

1.50 (actual) 95.0 0.010 0.0 92 0.0 0.0 

217 0.99 (equivalent) 94.9 0.000 0.0 91 0.0 0.0 

1.25 (actual) 95.0 0.000 0.0 91 0.0 0.0 

219 1.37 (equivalent) 95.0 0.006 0.0 90 0.0 0.0 

1.50 (actual) 95.0 0.006 0.0 90 0.0 0.0 

221 1.24 (equivalent) 95.0 0.000 0.0 90 0.0 0.0 

1.25 (actual) 95.0 0.000 0.0 90 0.0 0.0 

223 1.48 (equivalent) 95.0 0.008 0.0 84 0.0 0.0 

1.50 (actual) 95.0 0.007 0.0 84 0.0 0.0 

259 1.47 (equivalent) 94.8 0.013 0.0 95 0.0 0.0 

1.50 (actual) 95.0 0.013 0.0 95 0.0 0.0 

261 1.24 (equivalent) 95.0 0.003 0.0 88 0.0 0.0 

1.25 (actual) 95.0 0.003 0.0 88 0.0 0.0 

262 1.20 (equivalent) 92.5 0.000 0.0 78 0.0 0.0 

1.25 (actual) 93.3 0.000 0.0 78 0.0 0.0 

263 1.05 (equivalent) 71.8 0.044 0.0 93 0.0 0.0 

1.25 (actual) 89.6 0.015 0.0 93 0.0 0.0 

265 1.18 (equivalent) 87.0 0.043 0.0 90 0.0 0.0 

1.50 (actual) 95.0 0.023 0.0 90 0.0 0.0 
101 

Table 53. Summary of AASHTOWare Pavement ME Design analyses results with actual 

LTPP distress data using the average equivalent and actual dowel diameter.

Test Sections Distress

Mean Residual

(As-Predicted 

Distress versus 

Actual Distress) 

Using Actual 

Dowel Diameter

Mean Residual

(As-Predicted 

Distress versus 

Actual Distress) 

Using Average 

Equivalent Dowel 

Diameter

All (N = 117) 

LTE (percent) 13.30 8.46** 

Faulting (inches) 0.01** 0.04 

Slab cracking (percent) −0.65 −0.65 

1.50-inch-diameter dowels (N = 61) 

LTE (percent) 14.44 12.00** 

Faulting (inches) 0.00 0.00 

Slab cracking (percent) −1.09 −1.09 

1.25-inch-diameter dowels (N = 56) 

LTE (percent) 12.07 4.62** 

Faulting (inches) 0.03** 0.08 

Slab cracking (percent) −0.17 −0.17 

Trimmed* (N = 101) 

LTE (percent) 8.12 3.19** 

Faulting (inches) 0.01** 0.03 

Slab cracking (percent) −1.05 −1.05 

1.50-inch-diameter dowels trimmed* 

(N = 51) 

LTE (percent) 7.96 5.32** 

Faulting (inches) 0.00 0.00 

Slab cracking (percent) −1.90 −1.90 

1.25-inch-diameter dowels trimmed* 

(N = 50) 

LTE (percent) 8.29 1.01** 

Faulting (inches) 0.02** 0.06 

Slab cracking (percent) −0.19 −0.19 

*Trimmed test sections represent only those that have measured LTE > 60 percent. 

**Lower residual value. 

N = number of sections used in the analyses.
102 

Source: FHWA.

Figure 111. Chart. Predicted and actual LTE Using AASHTOWare Pavement ME Design

from the LTPP database for 117 test sections using the actual and average equivalent dowel 

diameter. 

Source: FHWA.

Figure 112. Chart. Predicted and actual LTE Using AASHTOWare-Pavement ME Design

from the LTPP database for 117 test sections using the actual and average equivalent dowel 

diameter.
103 

CHAPTER 9. CONCLUSIONS AND RECOMMENDATIONS

Dowel-alignment data were collected from 3 GPS-3 and 121 SPS-2 LTPP test sections using an

MIT scanning device in various States to evaluate the effects of dowel misalignment on JPCP

performance. Dowel-alignment data were analyzed using the software provided with the MIT 

scanning device to calculate various dowel-alignment parameters, including horizontal skew, 

vertical tilt, longitudinal translation, and vertical translation. In addition, the joint score and 

equivalent dowel diameter were calculated for every transverse joint tested. These data were 

uploaded to the LTPP database. 

The results of the analyses indicate that approximately 50 percent of transverse joints have a 

joint score of less than 10 and 19 percent of transverse joints have joint scores greater than 30. 

The average effective reduction in dowel diameter for 1.25- and 1.5-inch-diameter dowels 

ranged from 0.1 to 76 percent. 

Only 8 SPS-2 test sections from North Carolina had dowels placed using a DBI. Dowels for the 

other 116 test sections were placed using dowel baskets. Because of the small sample size of test 

sections with dowels placed using a DBI, placement of dowels using a DBI versus dowel baskets 

was not meaningful and was not compared. 

Chi-square tests were performed to determine if there was a relationship between the joint score 

and slab cracking or spalling. Results of the statistical analyses did not indicate any definitive 

relationship between the joint score and transverse cracking or spalling of concrete slabs for most 

States—except for three instances (transverse cracking in Arizona and Arkansas and spalling in 

Iowa). These results suggest other factors have a stronger effect on transverse cracking and 

spalling but there may be some project-specific situations where dowel misalignment (as 

measured using the joint score) has some influence on transverse cracking and spalling. These 

results also suggest that dowel alignment may not be a primary factor affecting transverse 

cracking and spalling but may be a contributing factor exacerbating transverse cracking and 

spalling. Detailed analyses of the dataset were beyond the scope of this study and should be 

undertaken as a followup to this study. 

Joint openings on five transverse joints of Arizona LTPP test section 04_0215, which was an 

SMP test site, were analyzed. The data did not indicate any correlation between dowel 

misalignment/joint score and joint opening. However, as the sample size was limited, analysis of 

additional SMP sites is recommended by the researchers of the current study. 

The results of AASHTOWare Pavement ME Design runs using the actual and average equivalent 

dowel diameter show that using the average equivalent, instead of actual, dowel diameter 

produces a reduced bias of the in-service LTE as modeled using AASHTOWare Pavement ME

Design. It is likely that using the average equivalent dowel diameter as specified in NCHRP 

Report 637 is a less-biased estimator of long-term pavement LTE as modeled using 

AASHTOWare Pavement ME Design than using actual dowel diameter. However, the results 

were reversed when evaluating faulting. The results of the analyses show that using the average, 

instead of actual, dowel diameter produces a greater bias of faulting as modeled using 

AASHTOWare Pavement ME Design. 
104 

The two results of the analyses seem contradictory because faulting is correlated with LTE.

However, the results may make sense when considering AASHTOWare Pavement ME Design 

was calibrated using LTPP test sections. The researchers of the current study hypothesize that 

dowel misalignment in LTPP test sections is accounted for in the calibration. The calibration 

process for faulting may have removed some of the bias in faulting models but not necessarily in 

LTE models since LTE models are not calibrated with field-measured LTE data. 

Taken together, the data suggest that dowel misalignment affects long-term LTE of a concrete 

pavement. This result is consistent with the lab results conducted in NCHRP Report 637. 

However, the results show considerable scatter in LTE and faulting modeled using 

AASHTOWare Pavement ME Design versus actual LTE and faulting. The remaining bias and 

scatter suggests that the two models (i.e., the equivalent dowel diameter model from NCHRP 

Report 637 and the LTE model in AASHTOWare Pavement ME Design) can be improved using 

the data collected as part of this study. 

MIT scanning data collected as a part of this study provide a platform for future analyses to 

establish effective construction specifications based on field performance. Some potential future 

analyses include the following: 

• Understanding the effects of the joint score and dowel misalignment on LTE. 

• Reviewing, validating, and improving current joint score methodology. 

• Conducting project-level analyses comparing the joint score/dowel misalignment of 

transverse joints adjacent to slabs exhibiting cracking/spalling and slabs not exhibiting 

cracking/spalling. 

• Using local calibration factors for each State in AASHTOWare Pavement ME Design to 

better determine the use of the average equivalent dowel diameter as a measure of dowel 

misalignment.

• Surveying SMP sites to understand any potential correlation between the joint 

score/dowel misalignment and joint opening. 

• Enhancing the equivalent dowel diameter and AASHTOWare Pavement ME Design LTE 

models.
105 

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