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FHWA-SA-11-09

Roadway Departure Safety

A Manual for Local Rural Road Owners
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FHWA-SA-11-09

Roadway Departure Safety: A Manual for Local 

Rural Road Owners

The Contracting Officer’s Task Manager (COTM) for this document was Rosemarie Anderson, FHWA Office 

of Safety.

The Technical Oversight Working Group included John Dewar, Cathy Satterfield, Joseph Glinski, and David 

Morena, FHWA; David Engstrom, MNDOT; Stephen Ford, Mendocino County (CA); John Goodknight, 

Marion County (FL) ; Dale Wegner, Coconino County (AZ); Jim Wiechart, Mercer County (OH); Benjamin 

Colucci, Puerto Rico LTAP; and Nick Jones, Utah LTAP. 

According to the Federal Highway Administration, over 6 million lane-miles are in rural areas, and more 

than two-thirds of these rural roads are owned and operated by local entities. Rural areas face a number of 

highway safety challenges due to the nature of their facilities. Roadway departure crashes are frequently 

severe and account for the majority of fatalities in rural areas. 

This document provides information on effectively identifying roadway departure safety issues in local 

areas, choosing the countermeasures that address them, and evaluating the benefits of those treatments. 

It is geared toward local road managers and other practitioners with responsibility for operating and 

maintaining their roads. This document offers information on the procedures and processes to improve the 

safety of local rural roadways and to reduce the potential for future roadway departure crashes. 

Science Applications International Corporation (SAIC)

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Office of Safety

Federal Highway Administration

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Golembiewski, G.A. and Chandler, B.

Roadway Departure, Lane Departure, Safety, Final Report, Local, Rural, Run Off Road, Crashes, Systematic, 

Countermeasures, Analysis

No restrictions. 

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2. Government Accession No. 3. Recipient’s Catalog No.
Table of Contents

1 Introduction and Purpose ......................................................................1

1.1. The Roadway Departure Crash Problem ............................................2

1.2. Implementation Approaches..................................................................3

Systematic Approach .................................................................................................3

Spot Location Approach ..........................................................................................4

Comprehensive Approach .....................................................................................4

1.3. State Safety Plans........................................................................................5

Strategic Highway Safety Plans (SHSP) ...........................................................5

Roadway Departure Safety Implementation Plans .................................6

1.4. Information in this Document................................................................6

2 Identifying Safety Issues ......................................................................11

2.1. State and Local Crash Databases........................................................ 12

2.2. Law Enforcement Crash Reports........................................................ 13

2.3. Field Assessments.................................................................................... 13

2.4. Observational Information................................................................... 14

2.5. Public Notifications................................................................................. 15

2.6. Roadway Data ........................................................................................... 16

2.7. Exposure Data ........................................................................................... 16

3 Safety Analysis........................................................................................19

3.1. Quantitative Analysis.............................................................................. 19

Crash frequency .........................................................................................................19

Crash Rate........................................................................................................................20

3.2. Qualitative Analysis................................................................................. 20

Field Assessment .......................................................................................................20

Ensuring Compliance with MUTCD Standards .......................................21

4 Countermeasures ..................................................................................23

4.1. Select Roadway Departure Countermeasure ................................ 24

5 Evaluations ............................................................................................37

i | Roadway Departure Safety
6 Case Studies ...........................................................................................38

6.1. Low-cost Local Safety Solutions: Douglas County, Georgia ..... 38

6.2. Engineering and Enforcement Safety Solutions: 

Contra Costa County and Alameda County, California.............. 39

6.3. Signing and Marking Improvements: 

Mendocino County, California ............................................................. 40

6.4. Local Road Safety Audits: Cape May County, New Jersey ......... 41

7 Summary ............................................................................................43

Appendix A Additional Resources............................................................A-1

Appendix B 2009 MUTCD Standards for Traffic Control Devices........B-1

Appendix C Crash Rate Calculations........................................................C-1

List of Tables

Table 1 Spreadsheet to Monitor Roadway Departure Crashes ...17-18

Table 2 Example Table to Monitor Countermeasure Application 

History and Crash/Observational Data.....................................37

Table 3 Example of Roadway Departure Crash Rate Calculation 

by Vehicle Miles Traveled ..........................................................C-1

Table 4 Example of Roadway Departure Crash Rate Calculation 

by Route Length..........................................................................C-2

List of Figures

Figure 1 Steps to Address Roadway Departure Safety........................ 7-8

Figure 2 MUTCD Traffic Control Devices...................................................21

Figure 3 MUTCD Roadside Placement (MUTCD Figure 2A-2).............B-1

Figure 4 MUTCD Examples of Enhanced Conspicuity for Signs

(MUTCD, Section 2A.15).............................................................B-2

Figure 5 MUTCD Example of Warning Signs for a Turn........................B-4

Figure 6 MUTCD Roadside Placement with Plaque .............................B-6

Figure 7 MUTCD Object Markers .............................................................B-9

Roadway Departure Safety | ii
1 | Roadway Departure Safety

1 Introduction and Purpose

Why Has This Manual Been Developed?

Local rural roads vary from two-lane paved highways to gravel or dirt 

roads in mountainous, forest, or tribal areas. A portion of these roadways 

lack basic signing, pavement markings, and appropriate alignment and 

delineation features. In many cases local agencies have no plans for 

improvements due to factors such as funding, low traffic volumes, or 

topographical challenges.

This document provides local road practitioners with relevant 

information to reduce roadway departure crashes on the roadway 

network. It discusses identifying locations with historical or potential 

rural roadway departure issues and countermeasures that address them. 

It offers information on the procedures and processes to improve safety 

by reducing the potential for roadway departure crashes.

Local roads are managed by more than 38,000 counties, villages, towns, 

and tribal governments.1

 Local administrators, township managers, 

and public works officials maintain and operate a variety of road types; 

often roadway safety and infrastructure maintenance may be only a 

small part of their job. The information is geared toward local road 

managers and other practitioners with responsibility for operating and 

maintaining local roads, regardless of safety-specific highway training. 

This document is designed to provide the practitioner with targeted 

information on roadway departure safety.2 It is not intended as a 

comprehensive guide for improving roadway departure crashes. It does, 

however, provide a framework that can be used to assess and improve 

the safety of the local road network and its potential for this type of 

crash.

1 McNinch, T.L. and Colling, T.K. “Traffic Safety Education for Nonengineers.” Public Roads, May/June, 

2009, pp 32-39.

2 The Federal Highway Administration (FHWA) defines roadway departure crashes as, “a nonintersection crash which occurs after a vehicle crosses an edge line or a center line, or otherwise 

leaves the traveled way.”
Roadway Departure Safety | 2

1.1. The Roadway Departure Crash Problem

In 2008 the Fatality 

Analysis Reporting System 

(FARS) indicated that 56 

percent of fatalities on 

U.S. roadways occurred 

in rural areas. This is out 

of proportion, since rural 

roadways account for just 

40 percent of all vehicle 

miles traveled nationally.3

 

There were 17,818 fatal roadway departure crashes in the same year, 

which was 53 percent of the fatal crashes in the United States.4 More 

than 28 percent of all fatal crashes were associated with horizontal 

curves. The average crash rate for horizontal curves is about three times 

that of other types of highway segments. About three-quarters of curverelated fatal crashes involve a single vehicle leaving the roadway and 

striking trees, utility poles, rocks or other fixed objects, or overturning.5 

Eleven percent are head-on crashes, which are the result of a vehicle 

entering the opposing lane.6 This can occur when a driver enters the 

opposing lane to maintain speed around the curve, or when a driver 

overcorrects after running off the right side of the roadway. 

To reduce the number and severity of roadway departure crashes, safety 

practitioners focus on a hierarchy of three objectives: 

1. Keep vehicles on the roadway;

2. If a vehicle leaves the roadway, provide an opportunity to return to the road 

safely; and 

3. Minimize the severity of a roadway departure crash if it occurs.

A data-based approach to identifying roadways with a history of 

roadway departure crashes and those with the potential for these 

crashes is discussed in this document. Potential locations are based on 

factors such as road geometry and the presence of fixed objects in the 

clear zone. 

3 University of California – Berkeley, Safe Transportation Research and Education Center, “SafeTrec – 

Rural Road Safety” web page, 2009. Available at http://www.tsc.berkeley.edu/research/ruralroads.html 

4 Federal Highway Administration, “Roadway Departure Safety” website. Available at:

http://safety.fhwa.dot.gov/roadway_dept/horicurves/ 

5 University of California – Berkeley, Safe Transportation Research and Education Center, “SafeTrec – 

Rural Road Safety” web page, 2009. Available at http://www.tsc.berkeley.edu/research/ruralroads.html 

6 American Association of State Highway and Transportation Officials, Driving Down Lane Departure 

Crashes: A National Priority, (Washington, DC: April 2008). Available at:

http://downloads.transportation.org/PLD-1.pdf 

Roadway departure 

crashes are frequently 

severe and account for 

the majority of U.S. 

highway fatalities.
3 | Roadway Departure Safety

1.2. Implementation Approaches

When working to reduce roadway departure crashes on the local rural 

road network, the practitioner should consider the implementation 

approach. Typical approaches include: 

•	 Systematic approach;

•	 Spot location approach; and

•	 Comprehensive approach incorporating human behavior issues.

Systematic Approach

For the systematic approach the primary basis is crash types and proven 

safety countermeasures with specific crash locations selected based on 

those types. 

In one application of the systematic approach, common crash types are 

selected from analysis. Locations experiencing these crash types and 

locations with similar geometric features as those experiencing selected 

crash types are chosen and treated systematically with low cost proven 

safety countermeasures. 

Another application of the systematic approach begins with identifying 

low-cost, effective countermeasures to common traffic safety issues. 

Once a basic set of countermeasures is identified, the crash data system 

is analyzed to choose locations where the countermeasures can be costeffectively deployed. Estimates of the impacts of implementation can be 

made in terms of deployment cost and the benefits measured in traffic 

crash reduction. 

Benefits of the systematic approach may include:

•	 Widespread effect. The systematic approach can impact safety issues at 

a large number of locations on an entire local roadway network.

•	 Crash Type Prevention. Using predominant crash types with a high 

or moderate level of crashes, an agency can address locations that have 

not yet experienced these crash types, but have similar characteristics 

to locations with such crash histories (e.g., geometric conditions, traffic 

volume).

•	 Cost-effectiveness. Implementing low-cost solutions across an entire 

system can be a more cost-effective approach to addressing system-wide 

safety.

•	 Reduced data needs. The systematic approach can be used without 

detailed crash history for specific locations, thereby reducing data needs. 
Roadway Departure Safety | 4

Drawbacks of the systematic approach may include:

•	 Justifying improvements can be difficult. Because this approach does 

not always address locations with a history of crashes with recommended 

treatments, it can be difficult to justify improvements at locations without a 

crash history. The systematic approach will rarely include a recommendation 

for a large-scale safety improvement at a single location. Since these are 

the types of projects that garner attention from decision makers, the media, 

elected officials, and the general public, it can require additional effort from 

the safety practitioner to explain the systematic approach and its benefits to 

those groups.

Spot Location Approach

The spot location approach has typically been based exclusively on 

an analysis of crash history. Due to the fact that some locations in a 

jurisdiction will likely have a significantly higher number of crashes than 

most of the others, it is important to identify those locations and treat 

them accordingly. 

The benefits to the spot location approach may include:

•	 Focus on Demonstrated Needs. The spot location approach focuses 

directly on locations with a history of crashes and addresses those. 

Drawbacks of the spot location approach may include:

•	 Assumption that the past equals the future. This approach assumes 

locations with a history of crashes will continue to have the same number 

and type of crashes in the future.

•	 Minimal overall benefit. This approach often focuses on specific 

locations, and because of this, it is difficult to have a significant impact on 

the entire network.

The spot location approach to traffic safety can be implemented in 

parallel with the systematic approach to provide the best combination 

of safety treatments in a jurisdiction. In addition, the spot location 

approach could be applied to those locations that have had low cost 

countermeasures installed systematically but, after an assessment, 

continue to show a higher than average crash rate.

Comprehensive Approach

The comprehensive approach introduces the concept of the “4 E’s of 

Safety”: Engineering, Enforcement, Education, and Emergency Medical 

Services (EMS). This approach recognizes that not all locations can be 

addressed solely by infrastructure improvements. Incorporating other 

elements is often required to achieve marked improvement in rural 

safety.
5 | Roadway Departure Safety

Some roadway segments will be identified that have frequent 

driving violations for which targeted enforcement is an appropriate 

countermeasure. In general, the most common violations are speeding, 

failure-to-yield, aggressive driving, failure to wear safety belts, and 

driving while impaired. When locations are identified that have reports 

and observations of these violations, coordination with the appropriate 

law enforcement agencies is needed to deploy visible targeted 

enforcement at the identified segments and corridors to reduce the 

potential for future driving violations and related crashes. Education and 

outreach efforts should supplement enforcement to improve the effect 

of each. 

1.3. State Safety Plans

State highway agencies have developed statewide plans to address 

roadway departure safety problems. As local agencies learn about 

their own roadway departure safety needs, the State highway agency 

and State Local Technical Assistance Program (LTAP) office could be of 

assistance.

Strategic Highway Safety Plans (SHSP)

Beginning in 2005, States were required by the transportation legislation 

to develop an SHSP to be eligible for Federal safety funding. An SHSP 

is a statewide-coordinated safety plan that provides a comprehensive 

framework for reducing highway fatalities and serious injuries on 

all public roads. It is developed by the State highway agency in a 

cooperative process with local, State, Federal, and private sector safety 

stakeholders. The SHSP is a data-driven, comprehensive plan that 

establishes statewide goals, objectives, and key emphasis areas and 

integrates the four E’s of safety – engineering, education, enforcement 

and emergency medical services. In most SHSPs, roadway departure is 

listed as a key emphasis area.

The purpose of an SHSP is to identify the State’s safety needs and guide 

investment decisions to achieve significant reductions in highway 

fatalities and serious injuries on all public roads. The SHSP allows all 

highway safety programs in the State to work together in an effort to 

align and leverage its resources. It also positions the State and its safety 

partners to address the State’s safety challenges on all public roads 

collectively.
Roadway Departure Safety | 6

There are two Federally-funded safety programs related to the SHSP that 

are potentially available for local public agency use:

•	 The Highway Safety Improvement Program (HSIP) is a Federal aid program 

focused on improving traffic safety on all public roads with infrastructure 

solutions.

•	 The High Risk Rural Roads Program (HRRRP) is a set aside program from HSIP 

that focuses on addressing rural road safety needs on eligible rural major 

and minor collectors and local rural roads with construction and operational 

improvements.

For additional information about these safety programs and the 

SHSP requirements, see Appendix A for links to the Federal Highway 

Administration (FHWA) websites on each topic.

Roadway Departure Safety Implementation Plans

The Federal Highway Administration currently offers roadway departure 

technical assistance to State highway agencies in the form of crash data 

analysis and implementation plan development. Roadway Departure 

Implementation Plans have been developed for Kentucky, Louisiana, 

North Carolina, Oregon, South Carolina, and Tennessee, with additional 

State plans at various stages of development. Each plan is designed 

to address roadway departure safety issues on both State and local 

roadways. 

In participating States, FHWA has developed a data analysis package 

focused on crash history and roadway attributes for each state, and 

a set of strategies that can be used to reduce roadway departure 

crashes. A set of cost-effective countermeasures, deployment levels, 

and funding needs is identified to reduce the number and severity of 

roadway departure crashes in the State by a certain amount. The final 

plan quantifies the costs and benefits of a roadway departure-focused 

initiative and provides a step-by-step process for implementation.7

1.4. Information in this Document

The purpose of this document is to provide information on effectively 

identifying roadway departure safety issues and countermeasures 

that address them, leading to the effective implementation of safety 

projects to improve safety on affected roadways. This includes pertinent 

information on conducting field reviews, identifying rural roadway 

segments with multiple crashes and/or high potential for future crashes, 

and selecting the appropriate low-cost improvement to implement on 

these roadways.

7 For additional information about this initiative, visit the FHWA Strategic Approach to Roadway 

Departure website at http://safety.fhwa.dot.gov/roadway_dept/strat_approach.
7 | Roadway Departure Safety

Safety issues can be identified by collecting crash history, roadway, and exposure information from the following sources:

•	State and local crash databases

•	Law enforcement crash reports and citations

•	Observations by law enforcement or road maintenance crews

•	Public notifications

•	Hospital records

•	State and local roadway databases

•	Traffic count records

Compile information in a table that includes the source of 

the information, the type of problem, and other attributes of 

the crash, observation, or notification.

Step 1

Identify Roadway Departure Safety Issues

(Manual: Section 2)

Step 2

Record Information for Safety Analysis

(Manual: Table 1)

Steps 3 & 4

Data Analysis, Countermeasure Selection, 

and Installation

Depending on the approach, the order of data analysis, 

countermeasure selection, and countermeasure installation 

steps may vary.

Spot Location Approach 

and Systematic Approach 

(Crash Type Focus)

Systematic Approach 

(Countermeasure Focus)
Roadway Departure Safety | 8

Data can be analyzed in the 

following ways, based on 

available information:

•	Crash frequency

•	Crash rate calculations

•	Qualitative analysis

Details from crash data and 

analysis feed the countermeasure selection process.

•	Warning signs and curve 

delineation

•	Pavement markings and RPMs

•	Rumble strips

•	Other

Step 3

Analyze Data

(Manual: Section 3)

Step 4

Select and Install

Countermeasures

(Manual: Section 4)

Step 5

Assessment and Follow-up

(Manual: Section 5)

Evaluate roadway departure safety treatments after installation.

•	Track countermeasure installations

•	Monitor crash experience at treated locations

Step 3

Select Countermeasures

(Manual: Section 4)

Develop a list of countermeasures and thresholds for 

their application (e.g. crash 

frequency, crash type, traffic 

volumes).

Step 4

Analyze Data and Install 

Countermeasures

(Manual: Section 3 and 4)

•	Search crash data for the 

criteria identified in

Step 3.

•	Determine cost-effective 

level of deployment for each 

countermeasure.

Spot Location Approach 

and Systematic Approach 

(Crash Type Focus)

Systematic Approach 

(Countermeasure Focus)

Figure 1 – Steps to Address Roadway Departure Safety
9 | Roadway Departure Safety

This document is geared toward local road managers and other 

practitioners with responsibility for operating and maintaining local 

roads regardless of training. In many cases, the person responsible for 

highway safety may have multiple responsibilities including public works 

functions such as water and wastewater treatment, trash collection, and 

snow removal. In these cases, roadway safety may be only a small part 

of the job. The document is intended to provide appropriate, focused 

roadway departure safety information in one report. 

This report suggests a process for the planning and implementation 

of roadway departure safety improvements. The processes which are 

discussed in this document can be summarized in Figure 1.

Section 2 provides an overview of the types of data to collect for the 

identification of problem roadway segments. It describes the types of 

information available and how they can be used, and it defines and 

describes various approaches for implementing safety strategies. 

Section 3 summarizes the types of analyses that can be conducted 

to determine if roadway departure countermeasures should be 

implemented. This discussion builds on the information discussed in 

Section 2 and provides definitions and examples of the factors that 

should be considered. 

Section 4 provides a description of selected countermeasures that 

have been shown to improve safety to address roadway departure 

crashes on local rural roads. They include basic countermeasures such 

as standard curve warning signing and curve delineation, and also 

systematic solutions like rumble strips and the safety edge. This section 

also provides an example of a recommended process to document the 

information and the decisions made about the countermeasure(s) to be 

installed. 
Roadway Departure Safety | 10

The process to complete an evaluation of installed treatments is 

presented in Section 5. After the countermeasures are installed, 

assessing their effectiveness will provide valuable information and can 

help determine which countermeasures should continue to be installed 

on other roadways to make them safer as well.

Section 6 includes case studies of local jurisdictions around the country 

addressing roadway departure crashes. Examples include signing 

improvements, enforcement solutions, and road safety audits (RSAs).

Section 7 provides a summary of this manual.

A list of resources and references is presented in Appendix A. This 

list covers numerous topics from publications that focus on roadway 

departure countermeasures, research that supports their use, and 

various studies that document their effectiveness. The Appendix also 

includes references related to Federal safety funding programs that can 

potentially be used by local agencies.

Appendix B presents an overview of the Manual on Uniform Traffic 

Control Devices (MUTCD) minimum requirements for traffic control 

devices most likely to be used in response to roadway departure crashes. 

The MUTCD provides the standards used by road managers nationwide 

to install and maintain traffic control devices on all public streets, 

highways, bikeways, and private roads open to public travel.

Appendix C contains the formulas to calculate the crash rate of roadway 

segments. Additionally, examples are included for crash rates by traffic 

volume and crash rates by length of roadway.
11 | Roadway Departure Safety

2 Identifying Safety Issues 

There are a number of information sources that can be accessed to get 

a picture of the roadway departure issues on the rural roadway network. 

These can be formal information sources or informal sources, including:

•	 Formal sources:

» State and local crash databases;

» Law enforcement crash reports, citations; and

» Field assessments.

•	 Informal sources:

» Observational information from road maintenance crews; and 

» Citizen notification of safety concerns.

Examining the crash history will help practitioners identify locations 

with an existing roadway departure problem, and it will also provide 

information to identify locations that are susceptible to future roadway 

departure crashes. In addition to the location, the data can also provide 

information regarding crash causation. This will provide insights into 

identifying potentially effective countermeasures.

For the systematic treatment of roadway departure crashes based on 

proven low cost countermeasures, the available crash data is used to 

determine where specific crash types are predominant. 

Emphasis on data-driven decisions is indicative of reliability and 

efficiency. The more reliable the data, the more likely the decisions 

regarding safety improvements will be effective. However, detailed, 

reliable crash data are not available in all areas. Under this circumstance 

the practitioner should use the best available information and 

engineering judgment to make the best decisions. 

As a guideline, it is generally accepted that at least 3 years of historical 

data be used for crash history analysis, though additional years of data 

can provide more information. Due to the randomness of crashes in 

a given year, a multi-year average of safety data will smooth outlier 

years of relatively high or low roadway departure crash occurrences. 

If only severe crashes are analyzed (those that resulted in a fatality 

and/or serious injury), more years of data may be necessary for 

effective evaluation. In using data more than 5 years old, however, the 

practitioner should consider possible changes in traffic patterns and 

infrastructure when conducting the analysis.
Roadway Departure Safety | 12

2.1. State and Local Crash Databases

Each state has a central repository for storing crash data. This is generally 

the most comprehensive data for roadway safety analysis, particularly 

if all public roads are included in the database. Several states share this 

information with the local road agencies. Alternatively, many states that do 

not currently share the raw crash data often provide comprehensive data 

analysis to local agencies upon request. 

If the data are available, the local road practitioner can use these data 

to identify locations with multiple roadway departure crashes, conduct 

an analysis that can produce predominant crash types, and identify 

associated roadway features that may have contributed. The local agency 

can work with the State to compare its crashes to those occurring in 

similar areas around the state. 

This information can be used for both spot location treatments and 

systematic deployments, depending on the details of the collected data. 

For example, if a high number of crashes are occurring at a particular 

curve or along a segment of roadway, a spot treatment at that location 

may be appropriate. However, systematic treatment of multiple locations 

experiencing specific crash types or location with the potential for those 

crash types may be necessary.

Action: Obtain at least 3 years of data to identify local roads that have 

a history of roadway departure crashes. Identify predominant roadway 

departure crash sub-types and other common characteristics. 

Begin a spreadsheet of crashes, law enforcement reports, and citizen 

notifications by starting with crash history data (see Table 1). This can serve 

as a database to help an agency identify common crash characteristics 

and identify the appropriate countermeasures. 
13 | Roadway Departure Safety

2.2. Law Enforcement Crash Reports 

Both State and local law enforcement officials can be an important source 

of roadway departure crash data. Law enforcement crash reports can be 

valuable in identifying the location and contributing circumstances to 

roadway departure crashes. For these crash types, the following variables 

(at a minimum) should be extracted and compiled from the crash reports:

•	 Location;

•	 Date and time;

•	 Crash type;

•	 Crash severity;

•	 Weather conditions;

•	 Light conditions;

•	 Sequence of events; and

•	 Contributing circumstances.

The local practitioner using multiple sources of law enforcement crash 

reports should be aware that they may differ by jurisdiction; however, 

the basic information is always included and should provide sufficient 

data to identify crashes on local roads. 

Similar to the crash database, the information in the crash reports 

can be used to assist in the identification of potential treatments and 

deployment approach. 

Action: Develop a relationship with law enforcement officials 

responsible for enforcement and crash investigation on their roads. This 

could foster cooperation in sharing crash reports and safety information 

and collaboration on problem roadway segments. 

2.3. Field Assessments

Many local jurisdictions do not have formal crash databases, and some 

State databases do not include local road crash data. Additionally, some 

local entities may not have a local police force, and in some cases State 

forces may not share their crash reporting with these local entities. In 

this case, the local road practitioner can still conduct field assessments 

to help determine the safety of the roadway network. 

Regardless of data availability and quality or the implementation 

approach, a field assessment should be conducted at selected locations. 

Assessing locations in the field provides additional information to 

the local practitioner that will factor into issue identification and 

countermeasure selection.
Roadway Departure Safety | 14

An assessment can be as informal as driving or walking the road network 

looking for evidence of roadway departure crashes. An informal field 

assessment can be performed by an in-house multidisciplinary team with 

a traffic safety expert and law enforcement personnel. The team can visit 

several sites and document evidence of crashes or deficiencies on the 

roadway or roadside. Examples include damaged trees or fences, skid 

marks, ruts on the shoulder, car parts on the shoulder, and/or pavement 

drop-offs. This information can be used to develop recommendations for 

improvement.

Field reviews can also be more formalized in the form of a Road Safety 

Audit (RSA). An RSA is a formal safety performance examination of an 

existing or future road by an independent, multidisciplinary team. The 

team examines and reports on potential road safety issues and identifies 

opportunities for safety improvements for all road users. 

As with other sources of information, evidence discovered in a field 

assessment can help support spot location treatments and/or systematic 

deployments, depending on the information found. For example, if 

evidence is found of multiple roadway departure crashes on a single 

curve (due to multiple ruts on the roadside, fence repairs, or vehicle parts 

found on the roadside from more than one vehicle), a spot treatment may 

be appropriate to address safety at the curve. If similar types of crashes 

are occurring on several curves on the roadway network, then systematic 

deployment of appropriate countermeasure(s) can a viable solution.

2.4. Observational Information 

Law enforcement officers and local crews who maintain the roads can 

serve as valuable resources to identify problem areas. Since they travel 

extensively on the local roads, they can continuously monitor the roads 

for actual or potential problems (e.g., poor delineation, fixed objects near 

the roadway, missing signs, signs of vehicles leaving the road). 

Law enforcement officers patrol the local jurisdiction at night and on 

weekends when most public agency employees are not in the field. Their 

observations of driver behavior and roadway elements at these times 

can provide valuable insight to the local road agency. Additionally, law 

enforcement officers are sometimes aware of problem areas based on 

citations written, even if crashes related to the violations have not yet 

occurred. 

Road maintenance crews often keep logs of their work, including 

sign replacements and edge drop-off repairs. These logs can provide 

supplemental information about crashes that may have not been 

reported to law enforcement. 
15 | Roadway Departure Safety

Very similar to field assessments, information obtained from road 

maintenance crews and law enforcement officers while they are 

completing their normal duties can help support all three methods of 

implementation - spot location treatments, systematic deployments, 

and the comprehensive approach. Often, offenses such as speeding 

and impaired driving lend themselves to education and enforcement 

solutions to address these behaviors and supplement infrastructure 

countermeasures. 

Action: Add information received from law enforcement and road 

maintenance crew observations to the spreadsheet (see Table 1).

Add information received from law enforcement citations to the 

spreadsheet.

Develop a system for maintenance crews to report and record observed 

roadway departure safety issues and a mechanism to address them.

2.5. Public Notifications

Occasionally, when unsafe situations are observed, local citizens may 

notify the local government by email, letter, telephone call, or at a public 

meeting. While this is anecdotal information, these sources can serve 

as indicators that a safety issue may exist; the notifications potentially 

warrant further review and analysis to determine the extent of the issues. 

Information identifying safety issues on local roads may also come from 

community or regional newspapers and newsletters or correspondence 

from local homeowner and neighborhood associations. This information 

can help pinpoint which segments are candidates for review, and it can 

support the local agency’s relationships with the community that will 

benefit the safety program. 

Action: Review and summarize the information, identifying segments or 

corridors with multiple notifications and recording the locations, dates, 

and nature of the problem that is cited. 

Add information received from public notifications to the Table 1 

spreadsheet.
Roadway Departure Safety | 16

2.6. Roadway Data

It is also valuable to obtain information about the roadway infrastructure. 

The following roadway data are often used to assist practitioners in 

safety analyses on roadway segments:

•	 Roadway surface (dirt, aggregate, asphalt, concrete);

•	 Lane information (number, width);

•	 Shoulder information (width, type);

•	 Median (type, width); and

•	 Traffic control devices present (signs, pavement marking).

This information can be combined with crash data to help local 

practitioners identify appropriate locations and treatments to improve 

safety. For example, if a local rural segment is experiencing a high 

number of horizontal curve-related crashes, analysis of the inventory 

of roadway elements could reveal that the roadway does not have 

sufficient signing installed in advance of many of those curves. 

2.7. Exposure Data

The raw number of crashes can sometimes provide misleading 

information about the most appropriate locations for treatment. 

Introducing exposure data helps to create a more effective comparison 

of locations. Exposure data provide a common metric to the crash 

data so roadway segments and intersections can be compared more 

appropriately.

The most common type of exposure data used on roadway segments 

is traffic volume. A count of the number of vehicles can provide 

information to the practitioner for comparison. For example, if two 

roadway segments have the same number of crashes but different traffic 

volumes, the segment with fewer vehicles (i.e., less exposure) will have 

a higher crash rate, meaning that vehicles were more likely to have 

experienced a crash along that roadway segment. 

In situations where traffic volume is not available, segment length can 

serve as an effective exposure element for comparison.
17 | Roadway Departure Safety

Location Source of 

Information Date Type of Information Problem Nature of Crash

Rt. 123, 2 

miles North of 

Fox Mill Road

Local 

Newspaper 12/1/2007 Citizen Observation Speeding N/A

Rt. 123 West / 

1/2 mile south 

of intersetion 

with Fox 

Mill Road to 

intersection

Citizen Call 3/8/2008 Observation

Drivers losing 

control at 

curve

N/A

Miller’s Curve 

on Rt. 430, 3 

miles South of 

city limits

Local Police 2/1/2008 Police 

Report Crash Report Driver ran off road at curve

Rt. 657; 1/2 

mile South of 

Glade Drive

Local Police 4/1/2008 Police 

Report Crash

Driver hit tree on 

shoulder; single 

vehicle

Rt. 657; 1/4 

mile South of 

Glade Drive

State Police 10/4/2008 Police 

Report Crash Report Driver ran off road; single vehicle

Clifton Road; 

South of Veirs 

Mill Road

State Police 11/11/2008 Police 

Report Crash

Driver ran off road 

on curve; exceeding 

posted speed

Oakwood Road 

near Jones 

Elementary

Local Police 11/12/2009 Police 

Report

Speeding 

Sitation N/A

Rt. 657; 1/4 

mile South of 

Glade Drive

Local Police 11/24/2009 Police 

Report

Oakwood Road 

just North of 

post office

Maintenance 

Crew 7/9/2009 Observation Trees covering 

warning signs N/A

Middlebrook 

Pike; 1 mile 

North of 

Running Cedar 

Road

Maintenance 

Crew 12/12/2009 Observation

Numerous tire 

tracks on curve 

approach

N/A

Table 1 – Spreadsheet to Monitor Roadway Departure Crashes
Roadway Departure Safety | 18

Time of Day Weather 

Conditions

Other Contributors Review Site? Action? Date of Action

Y Pending

Speeding Y Pending

7:22 Clear N

23:03 Snow Alcohol 

involved N

19:21 Rain N

12:23 Rain Speeding N

10:06 Rain Speeding N

23:04 Rain N

Y Trimmed trees 7/16/2009

Y

Advanced 

Curved Warning 

Signs Added

1/8/2010

Table 1 (continued) – Spreadsheet to Monitor Roadway Departure Crashes
19 | Roadway Departure Safety

3 Safety Analysis

Safety analysis will assist with making informed decisions on the type, 

deployment levels, and locations for safety countermeasures. This 

builds on the previous discussions on information sources to identify 

roadway departure issues. Regardless of implementation approach 

selected, some level of data analysis will be relevant. These analyses are 

most relevant for the identification and prioritization of locations with 

safety issues and selection of appropriate countermeasures for the spot 

location approach, for the countermeasure-based systematic approach, 

the safety analysis discussed in this section would occur only after 

the selection of proven low cost countermeasures. In the crash typebased systematic approach, analysis will focus only on those roadway 

departure crash types identified as pertinent in the local jurisdiction.

3.1. Quantitative Analysis

Crash data analysis is used to determine the extent of the roadway 

departure safety issue, the priority for the application of scarce 

resources, and selection of appropriate countermeasures. The two main 

quantitative analysis methods for roadway departure crashes are crash 

frequency and crash rates.

Crash Frequency

Crash frequency is defined as the number of crashes occurring within 

a determined study area. A local practitioner can determine crash 

counts using information compiled from the State crash database or law 

enforcement crash reports. This will allow the practitioner to:

•	 Summarize the crashes by attributes such as type, severity and location;

•	 Spatially display the sites on a map using push pins or a GIS software 

package; 

•	 Provide a report sorted by location and crash type to identify problem 

locations;

•	 Determine predominant roadway departure crash types and associated 

roadway physical characteristics; and

•	 Determine appropriate countermeasures.

Once this information is collected and displayed, the practitioner can 

complete a methodical analysis by county or route, and also a cluster 

analysis to determine those roadway locations that have experienced a 

high or moderate level of crashes.
Roadway Departure Safety | 20

Crash Rate

Crash rates can be an effective tool to measure the relative safety at a 

particular location. The calculation of crash frequency (crashes per year) 

divided by vehicle exposure (traffic volumes, or roadway length) results 

in a crash rate. Crash rate analysis can be a useful tool to determine how 

a specific roadway or segment compares to an average roadway on the 

network. A count of the number of crashes is often inadequate when 

comparing multiple roadways of varying lengths and/or traffic volume. 

Crash rate is often used to prioritize locations for safety improvements 

when working with limited budgets and trying to achieve the greatest 

safety benefits with limited resources.

For example, it is possible that two roadways in a jurisdiction (Route A 

and Route B) each have the same number of crashes. However, Route 

A could have more than double the number of vehicles on a typical day 

than does Route B. To effectively compare the relative safety of the two 

locations, the practitioner must factor in the level of exposure on each 

route. Exposure is often represented by number of vehicles using the 

route or by the length or roadway. 

One limitation of crash rates for low volume roads is the sensitivity of 

the formula to low traffic volume. The crash rate calculation is not as 

beneficial at low volumes as it is with higher volume roads, as small 

changes in the number of vehicles results in a disproportionate change 

in the crash rate for the segments that in reality operate similarly.

Where traffic volume data is unavailable, other information can be used 

to provide exposure information. One often-used factor is the length of 

the roadway segment on each route studied. Comparing the number 

of roadway departure crashes per mile can help an agency identify 

potential opportunities to improve safety. 

Appendix C includes formulas for calculating crash rates on roadway 

segments and examples of crash rate calculations by vehicle miles 

traveled and by roadway mileage.

3.2. Qualitative Analysis

Qualitative analysis considers the physical characteristics of the 

identified sites. This can take the form of examination of maps and 

photographs or field assessment. 

Field Assessment

As discussed in Section 2, field assessments can be an informal review 

of the safety of the roadway, or be more formalized in a Road Safety 

Audit. The RSA will qualitatively estimate and report on existing and 
21 | Roadway Departure Safety

potential roadway departure safety issues and identify opportunities 

for improvements. In the case of the countermeasure-based 

systematic approach, the field assessment can be used to validate the 

countermeasures selected. 

Ensuring Compliance with MUTCD Standards

During the field assessment, it is important to determine if identified 

locations comply with the minimum standards for signs and pavement 

markings included in the Manual on Uniform Traffic Control Devices

(MUTCD). The MUTCD provides the minimum standard requirements 

for traffic control devices on all public streets, highways, bikeways, and 

private roads open to public travel.8

 Complying with these requirements 

can assist in improving safety on the transportation system. Local 

practitioners should also contact the State DOT for the State’s minimum 

requirements, as often they are more stringent than the requirements in 

the MUTCD.

If the traffic control devices on the segment are not in compliance with 

MUTCD or the State minimum requirements, appropriate devices should 

be installed. Non-compliance is an important consideration that can 

affect road safety and might have liability implications for a jurisdiction.

Figure 2 shows some of the most common traffic control devices related 

to roadway departure treatments.

Speed Limit Signs

R2-1 W3-5

OM1-1 OM1-2 OM1-3

OM3-L OM3-C OM3-R

Type 1 Object Markers

(obstructions within the roadway)

Type 3 Object Markers

(obstructions adjacent to or within the roadway)

Type 2 Object Markers

 (obstructions adjacent to the roadway)

OM2-1V OM2-2V OM2-1H OM2-2H

W1-1 W1-2 W1-3 W1-4

W1-6 W1-8 W13-1P

Horizontal Alignment Signs

W14-3

No Passing Zone

Figure 2 - MUTCD Traffic Control Devices

8 The MUTCD can be found at http://mutcd.fhwa.dot.gov. Local practitioners should be cognizant 

that many States adopt standards that are more stringent than the MUTCD. Where these exist, the 

local practitioner is required to comply with those State standards. This information can be obtained 

from the State Department of Transportation or their LTAP Center.
Roadway Departure Safety | 22

Signing

•	 Speed Limit. Speeding is often a contributing factor in roadway 

departure crashes. Posting appropriate speed limit signs along a roadway 

provides motorists with guidance for safe driving speeds. 

•	 Reduced Speed Ahead. When the speed limit is reduced (for example, 

when entering the city limits of a city, town or village), the Reduced Speed 

Ahead sign can provide motorists warning of that change. 

•	 Curve Warning Signs 

» Curve/Turn and Reverse Curve/Turn. These horizontal alignment signs are 

the basic treatment for a horizontal alignment change. Care should 

be taken to choose the most appropriate sign and to place it at the 

optimum location for approaching motorists.

» Advisory Speed Plaque. The advisory speed plaque provides drivers 

with additional information regarding the relative sharpness of an 

approaching curve or turn. 

» Chevron Alignment Signs. These signs are placed within the curve or turn 

to provide delineation and guidance to motorists as they drive through 

the curve. Chevron signs are particularly helpful with combination 

horizontal/vertical curves, as the vertical curvature can hide the 

horizontal alignment change from view of motorists. The delineation 

provided by chevrons can help guide drivers through this complex 

alignment.

» One-direction Large Arrow. The large arrow sign is used to supplement 

curve or turn signs to provide motorists additional warning within the 

curve or turn.

•	 Object Markers (Type 1, 2, 3). Object markers are used to warn drivers 

of obstructions within the roadway or adjacent to the roadway (e.g., culvert, 

other roadside obstacle).

No Passing Zones

•	 Pavement Marking. No Passing Zones are marked at locations where 

drivers do not have sufficient sight distance to safely overtake a slower 

moving vehicle. The solid yellow line on the motorist’s side of the center 

line is an indication that the motorist should wait for a safe passing 

opportunity.

•	 No Passing Zone Pennant Sign. The No Passing Zone pennant 

sign supplements the pavement marking to further emphasize the sight 

distance restrictions.
23 | Roadway Departure Safety

4 Countermeasures

The decision regarding which countermeasures to install to address a 

safety issue can be challenging. When necessary, the local practitioner 

should seek engineering expertise from a county engineer, State 

DOT, or through the State Local Technical Assistance Program (LTAP). 

To make the most informed decision regarding roadway departure 

countermeasure selection, an agency should use all available data, 

both quantitative and qualitative. Through the work of several agencies 

(Federal, State and local) and universities, several proven, effective 

countermeasures have been identified to address roadway departure 

crashes. When using the countermeasure-based systematic approach, 

the practitioner should determine the appropriate conditions for which 

the countermeasure is most effective (crash type, geometric features, 

traffic conditions).

For a relatively small number of high crash locations with varying 

causes, the spot location implementation approach may be the most 

appropriate. Systematic implementation of proven low-cost safety 

countermeasures is often the most effective approach when there are 

several locations on the roadway network experiencing similar types of 

roadway departure crashes. For locations that have yet to experience 

crashes, but have identified features that contribute to roadway 

departure crashes, systematically applying safety treatments may be the 

best approach to prevent future crashes.

A high proportion of crashes tend to occur at locations that share 

common geometric or operational elements. Installing the same 

countermeasure at multiple locations (where appropriate) could, in 

many cases, increase the cost effectiveness of the safety improvement, 

allowing an increased number of treatments to be applied.
Roadway Departure Safety | 24

4.1. Select Roadway Departure Countermeasure 

The countermeasures discussed in this section of the document are not 

all-inclusive of all those available to reduce the frequency and severity 

of roadway departure crashes on local, rural roads. Those discussed have 

shown to be effective for the appropriate roadway departure crashes.

The determination of sites to consider for countermeasure 

implementation is based on the analysis performed. Each 

countermeasure discussed in this section includes the following 

information:

•	 Crash Type Addressed – In order to effectively reduce the number 

and severity of roadway departure crashes, it is necessary to match 

countermeasures to the crash types they are intended to address. 

Depending on the type of problem, one or more of a wide range of 

treatments could be the most effective way to reduce the number and 

severity of future crashes.

•	 For example, if the most frequent crash type on a corridor involved vehicles 

running off the road around curves, the most effective countermeasures 

will likely be those that address curve crashes directly, which include curve 

warning signs, curve alignment signs, and pavement marking.

•	 Where to use – Roadway segments with specific common characteristics 

can be addressed with similar countermeasures that are most effective. 

•	 Why it works – A discussion of the benefit of a countermeasure is important 

to determine its appropriateness in addressing certain roadway departure 

crash types at areas with specific issues as determined by the data and 

roadway features. 

•	 Timeline for Implementation – This category refers to the approximate 

relative time it can take to implement the countermeasure.

Short Time Period

Moderate Time Period

Long Time Period
25 | Roadway Departure Safety

•	 Estimated cost – Most countermeasures included in this report are 

considered low cost; low to moderate cost; or moderate cost. These 

categories represent relative costs of the countermeasures to each other. 

Note that costs can vary considerably due to local conditions.

•	 Crash Reduction Factor – The crash reduction factor (CRF)9 is an indication 

of the effectiveness of a particular treatment, measured by the percentage 

of crashes it is expected to reduce. The CRF for a given countermeasure 

is calculated based on research conducted on the pre- and post-crash 

frequencies at sites where the countermeasure has been installed. The 

higher the CRF, the greater the expected reduction in crashes. For instance, 

a CRF of 20 is interpreted as an expected reduction of 20 percent of 

previously-experienced crashes. The effect of a countermeasure on crashes 

can also be expressed as a Crash Modification Factor (CMF). It is defined 

mathematically as 1 – CRF. In the example above, a 20 percent reduction of 

crashes is represented by a CMF of 0.80. This effect of the countermeasure 

can be calculated by multiplying its value by the number of current crashes 

to determine an expected number of future crashes. For instance, if there 

are 50 current crashes, by multiplying the CMF of 0.80 times 50, one could 

expect 40 future crashes.

9 Federal Highway Administration in conjunction with the University of North Carolina Highway 

Safety Research Center, “Crash Modification Factors Clearinghouse” website. Available at:

http://www.cmfclearinghouse.org/ 
Roadway Departure Safety | 26

(This page intentionally left blank)
Unless otherwise noted, all Crash Reduction Factors (CRFs) in this document are from “Toolbox of Countermeasures and Their Potential Effectiveness 

for Roadway Departure Crashes,” FHWA, 2008.

27 | Roadway Departure Safety Crash type addressed Roadway departure crashes attributed to motorists running off the road while attempting to negotiate a curve or turn in the roadway. In some situations, the driver was not aware they were 

approaching a curve or turn.

Time:Cost: LowCRF: 30%

Where to useAny curve or turn with a history of roadway departure crashes, and curves or turns with similar geometry or traffic volume yet to experience crashes. According to the 2009 MUTCD (Table 2C-5), warning signs are required on curves or turns where the advisory speed is 10 mph less than the posted speed.Why it worksInstalling warning signs in advance of a curve or turn provides information to motorists before they enter the curve, giving them a chance to modify their approach speed as they enter the new horizontal alignment.

Install Advanced Curve Warning Signs
Roadway Departure Safety

| 28Unless otherwise noted, all Crash Reduction Factors (CRFs) in this document are from “Toolbox of Countermeasures and Their Potential Effectiveness 

for Roadway Departure Crashes,” FHWA, 2008.

Crash type addressedRoadway departure crashes attributed to motorists running off the road while attempting to negotiate a curve or turn in the roadway. In some situations, the driver was not aware of the severity of the curve in relation to their operating speed.

Time:Cost: LowCRF: 35%

Where to useAny curve or turn with a history of roadway departure crashes, and curves or turns with similar geometry or traffic volume yet to experience crashes. According to the 2009 MUTCD (Table 2C-5), alignment delineation (or a one direction large arrow) is required on curves or turns where the advisory speed is 15 mph less than the posted speed limit.Why it worksInstalling alignment delineation within a curve or turn provides information to motorists where they need it most – within the actual horizontal alignment. The signs show the shape and degree of curvature, and they guide drivers through the entire curve or turn. 

Provide Curve Delineation Signing (Chevrons)
29 

| Roadway Departure Safety

Install Object Markers

Crash type addressedRoadway departure crashes attributed to motorists hitting a fixed object along the side of the roadway. Contributing circumstances include speedand inattention.

Time:Cost: LowCRF: Unknown

Where to useAny road with a history of fixed object crashes is a candidate for this treatment, as are roadways with similar fixed objects along the roadside that have yet to experience crashes. If a fixed object cannot be relocated or made break-away, placing an object marker can provide additional information to motorists.Why it worksObject markers delineate the location of potentially hazardous fixed objects along the roadside. In a situation where a motorist departs the roadway, the marker can provide information to motorists so they can avoid the object.

Unless otherwise noted, all Crash Reduction Factors (CRFs) in this document are from “Toolbox of Countermeasures and Their Potential Effectiveness for Roadway Departure Crashes,” FHWA, 2008.
Roadway Departure Safety

| 30Unless otherwise noted, all Crash Reduction Factors (CRFs) in this document are from “Toolbox of Countermeasures and Their Potential Effectiveness 

for Roadway Departure Crashes,” FHWA, 2008.

Install Center Line and Edge Line Pavement Markings

Crash type addressedRoadway departure crashes attributed to motorists running off the right side of the road, crossing the center line, or dropping off the roadway on an edge drop-off. Contributing circumstances include speed and inattention. 

Time:Cost: Low-ModerateCenter Line CRF: 33%Edge Line CRF: 38-44%

Where to use

Any road with a history of run-off-road right, head-on, opposite-direction-sideswipe, or run-off-road-left crashes is a candidate for this treatment. Depending on the width of the roadway, various combinations of edge line and/or center line pavement markings may be the most appropriate.Why it worksPavement markings provide motorists important guidance information regarding the edge of the traveled way on the right and the location of the opposing lane on the left. When used around curves, pavement markings serve as curve delineation. 
31 

| Roadway Departure Safety Crash type addressed Crashes attributed to roadway departure in wet and/or dark conditions, due to driver inability to see lane markings. This treatment is most applicable in situations where the crashes 

have occurred at night or on wet pavement. 

Time:Cost: ModerateCRF: Up to 24%

Where to use

RPMs are designed to supplement the delineation provided by pavement markings. They should be installed on routes with sufficient pavement quality to hold the devices in place. The type of RPM to install is dependent on regional climate. For example, in areas that experience snowfall, snow plowable RPMs should be used. Why it worksDuring certain conditions, particularly on wet roads in the dark, it is sometimes difficult for motorists to determine the location of the center line and edge line pavement markings. This increases the likelihood of the vehicle departing the roadway. By installing RPMs, the pavement markings are much more prominent in adverse weather conditions, providing important information to the driver.

Install Raised Pavement Markers (RPMs)

Unless otherwise noted, all Crash Reduction Factors (CRFs) in this document are from “Toolbox of Countermeasures and Their Potential Effectiveness for Roadway Departure Crashes,” FHWA, 2008.
Roadway Departure Safety

| 32Persaud, B. N., Retting, R. A., and Lyon, C., “Crash Reduction Following Installation of Center Line Rumble Strips on Rural Two-Lane Roads.” Arlington, Va., Insurance Institute for Highway Safety, (2003)

Carrasco, O., McFadden, J., and Chandhok, P., “Evaluation of the Effectiveness of Shoulder Rumble Strips on Rural Multi-lane Divided Highways In Minnesota.” Washington D.C., 83rd Transportation Research Board Annual Meeting, (2004)

Crash type addressedRun-off-road-right, run-offroad-left, and head-on crashes attributed to a vehicle leaving its lane of travel. Contributing circumstances include speeding, impaired driving, and inattention.

Time:Cost: LowCenter Line CRF: 15-25%Edge Line CRF: 10-22%

Where to useCenter Line rumble strips/stripes can be used on virtually any roadway – especially those with a history of headon crashes. Shoulder and edge line milled rumble strips/stripes should be used on roads with a history of roadway departure crashes. It is recommended that rumble strips/stripes be applied systematically along an entire route instead of only at spot locations. For all rumble strips/stripes, pavement condition should be sufficient to accept milled rumble strips. Why it worksRumble strips provide an auditory indication and tactile rumble when driven on, alerting drivers that they are drifting out of their travel lane, giving them time to recover before they depart the roadway or cross the center line. Additionally, rumble stripes (pavement marking in the rumble itself) provide an enhanced marking, especially in wet dark conditions.

Install Edge Line, Shoulder, or Center Line Rumble Strips/Stripes

Removing fixed objects
33 

| Roadway Departure Safety

Lyon, C and B. Persaud. “Safety Effects of a Targeted Skid Resistance Improvement Program.” 87th Annual Meeting of the Transportation Research Board, 2008 Annual Meeting CD-ROM.

Crash type addressedRoadway departure crashes attributed to motorists sliding off the roadway. This treatment is most applicable in situations where the crashes have occurred on wet pavement. 

Time:Cost: Moderate-HighCRF: 40-75%

Where to useEpoxy-based, microsurface, or chip seal overlays can address spot locations (e.g., a single curve, interchange ramp, bridge, or short roadway section). It should be used at locations with severe slick conditions that could benefit from increased friction.Why it worksVehicles often leave the road due to lack of friction – especially in wet conditions when water gets between the tires and pavement causing hydroplaning. The epoxy overlay can reduce the number of wet crashes by improving friction at specific locations of need.

Install Pavement Friction Treatments

Wet crashes
Roadway Departure Safety

| 34Research is currently being finalized to develop an official crash reduction factor for this countermeasure.

Crash type addressedRoadway departure crashes attributed to motorists dropping off the roadway due to an edge drop-off. Contributing circumstances include speed, weather issues, and inattention.

Time:Cost: LowCRF: Unknown*

Where to useThis treatment is designed to be a standard policy for any overlay project. Instead of an overlay project ending with a 90-degree asphalt or concrete face at the edge of pavement, the Safety Edge provides a 30-degree angle at the edge. Why it worksAs earth or gravel falls away from the edge of a typical pavement, a vertical edge drop-off is exposed. The Safety Edge eliminates the vertical edge by providing an angled edge to the side of the roadway, also providing a more durable pavement edge. A motorist can more safely re-enter the traveled way after the tires leave the pavement.

Provide Safety Edge for Pavement Edge Drop-off
35 

| Roadway Departure Safety Crash type addressed Roadway departure crashes attributed to vehicles striking a fixed object on the side of the roadway. Examples include trees, utility poles, and culverts. Time: Varies Cost: Varies

CRF: Up to 71%

Where to useDepending on the situation, fixed objects on any roadway should be addressed in the following prioritized order:Why it worksRemoving, redesigning, marking, or relocating the fixed object reduces the likelihood of a crash. If a crash occurs, adding breakaway features, crash cushions, or redirection devices reduces crash severity.

Removing, Moving, or Marking Fixed Objects

1. Remove the obstacle.2. Redesign the obstacle so it can be safely traversed.3. Relocate the obstacle to a point where it is less likely to be struck.4. Reduce impact severity by using an appropriate breakaway device.

5. Use impact attenuation devices to shield the obstacle, reducing crash severity.6. Protect the driver through redirection of the errant vehicle.7. Mark the object to provide motorist information.

Removal is 71%, others are unknown

Unless otherwise noted, all Crash Reduction Factors (CRFs) in this document are from “Toolbox of Countermeasures and Their Potential Effectiveness for Roadway Departure Crashes,” FHWA, 2008.
Roadway Departure Safety

| 36Unless otherwise noted, all Crash Reduction Factors (CRFs) in this document are from “Toolbox of Countermeasures and Their Potential Effectiveness 

for Roadway Departure Crashes,” FHWA, 2008.

Crash type addressedRoadway departure crashes attributed to striking fixed objects, ditches, or other roadside obstacles.

Time:Cost: Low-ModerateCRF: 13-44%

Where to useA clear zone should be developed on every roadway, as space is available. In situations where public rightof-way is limited, steps should be taken to request assistance from property owners, as appropriate. For additional information about clear zones, visit the FHWA Office of Safety website at http://safety.fhwa.dot.gov/roadway_dept/clear_zones.Why it worksA clear zone is an unobstructed, traversable roadside area that allows a driver to stop safely or regain control of a vehicle that has left the roadway. Removing or moving fixed objects, flattening slopes, or providing recovery areas reduces the likelihood of a crash.

Create Clear Zones
37 | Roadway Departure Safety

5 Evaluation

Evaluation of roadway departure treatments after they are installed to 

determine effectiveness can be used to guide future decisions regarding 

roadway departure countermeasures.

A record of crash history and countermeasure installation forms the 

foundation for assessing how well implemented strategies have 

performed. An important database to keep is a current list of installed 

countermeasures with documented “when/where/why” information. 

Periodic assessments will provide the necessary information to make 

informed decisions on whether each countermeasure contributed to 

an increase in safety, whether the countermeasure could or should be 

installed at other locations, and which factors may have contributed to 

each countermeasure’s success.

In order to perform the assessment, it is necessary to collect the required 

information for a certain period after strategies have been deployed 

at the locations. The time period varies, but should be no less than 

one full year (with 2-3 years preferred). The information required may 

consist of public input and complaints, police reports, observations from 

maintenance crews, and local and State crash data. 

It is important to keep the list of strategy installations up to date since it 

will serve as a record of countermeasure deployment history (see Table 

2 for an example). By using this type of system, assessment dates can 

be scheduled to review the crashes and other pertinent information 

on segments where roadway departure countermeasures have been 

installed. 

Action: Develop a spreadsheet to track future safety project installations 

and record 3 years of “before” crash information at those locations.

Location

Type of 

Countermeasure 

Installed

Date 

Installed

Crashes 

Before

Crashes 

After Comments

Middlebrook Pike, 

1 mile north of 

Running Cedar Rd.

Advanced Curve 

Warning Sign 11/10/2009 3 in 3 years Subdivision built in Summer 2010 near this location.

Route 657, 1⁄2 mile 

south of Glade Drive Chevrons 12/19/2009 5 in 3 years

Traffic volume has increased 

25% between the installation 

date and the “after” period.

Clifton Road, South 

of Veirs Mill Road Speed Limit Signs 2/3/2010 2 in 1 year

Table 2 - Example Table to Monitor Countermeasure Application History and Crash/

Observational Data
Roadway Departure Safety | 38

6 Case Studies

This section contains descriptions of programs and projects 

implemented by select local jurisdictions to address roadway departure 

crashes. These programs illustrate how local practitioners have instituted 

processes or select countermeasures to address roadway departure 

crashes on their roadways. 

6.1. Low-cost Local Safety Solutions: Douglas County, Georgia10

Douglas County, Georgia developed a County Curve Action Plan as part of 

the Georgia Department of Transportation’s Safety Action Plan Program. 

This plan has been particularly helpful to the county as it supported 

funding opportunities through the Georgia Off-System Safety Program. 

One of the principal components of their safety action plan, which 

aligns with the Georgia SHSP, is a focus on roadway departure crashes 

along curves. Horizontal curves on local and rural roadways represent 

a major concern in Douglas County, because many of their roads are 

former wagon trails that were paved over time without addressing the 

roadway alignment, shoulders, clear zones, and lighting to meet current 

standards. Consequently, the County experiences a significant number 

of roadway departure crashes associated with these types of curves. 

With a lack of comprehensive data, the County depended on their 

County Road Department staff, historic knowledge from the sheriff 

department, and residents to supplement the available data to develop 

the Curve Action Plan. High-risk locations were identified. A consultant 

was hired to conduct a qualitative analysis of critical locations and 

identify countermeasure strategies where appropriate. Improvement 

strategies included signing and striping modifications as well as center 

line and edge line raised pavement markers. 

There has been a significant reduction in roadway departure crashes 

since the county began implementing low cost strategies such as 

warning signs, chevron signs and raised pavement markers along the 

curves. After installing the double advance warning signs, chevrons 

alignment signs, and raised pavement markers, a number of crashes 

continued to occur along some curves. The County took another step 

by adding the “curve ahead” markings on the pavement, including 

arrows, developed by Pennsylvania Department of Transportation. The 

pavement markings have made a tremendous difference as there have 

been no crashes in the treated locations since the installation. 

10 Federal Highway Administration, “Noteworthy Practices: Addressing Safety on Locally-Owned and 

Maintained Roads.” (Washington, D.C.: 2010). Available at

http://safety.fhwa.dot.gov/local_rural/training/fhwasa10027/
39 | Roadway Departure Safety

Contact:

Keary Lord, Assistant Director 

Douglas County DOT

(678) 715-5372

klord@co.douglas.ga.us 

6.2. Engineering and Enforcement Safety Solutions: Contra Costa 

County and Alameda County, California11

Winding curves, lack of guardrails, and short sight distance in certain 

areas were creating a difficult environment for motorists utilizing the 

heavily congested Vasco Road in both Contra Costa and Alameda 

Counties. The traffic volumes on Vasco Road had more than doubled 

from 10,000 vehicles per day in 1990 to over 22,000 in 2007, resulting in a 

high number of collisions. Between 2002 and 2004, 72 crashes occurred 

along the project corridor, many of them related to roadway departure.

To address the high incidence of roadway departure crashes, a 

comprehensive, cooperative, and multijurisdictional approach was 

taken to address speeding and aggressive driving on Vasco Road. As a 

result, in 2004, the Alameda County Public Works Agency, the Contra 

Costa County Public Works Agency, City of Brentwood, City of Livermore, 

the Alameda County Sheriff’s Department, and the California Highway 

Patrol offices in both counties joined with community groups and 

elected officials in an attempt to reduce crashes along Vasco Road. They 

introduced a variety of safety measures, including the following:

•	 Speed display signs;

•	 Community safety signs;

•	 Daytime headlight signs;

•	 Center line rumble strips;

•	 Soft median barrier striping;

•	 Center line delineators;

•	 Double fine zone; and

•	 Coordinated speed enforcement 

These measures have produced extraordinary results. The collaborative 

traffic engineering, speed enforcement, and funding efforts of both 

counties have significantly reduced head-on collisions and improved overall 

roadway departure safety along Vasco Road. The crash rate per million 

vehicle miles dropped from 0.58 to 0.42. Between 2005 and 2007, there 

have been just 46 collisions, a 36 percent reduction from previous years. 

Contact: 

11 2009 National Roadway Safety Awards Best Practices. Accessed at http://www.roadwaysafety.org/
Roadway Departure Safety | 40

Paul Keener

Alameda County Public Works Department

510.670.5247

PaulK@acpwa.org

6.3. Signing and Marking Improvements: Mendocino County, 

California.12,13,14 

The terrain of Mendocino County, a large rural county with more than 

1,000 center line miles of county-maintained roads, is mountainous with 

a few small valleys. Traffic-related injuries and fatalities in the county are 

primarily the result of roadway departure crashes.

In the 1990s the Mendocino County Department of Transportation 

(MCDOT) developed a Road System Traffic Safety Review program to 

improve signing and markings on the arterial and collector roadways 

on their system. Each year the team completes a systematic review of 

one-third of the county roads, identifying potential signing and marking 

deficiencies, recommending changes based on the current California 

Department of Transportation (Caltrans) signing and marking guidelines, 

and implementing the results. 

During recurring three-year cycles, all arterials, all collectors, and a 

number of selected local roadways are reviewed. These annual reviews 

are funded through the Mendocino Council of Governments (MCOG) 

with a combination of state and local monies. Early efforts in Mendocino 

County concentrated on improving signing for curves and eliminating 

nonstandard signing in order to conform to current Caltrans standards. 

Funding from the Caltrans Hazard Elimination Safety (HES) Program was 

used to upgrade approximately one-quarter of the county’s signs the 

first year. Since then, funds to implement the recommendations of the 

annual reviews have been allocated in the MCDOT budget.

The effectiveness of the Traffic Safety Review project was measured 

by comparing roadway departure crash data for reviewed roads with 

data for roads not included in, or influenced by, the reviews. Over two 

consecutive, three-year cycles, the number of crashes on the reviewed 

roads fell dramatically by 42.1 percent while on those county-maintained 

roads not reviewed increased by 26.5 percent. Using cost data provided 

12 The American Traffic Safety Services Association and the National Association of County Engineers, 

Low-cost Local Road Safety Solutions (Fredericksburg, VA: 2008). Accessed at:

http://www.atssa.com/galleries/default-file/Low%20Cost%20Local%20Roadsrev10-09-08-reduced.pdf 

13 Federal Highway Administration and the Roadway Safety Foundation, 2007 National Roadway Safety 

Awards Best Practices Guidebook (Washington, DC: October 2007). Accessed at:

http://www.roadwaysafety.org/wp-content/uploads/2007awards.pdf 

14 Peaslee, G. “Signs Show the Way to Cost-Effective Rural Safety,” Public Roads, January/February 2005. 

Accessed at: http://www.tfhrc.gov/pubrds/05jan/08.htm
41 | Roadway Departure Safety

by the California Department of Transportation, the County calculates 

that, for an expenditure of $79,300, the project prevented between $12.6 

million and $23.7 million in traffic crash losses.

The results speak for themselves. Mendocino County has since expanded 

the Road Traffic Safety Review program to cover its entire countymaintained road system

Contact:

Stephen Ford

Mendocino County Department of Transportation

707-463-4351

fords@co.mendocino.ca.us

6.4. Local Road Safety Audits: Cape May County, New Jersey15

The South Jersey Transportation Planning Organization (SJTPO) 

instituted its Local Road Safety Audit program in 2004 in response to the 

disproportionate share of roadway departure crashes occurring on rural 

two-lane roads in the SJTPO region. SJTPO took a data-driven approach 

to the safety audit program. Audits were first conducted on two Cape 

May County roads with documented crash histories and significant 

roadway departure crash potential. 

A consultant firm conducted the audits with the assistance of the 

Cape May County Engineer’s office and SJTPO. Of special interest is 

the interdisciplinary nature of the audit teams, which consisted of 

county representatives, law enforcement, engineering and public works 

staff of the affected municipalities, the New Jersey Department of 

Transportation, the Division of Highway Traffic Safety and the Federal 

Highway Administration. 

The audits have raised awareness among local decision makers by 

15 Federal Highway Administration and the Roadway Safety Foundation, 2005 National Roadway Safety 

Awards Best Practices Guidebook (Washington, DC: 2005). Accessed at:

http://www.roadwaysafety.org/wp-content/uploads/2005awards.pdf 
Roadway Departure Safety | 42

identifying low-cost, quick turn-around safety improvements that 

are expected to yield immediate safety benefits to address roadway 

departure crashes. It was one of the first local programs of its kind, 

utilizing Federal planning funds to systemically identify local road 

segments of concern, organize a team of independent specialists, 

engage a consultant team for the audits, and secure Federal funding for 

the resulting recommended improvements.

Contact:

Timothy Chelius

South Jersey Transportation Planning Organization 

856-794-1941 

Tchelius@sjtpo.org

Source: 2005 National Roadway Safety Awards Best Practices

http://www.roadwaysafety.org/
43 | Roadway Departure Safety

7 Summary

Roadway departure crashes account for 53 percent of national fatalities, 

many of which occur in rural, local areas. Local administrators, township 

managers, and public works officials who maintain and operate 

local rural roads need to be engaged in roadway safety by reviewing 

understandable literature to guide their identification of roadway 

segments with safety issues and the countermeasures to address them. 

To date, several States have completed Roadway Departure Safety 

Implementation Plans with assistance from FHWA. These plans were 

developed to guide roadway departure safety implementation activities 

on State and local roads arising from the State Strategic Highway Safety 

Plans. The implementation plans include the activities, countermeasures, 

strategies, deployment levels, implementation steps, and estimate 

of funds necessary to achieve the State’s roadway departure safety 

goals. The local road practitioners should consult their State’s Roadway 

Departure Safety Implementation Plan, if available, before embarking on 

an improvement strategy.

When seeking to address local rural road safety, the local practitioners 

should consider which implementation approach to institute. The three 

main approaches are – Systematic, Spot location, and Comprehensive. 

Availability and quality of crash and roadway data, number of locations 

to be addressed, and funding are factors that may play a role in the 

selection of an implementation approach.

Determining the nature of the problems and their locations will assist in 

making the most informed decisions for countermeasure selection and 

implementation in addressing roadway departure safety issues. When 

conducting a safety analysis, a minimum of 3 years of data is desired 

to obtain an accurate picture of the crash history within a jurisdiction, 

since crashes are relatively rare events and are not universally distributed 

across the system. Due to the possibility of changes in traffic patterns 

and the roadway itself, data more than 5 years old are typically not 

desirable for assessing the safety issues.

Analysis can range from simple “push pin” maps for identifying crash 

clusters to statistical analyses of crash rates, depending on the crash 

history and other available data. There are a number of information 

sources that can be used to identify crashes – State and local crash 

databases, law enforcement crash reports and citations, observational 
Roadway Departure Safety | 44

information from road maintenance crews and law enforcement, and 

public notification of safety concerns. Other variables to be considered 

when conducting analysis include crash location, date and time, 

crash type, crash severity, weather conditions, sequence of events, 

and contributing circumstances. In addition, roadway data and traffic 

volumes are factors to be considered when determining the roadway 

departure safety issues.

Regardless of the implementation approach chosen, a field review 

should be conducted at identified locations. Field reviews have 

the potential to identify safety issues and solutions that cannot be 

determined by data analysis alone. These reviews can be conducted as 

informal field reviews or as formal Road Safety Audits (RSAs). 

Decisions regarding which countermeasures to install to address a safety 

issue can be challenging. When appropriate, the local practitioner should 

seek engineering expertise from a State or local engineer or through the 

State Local Technical Assistance Program (LTAP). For conventional rural 

roadway segments, warning signs, curve delineation, rumble strips, and 

fixed object removal should be considered. In addition, a large number 

of supplemental countermeasures are available for deployment based 

on crash history, location, and level of effectiveness.

Countermeasure assessment after implementation is important to the 

roadway departure safety program. This will inform the practitioner of 

the effectiveness of the strategy and if it should be applied to other 

locations. The most common methodology for the evaluation of a 

given countermeasure is the analysis of crash data before and after 

its installation. Three years of data after the installation is ideal for 

evaluation; however, changes in traffic volume and roadway information 

can also affect the outcome, so they should be taken into account 

during assessment.

While the challenge to decrease the number of roadway crashes on local 

rural roads may seem overwhelming due to limited resources, there are a 

number of low cost proven countermeasures that can be installed; many 

can be installed relatively quickly. 

Local highway agencies have unique responsibilities and challenges 

related to the safety of their roadway system. By beginning any traffic 

safety effort using a data-supported approach, those agencies will be in 

a better position to address their highway safety needs.
A-1 | Roadway Departure Safety

 Appendix A – Additional Resources

This section contains additional references on the types of roadway 

departure countermeasures, studies and technical reports on local and 

rural roads, and guidelines used for countermeasure installation. 

Federal Funding Opportunities

Federal Highway Administration, “Highway Safety Improvement Program 

(HSIP) website.” Available at http://safety.fhwa.dot.gov/hsip

Federal Highway Administration, “High Risk Rural Roads Program (HRRRP) 

website.” Available at 

http://safety.fhwa.dot.gov/safetealu/memos/memo051906.cfm

Selected Technical Resources

Federal Highway Administration, “Low Cost Treatments for Horizontal 

Curve Safety,” FHWA-SA-07-002 (Washington, D.C.: 2006). Available at 

http://safety.fhwa.dot.gov/roadway_dept/horicurves/fhwasa07002

Federal Highway Administration, “9 Proven Crash Countermeasures 

website.” Available at http://safety.fhwa.dot.gov/policy/memo071008

This guidance memorandum highlights when and where certain 

processes, design techniques, or safety countermeasures should be used:

“NCHRP Report 500: Guide and for Implementation of the AASHTO 

Strategic Highway Safety Plan” – a series in which relevant information is 

assembled into single concise volumes, each pertaining to specific types 

of highway crashes (e.g., run-off-road, head-on) or contributing factors 

(e.g., aggressive driving). Specific volumes include:

Volume 03: A Guide for Addressing Collisions with Trees 

in Hazardous Locations:

http://safety.transportation.org/guides.aspx?cid=24

Volume 06: A Guide for Addressing Run off Road Collisions: 

http://safety.transportation.org/guides.aspx?cid=27

Volume 07: A Guide for Reducing Collisions on Horizontal Curves: 

http://safety.transportation.org/guides.aspx?cid=32

Volume 08: A Guide for Reducing Collisions Involving Utility Poles: 

http://safety.transportation.org/guides.aspx?cid=31
Roadway Departure Safety | A-2

Road Safety Audits: 

http://safety.fhwa.dot.gov/rsa/

U.S. Department of Transportation (2008). The U.S. Department of 

Transportation Rural Safety Initiative. Available at 

http://www.dot.gov/affairs/ruralsafety/ruralsafetyinitiativeplan.htm

American Traffic Safety Services Association (ATSSA), “Low Cost Local 

Road Safety Solutions,” 2006.

Federal Highway Administration, “Safety Evaluation of Improved Curve 

Delineation” (Washington, DC: 2009). Available at 

http://www.tfhrc.gov/safety/pubs/09046/index.htm

McNinch, T.L. and Colling, T.K. U.S. Department of Transportation, 

Federal Highway Administration (2009), “Traffic Safety Education for 

Nonengineers.” Pp. 32-38, Public Roads, May/June. 

http://www.fhwa.dot.gov/publications/publicroads/09june/05.cfm

Federal Highway Administration, “Crash Reduction Factors website.” 

Available at http://safety.fhwa.dot.gov/tools/crf/

Gross, F. and Yunk, K. U.S. “Using CRFs to Improve Highway Safety.” 

Department of Transportation, Federal Highway Administration, Public 

Roads, May/June 2009, pp. 26-31. Available at 

http://www.fhwa.dot.gov/publications/publicroads/09june/04.cfm

Federal Highway Administration, Highway Safety Facts and Statistics 

website. Available at http://safety.fhwa.dot.gov/facts_stats/

National Highway Traffic Safety Administration, Center for Statistics and 

Analysis, Fatality Analysis Reporting System (FARS). Available at 

http://www-fars.nhtsa.dot.gov/Main/index.aspx

Federal Highway Administration, Crash Modifications Factors 

Clearinghouse website. Available at http://www.cmfclearinghouse.org/ 

Resources Related to Program Development/Program Coordination

National Local Technical Assistance Program (LTAP) website. Available at

http://www.ltapt2.org/nltapa

This website summarizes the roles and function of the LTAP program and 

provides links, by state, for local points of contact who may help identify 

data, resources, and offer assistance.
A-3 | Roadway Departure Safety

Examples of State Programs/Initiatives

Federal Highway Administration, “Making the Case for Transportation 

Safety – Ideas for Decision Makers” (Washington, DC: 2008) Available at 

http://tsp.trb.org/assets/briefing%20book%20hi-res.pdf

Pennsylvania Department of Transportation (2008). District Highway 

Safety Guidance Manual. Federal Highway Administration, Wyoming 

Technical Transfer Center, Kansas LTAP, Field Guide for Unpaved Rural 

Roads. Available at http://www.t2.unh.edu/pubs/field_guide.pdf
Roadway Departure Safety | B-1

Appendix B: 2009 MUTCD Standards for Traffic 

Control Devices

All Signs

A - ROADSIDE SIGN

IN RURAL AREA

12 ft MIN.

5 ft

MIN.

B - ROADSIDE SIGN

IN RURAL AREA

6 ft MIN.

Shoulder wider than 6 ft

5 ft

MIN.

Figure 3 - MUTCD Roadside Placement (MUTCD Figure 2A-2)

For a typical rural road with no shoulder, the sign should be placed on 

the right-hand side of the roadway, 12 feet laterally from the edge of the 

traveled way. In terms of vertical height, the bottom of the sign should be 

installed at least 5 feet above the ground elevation at the edge of pavement. 

Enhancing Sign Conspicuity Cost Effectively (MUTCD, Figure 2A-2).
B-2 | Roadway Departure Safety

Figure 2A-1. Examples of Enhanced Conspicuity for Signs

B – Red or orange ags

above a regulatory,

warning, or guide sign 

C – W16-18P plaque above 

a regulatory sign 

D – Solid yellow, solid uorescent

yellow, or diagonally striped 

black and yellow (or black and 

uorescent yellow) strip of

retroreective sheeting

around a warning sign

E – Vertical retroreective

 strip on sign support

F – Supplemental beacon

A – W16-15P plaque above 

a regulatory or warning 

sign if the regulation or 

condition is new

Figure 4 - MUTCD Examples of Enhanced Conspicuity for Signs (MUTCD, Section 2A.15)

•	 In a situation where it is desired to enhance a sign’s conspicuity, the 

following are among the methods that may be used:

» Increasing the size of the sign. 

» Doubling-up by adding a second identical sign on the left-hand 

side of the roadway.

» Adding a strip of retroreflective material to the sign support 
Roadway Departure Safety | B-3

Speed Limit Signs

Speed Limit (R2-1; MUTCD, Section 2B.13)

Minimum Sign Size: 24” x 30”

When to use

•	 The Speed Limit sign shall display the limit established by law, ordinance, 

regulation, or as adopted by the authorized agency based on the 

engineering study. 

•	 The speed limits displayed shall be in multiples of 5 mph.

•	 Speed Limit signs shall be located at the points of change from one speed 

limit to another.

•	 Additional Speed Limit signs shall be installed beyond major intersections 

and at other locations where it is necessary to remind road users of the 

speed limit that is applicable.

•	 Speed Limit signs indicating the statutory speed limits shall be installed at 

entrances to the State.

Reduced Speed Limit Ahead (W3-5, W3-5a; MUTCD, Section 2C.38)

Minimum Sign Size: 36” x 36”

When to use

A Reduced Speed Limit Ahead (W3-5 or W3-5a) sign should be used 

to inform road users of a reduced speed zone where the speed limit is 

being reduced by more than 10 mph, or where engineering judgment 

indicates the need for advance notice to comply with the posted speed 

limit ahead.
B-4 | Roadway Departure Safety

W1-8R

W1-8L

W1-1aR

(optional)

W1-1R

W13-1P

W1-6L (optional)

Legend

Direction of travel

W1-8

W1-6R (optional)

W1-8

W1-8

W1-1L

W13-1P

Notes:

1. See Table 2C-4 for advance placement distance guidelines

2. See Table 2C-5 for the selection of horizontal alignment signs

3. See Table 2C-6 for spacing of W1-8 signs

4. A 25-mph advisory speed is shown for illustrative purposes only

Figure 2C-2. Example of Warning Signs for a Turn

W1-1aL (optional)

Figure 5 - MUTCD Example of Warning Signs for a Turn
Roadway Departure Safety | B-5

Horizontal Alignment Signs

All square/diamond warning signs have a minimum sign size of 30” x 30”. 

When to use

In advance of horizontal curves on freeways, on expressways, and on 

roadways with more than 1,000 AADT that are functionally classified as 

arterials or collectors, horizontal alignment warning signs shall be used 

in accordance with Table 2C-5 based on the speed differential between 

the roadway’s posted or statutory speed limit or 85th-percentile speed, 

whichever is higher, or the prevailing speed on the approach to the 

curve, and the horizontal curve’s advisory speed.

Horizontal Alignment Warning signs may also be used on other 

roadways or on arterial and collector roadways with less than 1,000 

AADT based on engineering judgment.

Curve signs (W2-1) vs. Turn signs (W1-1) (MUTCD, Section 2C.07)

When to use

A Turn sign shall be used instead of a Curve sign in advance of curves 

that have advisory speeds of 30 mph or less.

Reverse Curve (W1-4) and Reverse Turn (W1-3) (MUTCD, Section 2C.07)

When to use

Where there are two changes in roadway alignment in opposite 

directions that are separated by a tangent distance of less than 600 feet, 

the Reverse Turn sign should be used instead of multiple Turn signs and 

the Reverse Curve sign should be used instead of multiple Curve signs.
B-6 | Roadway Departure Safety

Combination Horizontal Alignment / Intersection Warning Signs (W1-10 

Series; MUTCD, Section 2C.11)

When to use

The Turn sign or the Curve sign may be combined with the Cross 

Road sign or the Side Road sign to create a combination Horizontal 

Alignment/Intersection warning sign that depicts the condition where 

an intersection occurs within or immediately adjacent to a turn or curve.

Elements of the combination Horizontal Alignment/Intersection warning 

sign related to horizontal alignment should comply with the provisions 

of Section 2C.07, and elements related to intersection configuration 

should comply with the provisions of Section 2C.46.

The symbol design should approximate the configuration of the 

intersecting roadway(s). No more than one Cross Road or two Side 

Road symbols should be displayed on any one combination Horizontal 

Alignment/Intersection warning sign.

Advisory Speed Plaque (W13-1P; MUTCD, Section 2C.08)

Minimum Plaque Size: 18” x 18”

Roadside Placement: The sign height changes when a speed plaque is 

added. 

D - WARNING SIGN WITH ADVISORY

SPEED PLAQUE IN RURAL AREA

12 ft MIN.

4 ft

MIN.

Figure 6 - MUTCD Roadside Placement with Plaque

When to use

The use of the Advisory Speed plaque for horizontal curves shall be in 

accordance with the information shown in Table 2C-5. The Advisory 

Speed plaque shall also be used where an engineering study indicates 

a need to advise road users of the advisory speed for other roadway 

conditions.

If used, the Advisory Speed plaque shall carry the message XX MPH. The 

speed displayed shall be a multiple of 5 mph.
Roadway Departure Safety | B-7

Except in emergencies or when the condition is temporary, an Advisory 

Speed plaque shall not be installed until the advisory speed has been 

determined by an engineering study.

The Advisory Speed plaque shall only be used to supplement a warning 

sign and shall not be installed as a separate sign installation.

The advisory speed shall be determined by an engineering study that 

follows established engineering practices. Among the established 

engineering practices that are appropriate for the determination of the 

recommended advisory speed for a horizontal curve are the following:

•	 An accelerometer that provides a direct determination of side friction 

factors

•	 A design speed equation

•	 A traditional ball-bank indicator using the following criteria:

» 16 degrees of ball-bank for speeds of 20 mph or less

» 14 degrees of ball-bank for speeds of 25 to 30 mph

» 12 degrees of ball-bank for speeds of 35 mph and higher

Combination Horizontal Alignment/Advisory Speed Signs (W1-1a, W1-

2a) (MUTCD, Section 2C.10)

When to use

The Turn sign or the Curve sign may be combined with the Advisory 

Speed plaque to create a combination Turn/Advisory Speed sign or 

combination Curve/Advisory Speed sign.

The combination Horizontal Alignment/Advisory Speed sign may be 

used to supplement the advance Horizontal Alignment warning sign 

and Advisory Speed plaque based upon an engineering study.

If used, the combination Horizontal Alignment/Advisory Speed sign 

shall not be used alone and shall not be used as a substitute for a 

Horizontal Alignment warning sign and Advisory Speed plaque at the 

advance warning location. The combination Horizontal Alignment/

Advisory Speed sign shall only be used as a supplement to the advance 

Horizontal Alignment warning sign. 

If used, the combination Horizontal Alignment/Advisory Speed sign shall 

be installed at the beginning of the turn or curve.

The advisory speed displayed on the combination Horizontal Alignment/

Advisory Speed sign should be based on the advisory speed for the 

horizontal curve and match that speed.
B-8 | Roadway Departure Safety

Chevron Alignment Signs (W1-8; MUTCD, Section 2C.09) 

Minimum Sign Size: 18” x 24”

Sign Design: The Chevron Alignment sign shall be a vertical rectangle. 

No border shall be used on the Chevron Alignment sign.

When to use

The use of the Chevron Alignment sign to provide additional emphasis 

and guidance for a change in horizontal alignment shall be in 

accordance with the information shown in Table 2C-5.

Sign Placement

If used, Chevron Alignment signs shall be installed on the outside 

of a turn or curve, in line with and approximately at a right angle to 

approaching traffic. Chevron Alignment signs shall be installed at a 

minimum height of 4 feet, measured vertically from the bottom of the 

sign to the elevation of the near edge of the traveled way.

Spacing Around Turns/Curves

The approximate spacing of Chevron Alignment signs on the turn or 

curve measured from the point of curvature (PC) should be as shown 

in Table 2C-6. Chevron Alignment signs should be visible for a sufficient 

distance to provide the road user with adequate time to react to the 

change in alignment.

One-Direction Large Arrow Sign (W1-6; MUTCD, Section 2C.12)

Minimum Sign Size: 48” x 24”

Sign Design: The One-Direction Large Arrow sign shall be a horizontal 

rectangle with an arrow pointing to the left or right.

When to use

A One-Direction Large Arrow sign may be used either as a supplement 

or alternative to Chevron Alignment signs in order to delineate a change 

in horizontal alignment (see Figure 2C-2). The use of the One-Direction 

Large Arrow sign shall be in accordance with the information shown in 

Table 2C-5.

A One-Direction Large Arrow sign may be used to supplement a Turn or 

Reverse Turn sign to emphasize the abrupt curvature.

Sign Placement

If used, the One-Direction Large Arrow sign shall be installed on the 

outside of a turn or curve in line with and at approximately a right angle 

to approaching traffic. The One-Direction Large Arrow sign should be 

visible for a sufficient distance to provide the road user with adequate 

time to react to the change in alignment.
Roadway Departure Safety | B-9

Object Markers (MUTCD, Sections 2C.63 through 2C.65)

Minimum Sign Sizes

Type 1: 18” x 18”

Type 2: 6” x 12”

Type 3: 12” x 36”

Sign Design: Object markers shall not have a border and shall consist of 

an arrangement of one or more of the following types shown in Figure 

2C-13.

OM1-1 OM1-2 OM1-3

OM3-L OM3-C OM3-R

Type 1 Object Markers

(obstructions within the roadway)

Type 3 Object Markers

(obstructions adjacent to or within the roadway)

Type 2 Object Markers

 (obstructions adjacent to the roadway)

OM2-1V OM2-2V OM2-1H OM2-2H

Figure 2C-13. Object Markers

Figure 7 - MUTCD Object Markers
B-10 | Roadway Departure Safety

When to use

Type 1 object markers are used to mark obstructions within the 

roadway.

Type 2 and 3 object markers are used to mark obstructions adjacent to 

the roadway. 

Obstructions not actually within the roadway are sometimes so close to 

the edge of the road that they need a marker. These include underpass 

piers, bridge abutments, handrails, ends of traffic barriers, utility poles, 

and culvert headwalls. In other cases there might not be a physical 

object involved, but other roadside conditions exist, such as narrow 

shoulders, drop-offs, gores, small islands, and abrupt changes in the 

roadway alignment, that might make it undesirable for a road user to 

leave the roadway, and therefore would create a need for a marker.

Object Marker Placement – Type 1, 2, 3

When used for marking obstructions within the roadway or obstructions 

that are 8 feet or less from the shoulder or curb, the minimum mounting 

height, measured from the bottom of the object marker to the elevation 

of the near edge of the traveled way, should be 4 feet.

When used to mark obstructions more than 8 feet from the shoulder or 

curb, the distance from the bottom of the object marker to the ground 

should be at least 4 feet.

When object markers or markings are applied to an obstruction that by 

its nature requires a lower or higher mounting, the vertical mounting 

height may vary according to need.

If a Type 2 or Type 3 object marker is used to mark an obstruction 

adjacent to the roadway, the edge of the object marker that is closest 

to the road user shall be installed in line with the closest edge of the 

obstruction.
Roadway Departure Safety | B-11

No Passing Zones 

Pavement Markings (MUTCD, Section 3B.02)

On roadways with center line markings, no-passing zone markings shall 

be used at horizontal or vertical curves where the passing sight distance 

is less than the minimum shown in Table 3B-1 for the 85th-percentile 

speed or the posted or statutory speed limit. 

Figure 3B-4 details the measurements needed to determine No Passing 

Zones at curves.

Where the distance between successive no-passing zones is less than 

400 feet, no-passing markings should connect the zones.

Sign Enhancement for No Passing Zones

No Passing Zone pavement marking can be enhanced with the 

following signs as desired.

Do Not Pass (R4-1) (MUTCD, Section 2B.28)

Minimum Sign Size: 24” x 30”

When to use

The DO NOT PASS sign may be used in addition to pavement markings 

to emphasize the restriction on passing. The DO NOT PASS sign may be 

used at the beginning of, and at intervals within, a zone through which 

sight distance is restricted or where other conditions make overtaking 

and passing inappropriate.

Pass With Care (R4-2) (MUTCD, Section 2B.29)

Minimum Sign Size: 24” x 30”

When to use

The PASS WITH CARE sign should be installed at the downstream end 

of a no-passing zone if a DO NOT PASS sign has been installed at the 

upstream end of the zone.

No Passing Zone pennant (W14-3) (MUTCD, Section 2C.45)

Minimum Sign Size: 48” x 48” x 36”

When to use

If signing is needed on the left-hand side of the roadway for additional 

emphasis, NO PASSING ZONE signs may be used. 

When used, the NO PASSING ZONE sign shall be installed on the 

left-hand side of the roadway at the beginning of no-passing zones 

identified by pavement markings.
B-12 | Roadway Departure Safety

Retroreflectivity Requirements (MUTCD, Section 2A.08)

2009 MUTCD “Section 2A.08 Maintaining Minimum Retroreflectivity”

The MUTCD provides suggestions for methods to be used:

Visual Nighttime Inspection

The retroreflectivity of an existing sign is assessed by a trained sign 

inspector conducting a visual inspection from a moving vehicle during 

nighttime conditions. Signs that are visually identified by the inspector 

to have retroreflectivity below the minimum levels should be replaced.

Measured Sign Retroreflectivity

Sign retroreflectivity is measured using a retroreflectometer. Signs with 

retroreflectivity below the minimum levels should be replaced.

Expected Sign Life

When signs are installed, the installation date is labeled or recorded so 

that the age of a sign is known. The age of the sign is compared to the 

expected sign life. The expected sign life is based on the experience of 

sign retroreflectivity degradation in a geographic area compared to the 

minimum levels. Signs older than the expected life should be replaced.

Blanket Replacement

All signs in an area/corridor, or of a given type, should be replaced at 

specified intervals. This eliminates the need to assess retroreflectivity or 

track the life of individual signs. The replacement interval is based on the 

expected sign life, compared to the minimum levels, for the shortest-life 

material used on the affected signs.

Control Signs

Replacement of signs in the field is based on the performance of a 

sample of control signs. The control signs might be a small sample 

located in a maintenance yard or a sample of signs in the field. The 

control signs are monitored to determine the end of retroreflective life 

for the associated signs. All field signs represented by the control sample 

should be replaced before the retroreflectivity levels of the control 

sample reach the minimum levels.

Other Methods

Other methods developed based on engineering studies can be used.

Additional guidance on retroreflectivity requirements for various signs is 

provided in Table 2A-3.
Roadway Departure Safety | B-13
C-1 | Roadway Departure Safety

Appendix C: Crash Rate Calculations

The crash rate for roadway departure crashes on a roadway is calculated 

as:

R = C x 1,000,000

V x 365 x N x L

The variables in this equation are: 

R = Roadway Departure crash rate for the road segment expressed as 

crashes per 100 million vehicle-miles of travel,

C = Total number of roadway departure crashes in the study period

V = Traffic volumes using Average Annual Daily Traffic (AADT) volumes

N = Number of years of data

L = Length of the roadway segment in miles

This equation relies on having traffic volume information To determine 

how to obtain actual and estimated traffic volumes for a particular 

roadway, a local agency can contact its State highway agency, LTAP 

representative, or other state agencies.

Example 1. Crash Rate by Vehicle Miles Traveled

In this example, two roadways have the same number of crashes but 

different traffic volumes. By factoring in exposure, the calculation 

indicates that Route B may be more susceptible to future crashes. 

However, before any decision is made, other factors such as roadway 

geometrics, cross section, and other potential differentiating factors 

should be considered. There could be other issues not related to traffic 

volume that affect crash rates.

Roadway RD Crashes 

(C)

Traffic 

Volume (V)

Years 

of Data (N)

Length 

of Segment (L)

Crash 

Rate (R)

Route A 15 4,000 5 12 miles 0.98

Route B 15 2,500 5 12 miles 1.85

Table 3 - Example of Roadway Departure Crash Rate Calculation by Vehicle Miles Traveled
Roadway Departure Safety | C-2

Route A has experienced 0.98 crashes per 100 million vehicle-miles 

traveled on that roadway. Route B has experienced 1.85 crashes per 100 

million vehicle-miles traveled. This data can be used to compare the two 

roadways. In this case, even though both routes had the same number 

of crashes, Route B is more susceptible to crashes based on the level 

of exposure. The practitioner could consider Route B a more promising 

candidate for a safety treatment than Route A due to its higher crash rate.

Example 2. Crash Rate by Route Length

In this example, two roadways have the same number of crashes but 

different roadway lengths. Traffic volume data is not available. 

A “crashes per mile” rate for road segments is calculated as:

R = C

N x L

Where:

R = Crashes per mile for the road segment expressed as crashes per each 

1 mile of roadway per year.

C = Total number of crashes in the study period.

N = Number of years of data.

L = Length of the roadway segment in miles.

Roadway RD Crashes 

(C)

Years of Data 

(N)

Length 

of Segment (L)

Crashes 

per Mile (R)

Route A 12 5 17 miles 0.71

Route B 12 5 26 miles 0.46

Table 4 - Example of Roadway Departure Crash Rate Calculation by Route Length

In this example, Route A has experienced 0.71 crashes per roadway mile. 

Route B has experienced 0.46 crashes per mile of roadway. In this case, 

even though both routes have the same number of crashes, Route A 

may be more susceptible to future crashes. Therefore Route A may be a 

more promising candidate for safety treatments.
For More Information

Office of Safety

Federal Highway Administration

1200 New Jersey Ave, SE

Washington, DC 20590-9898

http://safety.fhwa.dot.gov

FHWA-SA-11-09