Rural Roadway Departure

Countermeasure Pocket Guide
Introduction

Each year in the U.S., nearly 12,000 people die when their car leaves its travel lane on a rural road. 

That is more than 30 people today, and every day.

It is easy to overlook how serious a problem this is because those deadly crashes happen in 

random locations across vast rural roadway networks. Based on data from the National Highway 

Traffic Safety Administration’s (NHTSA) Fatal Analysis Reporting System, these crashes account for 

roughly 30 percent of our nation’s annual roadway deaths.

Solutions exist. There are many cost-effective countermeasures that are proven to reduce 

rural roadway departures. This guide is meant to help you make smart choices about the 

countermeasures that fit best in your community, based on your data and experience. Use it to 

start reducing rural roadway departure crashes on your roads today.
Purpose of this Guide

The purpose of this guide is to provide you a quick reference of options for reducing roadway 

departure crashes in your community. The countermeasures in this guide are organized around 

three objectives:

1. Keep vehicles in their lane.

2. Reduce the potential for crashes if they do leave their lane.

3. Minimize the severity of a crash if there is one.

Each countermeasure addresses a specific crash type and can be used to accomplish the above 

goals. There is also information about where to use the countermeasure, crash reduction data, 

considerations, and ways to enhance their effectiveness.

This guide is not exhaustive but is designed to provide you a menu of common options to choose 

the countermeasures that work best for you.
Countermeasure Effectiveness

Throughout this guide, you will see references to crash reduction factors (CRF), which are based 

on crash modification factors (CMFs). The FHWA maintains the Crash Modification Factor 

Clearinghouse (www.cmfclearinghouse.org) as a searchable source for identifying countermeasure 

effectiveness and additional resources for using CMFs to estimate project benefits.

A CMF is used to estimate the expected number of crashes at a location after installing a 

countermeasure. A CRF provides the expected crash reduction for a target crash type and severity 

when installing the countermeasure.

For example, a countermeasure CMF from the clearinghouse of 0.70 is equivalent to a CRF of 30 

percent. The CRFs in this guide are primarily for non-intersection crashes on 2-lane rural roads, and 

may only apply to certain target crash types, as indicated.

This guide provides the CMF ID for each CRF, if applicable, which may be searched in the CMF 

Clearinghouse to find more information on applicability and expected effectiveness.
Countermeasure Summary Table by Roadway Departure Objective



Primary countermeasure for 

this type of crash



Countermeasure to consider

L:

Low-cost – up to $5,000 per 

mile or per curve/location

M:

Medium-cost – $5,000 to 

$50,000 per mile or per curve/

location

H:

High-cost – More than $50,000 

per mile or per curve/location

Table Key Objective Countermeasure

Target Crash Types Cost

H-M-L

Option on 

Narrow 

Roads*

Option on 

Unpaved 

Roads

More 

Details on 

Head-On Roll over Fixed Object Curve Page

Keep Vehicles 

in Lane

Edge Line Markings    L  5

Center Line Markings   L 5

Curve Warning Signs    L   7

Delineators    L   9

Shoulder Rumbles    L 11

Center Line Rumbles   L 11

HFST  M  10

Reduce 

Potential for

a Crash

Shoulder Widening     M-H  13

SafetyEdgeSM    L  15

Center Line Buffer Area  L 17

Removed Fixed Objects   L-H   14

Slope Flattening   M-H   18

Minimize 

Severity

Roadside Barriers    M-H   19

Breakway Features    L   21

*For the purpose of this guide, narrow roads are defined as a two-way road with less than 20 feet of total traveled way.
Description

Edge and center lines delineate the edges of the lane and provide a preview of 

alignment changes. They provide a visual reference to guide motorists and help 

reduce drifting into opposing lanes or onto the shoulder and roadside area.

Markings that must be visible at night are required by the Manual of Uniform Traffic 

Control Devices (MUTCD) to be retroreflective unless ambient illumination assures 

they are visible.

Where to Use

The MUTCD Part 3 contains requirements and recommendations for edge lines and 

center lines. The recommendations vary based on traffic volume, functional class 

and pavement width. Studies indicate adding edge lines to lower volume roads 

results in crash reductions as indicated by the CRFs below.

Edge Line and Center Line Markings

Source: Thurston County, WA

5
Effectiveness

Retroreflective edge and center line pavement markings can 

reduce:

• Curve crashes

• Run-off-road crashes

• Nighttime crashes

• Head-on Crashes

Enhancements and Considerations

Wider edge lines (6-inch to 8-inch) reduce injury crashes by 37 

percent (CMF ID 4737) compared to 4-inch edge lines.

High-build paint, thermoplastic or other durable marking materials can provide a longer life, thus reducing maintenance and 

worker exposure. 

Raised pavement markers (RPMs) or wet reflective markings 

can increase nighttime visibility.

CRFs for Rural 2-Lane Roads

Add Edge and Center Lines – 24% (CMF ID 101)

Add Edge Lines – 15% (CMF ID 10243) or 

19% for severe crashes (CMF ID 10244)

Add Edge Lines on Curves – 26% (CMF ID 1939)

Source: Thurston County, WA

6
Description

Advance curve warning signs alert a driver to changes in the road alignment, 

advisory speed plaques warn drivers of appropriate speed reduction, and chevrons 

delineate the curve. 

Where to Use

The MUTCD Part 2 contains standards for horizontal alignment warning signs 

based on functional class, traffic volume, and the difference be tween the speed 

limit and advisory speed. The types of signs to which the MUTCD standards and 

guidance apply include:

• Advance warning signs, such as curve, turn, and winding road signs

• Advisory speed plaques 

• Chevrons or large arrow signs

Curve Warning Signs

Source: FHWA

Source: FHWA

7
Effectiveness

Advance curve warning signs and chevron alignment signs can reduce:

• Curve crashes

• Run-off-road crashes

• Nighttime crashes

Enhancements and Considerations

A large arrow sign may supplement chevron alignment signs, or be used as 

an alternative for short curves or where conditions make chevron sign placement difficult.

Options to make warning signs more noticeable include: 

• Oversized or doubled-up signs

• Retroreflective strips on sign posts

• Fluorescent yellow sheeting (particularly effective at dusk or dawn). 

This can reduce injury crashes by 25 percent (CMF ID 2433).

• Flashing beacons or dynamic curve warning systems

CRFs for Rural 2-Lane Roads

Add Chevrons 

 • 16% for injury crashes (CMF ID 2438)

 • 25% for nighttime crashes (CMF ID 2439)

Source: FHWA

8
Description

Post mounted delineators are retroreflective devices 

mounted above the roadway surface and along the side 

of the road in a series to communicate the roadway alignment to the driver.

Where to Use

Can be used on unpaved roads and on paved roads 

with or without pavement markings. Can also be used in 

curves where chevrons are not required.

The MUTCD Part 3 requires the retroreflective 

delineator to match the color of the edge line. 

This means white delineators on both sides of 

two-lane roads.

Delineators

CRFs for Undivided Roads

Installing delineators, center lines 

and edge lines in combination – 

45% reduction in injury crashes 

(CMF ID 102).

Effectiveness

Delineators can reduce: 

• Curve crashes

• Run-off-road crashes

• Nighttime crashes

• Wet or snowy weather 

crashes

Source: FHWA

Source: FHWA

9
Description

HFST provides durable skid resistant properties at high friction demand locations 

like curves, intersections, and downgrades. HFST is comprised of a special 

aggregate (calcined bauxite) that is bonded to the pavement with a polymer resin 

binder.

Where to Use

At locations with poor pavement friction, high friction demand, or a history of 

wet-pavement related crashes.

Effectiveness

HFSTs can reduce:

• Curve and intersection crashes

• Run-off-road crashes

• Wet weather crashes

High Friction Surface Treatments (HFST)

CRFs for Rural 2-Lane Roads

Injury – 48% (CMF ID 10333)

Run-off-road – 72% (CMF ID 10334)

Wet road – 83% (CMF ID 10335)

Source: FHWA

10
Description

Center line and shoulder rumble strips are milled corrugations in the pavement to 

alert inattentive drivers that they are leaving the roadway. 

Where to Use

Consider center line rumble strips in both passing and no passing zones where risk 

factors, such as traffic volume, indicate a higher probability of head-on crashes. 

Consider shoulder rumble strips where risk factors indicate a higher probability of 

run-off-road crashes.

Effectiveness

Center line and shoulder rumble strips can reduce:

• Head-on crashes

• Run-off-road crashes

• Distracted/drowsy driver crashes

• Fixed object crashes

• Rollovers

Center Line and Shoulder Rumble Strips

Source: FHWA

11
Enhancements and Considerations

Placing pavement markings directly on top of 

rumble strips can improve nighttime visibility. 

Consider adjusting dimensions, offset, and gaps 

when in noise sensitive areas or when bicycle or 

other non-motorized vehicle traffic is expected.

Address pavement quality issues prior to 

installation. If chip sealing is anticipated in the 

future, a deeper rumble should be considered.

Shoulder rumble strips may be combined with 

shoulder widening and SafetyEdgeSM to enhance 

their effectiveness and to improve conditions for 

non-motorized users.

CRFs for Rural 2-Lane Roads

Add Center Line Rumble Strips

– 45% Injury Roadway Departures (CMF ID 3360)

Add Shoulder Rumble Strips

– 36% Injury Roadway Departures (CMF ID 3454)

Source: FHWA

12
Description

Adding a paved shoulder provides an errant driver an opportunity to regain control. 

Where to Use

Corridors with no shoulders or with narrow 

shoulders where risk factors, such as 

traffic volume, indicate a higher probability 

of roadway departure crashes. Can also 

be used for specific locations such as 

horizontal curves.

Effectiveness

Shoulders can reduce all roadway 

departure crash types.

Shoulder Widening

Before

After

Source: FHWA

Source: FHWA

13
Description

Establishing and maintaining a clear zone provides an unobstructed, traversable 

area where an errant driver can recover to reduce fixed object crashes.

Where to Use

Where there are fixed objects located close to the edge of the traveled way, particularly on the outside of horizontal curves, or where risk factors such as speed and 

traffic volume indicate a higher probability of roadway departure crashes.

Remove Fixed Objects

CRFs on Rural 2-Lane Roads

Tree Crashes

 – increase 3 ft, 22% 

 – increase 5 ft, 34% 

 – increase 10 ft, 57% 

 – increase 15 ft, 71%

Source: NCHRP Report 440

Effectiveness

Removing trees, poles, fences, mailboxes, headwalls, and guardrail have 

been proven to reduce fixed object 

crashes.

Source: FHWA

Source: FHWA

14
Description

SafetyEdgeSM eliminates tire scrubbing due to vertical edge drop-offs, improving 

driver control as the vehicle returns to the pavement after a roadway departure. A 

paver attachment forms the SafetyEdgeSM – a consolidated 30 degree edge.

Where to Use

Paving projects where curbs are not present.

SafetyEdgeSM

Effectiveness

SafetyEdgeSM can reduce: 

• Run-off-road crashes

• Head-on crashes

• Rollovers Typical drop-off crash with tire scrubbing

Source: FHWA

15
Considerations and Enhancements

Cost is negligible for asphalt overlays and it improves pavement edge 

durability. There is additional cost when installing on concrete pavement.

After paving, the adjacent graded material should be brought back up 

flush with the pavement surface.

This treatment can be combined with shoulder widening and rumble 

strips to enhance effectiveness.

CRFs on Rural 2-Lane Roads

Drop-Off Crashes – 35% (CMF ID 9671)

Run-off-Road – 21% (CMF ID 9661)

Head-On – 19% (CMF ID 9662)

Injury Crashes – 11% (CMF ID 9660)

Source: FHWA

Source: FHWA

16
Description

A center line buffer area provides extra space between the two solid center 

line markings, further separating opposing directions of traffic.

Where to Use

In no-passing zones with enough right-of-way, where risk factors such as 

traffic volume indicate higher probability of head-on crashes.

Enhancements and Considerations

Center line rumble strips may be provided 

within the buffer area.

Consider impacts of pavement and shoulder 

width as well as edge drop-offs and other 

roadside conditions when restriping existing 

pavement to add or widen center line buffer 

area.

Effectiveness

Center Line Buffer Areas can 

reduce head-on crashes.

Center Line Buffer Area

Crash Reduction on Rural 

2-Lane Roads

Head-on Crashes

 – 2 ft buffer, 35% 

 – 4 ft buffer, 64%

 – 10 ft buffer, 90% 

Source: NCHRP Project 17-66

Source: FHWA

17
Description

Flattening steep sideslopes increases driver ability to keep the vehicle stable, 

regain control of the vehicle, and avoid obstacles.

Where to Use

Roadsides with non-traversable sideslopes located close to the edge of the 

traveled way where risk factors, such as traffic volume, indicate a higher probability 

of roadway departure crashes. Slope flattening on the outside of curves is 

particularly important. Consider grading barn-roof

designs to one consistent, recoverable slope.

Effectiveness

Slope flattening can reduce:

• Rollovers

• Run-off-road crashes

Slope Flattening

Crash Reductions (%) for

Single Vehicle Crashes

Before 

Sideslope

After Sideslopes

1V:4H 1V:5H 1V:6H

1V:2H 10 15 21

1V:3H 8 14 19

1V:4H - 6 12

1V:5H - - 6

Source: AASHTO Highway Safety Manual

18

Source: Google Maps

Source: FHWA

Before

After
Roadside Barriers

Effectiveness

Roadside barriers can reduce the 

severity of:

• Rollovers

• Fixed object crashes

• Other run-off-road crashes

Description

Roadside barriers are designed to redirect and slow vehicles while 

shielding them from obstacles likely to result in a more severe crash, such 

as rigid fixed objects, steep slopes, or bodies of water.

Where to Use

Roadsides with non-traversable slopes or fixed objects located close to 

the edge of the traveled way where risk factors, such as traffic volume, 

indicate a higher probability of roadway departure crashes. Typically 

provided when delineation and signing are not sufficient, it is not feasible 

to clear obstacles or flatten side slopes, and the likelihood of harm from 

striking the shielded object is greater than the harm from striking the 

barrier system.

Source: FHWA

19
Enhancements and Considerations

The crashworthiness of barriers is evaluated through 

crash testing. AASHTO and FHWA encourage 

developers of safety hardware to use the AASHTO 

Manual for Assessing Safety Hardware (MASH) 2016.

Consideration should be given to barrier type. 

More flexible barrier types may result in less severe 

crashes; however, more rigid barriers require less 

maintenance. Additionally, barrier deflection should 

be considered when shielding fixed objects. 

Barriers can be enhanced with supplemental 

delineators. This can reduce nighttime crashes on 

horizontal curves by 14 percent (CMF 10307).

Crash Reduction on Rural 2-Lane Roads

Injury Crashes – 48% (FHWA-HRT-21-076)

Source: Kitsap County, WA

20
Breakaway Features

Description

Roadside signs, luminaire supports, and utility poles can be designed to have 

features that will allow them to breakaway in a controlled manner when hit by a 

vehicle in a roadway departure.

Where to Use

Roadsides, within the clear zone, where the sign or 

support is not shielded and cannot be removed or 

relocated. Supports should be designed properly and 

carefully located to minimize the likelihood of impact by 

errant vehicles or that the breakaway mechanism is not 

impacted by environmental conditions.

Effectiveness

No reliable safety effectiveness evaluations have been 

conducted to date that indicate the amount of crash 

Source: FHWA Source: FHWA reduction to be expected.

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Edge and Center Line Striping: https://safety.fhwa.dot.gov/roadway_dept/night_visib/pavement-markings.cfm

Curve Warning Signs: https://safety.fhwa.dot.gov/provencountermeasures/enhanced_delineation

Center Line and Shoulder Rumble Strips: https://safety.fhwa.dot.gov/roadway_dept/pavement/rumble_strips

High Friction Surface Treatment: https://safety.fhwa.dot.gov/roadway_dept/pavement_friction

Remove Fixed Objects: https://safety.fhwa.dot.gov/roadway_dept/countermeasures/safe_recovery/clear_zones

SafetyEdgeSM: https://safety.fhwa.dot.gov/safetyEdge

Barriers: https://safety.fhwa.dot.gov/roadway_dept/countermeasures/reduce_crash_severity/

Manual on Uniform Traffic Control Devices: https://mutcd.fhwa.dot.gov/

Links for More Information

Scan the QR Code for each URL

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FHWA-SA-21-064

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation (USDOT) in the interest of information 

exchange. The U.S. Government assumes no liability for the use of the information contained in this document. 

Unless otherwise indicated, the source of all tables, graphics, and photos in this document is FHWA.

Use of the countermeasures in this guide are voluntary and are not required under federal regulations except as provided in the MUTCD.

The contents of this document do not have the force and effect of law and are not meant to bind the public in any way. This document is 

intended only to provide information to the public regarding existing requirements under the law or agency policies.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a 

manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, 

and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous 

quality improvement.