January 5, 2012 

Safety EdgeSM Design and 

Construction Guide 

Final Report 

January 5, 2012 
January 5, 2012 

FOREWORD 

The main focus of this document is to explain the important design, construction, and 

materials-related considerations for constructing the Safety EdgeSM. The target audience of 

this report is pavement design and construction personnel who will specify and construct the 

Safety EdgeSM. 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

January 5, 2012 

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

3. Title and Subtitle 

Safety EdgeSM Design and Construction Guide 

5. Report Date 

 January 5, 2012 

6. Performing Organization Code 

7. Authors 

Andy Mergenmeier, P.E., Harold Von Quintus, P.E, Jagannath Mallela, 

and Paul Littleton, 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. 

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 

 Design and Construction Guide

 April 2010 – July 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 Federal Highway Administration (FHWA) 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 Design and Construction Guide shares the findings from ten demonstration projects in multiple states and other ad hoc 

projects in which the Safety EdgeSM was implemented. This Guide supports the FHWA's efforts to implement the Safety 

EdgeSM technology by providing standards, guidance, and specifications for adopting this treatment as a standard practice 

on all applicable new and resurfacing pavement projects. 

The Guide provides information on the various elements to consider when designing and constructing pavement projects 

with the Safety EdgeSM. The Guide provides insights and lessons learned on previously constructed projects, highlighting 

items that may vary from conventional pavement design and construction. 

17. Key Words 

Safety EdgeSM, slope, asphalt concrete materials, 

PCC, roadway departure 

18. Distribution Statement 

No restriction. 

19. Security Classif.(of this report) 

Unclassified 

20. Security Classif. (of this page) 

Unclassified 

21. No. of Pages 22. Price 

Form DOT F 1700.7 (8-72) 

ii 
 

January 5, 2012 

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) 

LENGTH 

 mil 25.4 micrometers 

 inches 25.4 millimeters 

feet 0.305 meters 

 yards 0.914 meters 

 miles 1.61 kilometers 

AREA 

square inches 645.2 square millimeters 

square feet 0.093 square meters 

square yards 0.836 square meters 

acres 0.405 hectares 

square miles 2.59 square kilometers 

VOLUME 

fluid ounces 29.57 millimeters 

gallons 3.785 liters 

cubic feet 0.028 cubic meters 

cubic yards 0.765 cubic meters 

NOTE: volumes greater than 1000 L shall be shown in m3 

MASS 

 ounces 28.35 grams 

 pounds 0.454 kilograms 

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

TEMPERATURE (exact degrees) 

Fahrenheit 5 (F-32)/9 

or (F-32)/1.8 

Celsius 

ILLUMINATION 

foot-candles 10.76 lux 

foot-Lamberts 3.426 candela per square meter 

FORCE and PRESSURE or STRESS 

 poundforce 4.45 Newtons 

poundforce per square inch 6.89 kiloPascals 

kips per square inch 6.89 megaPascals 

DENSITY 

pounds per cubic foot 16.02 kilograms per cubic meter 

μm 

mm 

m 

m 

km 

mm2 

m2 

m2 

ha 

km2 

mL 

L 

m3 

m3 

g 

kg 

Mg (or "t") 

°C 

lx 

cd/m2 

N 

kPa 

MPa 

kg/m3 

APPROXIMATE CONVERSIONS FROM SI UNITS 

Symbol When You Know Multiply By To Find Symbol 

μm 

mm

m 

m 

km

mm2 

m2 

m2 

ha

km2 

mL

L 

m3 

m3 

g 

kg

Mg (or "t") 

°C

lx

cd/m2 

N 

kPA 

MPa 

LENGTH 

micrometers 0.039 mil 

 millimeters 0.039 inches 

meters 3.28 feet 

meters 1.09 yards 

 kilometers 0.621 miles 

AREA 

square millimeters 0.0016 square inches 

square meters 10.764 square feet 

square meters 1.195 square yards 

 hectares 2.47 acres 

square kilometers 0.386 square miles 

VOLUME 

 milliliters 0.034 fluid ounces 

liters 0.264 gallons 

cubic meters 35.314 cubic feet 

cubic meters 1.307 cubic yards 

MASS 

grams 0.035 ounces 

 kilograms 2.202 pounds 

megagrams (or "metric ton") 1.103 short tons (2000 lb) 

TEMPERATURE 

 Celsius 1.8C+32 Fahrenheit 

ILLUMINATION 

 lux 0.0929 foot-candles 

candela per square meter 0.2919 foot-Lamberts 

FORCE and PRESSURE or STRESS 

Newtons 0.225 poundforce 

kiloPascals 0.145 poundforce per square inch 

megaPascals 0.145 kips per square 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 the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. (Revised March 

2003) 

iii 
Topic Page

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

SECTION 1: INTRODUCTION ................................................................................................ 1
 

1.1 INTRODUCTION .................................................................................................................... 1
 

1.2 PURPOSE OF THE GUIDE ...................................................................................................... 1
 

1.3 SCOPE OF THE GUIDE .......................................................................................................... 1
 

SECTION 2: SAFETY EDGESM – GENERAL DESIGN AND CONSTRUCTION 

CONSIDERATIONS .................................................................................................................... 3
 

2.1 SAFETY EDGESM USE ........................................................................................................... 3
 

Where the Safety EdgeSM Can Be Placed................................................................................ 4
 

Where the Safety EdgeSM Should Not Be Placed..................................................................... 4
 

2.2 PRE-CONSTRUCTION AND DISCONTINUOUS PAVING OPERATIONS ................................... 5
 

2.3 PAVEMENT EDGE/SHOULDER PREPARATION ..................................................................... 7
 

2.4 SLOPE MEASUREMENT ........................................................................................................ 9
 

2.5 BACKING MATERIAL PLACEMENT...................................................................................... 9
 

SECTION 3: SPECIFIC CONSIDERATIONS FOR CONSTRUCTING THE
 

SAFETY EDGESM IN CONJUNCTION WITH NEW AC PAVEMENTS OR AC 

OVERLAYS ................................................................................................................................ 11
 

3.1 DESIGN FEATURES AND SHAPE.......................................................................................... 11
 

3.2 EQUIPMENT – ACSAFETY EDGESM DEVICES ................................................................... 13
 

Devices Attached to the Screed ............................................................................................. 13
 

Modification to the End Plate ............................................................................................... 13
 

3.3 ASPHALT CONCRETE MATERIALS .................................................................................... 13
 

3.4 SAFETY EDGESM CONSTRUCTION ..................................................................................... 14
 

Safety EdgeSM Device Installation ........................................................................................ 14
 

AC Placement........................................................................................................................ 15
 

Rolling ................................................................................................................................... 18
 

3.5 QUALITY MEASUREMENT.................................................................................................. 19
 

 

January 5, 2012 

Table of Contents 

iv 
Topic Page

SECTION 4: SPECIFIC CONSIDERATIONS FOR CONSTRUCTING THE
 

SAFETY EDGESM IN CONJUNCTION WITH NEW CONCRETE PAVEMENTS 

OR CONCRETE OVERLAYS.................................................................................................. 20
 

4.1 DESIGN FEATURES AND SHAPE.......................................................................................... 20
 

4.2 EQUIPMENT – PCCSAFETY EDGESM DEVICES................................................................. 20
 

4.3 CONCRETE MIXTURES....................................................................................................... 21
 

4.4 SAFETY EDGESM CONSTRUCTION ..................................................................................... 21
 

PCC Placement..................................................................................................................... 21
 

Transitioning Between Different Edge Profiles .................................................................... 22
 

Vibration ............................................................................................................................... 23
 

Curing ................................................................................................................................... 23
 

Sawcutting ............................................................................................................................. 23
 

4.5 QUALITY MEASUREMENT.................................................................................................. 24
 

REFERENCES............................................................................................................................ 25
 

APPENDICES ............................................................................................................................. 26
 

 

January 5, 2012 

Table of Contents 

v 
January 5, 2012 

SECTION 1: INTRODUCTION 

1.1 Introduction

The Safety EdgeSM is a relatively simple but effective solution that can help save lives by 

allowing drivers who drift off highways to return to the road safely. 

During conventional paving processes, the pavement is constructed with vertical or near 

vertical edges. Instead of a vertical drop-off, the finished Safety EdgeSM forms the edge of 

the pavement with a slope of approximately 30 degrees. Research has shown this “transition 

from on-roadway surface to shoulder and back is so smooth it defies assignment of any 

degree of severity.” The Safety EdgeSM provides a strong, durable transition for all vehicles 

and helps prevents pavement edge raveling. 

The recommended practice of bringing the adjacent soil or aggregate material (unpaved 

shoulder or modified soil) flush with the top of the pavement often requires frequent 

maintenance. When the vertical edge is exposed due to wear/erosion, it can contribute to 

drivers losing control of the vehicle when attempting to recover from a roadway 

departure. The Safety EdgeSM concept is when drop-offs along the pavement edge occur, the 

edge will not be vertical, but has a shape that will not induce tire scrubbing. By including the 

Safety EdgeSM detail while paving, this safety countermeasure can be implemented systemwide at little or no cost. 

1.2 Purpose of the Guide 

The Federal Highway Administration (FHWA) works with States and Industry to accelerate 

the use of innovative technologies. This Guide supports efforts to implement the Safety 

EdgeSM technology by providing information and guidance to assist agencies in developing 

standards and specifications for adopting this treatment as a standard practice on all 

applicable new and resurfacing pavement projects. 

The Guide provides information on the various elements to consider when designing and 

constructing pavement projects with the Safety EdgeSM. The Guide provides insights and 

lessons learned on previously constructed projects, highlighting items that may vary from 

conventional pavement design and construction. 

1.3 Scope of the Guide 

The information for this Guide draws significantly from experiences obtained from 10 formal 

construction project evaluations conducted in 2010 and 2011, as well as several ad hoc 

evaluations. It is expected that significant enhancements in equipment and procedures will 

be forthcoming as the Safety EdgeSM is implemented into standard practice. 

The Guide is grouped into four sections, including this introductory section. Section 2 is 

focused on general design and construction considerations that are applicable to all pavement 

types and rehabilitation projects. Sections 3 and 4 identify specific considerations for 

1 
January 5, 2012 

constructing a Safety EdgeSM for asphalt concrete materials (AC) and Portland cement 

concrete (PCC) pavements, respectively. 

2 
January 5, 2012 

SECTION 2: SAFETY EDGESM – GENERAL DESIGN AND 

CONSTRUCTION CONSIDERATIONS 

In terms of paving operations, there is little difference between the placement and 

construction of AC and PCC materials (refer to Figure 1) with and without the inclusion of 

the Safety EdgeSM. However, there are important considerations that should be accounted for 

when incorporating the Safety EdgeSM into a paving operation. This section of the Guide 

highlights the general design and construction details when constructing a Safety EdgeSM in 

conjunction with AC or PCC pavements. 

2.1 Safety EdgeSM Use 

The Safety EdgeSM provides two important safety related functions. It serves as a mitigating 

measure to help with pavement edge drop off that occurs after an AC layer is placed, but 

before shoulders can be reconstructed flush with the paved surface. The Safety EdgeSM also 

serves as a long-term safety feature for areas susceptible to material displacement and/or 

erosion adjacent to the paved surface. 

An additional benefit of the Safety EdgeSM is that the density of the AC mat adjacent to the 

pavement edge was found to be higher in most areas with the Safety EdgeSM in comparison 

to areas without the Safety EdgeSM. The Safety EdgeSM is believed to serve as a restriction to 

the lateral movement of the AC mat along an unconfined edge. This observation was found 

from multiple demonstration projects. Visual assessment of many Safety EdgeSM treatments 

have shown that trucks loaded with asphalt do not deform/damage the finished edge. 

(a) AC Project. (b) PCC Project. 

Break point 

Figure 1. Safety EdgeSM placed on an AC and PCC project. 

3 
Where the Safety EdgeSM Can Be Placed 

Where the Safety EdgeSM Should Not Be Placed 

January 5, 2012 

The Safety EdgeSM can be used in almost every situation to provide a condition towards 

preventing near vertical lane-shoulder drop offs during construction and over time. It also 

provides added insurance until such time that maintenance personnel are able to repair 

eroded areas of the shoulder adjacent to the paved surface. 

A site condition where the Safety EdgeSM should not be used is where the 

foreslope/embankment or ground surface has a steeper slope than the slope of the Safety 

EdgeSM. This condition may exist for a portion of the road being paved, thus the Safety 

EdgeSM should be considered for use on the remainder of the road. Figure 2 depicts this 

condition. 

Figure 2. Example of where a foreslope/embankment is too steep for the Safety EdgeSM. 

The Safety EdgeSM should be excluded in areas where curb and gutter have been or will be 

placed as the Safety EdgeSM is appropriate for the interface of a paved material and an 

unpaved/unbound material. In areas where there is a restriction for vehicles leaving the 

paved surface (for example; guardrails and other safety features) whether or not to use the 

Safety EdgeSM must be assessed on a case-by-case situation. The agency may see value in 

using the Safety EdgeSM for its pavement quality benefit, and thus may want to use it in these 

applications. 

4 
January 5, 2012 

2.2 Pre-Construction and Discontinuous Paving Operations 

The pre-construction activities for Safety EdgeSM projects are to review the paving plan and 

make sure the Safety EdgeSM can be placed in suitable areas along the project. If there are 

areas with restrictions along the edge of the pavement (for example, guardrails, intersections, 

and bridges), the width of the roadway and width of paving should be considered so that 

there is sufficient room for the Safety EdgeSM device for resurfacing projects. As an example, 

narrow bridges along some low volume roadways can result in conditions where the AC 

paver screed extensions cannot be moved-in sufficiently when using Safety EdgeSM devices 

that are bolted to the paver screed, so the paver operator must steer the paver more towards 

the center of the roadway during paving operations (center line crown or other cross slope 

changes need to be considered in these conditions). Other areas where the foreslope is steeper 

than the Safety EdgeSM slope should be noted. These conditions should be discussed in the 

contractors quality control plan and/or pre-paving meeting and how the condition will be 

resolved. 

Paving across intersections and driveways with the Safety EdgeSM device in place is 

generally no different than when paving without the Safety EdgeSM. The differences for both 

AC and PCC paving are noted below. All of these conditions or paving anomalies should be 

identified and addressed prior to beginning paving operations. 

	 For AC paving, extra attention from the paver and screed operators may be necessary to 

accommodate the Safety EdgeSM at transitions for intersections, driveways, and changes 

in longitudinal elevations or profile. The reason for this extra attention is discussed in 

Section 3 of the Guide. Specifically, Section 3.2 discusses the different Safety EdgeSM 

devices and their attachment to the paver. For devices attached to the screed, the screed 

operator can keep the Safety EdgeSM device lowered or can raise the device above the 

bottom of the screed so that the Safety EdgeSM is not placed through some intersections 

(refer to Figure 3). The capability for lowering and raising the device allows the paving 

operation to continue without disruption when discontinuous features or adjacent features 

are encountered. For devices attached to the end plate, the screed operator needs to 

monitor the height of the end plate ski to ensure the desired shape is placed. 

	 For PCC slip-form paving, the PCC material at the intersection or driveway will need to 

be sawcut to remove the Safety EdgeSM (refer to Figure 4) or build up the Safety EdgeSM 

by hand in order to tie into pavement intersections. 

5 
 

January 5, 2012 

Screed operator raised the 

Safety EdgeSM device in 

paving across this 

intersection. The Safety 

EdgeSM device can be kept 

lowered when paving 

across driveways. 

Agreement on how to treat 

this condition should be 

established before paving 

starts. 

Sawcut 

Figure 3. Placing an AC overlay at an intersection of a Safety EdgeSM project. 

Figure 4. Sawcut on a PCC project at an intersection to remove the Safety EdgeSM. 

6 
January 5, 2012 

2.3 Pavement Edge/Shoulder Preparation 

The pavement edge should be prepared in accordance with standard agency paving 

operations for both AC and PCC surfaces (refer to Figure 5). 

Motor grader is used to 

remove vegetation and soil 

build-up along the edge of the 

pavement. 

A motorized broom cleans the 

surface of the pavement prior 

to applying the tack coat to the 

surface of the existing 

pavement. 

A tack coat is applied to the 

cleaned pavement surface prior 

to placing the asphalt overlay. 

Figure 5. Surface preparation activities performed prior to placing an AC overlay. 

7 
 

January 5, 2012 

The following items are highlighted to ensure the agency considers them as they have been 

shown to adversely impact Safety EdgeSM construction on some projects. 

	 If vegetation exists along the pavement edge consideration should be given to 

removing this vegetation in the area supporting the Safety EdgeSM prior to paving. 

Good asphalt paving practice includes not paving on vegetation as the asphalt will not 

adequately compact and thus will not perform adequately. Figure 6 shows an 

example of a Safety EdgeSM edge placed over vegetation. For asphalt paving, a 

clean/clearly visible pavement edge will help the screed operator monitor the material 

placement along the pavement’s edge. 

	 If the agency removes vegetation/soil from the edge of the pavement (edge clipping), 

ensure a reasonable grade elevation and slope of the pavement edge/shoulder is 

established to minimize use of excess pavement material along the edge. 

	 Edge clipping should extend far enough to accommodate the additional width of the 

Safety EdgeSM which may be a change in standard operating practice. The wedge 

part of the Safety EdgeSM is typically additional width, therefore paving a vertical 

edge depth of 3 inches will require clipping an additional 6 inches of width to 

accommodate the Safety EdgeSM. 

Figure 6. Example of Safety EdgeSM placed on heavy vegetation – due to lack of adequate 

compaction the Safety EdgeSM will deteriorate. 

8 
January 5, 2012 

2.4 Slope Measurement 

Including the Safety EdgeSM on a new construction or resurfacing project does not impact the 

agency’s material and construction specifications. The only difference in determining the 

quality between projects with and without the Safety EdgeSM is the measurement of slope for 

the as-built Safety EdgeSM itself. This part of the Guide discusses measuring the slope of the 

Safety EdgeSM. 

Figure 7 illustrates how the slope is measured or determined for an AC resurfacing project. 

The length of line B is determined as the distance of a vertical virtual line from the edge or 

toe of the Safety EdgeSM to the pavement surface cross slope extended. The toe of the Safety 

EdgeSM can be defined as where a straight line along the surface of the Safety EdgeSM 

contacts the ground surface. This point becomes important for asphalt mixtures with larger 

nominal maximum sized aggregate where the removal of one coarse aggregate particle can 

significantly change the measured slope. The length of line A is determined as the distance 

from the point where there is space between the straight edge placed on the pavement surface 

at the edge, defined as the break point, and the vertical virtual line through the toe of the 

Safety EdgeSM or vertical line B. The angle, θ, is calculated as θ = arctan B/A. This angle 

measurement is the angle that the vehicle tire encounters when the vehicle is attempting to 

return to the pavement. The slope of a PCC Safety EdgeSM is determined in the same 

manner. The angle measurement is made on the sloped portion of the Safety EdgeSM and 

does not include the vertical portion of the PCC edge. 

A 

B 

Toe of 

the slope 

Break point 

Figure 7. Measurement of Safety EdgeSM slope or angle. 

2.5 Backing Material Placement 

It should be remembered that the Safety EdgeSM is a mitigation of the drop off created by the 

AC or PCC overlay or new paved layer; it is not intended to substitute for a shoulder that is 

flush with the paved surface. After the paved layer or overlay has been placed, the shoulder 

or backing material needs to be graded back flush with the paved surface. The shoulder 

material should be placed in accordance with standard equipment and procedures specified 

9 
January 5, 2012 

by the owner agency for both AC and PCC pavements. The only cautionary note is to grade 

the backing or shoulder material over and along the Safety EdgeSM as soon as possible but, in 

the case of an AC pavement, after the mat has cooled sufficiently so that any scuffing or 

tearing of the surface from construction equipment is minimized. Similarly, PCC should be 

allowed to cure and gain sufficient strength so that the construction equipment grading the 

backing material does not damage the PCC Safety EdgeSM. After construction is completed, 

the Safety EdgeSM will be covered with the backing material and not seen by the road user as 

shown in Figure 8. 

Figure 8. Safety EdgeSM completely covered by shoulder backing material. 

10 
January 5, 2012 

SECTION 3: SPECIFIC CONSIDERATIONS FOR CONSTRUCTING 

THE SAFETY EDGESM IN CONJUNCTION WITH NEW AC 

PAVEMENTS OR AC OVERLAYS
 

This section of the Guide identifies issues that need to be monitored during the placement 

and compaction operations of the AC pavement. 

3.1 Design Features and Shape 

The paved lane/shoulder width and location of the Safety EdgeSM break point should be 

discussed and established prior to paving. The Safety EdgeSM can be constructed on the 

unimproved or improved shoulder with the break point lining up directly over the existing 

pavement edge or over any portion of the previously paved surface as shown in Figure 9. 

Figure 9. Paver positioned to align the Safety EdgeSM break point over the existing pavement. 

The intent is not to sacrifice paved lane/shoulder width to construct the Safety EdgeSM. 

Constructing the Safety EdgeSM onto the unimproved shoulder does not result in a decrease 

in paved lane/shoulder width. 

The Safety EdgeSM is designed to create a 30 degree finished angle, relative to the pavement 

cross slope, on the edge of the pavement. Agency-specific tolerances may vary from those 

shown in Figure 10 which is from the FHWA guide specification. On projects where 

multiple AC layers are used, it is recommended each AC layer (except leveling layer) of the 

final 5 inches of AC receive the Safety EdgeSM as shown in Figure 10. For new construction 

or reconstruction with thicker AC layers, consideration should be given to widening the 

underlying paved layers to accommodate the Safety EdgeSM without decreasing lane width as 

shown in Figure 10. On projets with multiple AC layers, it is expected the additional volume 

of AC required to form the Safety EdgeSMwill increase bid quantities. 

11 
 

Edge of  
 

Pavement

H

Shoulder

Backing

Material

For H ≤ 5 in. 

For H > 5 in. 

 

January 5, 2012 

* Note, Recommended Rise to Run ratio range 1:1.2 to 1:2.0. The range of slope is equal to 26° to 40°. 

Figure 10. Recommended Safety EdgeSM configuration for AC pavements and overlays. 

12 
Devices Attached to the Screed 

End Plate Modifying Devices 

January 5, 2012 

3.2 Equipment – AC Safety EdgeSM Devices 

The current commercial Safety EdgeSM devices can be grouped into two categories: (1) 

devices attached to the paver screed, and (2) modifications or attachments to the paver end 

plate. The devices listed below do not constitute an approved products list. Highway 

agencies should evaluate any new Safety EdgeSM hardware for compliance with 

specifications before approving for use on a project. 

Currently, there are three devices available from two different manufacturers, which are: (1) 

the “Shoulder Wedge Maker” manufactured by TransTech, www.transtechsys.com and (2) 

the “Advant-Edger” and “Ramp Champ” manufactured by the Advant-Edge Paving 

Equipment LLC, www.advantedgepaving.com. Each manufacturer provides detailed 

installation instructions for attaching their devices to the paver screed. The devices can be 

easily attached to and removed from the paver screed with a simple two-bolt connection. The 

Safety EdgeSM device should fit closely to the end plate to prevent AC from getting between 

the device itself and end plate. The Ramp Champ can be set to a range of angles, while the 

other devices have a fixed angle. 

The end plate modification devices are available from Carlson Paving Products, Inc. (Safety 

Edge End Gate) http://www.carlsonpavingproducts.com and Willow Designs LLC 

http://www.willowdesignsllc.com. The ski of the devices form the slope of the Safety EdgeSM 

and can be set to a range of angles. The screed operator can adjust the angle of the ski while 

paving to ensure the final angle of the Safety EdgeSM after rolling is close to 30 degrees. 

3.3 Asphalt Concrete Materials 

The Safety EdgeSM can be placed with all dense-graded AC materials that have been properly 

designed in accordance with existing mixture design methods, including: Hot Mix Asphalt 

(HMA), Warm Mix Asphalt (WMA), HMA with high amounts of Recycled Asphalt 

Pavement (RAP), HMA with Recycled Asphalt Shingles (RAS), polymer modified asphalt 

(PMA), rubberized gap graded and open graded mixes, and other specialty mixtures. The 

demonstration projects included HMA, RAP, RAS, WMA, and PMA mixtures. 

There are two critical material issues in terms of placing a Safety EdgeSM for AC mixtures: 

(1) lateral movement of the AC mix during compaction and (2) the size or amount of coarse 

aggregate in the AC mixture. 

	 Most AC mixtures exhibit some lateral movement under the rollers during 

compaction and that movement is mixture and application dependent. Lateral 

movement of the AC mix should not prevent the contractor from achieving an 

13 
Safety EdgeSM Device Installation 

January 5, 2012 

acceptable Safety EdgeSM slope after final rolling. Ensure that after rolling is 

completed the Safety EdgeSM break point lines up directly over the existing pavement 

edge or over any portion of the previously paved surface. If the break point is over 

the unimproved shoulder (i.e. different support structure) the potential of a 

longitudinal crack forming is greater (Figure 11). This material related issue is 

discussed in more detail in Section 3.4 - Safety EdgeSM Construction, under Rolling. 

	 The maximum nominal size aggregate of the mixture or amount of coarse aggregate 

can affect the surface texture or appearance of the Safety EdgeSM and measurement of 

the slope. Fine-graded AC mixtures were observed to have a tighter surface 

appearance and texture along the edge. Rough surface texture makes the measurement 

of the slope more difficult to quantify – increasing variability in slope measurements. 

Figure 11. Longitudinal crack due to Safety EdgeSM break point located on unimproved 

shoulder. 

3.4 Safety EdgeSM Construction 

This section discusses items of interest to asphalt paving projects when a Safety EdgeSM is to 

be placed as part of the new construction or rehabilitation project. 

Manufacturers of commercially available devices provide detailed instructions for attaching 

the Safety EdgeSM devices to the paver. Proper installation of the devices was discussed in a 

previous part of this section (Equipment – AC Safety EdgeSM Devices). A key issue for 

devices attached to the screed without guide rails is to ensure close installation to the end 

plate so loose mix does not get trapped between the device and end plate during paving 

operations. At the beginning of the day’s production, when pulling off a transverse joint, the 

screed operator needs to monitor the position of the device as the auger chamber and 

14 
 

AC Placement 

January 5, 2012 

extension are being charged to ensure the device is in contact with the end plate. These issues 

do not affect the end gate type device. 

The Safety EdgeSM can be placed with normal paving procedures, and no changes to the 

operation of the paver need to be made. More importantly, the Safety EdgeSM device has no 

impact on how the paver operates, whether paving on an embankment or crushed stone layer, 

recently placed AC, existing AC or PCC layers, or milled surface. 

For those agencies that require trial or control sections as part of standard AC paving 

operations, the slope of the Safety EdgeSM should be measured after all rolling has been 

completed to ensure the Safety EdgeSM slope did not “stand up” (substantial increase in the 

slope). Trial sections provide an opportunity for the screed operator to make adjustments to 

the Safety EdgeSM and screed before high production paving begins. For example, to obtain 

the 30o finished angle, the target angle to be achieved behind the paver by the Safety EdgeSM 

device may need to be shallower for a given mix, e.g., 25 degree. Trial sections can also be 

used to assess if the edge will “stand up” during the AC rolling operation. The issue of 

maintaining the slope of the Safety EdgeSM is discussed under the next subsection – Rolling. 

The screed operator needs to watch and adjust three items during the paving operation when 

using a Safety EdgeSM device attached to the screed, described in Section 3.2: (1) the Safety 

EdgeSM device itself, (2) the end plate, and (3) the screed (refer to Figure 12). If the Safety 

EdgeSM device with too much downward pressure rides on the AC or other stiff base material 

that has been previously placed, this can result in undesirable paving results, as described 

below. 

 When the Safety EdgeSM device rides on a base with a rough positive surface texture 

(e.g. coarse aggregate protruding upward such as in a chip seal) in some cases it may 

cause the screed to vibrate or jerk. The toe of the Safety EdgeSM can get caught on 

larger aggregate particles and when the particle breaks loose, the screed jerks. The 

screed operator will need to monitor the downward pressure of the Safety EdgeSM 

device so this does not happen in extreme cases. 

	 When the Safety EdgeSM device rides on a base with a varying longitudinal profile, 

the screed operator will need to monitor the downward pressure of the Safety EdgeSM 

device to keep the screed functioning as designed within the free-floating principle. 

The spring around the shaft of the Safety EdgeSM is designed to keep a relatively 

uniform pressure on the mixture being placed under the Safety EdgeSM – assuming 

the vertical operational limit of the Safety Edge is not exceeded. 

	 The screed operator also needs to monitor the downward pressure of the Safety 

EdgeSM device when it rides on soft surfaces. The leading edge of the device can dig 

into the soft shoulder pulling soil/aggregate into the asphalt wedge of the Safety 

EdgeSM. This is the same condition experienced in conventional paving when the 

paver end plate ski digs into the soft shoulder. 

15 
 

January 5, 2012 

Wrench used to 

adjust the elevation 

of the Safety EdgeSM 

device. 

Figure 12. Safety EdgeSM adjustment for raising and lowering the device. 

When paving begins the screed operator should pay close attention to the following items 

when using a Safety EdgeSM device attached to the screed. 

	 In charging the auger chamber with AC, the screed operator should ensure that the 

device is in close contact with the end plate so that mix does not get between the 

device and end plate and that there is sufficient material surrounding the device to 

keep it held against the end plate. 

	 After the paving operation begins and the full AC lift thickness has stabilized, the 

screed operator should adjust the Safety EdgeSM device by lowering the device into 

contact with the underlying surface. This adjustment should not be made prior to the 

paver moving off the shims at the start of a day’s paving operation. The screed 

operator should look behind the paver to ensure that the slope of the edge will 

produce a slope of about 30 degrees after rolling. 

16 
January 5, 2012 

	 The paver end plate ski needs to remain in contact with the surface being paved over. 

AC can extrude out under the end plate ski if not in contact with the existing surface 

which can reduce the amount of AC available for the Safety EdgeSM – affecting the 

slope and density of the wedge itself. 

	 When placing an AC overlay, the Safety EdgeSM can ride on the underlying layer. 

However, the screed operator should closely monitor the downward force on the 

Safety EdgeSM device relative to underlying hard surfaces with variable longitudinal 

profiles, which can change the forces on one side of the screed (free floating screed 

principle or mode). This concern is heightened at intersections or areas of increased 

variation of longitudinal profile. The spring around the shaft of the Safety EdgeSM is 

designed to keep a relatively uniform pressure on the mixture being placed under the 

Safety EdgeSM – assuming the vertical operational limit of the Safety Edge is not 

exceeded. 

	 The operator needs to be aware that the height adjustment screw can be bent from 

paving with too much downward force, especially if the shoe is in contact with a 

variable elevation of a hard surface. The height adjustment screw can also be bent 

from or hitting objects while in transport. 

	 The screed operator should monitor the surface texture and condition of the Safety 

EdgeSM . 

	 When drawing in the hydraulic extension, the screed operator needs to closely 

monitor the process to ensure that the Safety EdgeSM device does not come in contact 

with the cross feed auger. If this occurs, it can damage both the Safety EdgeSM device 

and auger. 

	 If the hydraulic extension of the screed is extended during mainline paving, the 

amount of mix in the extension can be reduced near the paver end plate. When this 

occurs the screed operator should monitor the amount of mix to ensure it is not 

getting between the end plate and Safety EdgeSM device itself, as the screed moves 

out. 

	 The flow of AC material to the Safety EdgeSM device should be closely monitored to 

make sure enough material is available to form a continuous edge and that the 

material feed augers are properly positioned. 

	 Paver manufactures commonly recommend material feed augers be no greater than 18 

inches from the end plate. 

	 When the paver is being moved, the Safety EdgeSM device should be removed or 

raised to its mounting height or uppermost position. This will ensure that the bottom 

of the device will not strike/get caught on any obstruction. 

When using a Safety EdgeSM device the screed operator needs to continually be aware of the 

position of the break point of the Safety EdgeSM slope and keep the break point on the 

structural base or existing pavement. 

At the beginning of the project, it is recommended that slope measurements be made 

immediately behind the paver and after each roller pass. The focus is on the final Safety 

EdgeSM slope angle after all rolling to determine how rolling impacts the final slope angle. 

17 
Rolling 

January 5, 2012 

The contractor may want to periodically make these measurements as part of the quality 

control process. 

No special rollers are required for compacting the AC mix along and adjacent to the Safety 

EdgeSM (refer to Figure 13). 

Figure 13. Rolling the Safety EdgeSM with standard rollers – No special rollers are required. 

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January 5, 2012 

Most AC mixtures exhibit some lateral movement under the rollers during compaction. 

Lateral movement of the AC mix should not prevent the contractor from achieving an 

acceptable Safety EdgeSM slope after final rolling. For some of the demonstration projects, 

the contractor did change or revise the standard rolling pattern to maximize the density of the 

AC mat, while retaining an appropriate Safety EdgeSM angle. Just like for any AC paving 

project, the optimum rolling pattern is AC mixture specific. A rolling pattern used to compact 

a low stiffness mix and high stiffness mix may be different to meet the density requirements. 

The following recommendations are made based on the findings from multiple demonstration 

projects. 

	 The contractor should roll the AC mat and pavement edges based on normal or 

standard compaction operation. This should ensure adequate density along and near 

the pavement edge. Multiple demonstration projects have been constructed 

successfully where the pavement edge was rolled with the contractor’s standard 

rolling pattern. 

	 After final rolling, the slope of the Safety EdgeSM should be measured. If the slope of 

the edge is too steep, the contractor should determine if the slope of the edge was 

steepened because of excessive rolling, the use of a mix that exhibits tenderness, or 

the AC mixture is simply too soft to retain the targeted slope angle. A variable angle 

Safety EdgeSM device can be used to place the Safety EdgeSM at an angle less than 30 

degrees behind the paver, which should assist the contractor in achieving 30 degrees 

after rolling. 

	 Delaying the rolling of the edge of the mat should be the last resort taken to retain the 

slope of the Safety EdgeSM. This becomes a decision between durability along and 

near the pavement edge and retaining a slope of the Safety EdgeSM . 

	 Continually monitor the slope of the Safety EdgeSM after final rolling. The slope of 

the Safety EdgeSM varied between 30 to 40 degrees on multiple demonstration 

projects without delaying the rolling of the Safety EdgeSM. 

3.5 Quality Measurement 

The same properties used or identified by the owner agency to measure the quality of AC 

pavement layers for acceptance should also be used on projects that include the Safety 

EdgeSM. The acceptance plan should not be modified for projects that include the Safety 

EdgeSM. More importantly, the density, strength, and/or smoothness requirements appropriate 

for a typical project should not be relaxed simply because the Safety EdgeSM is added to a 

resurfacing or new construction project. Thus, the only difference between projects with and 

without the Safety EdgeSM is the slope of the edge itself. 

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January 5, 2012 

SECTION 4: SPECIFIC CONSIDERATIONS FOR CONSTRUCTING 

THE SAFETY EDGESM IN CONJUNCTION WITH NEW CONCRETE 

PAVEMENTS OR CONCRETE OVERLAYS
 

This section identifies issues that need to be monitored during the construction of PCC 

pavements. All of the PCC demonstration projects that were used for preparing this Guide 

included the use of slip-form paving to form the Safety EdgeSM. A benefit of forming the 

Safety EdgeSM during PCC slip-form paving is the sensitivity to edge slump is reduced. 

4.1 Design Features and Shape 

The Safety EdgeSM is designed to create a 30 degree finished angle relative to the pavement 

cross slope as shown in Figure 14 and should be constructed on a similar structural base as 

the adjoining monolithically placed lane/shoulder. During design, the structural base width 

needs to account for the Safety EdgeSM width. 

2 in. Min.

Edge of

Pavement

H

5 in.

Approx.

Shoulder

Backing

Material

* Note, Recommended Rise to Run ratio range 1:1.2 to 1:2.0. The range of slope is equal to 26° to 40°. 

Figure 14. Recommended Safety EdgeSM configuration for PCC pavements and overlays. 

4.2 Equipment – PCC Safety EdgeSM Devices 

This part describes the modifications that must be made to a slip form concrete paver to form 

a Safety EdgeSM. It also notes the essential attributes of a concrete paver that are necessary 

to create an effective Safety EdgeSM. When a slip form paver is not being used, the Safety 

EdgeSM needs to be manufactured or created as part of the forms – one side of the forms will 

have an angle of 30 degrees rather than being vertical. 

Currently, there are no commercially available Safety EdgeSM devices for PCC pavers or 

forms. Custom devices, however, can be fabricated by modifying the finishing pan of the 

paver (refer to Figure 15). The pan is essentially configured to form an inverted curb under 

the pan close to the end gate. The steel components of the assembly need to be robust in 

order to resist bending during paving operations from the force of the plastic PCC. The 

following provides a description of the modifications that were made to a Gomaco paver that 

20 
PCC Placement 

January 5, 2012 

was used on one of the PCC demonstration projects and identifies some of the issues or items 

that should be considered in fabricating the Safety EdgeSM profile. 

	 A template was created for the Safety EdgeSM profile to ensure correct dimensions. 

The template was used to manufacture a stainless steel profile pan of the desired 

shape and dimensions. Portions of the existing profile pan were removed to fit in the 

new Safety EdgeSM profile. 

[Note: The contractor decided against welding the Safety EdgeSM profile to the bottom 

of the existing profile section or pan because of a concern that the welds might tear the 

finished PCC.] 

	 A 2-inch finish tail on the stainless steel Safety EdgeSM profile was fabricated to help 

finish the portion of the edge where it goes from slope to vertical. When going 

through existing intersections, driveways, or where the grade is not exact on the 

outside edge, the 2-inch finish tail did drag in some locations. For the demonstration 

project, the contractor cut one inch off of this tail and it performed well, but cutting 

0.5 inches from the tail would have also worked well. 

	 Adjusting bolts were fitted to the Safety EdgeSM profile pan. One adjustment bolt was 

on the sloped section in case an adjustment had to be made if the edge profile was not 

finishing properly. 

	 In setting up the paver, care was taken to position the vibrators in the specific 

locations for proper consolidation of the Safety EdgeSM–near the breakpoint. 

Unlike the Safety EdgeSM attachments for AC layers or overlays, the modifications made to 

the concrete paver cannot be easily removed and replaced. The modifications can be 

removed, but the parts must be cut from the pan using a torch or grinder. Touchup of the pan 

is required to return the unit to service on standard PCC pavements. 

4.3 Concrete Mixtures 

Demonstration projects completed to date have used standard concrete mixes. No changes to 

the mix were needed to accommodate the SE. 

4.4 Safety EdgeSM Construction 

This part of the Guide discusses items of interest to PCC paving projects when a Safety 

EdgeSM is to be placed as part of the new construction or rehabilitation project. 

Normal paving procedures are usually sufficient for forming the Safety EdgeSM on mainline 

sections of the roadway using slip form paving operations and equipment. Material 

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Transitioning Between Different Edge Profiles 

January 5, 2012 

properties of the hardened concrete from the edge and the interior of the pavement have been 

demonstrated to be similar. 

Safety EdgeSM device 

Figure 15. View of the Safety EdgeSM device from front of paver. 

It is recommended to have a transition from a no Safety EdgeSM section to a Safety EdgeSM 

section to avoid a vertical edge perpendicular to traffic (i.e. similar to beginning section of 

bridge concrete rail/parapet where the bottom of the rail/parapet is modified to reduce the 

probability of vehicle tire snagging). 

An important issue to be addressed is the intersection of cross roads where a vertical edge is 

required. Due to the fixed nature of the edge and shoe assembly, the contractor can consider 

different options depending on the number and extent of sections with different edge profiles. 

In either case, additional labor should be anticipated to tie into intersections or other areas 

requiring different edge profiles when paving using the Safety EdgeSM concept. The 

following provides an overview of the two options that were used on some of the 

demonstration projects. 

	 If there are only a few intersecting roadways, driveways or limited areas where a 

vertical face is required along the edge of the pavement, the contractor can consider 

placing the safety edge using normal paving operations. The Safety EdgeSM is sawcut 

22 
Vibration 

Sawcutting 

January 5, 2012 

and removed to create a vertical edge. The sawing of the Safety EdgeSM can be 

completed at the same time the transverse joints are sawed. This option has worked 

fine, but does waste some PCC and requires additional sawing. 

	 Another option is to box out the areas requiring different edge profiles and place 

forms. The PCC in these limited areas is placed by hand using normal construction 

practices in order to tie into pavement intersections, driveways, and other features. 

Generally, the standard spacing of the vibrators are sufficient to properly consolidate the 

fresh concrete at the Safety EdgeSM. Consolidation of the material within the Safety EdgeSM 

should be checked at the start of any project. If slip form pavers are not being used, hand 

vibrators need to be used to ensure that the PCC flows into the lower part of the Safety 

EdgeSM. As noted at the beginning of this section, all demonstration projects included the use 

of slip form pavers in construction the Safety EdgeSM. 

Curing 

Care should be taken to insure the specified curing procedures are properly followed for all 

surfaces at the edge of the pavement, including the Safety EdgeSM. The Safety EdgeSM, 

however, does not require any special curing requirements beyond that for typical PCC 

layers. 

Transverse control joint sawcutting can be stopped at the breakpoint of the Safety EdgeSM 

and not continued through the sloped surface of the edge. Experience shows the contraction 

cracks normally form at the end of the sawcut and extend through the Safety EdgeSM as 

planned (refer to Figure 16). 

23 
 

January 5, 2012 

Figure 16. Sawcut and crack at the formed joint on one of the Safety EdgeSM demonstration 

projects. 

4.5 Quality Measurement 

The same properties used or identified by the owner agency to measure the quality of PCC 

pavement layers for acceptance should also be used on projects that include the Safety 

EdgeSM. The acceptance plan should not be modified for projects that include the Safety 

EdgeSM. More importantly, the air void content, strength, and/or smoothness requirements 

appropriate for a typical project should not be relaxed simply because the Safety EdgeSM is 

added to a PCC overlay or new construction project. Thus, the only difference between 

projects with and without the Safety EdgeSM is the slope of the edge itself. 

24 
 

January 5, 2012 

REFERENCES 

EDC Safety EdgeSM field reports can be found at: 

http://www.fhwa.dot.gov/everydaycounts/technology/safetyedge/field_reports.cfm 

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January 5, 2012 

APPENDICES 

Safety EdgeSM guide specification can be found at: 

http://www.fhwa.dot.gov/everydaycounts/technology/safetyedge/specs.cfm 

26