Safety Edge SM

Demonstration Project

Little Divine Road in 

Johnston County, 

North Carolina 

Draft Field Report 

July 1, 2011 
Draft July 1, 2011 

FOREWORD 

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

mix asphalt (HMA) Safety EdgeSM project on Little Divine Road (State Route 1938). 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 7, 2011 and measurements taken 

during construction to evaluate the use of the device developed by Carlson Paving Products, 

Inc. Observations and data were collected to evaluate the slope and density of the Safety 

EdgeSM, recommend design adjustments, and identify benefits and complications with the use 

of the edge device. 
Draft July 1, 2011 

ii

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

3. Title and Subtitle 

Safety EdgeSM Demonstration Project, 

Little Divine Road in Johnston County, North Carolina 

5. Report Date 

 July 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

13. Type of Report and Period Covered 

 Field Report 

 April – June 2011

14. Sponsoring Agency Code 

15. Supplementary Notes 

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

 Contracting Officer’s Technical Manager: Andy Mergenmeier 

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 the Safety EdgeSM on a two lane highway hot mix

asphalt (HMA) overlay project on Little Divine Road in Johnston County, North Carolina. The Carlson end gate device wa

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. 

s

17. Key Words 

Safety EdgeSM, Slope, HMA, Carlson Paving 

Products, Inc. 

18. Distribution Statement 

No restriction. 

19. Security Classif.(of this report) 

Unclassified 

20. Security Classif. (of this page) 

Unclassified 

21. No. of Pages 

16 

22. Price 

Form DOT F 1700.7 (8-72)
iii

SI* (MODERN METRIC) CONVERSION FACTORS

APPROXIMATE CONVERSIONS TO SI UNITS

Symbol When You Know Multiply By To Find Symbol

(none)

in

ft

yd

mi

in2

ft2

yd2

ac

mi2

fl oz

gal

ft3

yd3

oz

lb

T

°F

fc

fl

lbf

lbf/in2 (psi)

k/in2 (ksi)

lb/ft3 (pcf)

mil

inches

feet

yards

miles

square inches

square feet

square yards

acres

square miles

fluid ounces

gallons

cubic feet

cubic yards

ounces

pounds

short tons (2000 lb)

Fahrenheit

foot-candles

foot-Lamberts

poundforce

poundforce per square 

kips per square inch

pounds per cubic foot

inch

LENGTH

25.4 micrometers

25.4 millimeters

0.305 meters

0.914 meters

1.61 kilometers

AREA

645.2 square millimeters

0.093 square meters

0.836 square meters

0.405 hectares

2.59 square kilometers

VOLUME

29.57 millimeters

3.785 liters

0.028 cubic meters

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

MASS

28.35 grams

0.454 kilograms

0.907 megagrams (or "metric ton")

TEMPERATURE (exact degrees)

5 (F-32)/9 Celsius

or (F-32)/1.8

ILLUMINATION

10.76 lux

3.426 candela per square meter

FORCE and PRESSURE or STRESS

4.45 Newtons

6.89 kiloPascals

6.89 megaPascals

DENSITY

16.02 kilograms per cubic meter

μm

mm

m

m

km

2 mm2 m2 m

ha

km2

mL

L

3 m3 m

g

kg

Mg (or 

°C

lx 2 cd/m

N

kPa

MPa

3 kg/m

"t")

APPROXIMATE CONVERSIONS FROM SI UNITS

Symbol When You Know Multiply By To Find Symbol

μm

mm

m

m

km

2 mm2 m2 m

ha

km2

mL

L

3 m

3 m

g

kg

Mg (or

°C

lx 2 cd/m

N

kPA

MPa

"t")

micrometers

millimeters

meters

meters

kilometers

square millimeters

square meters

square meters

hectares

square kilometers

milliliters

liters

cubic meters

cubic meters

grams

kilograms

megagrams (or "metric ton")

Celsius

lux

candela per square meter

Newtons

kiloPascals

megaPascals

FORCE 

LENGTH

0.039

0.039

3.28

1.09

0.621

AREA

0.0016

10.764

1.195

2.47

0.386

VOLUME

0.034

0.264

35.314

1.307

MASS

0.035

2.202

1.103

TEMPERATURE

1.8C+32

ILLUMINATION

0.0929

0.2919

and PRESSURE or 

0.225

0.145

0.145

mil

inches

feet

yards

miles

square inches

square feet

square yards

acres

square miles

fluid ounces

gallons

cubic feet

cubic yards

ounces

pounds

short tons (2000 lb)

Fahrenheit

foot-candles

foot-Lamberts

STRESS

poundforce

poundforce per square 

kips per square inch

inch

(none)

in

ft

yd

mi

in2

ft2

yd2

ac

mi2

fl oz

gal

ft3

yd3

oz

lb

T

°F

fc

fl

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 
iv

Table of Contents 

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

HMA Mixture .......................................................................................................................... 1

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

EVALUATION OF HMA OVERLAY WITH SAFETY EDGESM .......................................... 3

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

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

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

Slope Measurements ............................................................................................................... 4

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

Nuclear Density Test Calibration Using Core Density ......................................................... 6

Nuclear Density Test Results .................................................................................................. 7

OBSERVATIONS MADE DURING PAVING WITH THE SAFETY EDGESM ........................................ 10

Preparatory Work ................................................................................................................. 10

Placement/Paving Operations .............................................................................................. 11

Compaction Operations ........................................................................................................ 14

Shoulder Backing .................................................................................................................. 15

FINDINGS AND CONCLUSIONS ...................................................................................................... 15

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

 Overall, the Carlson device proved to be simple to operate and the contractor was 

able to produce a uniform and stable edge. The finished appearance of the Safety 

EdgeSM was nearly as smooth and sealed as the rest of the mat. 

Slope of the Safety EdgeSM

 The average slope of the edge was 29°. 

 The slope decreased by 1° whereas typically the angle tends to increase slightly. The 

minor change in slope indicates good slope stability. 

Edge preparation 

 The contractor broomed the pavement and used a small tractor to clip the shoulders as 

is the contractor's typical practice for conventional overlays on this type of road. 

However, soil/vegetation build up was higher than the edge of the road at a few 

isolated locations and more clipping was needed. It is important to clip the edge of 

the pavement and shoulder farther than conventional overlay projects to make room 

for the Safety EdgeSM. 

Construction/Compaction 

 The contractor had not used any Safety EdgeSM device prior to this project. The 

contractor noted that most of his pavers are equipped with 10-foot screeds which 

require the use of a cut off under the screed to reduce the paving width for narrow 

roads and he is unsure how to incorporate the edge device with the paver when using 

a cut off. 

 Statistical analysis suggest the density of the Safety EdgeSM test section is no different 

than the control test section either adjacent to the edge or 3 feet from the edge. 

HMA Mixture 

 The HMA mix behaved normally during paving operations, tearing or shoving was 

not observed. 

 Lateral movement of the mat was minor under the passes of the rollers. 
2

Future Considerations or Material Enhancements to Improve Performance 

 It is important to clip the shoulders far enough back so soil/vegetation does not 

become mixed with the edge of the asphalt during paving. Clipping should be 

extended farther into the existing shoulder than with conventional overlays to allow 

extra width for the Safety EdgeSM. 

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

maintenance efforts and life cycle cost of the Safety EdgeSM. 
3

EVALUATION OF HMA OVERLAY WITH SAFETY EDGESM

Introduction 

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

overlay along Little Divine Road with and without the inclusion of the Safety EdgeSM. The 

objective of this field study was to evaluate the quality of the in-place HMA material and 

Safety EdgeSM by investigating the following: 

 Correct use of the Safety EdgeSM device during paving. 

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

 Slope of the Safety EdgeSM. 

This project was located in Johnston County north of Smithfield on about 2 miles of Little 

Divine Road between State Route 96 and Buffalo Road. The contractor purchased the Safety 

EdgeSM end gate type device after observing it at the recent ConExpo. This end gate did not 

have a heating element.

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

mph. The contractor was S.T. Wooten Corporation. 

Figure 1. Project location. 

Project Location
4

Pavement Structure and Project Conditions 

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

lane width was 10 feet with 6- to 12-inch-wide unpaved shoulders consisting of fine-grained 

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

The scope of the contract was to maintain the original lane width therefore the edge of the 

new overlay was placed directly over the existing pavement edge. New construction called 

for a 1.5-inch HMA RS 9.5B mix designed with 15 percent recycled asphalt pavement (RAP) 

and 5 percent recycled shingles. 

This project included several long tangent sections, suitable for demonstrating the Safety 

EdgeSM in both lane directions. The Safety EdgeSM was not included in the contract but the 

contractor requested to build the Safety EdgeSM. 

Field Evaluation Tests 

One Safety EdgeSM test section and one non-Safety EdgeSM control section was established in 

the westbound lane. The following summarizes the pavement sections: 

 Test Section #1. This section had the Safety EdgeSM formed with the Carlson device 

and was 1,000-feet long beginning at the drive to the private residence address 1320 

Little Divine Rd. 

 Test Section #2. This section was paved with a conventional edge and was 200-feet 

long located about midway along the project limits and serves as the control section 

for comparing the test sections to conventional paving practice. 

Slope Measurements 

Slope measurements were recorded at 25-feet intervals using a straight-edge and ruler to 

measure the horizontal and vertical dimensions of the edge (see Figure 2). The Carlson 

device was set at a 25°angle and produced an average slope of 29° after compaction. 
5

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 

slope of the Safety EdgeSM 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). 

Figure 3 shows the layout of a typical core set. Table A-2 in Appendix A lists the stations 

from where these cores were taken and the respective core thicknesses measured. Laboratory 

density was determined from the bulk specific gravity at saturated surface dry test condition, 

the results of which are presented in Table A-3 in Appendix A. Figure 4 compares the 

laboratory core density measurements for the test sections. The core densities from the 

Safety EdgeSM section show more variability than the control section. 

Vertical 

Dimension

Horizontal 

Dimension
6

Figure 3. Photo shows the layout of cores and nuclear density tests (nuclear density tests 

were taken and then the overlay was cored). 

Figure 4. Comparison of core densities adjacent to the edge and 3 feet from the edge. 

Nuclear Density Test Calibration Using Core Density 

Before coring took place, nuclear density tests were conducted at each location on the 

pavement where the cores were to be cut for the purpose of calibrating the density readings 

of the nuclear gauge to the laboratory-determined densities from the cores. Table A-3 and 

Table A-4 in Appendix A present the results of the nuclear density testing and the laboratorydetermined core density results. Figure 5 compares the nuclear density readings to the 

densities measured from the cores. 

125.0

130.0

135.0

140.0

145.0

150.0

125.0 130.0 135.0 140.0 145.0 150.0

Core Density, 3 ft from Edge, pcf

Core Density, Adjacent to Edge, pcf

Safety Edge Control

Core sets recovered from selected stations; "A" location is 

adjacent to the edge and "B" location is 3 ft from the edge). 

B A
7

Figure 5. Comparison of the nuclear densities and core densities. 

Adjustment factors used to calibrate the nuclear gauge density values were determined from 

correlating the nuclear density readings and the densities from the laboratory results. The 

two test sections had unique adjustment factors and are summarized as follows: 

Adjustment Factor 

Location Safety EdgeSM Control 

Adjacent to the edge 1.016 0.984 

3 feet from the edge 0.989 1.007

Nuclear Density Test Results 

Nuclear density tests were conducted to evaluate the test sections. During testing, the nuclear 

density gauge was set in backscatter mode for 60-second test durations. Tests were 

conducted at 50-feet intervals adjacent to the edge and 3 feet from the edge. The adjusted 

densities using the adjustment factors are included in Tables A-5 and A-6 in Appendix A. 

Statistical analyses of the data using the t-test and Welch t-test (for unequal variances) at a 

significance level of 95 percent were used to test the hypothesis that the density of the Safety 

EdgeSM test section does not differ from that of the control test section, both adjacent to the 

edge and 3 feet from the edge, and similarly, the hypothesis that the densities do not differ 

between the test sections. 

Table 1 and Table 2 present the t-test results of the density values adjacent to the edge and 3 

feet from the edge within the individual Safety EdgeSM and control test sections. Table 3 and 

125.0

130.0

135.0

140.0

145.0

150.0

125.0 130.0 135.0 140.0 145.0 150.0

Nuclear Gauge Density Reading, pcf

Core Density, pcf 

Adjacent to Safety Edge 3ft from Safety Edge

Adjacent to control edge 3 ft from control edge
8

Table 4 present the results of comparing the density values between the Safety EdgeSM and 

control sections adjacent to the edge and 3 feet from the edge by using the Welch t-test. 

In all four comparisons the difference in the averages is contained within a 95 percent 

confidence interval that encompasses zero. This indicates that these data do not show any 

statistically significant differences in the averages between the test sections nor within the 

test sections. In other words, the results suggest the density of the Safety EdgeSM test section 

is no different than the control test section either near the edge or away from the edge. 

Table 1. T-test of the test data adjacent to the edge 

and 3 feet from the edge in the Safety EdgeSM test section. 

Adjacent to the Edge 3 feet from the Edge 

Mean 3

135.6 lbf/ft 3135.4 lbf/ft

Std Dev 2.45 2.48 

Test Results 

P-value 0.74

t-value 0.33

Difference in the means 0.25

95 percent confidence interval of the 

difference in the means -1.28 to 1.79

Table 2. T-test of the test data adjacent to the edge 

and 3 feet from the edge in the control test section. 

Adjacent to the Edge 3 feet from the Edge 

Mean 3

135.9 lbf/ft 3139.7 lbf/ft

Std Dev 5.67 3.87 

Test Results 

P-value 0.25

t-value 1.25

Difference in the means -3.83 

95 percent confidence interval of the 

difference in the means -11.09 to 3.43 

Table 3. Welch t-test of the test data adjacent to the edge 

in the Safety Edge and control test section. SM

Safety EdgeSM Control 

Mean 3

135.6 lbf/ft 3135.9 lbf/ft

Std Dev 2.44 5.67 

Test Results 

P-value 0.94

t-value 0.09

Difference in the means -0.22 

95 percent confidence interval of the

difference in the means -7.41 to 6.97 
9

Table 4. Welch t-test of the test data 3 feet from the edge 

in the Safety EdgeSM and control test section. 

Safety EdgeSM Control 

Mean 3

135.4 lbf/ft 3139.7 lbf/ft

Std Dev 2.48 3.87 

Test Results 

P-value 0.08

t-value 2.37

Difference in the means -4.30 

95 percent confidence interval of the 

difference in the means -9.34 to 0.73 

Figure 6 compares the density values taken adjacent to the edge and 3 feet from the edge. 

Generally, the Safety EdgeSM section shows no distinct trend in the relationship between data 

adjacent to the edge and 3 feet from the edge whereas, the values for the control section tend 

to be higher 3 feet from the edge. 

Figure 6. Comparison of the nuclear densities adjacent to the edge 

and 3 feet from the edge. 

Figure 7 compares the percent air voids (as calculated from the density test results and the 

maximum theoretical mix density). The percent air voids shows no clear trend for the Safety 

EdgeSM section whereas, the values for the control section were higher adjacent to the edge. 

125

130

135

140

145

150

Nuclear Gauge Density Reading, 3 ft from 

125 130 135 140 145 150

Edge, pcf

Nuclear Gauge Density Reading, Adjacent to Edge, pcf

Safety Edge Control
10

Figure 7. Comparison of the air voids adjacent to the edge and 3 feet from the edge. 

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 

Isolated HMA patching and continuous brooming was conducted prior to paving. In limited 

locations the contractor used a small tractor equipped with a blade to clip soil/vegetation 

from the edge of the road, exposing the existing edge of pavement. Figure 8 shows some of 

the vegetation removed by the preparatory work. There were a few isolated areas where the 

soil/vegetation was slightly higher than the existing pavement and should have been clipped 

back farther to make room for the Safety EdgeSM. It is important to clip the shoulders far 

enough back so the soil/vegetation does not become mix with the asphalt during paving. 

0

2

4

6

8

10

12

14

16

0 2 4 6 8 10 12 14 16

Percent Air Voids, 3 ft from Edge

Percent Air Voids, Adjacent to Edge

Safety Edge Control
11

Figure 8. Vegetation removed by clipping the edge of the existing pavement. 

Placement/Paving Operations 

The Carlson device proved to be simple to operate and the contractor was able to produce a 

uniform and stable edge. The HMA showed no signs of tearing or shoving. During the first 

pass of the breakdown roller minor lateral movement of the mix was observed and the mix 

movement under the subsequent roller passes was minimal. Some lateral movement of the 

HMA at the edge should be anticipated by the contractor and adjustments by the screed 

operator should be made accordingly. 

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

The contractor used a rubber tire Caterpillar 730 paver. The weather in the morning was 

calm, sunny, 50°F and rising. 

The Carlson device created a 0.25-inch vertical lip at the breakpoint of the edge as shown in 

Figure 9. The lip was compacted flat by the rolling operation. The texture of the finished 

slope face of the Safety EdgeSM edge as shown in Figure 10 was nearly as smooth and sealed 

as the rest of the mat. 

Vegetation clipped 

from the edge of the 

road. 
12

Figure 9. Vertical lip produced by the Carlson paver. 

Figure 10. Texture of the Safety EdgeSM slope face was nearly as smooth and sealed as the 

rest of the mat. 

The Carlson device was set at a horizontal angle to the mat as shown in Figure 11 to add 

confining pressure to the edge as the paver moved forward. Figure 12 shows the Safety 

EdgeSM directly behind the Carlson device. 

A vertical lip was left 

behind the paver but 

was compacted flat 

during rolling.
13

Figure 11. Angled approach of the Carlson device. 

Figure 12. Safety EdgeSM directly behind the Carlson device. 

The following measurements were taken at a single location to document the minor amount 

of slope change during compaction operations. In this case the angle of the slope decreased 

by 1° whereas typically the angle tends to increase slightly. Measurements were taken 
14

directly behind the paver (discounting the affect of the vertical lip on the measurement 

process) and after two passes of the breakdown roller overhanging the edge. Note that the 

breakdown roller made more passes but was located away from the edge as described in the 

next section. 

Roller Pass Slope 

slope measured directly behind the paver 25°

st 1 pass, 2 inches overhanging the edge with vibration 24° 

nd 2 pass, 3 inches overhanging the edge with vibration 24°

The contractor had no experience with any Safety EdgeSM device prior to this project. After 

a couple hours of production with the Carson device the contractor expressed the following 

concern: 

The majority of contractor’s paver fleet has 10-foot screed width. On roads 

with narrower than 20 feet the Safety EdgeSM may be an issue. The 

contractor can pave the entire width of pavement with one pull if traffic 

control is allowed to shut down the road and screed extensions are used (this 

scenario is not expected to apply to many roads). When paving roads less 

than 20 feet the contractor uses a cut off under the screed to reduce the 

paving width. Contractor was unsure how to incorporate a Safety EdgeSM

device with the paver when using a cut off. 

Compaction Operations 

A dual drum Volvo DD138 HFA steel wheel roller was used as the breakdown roller with the 

vibration set on 3 (on a 1 to 8 scale). There was no pneumatic intermediate roller. The 

finish roller was a dual drum Volvo DD118 HF steel wheel roller. Different sequencing of 

the rolling patterns were observed in the Safety EdgeSM section and the control section but 

the resulting number of coverages at the outside edge were the same. 

The rolling pattern in the Safety EdgeSM section was: 

Breakdown roller: 

st 1 pass was on the longitudinal centerline joint in vibratory mode 

nd 2 pass was on the longitudinal centerline joint in vibratory mode. 

rd 3 pass was 2 inches overhanging the outside edge in vibratory mode. 

th 4 pass was 3 inches overhanging the outside edge in vibratory mode. 

th 5 pass was on the longitudinal centerline joint in vibratory mode. 
15

Finish roller: 

st 1 pass was on the longitudinal centerline joint in vibratory mode. 

nd 2 pass was on the longitudinal centerline joint in static mode. 

rd 3 pass was directly over the outside edge in vibratory mode. 

Thus the Safety EdgeSM section outside edge received 2 vibratory coverages from the 

breakdown roller and 1 vibratory coverage from the finish roller. The roller sequence 

covered the longitudinal joint first then the outside edge. 

The rolling pattern in the control section was: 

Breakdown roller: 

st 1 pass was 1 inch overhanging the outside edge in vibratory mode. 

nd 2 pass was 1 inch overhanging the outside edge in vibratory mode. 

rd 3 pass was on the longitudinal centerline joint in vibratory mode. 

Finish roller: 

st 1 pass was on the longitudinal centerline joint in vibratory mode. 

nd 2 pass was on the longitudinal centerline joint in vibratory mode. 

rd 3 pass was 3 inches away from the outside edge in vibratory. 

th 4 pass was directly over the outside edge in static mode. 

th 5 pass was on the longitudinal centerline joint in static mode. 

So the outside edge of the control section received 2 vibratory coverages from the breakdown 

roller sooner in the pattern than the Safety EdgeSM section. The pattern of the finish roller on 

the outside edge was essentially the same for both 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 

HMA material and Safety EdgeSM by investigating three features: 

 Correct use of the Safety EdgeSM device during paving. 

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

 Slope of the Safety EdgeSM. 

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

the paving/compaction operations: 
16

 Some lateral movement of the HMA at the edge should be anticipated. Adjustments 

by the screed operator should be made accordingly to ensure the proper slope of the 

finished Safety EdgeSM. 

 The slope of the Safety EdgeSM decreased by 1° during rolling operations whereas 

typically the angle tends to increase slightly. The minor change in slope indicates 

good slope stability. 

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 longterm performance of the Safety EdgeSM. 
A-1

APPENDIX A. DATA TABLES FROM FIELD MEASUREMENTS 

This section of the field report provides a listing of 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 Carlson 3.25 1.25 21

1 00+25 Carlson 3.625 1.5 22

1 00+50 Carlson 3.375 1.5 24

1 00+75 Carlson 3.375 1.5 24

1 01+00 Carlson 2.75 1.5 29

1 01+25 Carlson 3.375 1.75 27

1 01+50 Carlson 2.75 1.5 29

1 01+75 Carlson 2.5 1.375 29

1 02+00 Carlson 3.25 1.375 23

1 02+25 Carlson 2.75 1.5 29

1 02+50 Carlson 2.375 2 40

1 02+75 Carlson 2.5 1.625 33

1 03+00 Carlson 2.625 1.75 34

1 03+25 Carlson 2.5 1.75 35

1 03+50 Carlson 2.5 1.75 35

1 03+75 Carlson 2.7 1.375 27

1 04+00 Carlson 2.25 1.438 33

1 04+25 Carlson 3.5 1.4375 22

1 04+50 Carlson 3.5 1.4375 22

1 04+75 Carlson 3.5 1.75 27

1 05+00 Carlson 4 1.875 25

1 05+25 Carlson 3.75 1.75 25

1 05+50 Carlson 3.75 1.875 27

1 05+75 Carlson 3.5 2 30

1 06+00 Carlson 3.25 1.75 28

1 06+25 Carlson 2.75 1.375 27

1 06+50 Carlson 2.75 1.625 31

1 06+75 Carlson 3.5 1.625 25

1 07+00 Carlson 3 1.75 30

1 07+25 Carlson 2.5 1.625 33

1 07+50 Carlson 2.5 1.375 29

1 07+75 Carlson 2.5 1.375 29

1 08+00 Carlson 2.625 1.375 28

1 08+25 Carlson 3.125 1.75 29

1 08+50 Carlson 3.25 1.625 27

1 08+75 Carlson 2.5 1.375 29

1 09+00 Carlson 2.25 1.5 34

1 09+25 Carlson 2.25 1.375 31

1 09+50 Carlson 2.25 1.5 34

1 09+75 Carlson 2.125 1.25 30

1 10+00 Carlson 2.25 1.25 29

2.9 1.6 29

0.5 0.2 4.1

17.8 12.8 14.4

Section Station Type of Device

Edge Measurement

Mean Value

Standard Deviation

Coefficient of Variation, %
A-2

Table A-2. Core Thickness Measurements. 

Table A-3. Nuclear Density Adjustment Ratios; Core Density/Nuclear Density for the 

Safety EdgeSM Section. 

Table A-4. Nuclear Density Adjustment Ratios; Core Density/Nuclear Density for the 

Control Section. 

A – Adjacent 

to Edge

B – 3 feet 

from Edge

1 WB 2+00 Safety Edge 1.50 1.75

1 WB 5+00 Safety Edge 1.75 1.75

1 WB 8+00 Safety Edge 1.88 2.13

2 WB 1+00 Control 1.50 1.50

2 WB 2+00 Control 1.50 1.38

1.63 1.70

0.18 0.29

10.88 16.93

Mean, in. 

Standard Deviation, in. 

Coefficient of Variation, % 

Core Thickness, in

Section Station Type of Section Lane 

Direction 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 2+00 Safety Edge 137.0 135.7 135.3 136.7 1.013 0.993

1 WB 5+00 Safety Edge 139.2 132.2 134.4 136.6 1.036 0.968

1 WB 8+00 Safety Edge 135.4 137.9 135.4 137.0 1.000 1.007

137.2 135.3 135.0 136.8 1.016 0.989

1.9 2.9 0.6 0.2 0.018 0.020

1.4 2.1 0.4 0.2 1.783 1.987

Adjustment Ratio

Section

Lane 

Direction

Station

Density of Cores Nuclear Density Values

Type of Device

Mean Value, pcf 

Standard Deviation, pcf 

Coefficient of Variation, % 

A – Adjacent

to Edge

B – 3-ft from 

Edge

A – Adjacent

to Edge

B – 3-ft from

Edge

A – Adjacen

to Edge

t B – 3-ft from

Edge

2 WB 1+00 Control 137.3 138.6 138.6 137.0 0.991 1.012

2 WB 2+00 Control 136.7 139.9 139.8 139.7 0.978 1.001

137.0 139.3 139.2 138.4 0.984 1.007

0.4 0.9 0.8 1.9 0.009 0.007

0.3 0.7 0.6 1.4 0.919 0.720

Nuclear Density Values Adjustment Ratio

Mean Value, pcf 

Standard Deviation, pcf 

Coefficient of Variation, % 

Section

Lane 

Direction

Station Type of Device

Density of Cores
A-3

Table A-5. Nuclear Gauge Readings for the Safety EdgeSM Section. 

Table A-6. Nuclear Gauge Readings for the Control Section. 

2.451 Max. Density, 

pcf: 152.9

A = 1.016

B= 0.989

A – Adjacen

to Edge

t 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 Safety Edge 130.9 136.1 133.01 134.60 13.0 12.0

1 WB 00+50 Safety Edge 133.3 136.9 135.45 135.40 11.4 11.5

1 WB 01+00 Safety Edge 130.4 135.7 132.50 134.21 13.4 12.2

1 WB 01+50 Safety Edge 132.3 136.7 134.43 135.20 12.1 11.6

1 WB 02+00 Safety Edge 135.3 136.7 137.48 135.20 1.75 10.1 11.6

1 WB 02+50 Safety Edge 132.1 141.7 134.23 140.14 12.2 8.4

1 WB 03+00 Safety Edge 134.0 140.5 136.16 138.96 11.0 9.1

1 WB 03+50 Safety Edge 130.9 136.6 133.01 135.10 13.0 11.7

1 WB 04+00 Safety Edge 130.8 130.1 132.90 128.67 13.1 15.9

1 WB 04+50 Safety Edge 130.2 136.7 132.30 135.20 13.5 11.6

1 WB 05+00 Safety Edge 134.4 136.6 136.56 135.10 1.75 10.7 11.7

1 WB 05+50 Safety Edge 133.9 137.5 136.05 135.99 11.0 11.1

1 WB 06+00 Safety Edge 134.7 137.8 136.87 136.29 10.5 10.9

1 WB 06+50 Safety Edge 138.5 134.0 140.73 132.53 8.0 13.3

1 WB 07+00 Safety Edge 135.0 141.0 137.17 139.45 10.3 8.8

1 WB 07+50 Safety Edge 136.7 137.1 138.90 135.59 9.2 11.3

1 WB 08+00 Safety Edge 135.4 137.0 137.58 135.49 2.125 10.0 11.4

1 WB 08+50 Safety Edge 133.9 133.7 136.05 132.23 11.0 13.5

1 WB 09+00 Safety Edge 132.2 138.4 134.33 136.88 12.2 10.5

1 WB 09+50 Safety Edge 137.4 137.9 139.61 136.39 8.7 10.8

1 WB 10+00 Safety Edge 131.0 136.0 133.11 134.51 13.0 12.1

133.5 136.9 135.6 135.4 1.9 11.3 11.5

2.4 2.5 2.4 2.5 0.2 1.6 1.6

1.8 1.8 1.8 1.8 11.5 14.1 14.1

Air Voids, %

Core Thickness 

Adjacent to 

Edge, in.

Section

Maximum Specific Gravity of Mix (Gmm):

Adjustment Ratios for Nuclear Gauge:

Station

Adjusted Nuclear 

Densities, pcf

Type of Section

Nuclear Densities, pcf

Lane 

Direction

Average Value, pcf

Standard Deviation, pcf 

Coefficient of Variation, % 

2.451 Max. Density, 

pcf:

152.9

A = 0.984

B= 1.007

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 0+00 Control 142.7 142.9 140.45 143.84 8.2 6.0

2 WB 0+50 Control 141.0 141.2 138.78 142.13 9.3 7.1

2 WB 1+00 Control 138.6 137.0 136.41 137.90 1.5 10.8 9.8

2 WB 1+50 Control 128.1 133.1 126.08 133.97 17.6 12.4

2 WB 2+00 Control 139.8 139.7 137.59 140.62 1.375 10.0 8.1

138.0 138.8 135.9 139.7 1.4 11.2 8.7

5.8 3.8 5.7 3.9 0.0 3.7 2.5

4.2 2.8 4.2 2.8 0.0 33.2 29.2

Core Thickness 

Adjacent to 

Edge, in.

Air Voids, %

Average Value, pcf

Standard Deviation, pcf

Adjusted Nuclear 

Densities, pcf

Maximum Specific Gravity of Mix (Gmm):

Adjustment Ratios for Nuclear Gauge:

Section

Lane 

Direction

Station Type of Section

Nuclear Densities, pcf

Coefficient of Variation, %