Safety Edge SM

Demonstration Project 

Brogden Road in 

Johnston County, 

North Carolina 

Field Report 

June 1, 2011 
FOREWORD 

The purpose of this field report is to provide a summary of observations made during the 

warm mix asphalt (WMA) Safety EdgeSM project on Brogden Road (State Route 1007) in 

Johnston County, North Carolina. These observations and data are to be used with similar 

information from other Safety EdgeSM projects to facilitate the development of standards and 

guidance for Safety EdgeSM construction and long-term performance. 

This report is a summary of the observations made on April 6, 2011, and measurements taken 

during construction to evaluate the use of two edge devices, the Troxler SafeTSlope Edge 

Smoother and a device developed by the North Carolina Department of Transportation 

(NCDOT). Observations and data were collected to compare Safety EdgeSM and non-Safety 

EdgeSM portions along the project, evaluate the slope and density of the edges, recommend 

design adjustments, and identify benefits and complications with the use of the edge devices. 
ii 

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

3. Title and Subtitle 

Safety EdgeSM Demonstration Project, 

Brogden Road in Johnston County, North Carolina 

5. Report Date 

 June 1, 2011 

6. Performing Organization Code 

7. Authors 

Paul Littleton and Jagannath Mallela 

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. 

12. Sponsoring Agency Name and Address 

 Office of Infrastructure 

 Federal Highway Administration 

 1200 New Jersey Avenue, SE 

 Washington, DC 20590 

15. Supplementary Notes 

 Contracting Officer’s Technical Representative: Byron Lord and Mary Huie

Contracting Officer’s Technical Manager: Andy Mergenmeier

13. Type of Report and Period Covered 

 Field Report 

 April – June 2011

14. Sponsoring Agency Code 

16. Abstract 

In a coordinated effort with highway authorities and industry leaders, the Every Day Counts initiative serves as a catalyst to 

identify and promote cost effective innovations to bring about rapid change to increase safety of our nations highway 

system, decrease project delivery time, and protect our environment. The Safety EdgeSM concept is an example of one such 

initiative in which the edge of the road is beveled during construction for the purpose of helping drivers who migrate off the 

roadways to more easily return to the road without over correcting and running into the path of oncoming traffic or running 

off the other side of the roadway. 

This field report documents the observations made on the construction of Safety EdgeSM on a two lane highway warm mix 

asphalt (WMA) overlay project on Brogden Road in Johnston County, North Carolina. The Troxler SafeTSlope Edge 

Smoother and a device developed by NCDOT were demonstrated during this project. Details regarding the performance of 

the device along with the shape and physical properties of the finished Safety EdgeSM are presented for the purpose of 

understanding what processes and techniques were most successful in forming the Safety EdgeSM. 

The findings from this overlay project and other similar ongoing projects form the basis for understanding the construction 

process and material performance necessary to bring this innovation into common highway practice and make our Nation’s 

highways safer. 

17. Key Words 

Safety EdgeSM, Slope, HMA, Troxler SafeTSlope

Edge Smoother, TransTech Shoulder Wedge Maker, 

Advant-Edger 

18. Distribution Statement 

No restriction. 

19. Security Classif.(of this report) 

Unclassified 

20. Security Classif. (of this page) 

Unclassified 

21. No. of Pages 

26 

22. Price 

Form DOT F 1700.7 (8-72)
SI* (MODERN METRIC) CONVERSION FACTORS

APPROXIMATE CONVERSIONS TO SI UNITS

Symbol When You Know Multiply By To Find Symbol

LENGTH

(none)

in

mil

inches

25.4 micrometers

25.4 millimeters

μm

mm

ft feet 0.305 meters m

yd

mi

yards

miles

0.914 meters

1.61 kilometers

m

km

in2

ft2

yd2

ac

mi2

square inches

square feet

square yards

acres

square miles

AREA

645.2 square millimeters

0.093 square meters

0.836 square meters

0.405 hectares

2.59 square kilometers

2 mm2 m2 m

ha

km2

VOLUME

fl oz fluid ounces 29.57 millimeters mL

gal

ft3

yd3

gallons

cubic feet

cubic yards

3.785 liters

0.028 cubic meters

0.765 cubic meters 3 NOTE: volumes greater than 1000 L shall be shown in m

L

3 m3 m

MASS

oz

lb

ounces

pounds

28.35 grams

0.454 kilograms

g

kg

T short tons (2000 lb) 0.907 megagrams (or "metric ton") Mg (or "t")

TEMPERATURE (exact degrees)

°F Fahrenheit 5 (F-32)/9 Celsius

or (F-32)/1.8

°C

ILLUMINATION

fc

fl

foot-candles

foot-Lamberts

10.76 lux

3.426 candela per square meter

lx 2 cd/m

FORCE and PRESSURE or STRESS

lbf

lbf/in2 (psi)

k/in2 (ksi)

poundforce

poundforce per square 

kips per square inch

inch

4.45 Newtons

6.89 kiloPascals

6.89 megaPascals

N

kPa

MPa

3 lb/ft (pcf) pounds per cubic foot

DENSITY

16.02 kilograms per cubic meter 3 kg/m

APPROXIMATE CONVERSIONS FROM SI UNITS

Symbol When You Know Multiply By To Find Symbol

LENGTH

μm

mm

micrometers

millimeters

0.039

0.039

mil

inches

(none)

in

m meters 3.28 feet ft

m

km

meters

kilometers

1.09

0.621

yards

miles

yd

mi

2 mm2 m2 m

ha

km2

square millimeters

square meters

square meters

hectares

square kilometers

AREA

0.0016

10.764

1.195

2.47

0.386

square inches

square feet

square yards

acres

square miles

in2

ft2

yd2

ac

mi2

VOLUME

mL milliliters 0.034 fluid ounces fl oz

L

3 m

3 m

liters

cubic meters

cubic meters

0.264

35.314

1.307

gallons

cubic feet

cubic yards

gal

ft3

yd3

MASS

g

kg

Mg (or "t")

grams

kilograms

megagrams (or "metric ton")

0.035

2.202

1.103

ounces

pounds

short tons (2000 lb)

oz

lb

T

TEMPERATURE

°C Celsius 1.8C+32 Fahrenheit °F

ILLUMINATION

lx 2 cd/mlux

candela per square meter

0.0929

0.2919

foot-candles

foot-Lamberts

fc

fl

FORCE and PRESSURE or STRESS

N

kPA

MPa

Newtons

kiloPascals

megaPascals

0.225

0.145

0.145

poundforce

poundforce per square 

kips per square inch

inch

lbf

lbf/in2 (psi)

k/in2 (ksi)

*SI is 

2003) 

the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. (Revised March 

iii
Table of Contents 

iv

Topic Page 

FOREWORD................................................................................................................................. 1

SUMMARY OF OBSERVATIONS ............................................................................................ 1

Overall Opinion of the Safety EdgeSM ..................................................................................... 1

Slope of the Safety EdgeSM ...................................................................................................... 1

Edge Preparation .................................................................................................................... 1

Construction/Compaction ....................................................................................................... 1

WMA Mixture .......................................................................................................................... 2

Future Considerations or Material Enhancements to Improve Performance ........................ 2

FIELD EVALUATION OF WMA OVERLAY WITH SAFETY EDGESM ........................... 3

INTRODUCTION ............................................................................................................................... 3

PAVEMENT STRUCTURE AND PROJECT CONDITIONS .................................................................... 4

FIELD EVALUATION........................................................................................................................ 4

Slope Measurements ............................................................................................................... 5

Cores ....................................................................................................................................... 5

Nuclear Density Test Results .................................................................................................. 6

OBSERVATIONS MADE DURING PAVING WITH THE SAFETY EDGESM .......................................... 9

Preparatory Work ................................................................................................................... 9

Placement/Paving Operations .............................................................................................. 12

Troxler SafeTSlope Edge Smoother ...................................................................................... 12

NCDOT Device ..................................................................................................................... 15

Compaction Operations........................................................................................................ 25

Shoulder Backing .................................................................................................................. 25

FINDINGS AND CONCLUSIONS ...................................................................................................... 25

APPENDIX A. DATA TABLES FROM FIELD MEASUREMENTS ............................... A-1
1

SUMMARY OF OBSERVATIONS 

This section of the report provides a summary of important observations made during the 

paving operations, interviews with paving personnel, and findings from the field 

measurements taken during paving that are expected to have a significant impact on the 

performance of the Safety EdgeSM. 

Overall Opinion of the Safety EdgeSM

 Both devices were used successfully on this project. One key finding was that the 

devices increased density and lowered air void content adjacent to the edge. 

Slope of the Safety EdgeSM

 The average slope of the edge produced by the Troxler device was 28°, and the 

average slope of the NCDOT device was 26°, both slightly less than the targeted 30° 

slope. 

 The slope from both devices increased 1° or less during compaction operations, 

indicating the WMA was stable. 

Edge Preparation 

 For this project it is key that the contractor's standard operating practice includes 

preparing the edge of the existing pavement. Soil and vegetation must be removed to 

expose the existing pavement and provide a firm base on which to support the edge of 

pavement. The edge of pavement separated from the mat at an isolated location 

where the edge of pavement was placed over soft soil/vegetation. This would have 

occurred regardless of the use of the Safety EdgeSM; nevertheless, this underscores the 

importance of preparing the edge of the pavement. 

Construction/Compaction 

 The contractor used two breakdown rollers in echelon operating close behind the 

paver. One roller was positioned on the longitudinal joint and the other was 

dedicated to rolling the edge (overhanging the edge in most passes). Each pass of the 

rollers generally was in the same position on the mat, such that the edge received the 

maximum compactive effort. This was the contractor’s preferred method of 

compacting WMA. 

 The densities were higher and the air voids were lower adjacent to the edge in the test 

sections with the Safety EdgeSM compared to the control section. This is an added 

benefit of using the edge device and may increase the long-term performance of the 

edge. 

 The contractor stated that the edge of pavement when using the Safety EdgeSM was 

not damaged when asphalt trucks drove off the edge of the pavement. Without the 
2

Safety EdgeSM the edge would be damaged and the contractor was required to repair 

the edge. This is an added benefit of using the Safety EdgeSM during construction. 

WMA Mixture

 The slope face produced by both devices appeared to be smooth and consistent 

throughout the project. 

 Only minor segregation was observed in the mat. Overall, the surface of the WMA 

appeared uniform. 

 Lateral movement under the roller and at the edge was insignificant. 

Future Considerations or Material Enhancements to Improve Performance 

 The service life of the devices could be extended by using a more wear-resistant steel 

where the shoe contacts the road. The point of the shoe was worn significantly after 

only a few miles of service. 

 The vertical adjustment screw is easily bent during normal use and should be made of 

stronger material and/or improved design. 

 The cotter pin that secures the top of the spring to the screw falls out easily and could 

be redesigned. 

This project presents the opportunity to evaluate long-term performance in terms of 

maintenance efforts and life cycle cost of the Safety EdgeSM placed by different types of 

devices. 
3

FIELD EVALUATION OF WMA OVERLAY WITH SAFETY EDGESM

Introduction 

A series of field tests were carried out to assess the placement and condition of the WMA

overlay along Brogden Road with and without the use of the Safety EdgeSM device. The 

purpose of these tests was to evaluate the quality of the in-place WMA material and Safety 

EdgeSM by investigating the following: 

 Correct use of the Safety EdgeSM devices during paving. 

 Safety EdgeSM versus non-Safety EdgeSM portions of project. 

 Slope of the Safety EdgeSM. 

This project was located in Johnston County between Smithfield and Goldsboro on Brogden 

Road from the border with Wayne County and extending west approximately 2 miles. The 

contract included eight routes, five of which were paved prior to paving Brogden Road. The

contractor used NCDOT's first prototype edge device on the previous routes, and the lessons 

learned are discussed later in the Placement/Paving Operations section. 

The general project location is shown in Figure 1. The maximum posted speed limit was 55 

mph. The contractor was Johnson Brothers Utility and Paving, Inc. 

Figure 1. Project location. 

Project Location 
4

Pavement Structure and Project Conditions 

The existing pavement was two lanes of HMA with a chip seal wearing surface. The typical 

lane width was 10.5 feet with 4- to 8-inch-wide unpaved shoulders consisting of fine-grained 

soil and vegetation. The distresses along the road were varying degrees of longitudinal and 

transverse cracking. 

New construction called for a 1.5-inch WMA overlay placed to match the width of the 

existing pavement. The edge of the overlay was to be placed directly over the existing 

pavement edge. The WMA was designed with 23 percent reclaimed asphalt pavement (RAP) 

and WMA water foam technology. 

This demonstration project included several long tangent sections, suitable for demonstrating 

the Safety EdgeSM, which was built in both directions. The target slope was 30°, and the 

contract specification was as follows: 

Attach a device, mounted on screed of paving equipment, capable of 

constructing a shoulder wedge with an angle of not more than 30 degrees 

along the outside edge of the roadway, measured from the horizontal plane in 

place after final compaction on the final surface course. Use an approved 

mechanical device or a device provided by the Department that will form the 

asphalt mixture to produce a wedge with uniform texture, shape and density 

while automatically adjusting to varying heights. Payment for use of this 

device will be incidental to the other pay items in the contract. 

Currently, NCDOT does not have a longitudinal joint density specification. 

Field Evaluation 

Two Safety EdgeSM test sections and one non-Safety EdgeSM control section were established 

in the westbound lane. The following summarizes the pavement sections: 

 Test Section #1. This section had the edge formed with the Troxler SafeTSlope Edge 

Smoother and was 1,000 feet long, generally located west of the Wayne County 

border and beginning at 45 feet east of the private residence, 12398 SR 1007. 

 Test Section #2. This section had the edge formed with the device developed by 

NCDOT and was 1,000 feet long, beginning at the entrance to the commercial 

property of Owen Kornegay Hog Farm, 11819 SR 1007. 

 Test Section #3. This section was paved with a conventional edge and was 400 feet 

long, located near the intersection with Buckleberry Road. This section serves as the 

control section for comparing the test sections to conventional paving practice. 
5

Slope Measurements 

Slope measurements were recorded on test sections #1 and #2 at 25-foot intervals using a 

straight-edge and ruler to measure the horizontal and vertical dimensions of the edge (see 

Figure 2). The following summarizes the average slope measurements: 

Pavement Section Slope 

Test Section #1, Troxler Device 28°

Test Section #2, NCDOT Device 26°

Section #3, Control NA

Figure 2. Slope measurement technique. 

Table A-1 in Appendix A contains slope measurements recorded at each individual 

measurement location. Accurate edge thickness measurements were not possible due the 

new overlay extending over the edge of the existing pavement, thereby exaggerating and 

confounding the edge thickness measurements. 

Cores 

Several pairs of cores were cut from each test section. Each pair of cores had a core taken 3-

feet from the edge of the mat (where the maximum number of roller passes were made) and a 

corresponding core taken adjacent to the edge (where fewer roller passes were made). Table 

A-2 in Appendix A lists the stations from where these cores were taken and the respective 

core thicknesses measured. The laboratory-determined densities from these cores serve to 

calibrate the nuclear density measurements. Laboratory density was determined from the 

bulk specific gravity at saturated surface dry test condition. Tables A-3 in Appendix A 

includes a summary of the laboratory density test results. Figure 3 compares the laboratory 

Vertical 

Dimension

Horizontal 

Dimension
6

core density readings for the test sections. As expected, the densities 3 feet from the edge 

were higher than those along the edge of the mat. 

Figure 3. Comparison of core densities adjacent to the edge and 3 feet from the edge. 

Nuclear Density Test Results 

Density tests were conducted using a nuclear density gauge in backscatter mode for 60-

second test durations. The tests were conducted at 50-foot intervals at 3-feet from the edge 

and adjacent to the edge. Table A-3 in Appendix A presents the results of the nuclear density 

testing along with the laboratory density results from these locations. Figure 4 compares the 

nuclear density readings to the densities measured on the cores. As shown, there is close 

correlation between the nuclear gage and core densities. 

150.0

4 0

 pcf

1 5.

e,Edg 

140.0 mfro ft 3 

135.0

tyiensDre 

130.0 oC

125.0

125.0 130.0 135.0 140.0 145.0 150.0

Core Density Adjacent to Edge, pcf
7

Figure 4. Comparison of the nuclear densities and core densities. 

Adjustment factors were determined from correlating the nuclear density readings and the 

core laboratory density results shown in Table A-3 in Appendix A. The factors were close to 

unity and were used to adjust the nuclear density gauge readings to be consistent with the 

densities that were measured in the laboratory. The adjusted or corrected densities using the 

correction factors are listed in Table A-4 in Appendix A and are summarized as follows: 

Location Adjustment Factor 

Adjacent to the edge 0.996

3 feet from the edge 1.009

The control section had a lower average density value (132.2 pcf) adjacent to the edge 

compared to section #1 (134.9 pcf) or section #2 (134.8 pcf), suggesting the confining effect 

of the edge devices helped to increase densification near the edge. The rolling pattern was 

the same for all three sections and is discussed later in this report. 

Figure 5 compares the nuclear densities taken adjacent to the edge and 3 feet from the edge. 

Generally, the densities were higher 3 feet from the edge in all sections. 

150.0

fcg, pin

145.0 adRe 

140.0

yitsnDe

135.0

age G

130.0 arlecNu

125.0

125.0 130.0 135.0 140.0 145.0 150.0

Core Density, pcf 

Adjacent to Edge 3-ft from Edge
8

Figure 5. Comparison of the nuclear densities adjacent to the edge 

and 3 feet from the edge. 

Figure 6 compares the air voids (as calculated from the density test results and the maximum 

theoretical mix density). As shown, the percentages of air voids in the mix usually were 

higher adjacent to the edge. 

Figure 6. Comparison of the air voids adjacent to the edge and 3 feet from the edge. 

Average air voids are summarized in Table 1. This table shows higher air voids in the 

control section near the edge, underscoring the favorable impact of edge devices on 

150

fcp ,egEd

145 mofr 

140

ft 3 tyisn

135

eD egaG

130 raelcuN

125

125 130 135 140 145 150

Nuclear Gage Density Adjacent to Edge, pcf

Troxler Device NCDOT Device Control

16

14

egEd

12 mo

10 frft 3 

8 sdio

6 V riAt 

4 necre

2 P

0

0 2 4 6 8 10 12 14 16

Percent Air Voids Adjacent to Edge

Troxler Device NCDOT Device Control
9

increasing the quality of the mat near the edge. It is theorized that the confining pressure the 

edge devices exert on the edge adds to the compaction at the edge. 

Table 1. Average air voids. 

Section Identification 

Air Voids Adjacent 

to the Edge 

Air Voids 

3 feet from the Edge 

Mean, % COV Mean, % COV

Test Section #1, Troxler Device 10.5 13.8 7.2 19.2 

Test Section #2, NCDOT Device 10.6 15.6 6.8 28.7 

Section #3, Control 12.3 13.5 7.9 14.1 

Observations Made During Paving with the Safety EdgeSM

This section provides an overview of the observations made during the paving and rolling 

operations. 

Preparatory Work 

Milling and significant patching were not preformed on Brogden Road. The existing 

pavement was cleaned with a power broom, and the edge was bladed with a motor grader to 

clip areas of soil and vegetation buildup. Clipping the edge with a motor grader or similar 

equipment is important for three reasons: 

 It creates room at the edge so the Safety EdgeSM devices can shape the proper angle 

of edge. 

 It creates a firm support for the pavement edge by exposing the existing pavement. 

 It reduces the chance the Safety EdgeSM device from plowing and mixing 

soil/vegetation into the fresh asphalt. 

For this project it is key that the contractor's standard operating practice includes preparing 

the edge of the existing pavement. If soil/vegetation adjacent to the pavement is encroaching

onto the pavement and/or is higher than the pavement, it is necessary to remove this material 

to expose the existing pavement edge. This condition often results in poor drainage of the 

existing surface. Figure 7 shows the exposed pavement after clipping the edge buildup. 
10

Figure 7. Exposed pavement after edge preparation. 

Paving over vegetation results in poor consolidation, and the asphalt material is not expected 

to perform as well as it would when paved on the existing pavement and soil/aggregate 

shoulder material. Essentially, the result will be as if no Safety EdgeSM were placed. The 

Safety EdgeSM requires a few more inches of clipping width compared to traditional paving 

without a Safety EdgeSM. The extra width shown in Figure 8 accommodates not only the 

Safety EdgeSM but the end gate of the paver as well. 

Figure 8. Extra width created by preparing the existing pavement edge/shoulder. 

Exposed edge of the 

existing pavement.

Soil and vegetation 

pushed back by the 

motor grader.

Existing pavement 

covered with tack coat

Extra width provides room for 

the Safety EdgeSM and end gate 

during paving.
11

The contractor clipped the shoulder which is standard practice for this scope of project. The 

conventional shoulder clipping operation was used, which did not take into account the extra 

width needed for the Safety EdgeSM. Figure 8 shows there was enough room at this 

particular location, but that was not always the case. At some isolated locations the shoulder 

was not clipped wide enough. Although equipment was used to prepare the shoulders, labor 

was needed occasionally to rake or shovel clumps of soil from the shoulder ahead of the 

paver. Figure 9 shows an isolated instance in which the Troxler SafeTSlope Edge Smoother 

was running on soft soil, resulting in the device plowing soil into the Safety EdgeSM. 

Figure 9. Example of the Safety EdgeSM device plowing up soil into the Safety EdgeSM. 

At some locations the clipping removed a large amount of buildup from the edge of the road. 

Figure 10 shows mounds of soil/vegetation piled up from the edge preparation. 

Figure 10. Soil/vegetation piled up from edge preparation work. 

Soil from the shoulder 

plowed into the edge.
12

 

Given the extent of shoulder clipping and preparations needed for the Safety EdgeSM, it is 

expected that more asphalt material would be placed than with conventional overlays. 

However, this will depend heavily on the existing site conditions. On this project, a reliable 

account of the extra tonnage of WMA was not available, and the contractor stated that all 

projects overrun the estimated amount of material regardless of a conventional edge or Safety 

EdgeSM. 

Placement/Paving Operations 

Overall, the WMA surface texture was uniform, with isolated areas of minor segregation. 

The WMA was significantly more stable during compaction than conventional hot mix 

asphalt (HMA). Little or no lateral movement was observed. The contractor also indicated 

that, based on his experience, the WMA moved significantly less during compaction than 

HMA. 

The WMA mat was placed 1.75 inches thick as it left the screed and compacted to 1.5 inches. 

The mix temperature in the truck at the job site varied from 260 to 275°F. Haul time from 

the plant was approximately 1 hour and 15 minutes. The contractor used a rubber tire 

Caterpillar AP-1000B paver with the material feed auger kept within 18 inches of the end 

gate. On the day of paving the weather in the morning was sunny, 40°F and rising. Paving 

the day before was postponed due to heavy rain. 

The contractor noted the edge of pavement where the Safety EdgeSM was used did not break 

off under traffic from the asphalt trucks, whereas a conventional edge would be damaged, 

necessitating repair. 

Paving operations began with the Troxler device installed on the paver. Later in the day the 

Troxler device was replaced with the NCDOT device. Both devices were supplied to the 

contractor through NCDOT. The following discussion addresses the experience with each 

device. 

Troxler SafeTSlope Edge Smoother 

The contractor had no problems operating the Troxler device. The device was raised and 

lowered quickly with an electric drill attached to the top of the vertical screw shown in 

Figure 12. Two bolts welded to the face of the screed box held the device in place. As 

shown in Figure 12, the shoe was free to swing horizontally. Under normal operation the 

lateral pressure of the asphalt mix holds the shoe against the end gate; however, asphalt can 

build up between the two surfaces, pushing the shoe to the inside and causing problems, such 

as increased edge slope angle. 
13

Figure 11. Troxler SafeTSlope Edge Smoother. 

Figure 12. Troxler SafeTSlope Edge Smoother. 

Electric 

drill used 

to adjust 

the 

vertical 

height of 

the device. 

Electric 

drill 

attaches to 

the device 

here.

Device is 

free to swing 

horizontally. 
14

The slope of the edge produced by the Troxler device appeared to be stable during 

compaction. The following measurements were taken at a single location to document the 

minor slope increase during passes of the breakdown roller closest to the edge: 

Roller Pass Slope 

st 1 pass, 3 inches over the edge with vibration 31°

nd 2 pass, 4 inches over the edge with vibration 31° 

rd 3 pass, 6 inches away from the edge with 

vibration 32° 

The texture of the slope face produced by the Troxler device was smooth and uniform. 

Figure 13 shows the uniform constancy of the slope face. 

Figure 13. Slope face produced by the Troxler device. 

At a few isolated locations, longitudinal cracks quickly developed near the breakpoint of the 

slope face after the breakdown roller finished making passes (Figure 14). The asphalt mix 

was removed with hand tools to reveal that the reason for the cracking was the pavement 

edge was placed over soil/vegetation and not on top of the existing pavement. This resulted 

in paving on top of differential structural support which resulted in the longitudinal crack. 

The longitudinal crack would happen regardless of the presence of the Safety EdgeSM. 
15

Figure 14. Isolated longitudinal edge cracking (left) and investigation revealed 

soil/vegetation under the pavement edge (right). 

NCDOT Device 

NCDOT purchased two TransTech Shoulder Wedge Makers in 2006. During the first two 

installations (about 2008 to 2009), NCDOT noticed the final angles approached 45°. Upon 

investigation of site implementation photos, NCDOT noticed that the shoe was rotating 

(moving horizontally) from asphalt getting between the end gate and the shoe. Figure 15 

shows the shoe rotated toward the paver. 

NCDOT decided to make a back plate similar to the Advant-Edger back plate. For the 

current routes that would receive the Safety EdgeSM (first route paved on March 18, 2011), 

the first change made to the TransTech device was to make a different back plate. NCDOT's 

first prototype combined the TransTech device with a custom backplate 16 inches long with 

2-inch sides for the guide plates on the side with one set of placement slots to attach to the 

paver. Instead of drilling holes and bolting the device to the screed box, the contractor tack 

welded two bolt ends to the screed box to attach the device. Figure 16 shows NCDOT's first 

prototype. Within the first 0.75 mile of use, the contractor snagged a driveway with the 

device, tore the back plate edge guides, and severely bent the screw. 
16

Figure 15. Shoe rotation. 

Figure 16. NCDOT's first prototype. 

First back plate 

was 16 inches 

long with 2-inch 

sides for guiding 

the shoe. 

Bolts tack welded to the 

back gate of the screed 

box. 

Asphalt between the 

shoe and end gate 

rotates the shoe 

toward the paver 

resulting in an 

increase in slope. 

angle
17

The next modification was to cut a radius into the leading edge of the shoe guide so it would 

no longer snag on driveways (this also reduced/eliminated the plowing of soil into the asphalt 

Safety EdgeSM). The screw and back plate edge guides were repaired, the cotter pin was 

replaced, and a new screw nut was welded into place. Figure 17 shows the modifications 

made to NCDOT's first prototype. The contractor finished the first four routes with the 

modified prototype. 
18

 

The shoe 

shoulder guide 

was given a 

radius to 

prevent the 

shoe from 

catching on 

driveways and 

plowing up soil 

into the asphalt. 

Figure 17. Images of the NCDOT's first prototype after modification. 

Screw 

was bent 

and 

unusable. 

Shoe 

edge 

guide 

was rewelded 

The size of the 

nuts and 

washers were 

increased. 

Cotter pin was 

replaced. 

Washer size increased. 
19

During the paving of the second, third, and fourth routes, the contractor had problems raising 

the device at driveways due to asphalt collecting above the shoe and interfering with the 

screw/spring. In fact, on the fourth route, the contractor had to remove the device seven 

times due to the multiple driveways and being unable to raise the device (on a 0.64-mile

section of road). This process included stopping the paver, digging out the device, removing 

the device, paving across the driveway, stopping the paver, digging out the asphalt for the 

device to be placed back against the screed box and end gate, and finally reattaching the 

device. This process took 5 to 10 minutes each time (which the contractor estimated as 

equivalent to not placing one truckload of asphalt). 

Figure 18. Asphalt buildup above the shoe. 

NCDOT developed a second prototype based on the experience gained with the first 

prototype. The second prototype back plate was built with 18-inch-long sides; the side 

closest to the end gate was built with 2-inch-deep guide plates, and the side closest to the 

material feed auger was built with 3-inch-deep guide plates. An 8-inch protection plate was 

bolted to the top of the shoe to prevent asphalt from reaching the screw and spring. Multiple 

mounting slots were cut into the back plate to accommodate different types of pavers. 

Figures 19, 20, and 21 show the details of the second prototype. 

Asphalt buildup 

above shoe and 

interfering with 

the spring. 
20

Figure 19. NCDOT's second prototype showing the protection plate and revised back plate 

and shoe guide. 

Second back plate 

was 18 inches 

long with 3-inch 

side for guiding 

the shoe.

8-inch asphalt 

protection 

plate bolted to 

forming box. 
21

Figure 20. NCDOT's second prototype showing a thicker back plate, larger holding collar 

and multiple mounting slots. 

Thicker 

steel back 

plate and 

larger 

holding 

collar, 

third 

cotter pin 

in use. 

Revised back 

plate has 

multiple 

mounting 

slots to 

accommodate 

different 

pavers. 
22

Figure 21. NCDOT second prototype in service showing the protection plate keeping asphalt 

from collecting on top of the shoe. 

The second prototype was used successfully on the fifth route under the contract prior to 

Brogden Road. The contractor used an electric drill with a 15/16 inch bit to raise and lower 

the device at driveways in a matter of seconds. Figure 22 shows an example of the short 

transition length created by the ability to raise the shoe quickly for an approaching driveway. 

The shoe did not have to be removed; however, the cotter pin holding the shoe up had a 

tendency to come loose as the device was being raised and lowered. 

Electric drill with 

socket attachment 

used to raise and 

lower the device. 

Protection plate 

prevents 

asphalt from 

collecting on 

top of the shoe 

and interfering 

with the spring. 

quickly
23

Quick transition at 

a driveway. 

Figure 22. Transition at a driveway. 

Fortunately, the contractor and NCDOT's machine shop were able to make changes to the 

device on short notice (sometimes hours and minutes). This method of trial and error has led 

to an efficient, reliable device that NCDOT feels confident using. After 4.75 miles of using 

the second prototype, NCDOT noted other issues that could be addressed: 

 The cotter pin has been replaced three times. The pin could be made of stronger 

material and/or redesigned to keep it better attached to the device. 

 The screw is susceptible to bending and had to be replaced on earlier prototypes. 

Hopefully, the longer side guide plates and the asphalt protection plate address this 

issue, but could the screw be made stronger? 

 The device already is showing a great amount of wear as shown in Figure 23 (as did 

the other device used on the first two roads several years ago). Could the leading 

edge of the shoe be made of stronger steel? 

 What is the expected service life for a device? 
24

Wear on the bottom 

of the shoe is 

significant after 4.75 

miles of use. 

Figure 23. Wear on the bottom of the shoe. 

NCDOT's measurements of the slope angles for the first five routes were: 

Route Slope 

#1 HMA 27°

#2 HMA 27°

#3 WMA 26°

#4 WMA 29°

#5 WMA 30°

About halfway through the paving day, the Troxler device was replaced with NCDOT's 

device (second prototype). The contractor noted the side plates performed as intended and 

prevented the shoe from rotating. The asphalt protection plate also worked as intended, 

keeping asphalt away from the spring. 

The following measurements were taken at a single location to document the lack of slope 

movement during passes of the breakdown roller closest to the Safety EdgeSM: 

Roller Pass Slope 

slope measured directly behind the paver 29° 

st 1 pass, 3 inches over the edge with vibration 29°

nd 2 pass, 3 inches over the edge with vibration 29°

rd 3 pass, 2 inches over the edge with vibration 29°

The slope of the edge produced by the NCDOT device remained the same during 

compaction. The texture of the slope face was fairly smooth and uniform. 
25

Compaction Operations 

The paver was followed closely by two double steel drum breakdown rollers, Caterpillar CB 

564D and Hypac C778B, operating in echelon. The Caterpillar roller was in front of the 

Hypac roller and made passes along the outer edge of the lane, and the Hypac operated along 

the longitudinal joint at the pavement centerline. Both rollers were set for low amplitude 

with vibration at about 3700 RPM. The contractor noted that, normally, when placing HMA, 

only one breakdown roller would be used, in which case the higher mat temperatures allows 

enough time for a single roller to achieve compaction. The intermediate roller was a Rosco 

9-wheel Tru-Pac 915 pneumatic roller. The finish roller was a double steel drum Ingersoll 

Rand DD-158 operating in static mode. 

The two breakdown rollers operating together made three passes, without wandering across 

the lane, each roller covering one-half of the width of the lane with each pass. Generally, 

during each of the three passes (one forward, one back, and then forward again) the 

Caterpillar roller overhung the outer edge 2 to 4 inches and the Hypac rolled over the 

centerline joint 2 to 4 inches. In some instances, the Caterpillar roller would make two 

passes overhanging the outer edge and the final pass either on the edge or a few inches away 

from the edge. The pneumatic roller then made up to 15 passes wandering across the lane, 

with 4 to 5 passes about 18 to 24 inches from the outer edge. The finish roller made two 

passes, one at the centerline joint and one right on the outer edge. The operators were 

observed maintaining this pattern for both test sections. 

Shoulder Backing 

Topsoil was to be placed as the shoulder backing material. Placement of the backing 

material was not observed. 

Findings and Conclusions 

As previously stated, the objective of this field study is to evaluate the quality of the in-place 

WMA material and Safety EdgeSM by investigating three features: 

 Correct use of the Safety EdgeSM devices during paving. 

 Safety Edge versus non-Safety Edge portions of project. SM SM

 Slope of the Safety EdgeSM. 

The following findings and conclusions can be made based on the observations made during 

the paving/compaction operations: 

 Preparing the edge of the existing pavement for this project was important to create 

room and remove vegetation for the Safety EdgeSM. 

 The edge of pavement separated from the mat at an isolated location where the edge 

of pavement was placed over soft soil/vegetation. This would have occurred 
26

regardless of the use of the Safety EdgeSM; nevertheless, this underscores the 

importance of preparing the edge of the pavement. 

 The contractor was able to attach and operate both devices successfully. 

 The design of the Troxler device was relatively simple but was free to rotate laterally. 

In the event that asphalt gets between the shoe and the end gate, the slope of the edge 

could increase. 

 The contractor noted the Safety EdgeSM was not damaged under traffic from the 

asphalt trucks, whereas a conventional edge normally would be damaged and the 

contractor would then have to repair the edge. 

 Guides on the NCDOT device prevent lateral rotation of the shoe. Protective plates 

attached above the shoe also improve the design by preventing asphalt from 

collecting on top of the shoe and interfering with the screw and spring. 

 The screw bent a few times in normal operation. Improvements should include a 

stronger materials or better design of the screw mechanism. 

 A more wear-resistant steel may help to extend the life of the devices. 

 The densities were higher and the air voids were lower adjacent to the edge in the test 

sections with the Safety EdgeSM compared to the control section. The confining 

effect of the devices, which results in additional densification at the edge, is an added 

benefit of the Safety EdgeSM and may increase the long-term performance of the 

edge. 

 The contractor was able to attach and operate both devices successfully to produce an 

edge slope close to the targeted 30°. The angle of the slopes made by both devices 

increased only slightly (1°) or not at all during the rolling process even though the 

breakdown roller overhung the edge on each pass. Stability of the WMA kept the 

slope angle increase to a minimum. 

The Safety EdgeSM should be inspected after the shoulder material has been placed to the 

final pavement elevation. 

Monitoring of this site would be beneficial in evaluating the long-term performance of the 

Safety EdgeSM. 
A-1

APPENDIX A. DATA TABLES FROM FIELD MEASUREMENTS 

This section of the field report documents the field measurements recorded during the paving 

operations. Note that the stationing shown in the tables refer to the length of each section 

and not the project stationing. 

Table A-1. Slope measurements. 

Width of 

Taper, in

Thickness of 

Taper, in

Slope, deg

1 00+00 Troxler 5.5 2.75 27

1 00+25 Troxler 6 3 27

1 00+50 Troxler 5.25 2.75 28

1 00+75 Troxler 5.5 3 29

1 01+00 Troxler 5 2.75 29

1 01+25 Troxler 5 2.5 27

1 01+50 Troxler 5 2.5 27

1 01+75 Troxler 5.5 3 29

1 02+00 Troxler 5.5 2.75 27

1 02+25 Troxler 4.5 2.5 29

1 02+50 Troxler 4.75 2.75 30

1 02+75 Troxler 4.75 2.75 30

1 03+00 Troxler 5 3 31

1 03+25 Troxler 5 2.5 27

1 03+50 Troxler 5.5 2.5 24

1 03+75 Troxler 6 2.75 25

1 04+00 Troxler 5.25 3 30

1 04+25 Troxler 5.5 3.25 31

1 04+50 Troxler 5 2.75 29

1 04+75 Troxler 5.5 3 29

1 05+00 Troxler 5.5 2.75 27

1 05+25 Troxler 5.5 3 29

1 05+50 Troxler 5 2.75 29

1 05+75 Troxler 5 2.5 27

1 06+00 Troxler 5.25 2.5 25

1 06+25 Troxler 5 2.5 27

1 06+50 Troxler 5.5 2.5 24

1 06+75 Troxler 5 2.75 29

1 07+00 Troxler 5.5 2.5 24

1 07+25 Troxler 5.5 3 29

1 07+50 Troxler 5.5 2.75 27

1 07+75 Troxler 5 2.75 29

1 08+00 Troxler 5 2.5 27

1 08+25 Troxler 5 2.75 29

1 08+50 Troxler 5 2.75 29

1 08+75 Troxler 5 2.5 27

1 09+00 Troxler 5 2.5 27

1 09+25 Troxler 5 2.75 29

1 09+50 Troxler 5.5 3 29

1 09+75 Troxler 5.5 2.75 27

1 10+00 Troxler 5 2 22

5.2 2.7 28

0.3 0.2 1.9

6.2 8.5 7.0

Section Station Type of Device

Safety Edge

Mean Value

Standard Deviation

Coefficient of Variation, %
A-2

Table A-1. Slope measurements, continued. 

Width of 

Taper, in

Thickness of 

Taper, in

Slope, deg

2 00+00 NCDOT 2.625 1.375 28

2 00+25 NCDOT 2.75 1.5 29

2 00+50 NCDOT 2.625 1.375 28

2 00+75 NCDOT 4.5 2.5 29

2 01+00 NCDOT 3.25 2.25 35

2 01+25 NCDOT 4 2.5 32

2 01+50 NCDOT 3 1.5 27

2 01+75 NCDOT 4.75 2.5 28

2 02+00 NCDOT 3.5 1.5 23

2 02+25 NCDOT 5 2 22

2 02+50 NCDOT 4.25 2.25 28

2 02+75 NCDOT 5.75 2.875 27

2 03+00 NCDOT 5.5 2.75 27

2 03+25 NCDOT 3.5 1.5 23

2 03+50 NCDOT 4 1.75 24

2 03+75 NCDOT 3.75 1.75 25

2 04+00 NCDOT 3.5 1.25 20

2 04+25 NCDOT 4.75 2.5 28

2 04+50 NCDOT 5.25 2.75 28

2 04+75 NCDOT 4.625 2.25 26

2 05+00 NCDOT 3.875 2.25 30

2 05+25 NCDOT 3.5 2.25 33

2 05+50 NCDOT 4.25 2.25 28

2 05+75 NCDOT 5.125 2.375 25

2 06+00 NCDOT 3.625 1.5 22

2 06+25 NCDOT 4.875 2.125 24

2 06+50 NCDOT 3 1.5 27

2 06+75 NCDOT 3.5 1.625 25

2 07+00 NCDOT 4.875 2.25 25

2 07+25 NCDOT 4.875 2.375 26

2 07+50 NCDOT 4.25 2.25 28

2 07+75 NCDOT 4.875 2.375 26

2 08+00 NCDOT 5.25 2.625 27

2 08+25 NCDOT 5 2.625 28

2 08+50 NCDOT 5.75 2.25 21

2 08+75 NCDOT 6 2.5 23

2 09+00 NCDOT 5 2.125 23

2 09+25 NCDOT 4.25 2.5 30

2 09+50 NCDOT 4 1.75 24

2 09+75 NCDOT 4.375 2 25

2 10+00 NCDOT 4.75 2.25 25

4.3 2.1 26

0.9 0.4 3.1

20.7 21.2 11.9

Mean Value

Standard Deviation

Coefficient of Variation, %

Section Station Type of Device

Safety Edge
A-3

Table A-2. Core thickness measurements. 

Table A-3. Nuclear density adjustment ratios; core density/nuclear density. 

A – Adjacent

to Edge

B – 3 feet 

from Edge

1 WB 0+00 Troxer 1.88 2.00

1 WB 0+50 Troxler 1.88 1.75

1 WB 5+00 Troxler 1.75 1.38

1 WB 8+50 Troxler 1.50 1.50

2 WB 2+50 NCDOT 1.75 1.75

2 WB 5+00 NCDOT 1.50 2.00

2 WB 8+50 NCDOT 2.00 1.75

3 WB 0+50 Control 1.88 --

1.75 1.73

0.19 0.23

10.91 13.45

Core Thickness, in

Section Station Type of Section Lane 

Direction

Mean, in. 

Standard Deviation, in. 

Coefficient of Variation, % 

A – Adjacent

to Edge

B – 3 ft from 

Edge

A – Adjacen

to Edge

t B – 3 ft from

Edge

A – Adjacent 

to Edge

B – 3 ft from 

Edge

1 WB 0+00 Troxer 139.3 140.3 136.7 140.2 1.019 1.001

1 WB 0+50 Troxler 137.0 139.3 134.2 138.5 1.021 1.006

1 WB 5+00 Troxler 133.0 139.7 135.9 138.7 0.979 1.007

1 WB 8+50 Troxler 134.7 138.9 138.3 137.3 0.974 1.012

2 WB 2+50 NCDOT 134.3 141.1 134.3 140.1 1.000 1.007

2 WB 5+00 NCDOT 136.9 139.5 137.8 135.3 0.993 1.031

2 WB 8+50 NCDOT 134.2 138.7 135.8 138.4 0.988 1.002

3 WB 0+50 Control 133.2 -- 132.3 139.4 1.007 --

135.6 139.6 136.1 138.4 0.996 1.009

2.2 0.8 1.6 1.7 0.018 0.010

1.6 0.6 1.2 1.2 1.840 1.011

Mean Value, pcf 

Standard Deviation, pcf 

Coefficient of Variation, % 

Adjustment Ratio

Section

Lane 

Direction

Station

Density of Cores Nuclear Density Values

Type of Device
A-4

Table A-4. Nuclear gauge readings. 

Max. Density, 

pcf: 150.8

A= 0.996

B= 1.009

A – Adjacent to

Edge

B – 3 ft from 

Edge

A – Adjacent to 

Edge

B – 3 ft from 

Edge

A – Adjacent to 

Edge

B – 3 ft from 

Edge

1 WB 00+00 Troxler 136.7 140.2 136.2 141.5 1.875 9.7 6.1

1 WB 00+50 Troxler 134.2 138.5 133.7 139.8 1.875 11.3 7.3

1 WB 01+00 Troxler 135.8 138.9 135.3 140.2 10.3 7.0

1 WB 01+50 Troxler 137.2 139.9 136.7 141.2 9.3 6.3

1 WB 02+00 Troxler 132.2 139.9 131.7 141.2 12.6 6.3

1 WB 02+50 Troxler 135.9 137.7 135.4 139.0 10.2 7.8

1 WB 03+00 Troxler 132.4 137.3 131.9 138.6 12.5 8.1

1 WB 03+50 Troxler 134.3 140.7 133.8 142.0 11.2 5.8

1 WB 04+00 Troxler 133.2 139.6 132.7 140.9 12.0 6.5

1 WB 04+50 Troxler 132.7 140.9 132.2 142.2 12.3 5.7

1 WB 05+00 Troxler 135.9 138.7 135.4 140.0 1.75 10.2 7.1

1 WB 05+50 Troxler 138.8 138.3 138.3 139.6 8.3 7.4

1 WB 06+00 Troxler 133.3 134.6 132.8 135.9 11.9 9.9

1 WB 06+50 Troxler 134.3 141.4 133.8 142.7 11.2 5.3

1 WB 07+00 Troxler 136.7 138.9 136.2 140.2 9.7 7.0

1 WB 07+50 Troxler 136.5 139.1 136.0 140.4 9.8 6.9

1 WB 08+00 Troxler 137.1 133.6 136.6 134.9 9.4 10.5

1 WB 08+50 Troxler 138.3 137.3 137.8 138.6 1.5 8.6 8.1

1 WB 09+00 Troxler 137.0 138.4 136.5 139.7 9.5 7.3

1 WB 09+50 Troxler 132.3 140.8 131.8 142.1 12.6 5.7

1 WB 10+00 Troxler 139.1 135.3 138.6 136.6 8.1 9.4

135.4 138.6 134.9 139.9 1.8 10.5 7.2

2.2 2.1 2.2 2.1 0.2 1.5 1.4

1.6 1.5 1.6 1.5 10.1 13.8 19.2

Maximum Specific Gravity of Mix (Gmm): 2.416

Adjustment Ratios for Nuclear 

Gauge:

Station

Adjusted Nuclear Densities, pcf Air Voids, %

Core Thickness

Adjacent to 

Edge, in.

Type of Device

Nuclear Densities, pcf

Section

Lane 

Direction

Average Value, pcf

Standard Deviation, pcf

Coefficient of Variation, %
A-5

Table A-4. Nuclear gauge readings, continued. 

Table 4. Nuclear gauge readings, continued. 

135.3 139.2 134.8 140.5 1.8 10.7 6.8

2.5 2.9 2.5 2.9 0.3 1.6 2.0

1.9 2.1 1.9 2.1 14.3 15.1 28.7

Average Value, pcf

Standard Deviation, pcf

Coefficient of Variation, %

Section

Lane 

Direction

Station Type of Device

Core Thickness 

Adjacent to 

Edge, in.

Nuclear Densities, pcf Adjusted Nuclear Densities, pcf Air Voids, %

A – Adjacent to 

Edge

B – 3 ft from 

Edge

A – Adjacent to

Edge

B – 3 ft from 

Edge

A – Adjacent to 

Edge

B – 3 ft from 

Edge

2 WB 00+00 NCDOT 133.8 133.4 133.3 134.7 11.6 10.7

2 WB 00+50 NCDOT 137.1 138.5 136.6 139.8 9.4 7.3

2 WB 01+00 NCDOT 130.3 140.0 129.8 141.3 13.9 6.3

2 WB 01+50 NCDOT 133.0 138.5 132.5 139.8 12.1 7.3

2 WB 02+00 NCDOT 138.7 -- 138.2 -- -- --

2 WB 02+50 NCDOT 134.3 140.1 133.8 141.4 1.75 11.2 6.2

2 WB 03+00 NCDOT 133.6 140.4 133.1 141.7 11.7 6.0

2 WB 03+50 NCDOT 135.0 134.9 134.5 136.2 10.8 9.7

2 WB 04+00 NCDOT 128.9 134.5 128.4 135.8 14.8 9.9

2 WB 04+50 NCDOT 133.5 140.3 133.0 141.6 11.8 6.1

2 WB 05+00 NCDOT 137.8 135.3 137.3 136.6 1.5 8.9 9.4

2 WB 05+50 NCDOT 135.4 139.9 134.9 141.2 10.5 6.3

2 WB 06+00 NCDOT 136.7 142.6 136.2 143.9 9.7 4.5

2 WB 06+50 NCDOT 136.8 143.6 136.3 144.9 9.6 3.9

2 WB 07+00 NCDOT 136.0 142.9 135.5 144.2 10.1 4.3

2 WB 07+50 NCDOT 137.6 139.9 137.1 141.2 9.1 6.3

2 WB 08+00 NCDOT 135.8 137.5 135.3 138.8 10.3 7.9

2 WB 08+50 NCDOT 137.4 138.4 136.9 139.7 2 9.2 7.3

2 WB 09+00 NCDOT 135.1 140.8 134.6 142.1 10.7 5.7

2 WB 09+50 NCDOT 135.7 138.9 135.2 140.2 10.3 7.0

2 WB 10+00 NCDOT 138.3 143.2 137.8 144.5 8.6 4.1

A – Adjacent to 

Edge

B – 3 ft from 

Edge

A – Adjacent to

Edge

B – 3 ft from 

Edge

A – Adjacent to 

Edge

B – 3 ft from 

Edge

3 WB 00+00 Control 137.0 139.4 136.5 140.7 9.5 6.7

3 WB 00+50 Control 132.3 139.4 131.8 140.7 1.875 12.6 6.7

3 WB 01+00 Control 133.3 135.1 132.8 136.4 11.9 9.5

3 WB 01+50 Control 130.1 137.1 129.6 138.4 14.0 8.2

3 WB 02+00 Control 130.8 138.6 130.3 139.9 13.6 7.2

3 WB 02+50 Control 133.3 137.0 132.8 138.3 11.9 8.3

3 WB 03+00 Control 134.6 139.3 134.1 140.6 11.0 6.7

3 WB 03+50 Control 134.0 135.8 133.5 137.1 11.4 9.1

3 WB 04+00 Control 128.8 136.3 128.3 137.6 14.9 8.7

132.7 137.6 132.2 138.8 1.9 12.3 7.9

2.5 1.7 2.5 1.7 0.0 1.7 1.1

1.9 1.2 1.9 1.2 0.0 13.5 14.1

Section

Lane 

Direction

Station Type of Device

Nuclear Densities, pcf

Coefficient of Variation, %

Adjusted Nuclear Densities, pcf

Core Thickness 

Adjacent to 

Edge, in.

Air Voids, %

Average Value, pcf

Standard Deviation, pcf