What is the Safety Edge?

The Safety Edge is a simple but effective solution 

that can help save lives by allowing drivers who drift 

off highways to return to the road safely. Instead of 

a vertical drop-off, the Safety Edge shapes the edge 

of the pavement to 30 degrees. Research has shown 

this is the optimal angle to allow drivers to re-enter 

the roadway safely. The asphalt Safety Edge provides 

a strong, durable transition for all vehicles. Even at 

higher speeds, vehicles can return to the paved road 

smoothly and easily. The FHWA’s goal is to accelerate 

the use of the Safety Edge technology, working 

with States to develop specifications and adopt this 

pavement edge treatment as a standard practice on 

all new paving and resurfacing projects.

The Safety Edge

A Pavement Edge Drop-Off 

Treatment

FAQs

Why should I change my current process to 

include the Safety Edge? 

The Safety Edge improves the short- and long-term 

safety of the roadway. Studies show that severe crashes 

may occur when a vehicle drops a tire over the edge 

of a nearly vertical pavement. The research shows that 

virtually all drivers can recover, even at high speeds, 

when the pavement edge is a 30-degree wedge. Using 

the Safety Edge also improves the durability of the 

pavement edge. 

Do I need to modify my paving process to install 

the Safety Edge on asphalt? 

Very few changes are needed. The key item is to 

add a specially designed shoe, per manufacturer’s 

instructions, to the paver to create the Safety Edge. 

While paving, the shoe should be monitored and 

adjusted to keep the bottom edge of the device in 

contact with the road shoulder surface. Using the 

Safety Edge should not affect the rate of production.

How much will the addition of the Safety Edge 

cost per mile?

It will be almost negligible for hot-mix asphalt. It does 

depend somewhat on the specific design and construction 

parameters, but typically the process compacts asphalt 

that often otherwise would break off because it was loose. 

When measured, it has been calculated to be less than 

1 percent additional asphaltic material. 

Contact Information

For training or more information on 

this Every Day Counts Initiative, please 

contact your local FHWA Division Office. 

To learn more about EDC, visit: 

http://www.fhwa.dot.gov/everydaycounts

The Safety Edge is shown here in the main photo 

during construction. Upon project completion, the 

adjacent unpaved material should be graded flush 

with the top of the pavement (inset photo). The 

Safety Edge creates a more durable pavement edge 

and makes recovery from any future drop-off much 

easier and safer. 

About Every Day Counts

Every Day Counts is designed to identify 

and deploy innovation aimed at shortening 

project delivery, enhancing the safety of our 

roadways, and protecting the environment.

This diagram shows how the Safety Edge is created 

during a repaving project. As the new graded material 

begins to settle or erode, the angled and more durable 

Safety Edge prevents a vertical edge from forming, 

making the pavement edge safer for drivers and cyclists.

30°

Reasonably Safe

Unsafe

Questionable

Safety

Marginally

Safe

Safe

Publication Number: FHWA-SA-10-034
Quick Facts

•	 The Safety Edge can help decrease highway

fatalities and serious injuries on our Nation’s 

highways.

•	 Because the Safety Edge provides an additional

level of consolidation on the edge, edge raveling 

is decreased. This contributes to longer pavement 

life. 

•	 The Safety Edge involves minimal time and cost

to implement. Typically, less than 1 percent 

additional asphalt is needed. The Safety Edge 

shoe, which creates the edge, can be installed on 

existing equipment. 

•	 The Safety Edge also can be installed on Portland

Cement concrete pavements. (Several differences 

should be considered. For more information, visit 

the Safety Edge Web site for details.) 

•	 Best practice isto maintain a flush edge,so that no

drop-off exists. The Safety Edge reduces the risk of 

drop-offs when maintenance forces cannot keep 

up with erosion or tire wear. 

•	 Vertical and near vertical pavement edge dropoffs have been a factor in a substantial percentage 

of severe crashes in which vehicles leave the 

road, particularly on rural roads with unpaved 

shoulders. The Safety Edge reduces this problem, 

providing a safer transition back to the road. 

•	 The Safety Edge is a safer design for motorcyclists

and bicyclists, as well as motorists.

How Does It Work?

Drivers leave the paved road for many reasons. 

When steering the tires back onto the pavement, 

a vertical edge can make it difficult for a driver to 

safely re-enter the travel lane. Drivers may oversteer and lose control of the vehicle, leading to 

severe crashes. The challenge is that a drop-off is 

created during most paving projects. Even when the 

unpaved shoulder is regraded to eliminate the dropoff, the edge often becomes exposed within a few 

months. The edge also may deteriorate. 

The Safety Edge is an effective solution to reduce 

pavement edge-related crashes, by shaping the edge 

of the pavement to 30 degrees using a commercially 

available device (called a shoe) that can be attached 

to the paver. The asphalt is extruded under the shoe, 

resulting in a durable edge that resists edge raveling. 

Research has shown this 30-degree shape allows 

drivers to re-enter the roadway safely.

After paving with the Safety Edge, the adjacent 

materialshould be regraded flush with the top of the

pavement. This is considered the best practice, and 

provides the safest pavement edge. The difference is 

that when the edge becomes exposed, this shape can 

be more safely traversed than a vertical edge.

Case Study: Iowa Adopts Safety 

Edge Policy

The Iowa FHWA Division and the Iowa Department of 

Transportation (IDOT) recently began working with 

counties to install the Safety Edge on projects with 

a history of roadway departure crashes. The Safety 

Edge was included at the county level on project 

plans or incorporated as change orders on alreadylet projects. During one of these county projects, 

the contractor’s safety officer felt positive about the 

results because the Safety Edge potentially reduced 

the contractor’s liability by providing immediate 

elimination of the vertical drop-off. 

After seeing how easily even large vehicles could 

traverse the pavement edge without loss of control 

or damaging the edge, the county decided its typical 

practice of bringing in a gravel wedge before 

nightfall was not necessary when the Safety Edge 

was present. The results were so positive that IDOT 

decided to use the Safety Edge on one of its State 

paving projects on a narrow road. Since then, IDOT 

has decided to adopt the Safety Edge as standard 

practice across the entire State. 

Pavement Edge Drop-Offs Can 

Contribute to Crashes

Roadway departures account for 53 percent of fatal 

crashes. State-level studies point to the life-saving 

potential of the Safety Edge. For example, researchers 

studying crashes in Missouri during 2002-2004 reported 

that pavement edges may have been a contributing 

factor in as many as 24 percent of rural run-off-road 

crashes on paved roadways with unpaved shoulders. 

This type of crash was twice as likely to include a 

fatality than rural crashes overall on similar roads.1

When a driver drifts off the roadway and tries to steer 

back onto the pavement, a vertical pavement edge 

can create a “tire scrubbing” condition that may result 

in over-steering. If drivers over-steer to return to the 

roadway without reducing speed, they are prone 

to lose control of the vehicle. The resulting crashes 

tend to be more severe than other crash types. The 

vehicle may veer into the adjacent lane, where it may 

collide with oncoming cars; overturn; or run off the 

opposite side of the roadway and strike a fixed object 

or overturn on a slope. 

Inexperienced drivers are not the only victims of tire 

scrubbing. Smaller, lighter vehicles have a harder time 

climbing a steep pavement edge. At high speeds, 

the climb is particularly dangerous. According to inservice evaluations, a vertical or near vertical drop-off 

of 2.5 inches or greater has been shown to pose a 

significant risk, while pavements built with the Safety 

Edge showed reductions of more than 5 percent of 

total crashes .

The shoe that creates the Safety Edge is a special edging 

device that asphalt paving contractors can install on new 

or existing resurfacing equipment.

Sharp, steep pavement edge drop-offs can contribute 

to crashes.

Safety Edge treatment being applied during an 

asphalt overlay.

This is a typical diagram for a crash caused by tire 

scrubbing. The vehicle at left scrubbed the edge 

of the pavement, and when it returned, the driver 

overcorrected, lost control, crossed into the adjacent 

lane, and struck an oncoming vehicle.

 (Graphic source: AAA Foundation for Highway Safety)

1

Hallmark et. al: Safety Impacts of Pavement Edge Drop-Offs, AAA 

Foundation for Highway Safety, Washington, DC, September 2006.