Research, Development, and Technology

Turner-Fairbank Highway Research Center

6300 Georgetown Pike

McLean, VA 22101-2296

PUBLICATION NO. FHWA-HRT-20-053 NOVEMBER 2020 

Contributing Factors for Focus

Crash and Facility Types:

Quick Reference Guide
FOREWORD

The research documented in this guide was conducted as part of the Federal Highway 

Administration’s (FHWA’s) Evaluation of Low-Cost Safety Improvements Pooled Fund Study 

(ELCSI-PFS). FHWA established this PFS in 2005 to conduct research on the effectiveness of 

the safety improvements identified by the National Cooperative Highway Research Program 

Report 500 Series as part of the implementation of the American Association of State Highway 

and Transportation Officials’ Strategic Highway Safety Plan.(1) The ELCSI-PFS studies provide 

a crash modification factor and benefit–cost economic analysis for each of the targeted safety 

strategies identified as priorities by the pooled fund member States.

The goal of this study was to identify common target crash types, their associated facility types, 

and contributing factors to inform applications of systemic safety improvements. This document 

serves as a quick reference guide for transportation professionals in State and local agencies that

are interested in applying a systemic approach to road-safety management. This guide provides 

brief overviews based on an analysis of national and State data of the systemic approach and

common focus crash types and facility types with their contributing factors. This guide 

supplements the technical report Contributing Factors for Focus Crash and Facility Types

(FHWA-HRT-20-052) developed under the Focus Crash Types and Contributing Factors 

study.(2) This guide will benefit safety engineers and safety planners by providing greater insight 

into highway safety. 

Brian P. Cronin, P.E. 

Director, Office of Safety and Operations 

Research and Development 

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation 

(USDOT) in the interest of information exchange. The U.S. Government assumes no liability for 

the use of the information contained in this document. 

The U.S. Government does not endorse products or manufacturers. Trademarks or 

manufacturers’ names appear in this report only because they are considered essential to the 

objective of the document. 

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve 

Government, industry, and the public in a manner that promotes public understanding. Standards 

and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its 

information. FHWA periodically reviews quality issues and adjusts its programs and processes to 

ensure continuous quality improvement.
TECHNICAL REPORT DOCUMENTATION PAGE

1. Report No.

FHWA-HRT-20-053

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

4. Title and Subtitle

Contributing Factors for Focus Crash and Facility Types: 

Quick Reference Guide

5. Report Date

November 2020

6. Performing Organization Code

7. Author(s)

Richard Porter (ORCID: 0000-0001-8535-3451), Thanh Le

(ORCID: 0000-0001-5809-2751), Frank Gross (ORCID: 0000-

0001-5081-4916), Daniel Carter (ORCID: 0000-0001-6572-

6548), Taha Saleem (ORCID: 0000-0002-2878-0980), and 

Raghavan Srinivasan (ORCID: 0000-0002-3097-5154)

8. Performing Organization Report No.

9. Performing Organization Name and Address

VHB

940 Main Campus Drive, Suite 500

Raleigh, NC 27606

10. Work Unit No.

11. Contract or Grant No.

DTFH61-13-D-000001

12. Sponsoring Agency Name and Address

U.S. Department of Transportation

Federal Highway Administration 

1200 New Jersey Avenue, SE

Washington, DC 20590

13. Type of Report and Period Covered

Reference Guide; March 2017–February 2018

14. Sponsoring Agency Code

HRDS-20

15. Supplementary Notes

The Federal Highway Administration (FHWA) Office of Safety Research and Development managed this study 

under the Development of Crash Modification Factors program. The FHWA Office of Safety Research and 

Development Program Manager and Contracting Officer’s Representative was Roya Amjadi (HRDS-20; ORCID: 

0000-0001-7672-8485) and the Technical Manager was Karen Scurry (HSA). 

16. Abstract

This document serves as a quick reference guide for transportation professionals in State and local agencies that

are interested in applying a systemic approach to road-safety management. This guide provides brief overviews 

of the systemic approach, common target crash types and their associated facility types, and contributing factors. 

It also provides a six-step process to identify countermeasures as well as lists and descriptions of specific 

countermeasures for common target crash types and facility types. The common target crash types, facility types, 

and contributing factors are based on an analysis of national and State data and serve as a quick reference for

agencies interested in applying systemic safety approaches to these most common crash and facility types. 

Agencies can reference the contributing factors in this guide to help identify countermeasures and prioritize sites 

for systemic safety improvements. Agencies with sufficient data and analysis capabilities can also refer to the 

FHWA’s Systemic Safety Project Selection Tool for discussions on how to analyze their own data to identify 

crash types, facility types, and contributing factors.(3)

17. Key Words

Systemic safety, focus crash types, contributing 

factors, random forests, crash prediction, proven 

countermeasures

18. Distribution Statement

No restrictions. This document is available to the public 

through the National Technical Information Service, 

Springfield, VA 22161.

http://www.ntis.gov

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

36 

22. Price

N/A

Form DOT F 1700.7 (8-72) Reproduction of completed pages authorized.
ii
iii

TABLE OF CONTENTS

CHAPTER 1. INTRODUCTION ................................................................................................ 1

Overview of Systemic Approach............................................................................................ 1

Overview of Quick Reference Guide ..................................................................................... 4

Target Audience ...................................................................................................................... 4

Resources ............................................................................................................................ 4

CHAPTER 2. IDENTIFYING FCFTS ....................................................................................... 5

CHAPTER 3. IDENTIFYING CONTRIBUTING FACTORS ................................................ 7

CHAPTER 4. IDENTIFYING TARGETED COUNTERMEASURES ................................ 11

Countermeasure Selection.................................................................................................... 11

Step 1. Identify a Focus Crash Type ................................................................................. 11

Step 2. Identify Contributing Factors for the Focus Crash Type ...................................... 11

Step 3. Assemble a List of Potential Countermeasures That Address the Focus Crash 

Type .................................................................................................................................. 11

Step 4. Identify Countermeasures That Explicitly Address Contributing Factors 

Associated with the Focus Crash Type ............................................................................. 12

Step 5. Identify Countermeasures with CMFs .................................................................. 12

Step 6. Select a Countermeasure ....................................................................................... 12

Systemic Countermeasures for Intersection FCFTs .......................................................... 12

Left- and Right-Turn Lanes .............................................................................................. 14

Yellow Change Intervals................................................................................................... 15

Backplates with Retroreflective Borders .......................................................................... 16

Application of Multiple Low-Cost Countermeasures ....................................................... 17

Advance Signs .................................................................................................................. 18

Systemic Countermeasures for Nonintersection FCFTs ................................................... 18

SafetyEdge ........................................................................................................................ 20

Rumble Strips and Stripes ................................................................................................. 21

Enhanced Friction for Horizontal Curves ......................................................................... 22

Enhanced Delineation for Horizontal Curves ................................................................... 23

Roadside Design Improvements at Curves ....................................................................... 24

Advance Markings for Curves .......................................................................................... 25

Advance Signs .................................................................................................................. 26

CHAPTER 5. SUMMARY AND CONCLUSIONS ................................................................. 27

REFERENCES ............................................................................................................................ 29
iv

LIST OF TABLES

Table 1. Contributing factors for intersection FCFTs. .................................................................... 8

Table 2. Contributing factors for nonintersection FCFTs. .............................................................. 9

Table 3. Systemic countermeasures for intersection contributing factors. ................................... 13

Table 4. Systemic countermeasures for nonintersection contributing factors. ............................. 19
v 

LIST OF ABBREVIATIONS

B/C benefit–cost

CMF crash modification factor

FCFT focus crash and facility type 

FHWA Federal Highway Administration

MUTCD Manual on Uniform Traffic Control Devices

NCHRP National Cooperative Highway Research Program 

SHSP strategic highway safety plan

1 

CHAPTER 1. INTRODUCTION

OVERVIEW OF SYSTEMIC APPROACH

At the most fundamental level, the process of road-safety management consists of three steps: 

planning, implementation, and evaluation. The intent of this process is to identify and improve 

sites expected to benefit the most from targeted, cost-effective crash countermeasures. This 

intent aligns with the purpose of the Highway Safety Improvement Program, to significantly

reduce fatalities and serious injuries on all public roads.(4) To achieve these goals, the process of 

road-safety management should seek to maximize opportunities to improve safety, otherwise

agencies might allocate resources inefficiently to sites with less potential for cost-effective safety 

improvement while locations with a higher potential for improvement remain untreated.

There are two general approaches to road-safety management: (1) selecting and treating sites 

based on the frequency and severity of crashes observed at specific sites (sometimes called the 

hot-spot approach) and (2) selecting and treating sites based on site-specific geometric, 

operational, and other attributes known to increase crash potential (the systemic approach). 

These two approaches are complementary and support a comprehensive approach to road-safety 

management. The primary difference between the two is the way in which analysts identify 

issues and develop projects in the planning stage. 

In the systemic approach, analysts identify potential sites for safety improvement based on 

site-specific geometric, operational, and other attributes (e.g., possibly including observed crash 

history) rather than on observed crash history alone. The first three steps that make up the 

planning component of the systemic approach to road-safety management are (1) identify focus 

crash and facility types (FCFTs) and contributing factors, (2) screen and prioritize candidate 

locations, and (3) select countermeasures. The following list provides an overview of these steps:

1. Identify FCFTs and contributing factors: The first step of the systemic approach is to 

select FCFTs and contributing factors. Focus crash types typically reflect prevalent 

severe crash types for a given jurisdiction. Focus facility types typically include the 

facility and site types where the focus crash types are most prevalent (e.g., rural two-lane 

undivided segments or urban four-leg signalized intersections). Contributing factors are 

site-specific attributes associated with an increased potential of focus crash types

occurring. Contributing factors may include site-specific crash history (if available), 

geometric and operational characteristics, and surrounding sociodemographic and 

environmental attributes. Refer to the Federal Highway Administration’s (FHWA’s) 

Systemic Safety Project Selection Tool for further information on identifying FCFTs and 

contributing factors.

(3)

2. Screen and prioritize candidate locations: The second step of the systemic approach is 

to develop a prioritized list of potential locations at which to install systemic 

improvements that will address a focus crash type. Using contributing factors for that 

crash type as a guide, analysts identify sites of the focus facility types as candidate 

locations. To prioritize candidate locations, analysts assign a level of crash potential to 

each site based on the site-specific geometric and operational characteristics, crash 
2 

history, and other attributes that indicate higher chances of crashes occurring. Analysts 

also apply thresholds or weights to each contributing factor to further prioritize the list of 

sites based on available resources and program objectives. Refer to FHWA’s Systemic 

Safety Project Selection Tool for further information related to screening and prioritizing 

candidate locations.(3)

3. Select countermeasures: The third step of the systemic approach is to select 

countermeasures. Given the list of contributing factors for the FCFTs, agencies select 

targeted countermeasures to address or mitigate the influence of the contributing factors 

at the prioritized locations across the network. Refer to the Systemic Safety Project 

Selection Tool for further information related to selecting countermeasures.(3)

Consider a scenario where an agency identified head-on crashes as a focus crash type based on 

the number of fatal and severe injury crashes of that type. The agency noted these crashes are 

most prevalent on rural four-lane road segments, so it selected them as the focus facility type for 

head-on crashes. The agency reviewed data for all head-on crashes that occurred on rural 

four-lane road segments and determined that potential contributing factors include narrow

roadway cross sections (i.e., lanes and shoulders), narrow or no medians, and no median barriers 

(for segments with medians). The agency noted that alternative countermeasures to address these

underlying contributing factors include installing centerline or median shoulder/edgeline rumble 

strips, widening roadway cross sections, widening medians, or installing median barriers 

(for segments with medians). The agency deemed the latter three options cost-prohibitive for the 

wide-scale deployment that is part of the systemic approach to road-safety management. As 

such, the agency selected rumble strips as an appropriate countermeasure to address the 

contributing factors (i.e., centerline rumble strips on undivided facilities, median shoulder, or 

edgeline rumble strips on divided facilities). At this point, the agency considered installing 

rumble strips on all rural four-lane roads. Considering budgetary constraints, the agency realized 

it did not have available funds to install rumble strips on all rural four-lane, roads. Instead, the 

agency began to prioritize candidate locations and established thresholds for countermeasure 

implementation (e.g., rural four-lane roads that have lane widths less than 11 ft). 

The following list includes potential uses for the systemic approach to road-safety management: 

• Agencies can use the systemic approach to target emphasis areas from their strategic 

highway safety plans (SHSPs). By targeting issues that are common among sites, 

agencies can implement similar countermeasures that address priority crash types and 

contributing factors across the sites. 

• Agencies typically aim to make modest site-specific safety improvements with proven 

countermeasures at sites with relatively high crash potential identified by the presence of 

contributing factors rather than by site-specific crash history alone. 

• Agencies can apply the systemic approach without site-level crash and exposure data or 

when the observed crash frequency at individual sites is relatively low (i.e., highly

dispersed crashes scattered across the road system at low densities).
3 

• When agencies implement similar improvements (e.g., enhancing signing or striping, 

installing rumble strips, or upgrading signal heads) across many sites (i.e., the systemic 

approach), the improvements are generally low cost. Nevertheless, agencies should still 

consider high-cost improvements, but the improvements should be highly effective to 

justify the increased costs. 

• While agencies should begin their systemic approach to road-safety management by 

identifying FCFTs, they can also begin with the intent to implement a proven, low-cost 

countermeasure and identify appropriate locations for implementation based on 

contributing factors. In general, the use of proven, low-cost countermeasures will result 

in a positive return on investment; however, a benefit–cost (B/C) analysis is useful to 

determine the most effective (i.e., greatest reduction in crashes and resulting injuries) and 

most efficient (i.e., greatest return on investment) alternatives.

The systemic approach is an opportunity to achieve safety benefits across a large portion of the 

system. This opportunity arises from the focus on priority crash types that may be highly 

dispersed across the road system and their contributing factors rather than focusing on 

site-specific crash history alone. For example, consider a $3 million safety program and the 

opportunity to implement one of two options. The first option is to install roundabouts at three 

sites at an average cost of $1 million per site. The sites identified have an average crash history 

of 20 crashes per year, and it is assumed that the treatment will result, on average, in a 

40-percent reduction in crashes. The system benefit for the first option is an expected reduction 

of 24 crashes per year. The second option is to install intersection-improvement packages at 

500 sites at an average cost of $6,000 per site. The sites identified have an average crash history 

of three crashes per year, and it is assumed that the treatment will result, on average, in a 

5-percent reduction in crashes. The system benefit for the second option is an expected reduction 

of 75 crashes per year. Even with a modest crash reduction per site, targeted systemic 

improvements can have a large impact on the system as a whole. 

The systemic approach addresses contributing factors rather than crash history. Specifically, it 

applies countermeasures to locations with features that increase crash potential, but the sites are 

not required to have a history of crashes to receive countermeasure treatments. This distinction is 

important because the types of crashes occurring on a system remain relatively consistent from 

year to year, while the locations of crashes tend to fluctuate, particularly on low-volume and 

rural roads. In many States, these roads exhibit a high proportion of severe crashes sparsely 

distributed across many segments and intersections. It is difficult to address these sites with the 

hot-spot approach due to the low density of crashes. The systemic approach helps to overcome 

these limitations by focusing on the underlying contributing factors across the network as 

opposed to only considering the crash history at individual locations.

A primary challenge related to the systemic approach is justifying the cost of improving sites, 

specifically those with no recent crash history. In some cases, there is also limited information on 

the safety effectiveness of countermeasures well suited to systemic implementation. While there 

are more than 5,000 crash modification factors (CMFs) available in the CMF Clearinghouse, 

many of these CMFs reflect the average safety effect of projects implemented based on the 

hot-spot approach or countermeasures that require substantial engineering work prior to 

implementation at each site.(5)

 It is generally unknown if systemic applications will result in the 
4 

same average level of benefit as the crash-based application for the same countermeasure. As 

such, it can be difficult to analyze the expected benefit and cost-effectiveness of some systemic

implementations. Project and maintenance costs can also range from negligible to relatively high 

depending on the type of countermeasure and level of implementation. Although the unit cost per 

site is often relatively low, the service life for low-cost countermeasures is typically less than the 

service life for high-cost countermeasures. As such, it is important to consider the lifecycle costs 

prior to implementation.

OVERVIEW OF QUICK REFERENCE GUIDE

This quick reference guide (herein referred to as “the guide”) serves as a concise reference on 

focus crash types, focus facility types, contributing factors, and countermeasures for applying the 

systemic approach to road safety management.

The guide is organized into five chapters. Chapter 1 provides an overview of the systemic 

approach, the guide, the target audience, and additional resources. Chapter 2 discusses 

identifying FCFTs, including common FCFTs based on an analysis of national and State data

documented in the technical report Contributing Factors for Focus Crash and Facility Types for

the Development of Crash Modification Factors program.

(2)

 Chapter 3 discusses identifying 

contributing factors, including common contributing factors for FCFTs, based on the same 

analysis of national and State data. Chapter 4 describes the process of matching appropriate 

countermeasures to contributing factors. It also provides a list of potential countermeasures to 

consider for systemic implementation, including a description of the countermeasure, typical 

reasons for implementation, target facility types, considerations, and related resources. Chapter 5 

provides a summary of the guide and conclusions. 

TARGET AUDIENCE

The guide’s target audience includes transportation professionals in State and local agencies, 

such as traffic and safety engineers and planners, who are interested in the systemic approach to 

road-safety management. 

Resources

The following are key resources relevant to the systemic approach to road-safety management: 

• Systemic Safety Project Selection Tool—presents a step-by-step process for 

incorporating systemic safety planning into road-safety management.(3)

• National Cooperative Highway Research Program (NCHRP) Report 500 Series—

presents 22 emphasis areas that affect overall highway safety, strategies for reducing 

crashes that correspond to these emphasis areas, and an outline of what is needed to 

implement each strategy.

(1)

• Reliability of Safety Management Methods: Systemic Safety Program—describes the 

state of the practice and latest tools that support systemic safety analyses.(6)
5 

CHAPTER 2. IDENTIFYING FCFTS

Readers with sufficient data and analysis capabilities may refer to FHWA’s Systemic Safety 

Project Selection Tool for discussion on how to analyze jurisdiction-specific data to identify 

FCFTs.

(3) Those with limited data and analysis capabilities may refer to State, regional, or local 

SHSPs to identify focus crash types based on emphasis areas. Further analysis of the emphasis 

areas can help identify focus facility types (i.e., in which facility types are the focus crash types 

more prevalent). Readers with limited data and analysis capabilities may also refer to the 

following lists of intersection and nonintersection FCFTs, which represent common priorities 

based on an analysis of national and State data documented in Contributing Factors for Focus 

Crash and Facility Types.

(2)

Potential intersection FCFTs include the following:

• Angle crashes on rural two-lane roads at four-leg minor-road stop-controlled intersections 

(daytime and nighttime). 

• Angle crashes on urban two-lane roads at four-leg minor-road stop-controlled 

intersections (daytime). 

• Angle crashes on rural two-lane roads at three-leg minor-road stop-controlled 

intersections (daytime). 

• Angle crashes on urban multilane divided roads at four-leg signalized intersections

(daytime). 

• Angle crashes on urban multilane undivided roads at four-leg signalized intersections

(daytime). 

• Angle crashes on rural multilane divided roads at four-leg minor-road stop-controlled 

intersections (daytime). 

Potential nonintersection FCFTs include the following: 

• Run-off-road crashes on rural two-lane roads on horizontal curves (daytime and 

nighttime). 

• Run-off-road crashes on rural two-lane roads on tangent segments (daytime and 

nighttime). 

• Lane-departure crashes on rural two-lane roads on horizontal curves (daytime and 

nighttime). 

• Lane-departure crashes on rural two-lane roads on tangent segments (daytime and 

nighttime). 

• Head-on crashes on rural two-lane roads on horizontal curves (daytime and nighttime). 

• Head-on crashes on rural two-lane roads on tangent segments (daytime and nighttime). 

• Angle crashes on rural two-lane roads on tangent segments (daytime). 

• Rollover/overturn crashes on rural two-lane roads on horizontal curves (daytime and 

nighttime). 

• Rollover/overturn crashes on rural two-lane roads on tangent segments (daytime and 

nighttime). 

7 

CHAPTER 3. IDENTIFYING CONTRIBUTING FACTORS

Analysts can identify contributing factors for FCFTs and relative crash potential by analyzing 

crash data from their jurisdictions or reviewing previous research studies. It is important to use 

reliable, data-driven methods to identify contributing factors and inform decisions. The Highway 

Safety Manual presents predictive methods to relate crash frequency to roadway design and 

operational characteristics using safety performance functions and CMFs.(7) A predictive 

approach based on a combination of historical crash, exposure, and roadway data is more reliable 

than an approach based only on cross-tabulations or ad hoc analyses to identify geometric and 

operational attributes that may increase crash potential. 

Agencies can use the systemic approach in the absence of high-quality, historical, site-level crash 

data. Rather than analyzing observed crash frequencies at specific locations, analysts investigate 

prevalent severe crash types across identified focus facility types to correlate the presence of 

potential contributing factors (e.g., selected geometric and operational roadway characteristics) 

with the crash types of interest. Agencies then use those roadway characteristics with higher 

crash potential as a basis for implementing countermeasures to address the focus crash types. 

Beyond the presence of contributing factors, analysts may identify thresholds at which a 

characteristic increases crash potential. For example, rather than simply identifying sites with 

horizontal curves, an analyst may specify the degree of curve over or radius under which crash 

potential increases. An analyst may also apply weights to these contributing factors to prioritize 

sites for countermeasure implementation. For example, contributing factors for 

roadway-departure crashes may include lane width, shoulder width, and horizontal curvature; 

however, sharper horizontal curves may increase crash potential more than narrower lanes. If this 

is the case, an analyst may place more weight on the curve-related contributing factor and less 

weight on the lane width–related contributing factor.

Readers with sufficient data and analysis capabilities may refer to the Systemic Safety Project 

Selection Tool for discussion on how to analyze data to identify contributing factors given a 

specific FCFT.

(3) However, readers with limited data and analysis capabilities may refer to 

Contributing Factors for Focus Crash and Facility Types, which identifies contributing factors 

based on an analysis of crash, traffic, roadway, weather, and sociodemographic data from 

multiple States using a random-forest approach.(2) Table 1 and table 2 present the common 

contributing factors from this analysis for intersection and nonintersection FCFTs.

(1) The 

conclusions and recommendations in this report touch on several limitations in the data and 

analysis, such as a lack of information on the presence and type of safety countermeasures at the 

analyzed sites and a lack of detail on some roadway features. The researchers’ work in this report 

is the first-known application of random forests in this context, and they offered 

recommendations for future refinements when using the approach. However, the roadway factors 

uncovered by the analysis as influencing the frequencies of the different crash types were 

generally consistent with expectations based on previous research and existing practice. 
8 

Table 1. Contributing factors for intersection FCFTs.

Contributing Factor

Angle R2L 

4ST

Angle U2L 

4ST

Angle R2L 

3ST

Angle UML 

Div. 4SIG

Angle UML 

Undiv. 4SIG

Angle 

RML Div. 

4ST

Larger mainline AADT ● ○ ● ● ○ ○

Larger cross street AADT ● ○ ○ ○ ○ ●

Smaller curve radius — — ○ — — — 

Wider lane width ● — ○ ○ — — 

Wider median width — — — ○ — ○

Absence of mainline leftturn channelization○ — — — — — 

Absence of cross-street 

right-turn channelization

— — — — ○ — 

Design speed/higher 

speed limit

● ● ○ ● ○ — 

●Contributing factor in multiple States.

○Contributing factor in select States.

—Not a contributing factor in any State. 

AADT = average annual daily traffic; N/A = not applicable; Angle R2L 4ST = angle crashes on rural two-lane roads 

at four-leg minor-road stop-controlled intersections; Angle U2L 4ST = angle crashes on urban two-lane roads at 

four-leg minor-road stop-controlled intersections; Angle R2L 3ST = angle crashes on rural two-lane roads at 

three-leg minor-road stop-controlled intersections; Angle UML Div. 4SIG = angle crashes on urban multilane 

divided roads at four-leg signalized intersections; Angle UML Undiv. 4SIG = angle crashes on urban multilane 

undivided roads at four-leg signalized intersections; Angle RML Div. 4ST = angle crashes on rural multilane 

divided roads at four-leg minor-road stop-controlled intersections.
9 

Table 2. Contributing factors for nonintersection FCFTs. 

Contributing Factor

ROR R2L 

Curve

ROR R2L 

Tangent

LD R2L 

Curve

LD R2L 

Tangent

HO R2L 

Curve

HO R2L 

Tangent

Angle R2L 

Tangent

RO/OT 

R2L 

Curve

RO/OT 

R2L 

Tangent

Larger AADT ● ● ● ● ● ● ● ● ●

Smaller percentage of 

trucks on the roadway

○ ○ ○ ○ ○ ○ — ○ ○

Larger percent grade ○ ○ ● ● ○ ○ — ● ●

Smaller curve radius ● N/A ● N/A ● N/A N/A ● N/A

Narrower surface width ○ ○ ○ ○ ○ ○ — ○ ○

Narrower shoulder width ● ● ○ ○ ○ — ○ ○ ○

Unpaved shoulder — ○ — ○ — ○ — — — 

Higher speed limit ○ ○ ○ ○ ○ ○ — ○ ○

Narrower lane width — — — ○ — — — — — 

Mountainous terrain — — — — — — — — ○

●Contributing factor in multiple States.

○Contributing factor in one State.

—Not a contributing factor in any State. 

AADT = average annual daily traffic; N/A = not applicable; ROR R2L Curve = run-off-road crashes on rural two-lane roads on horizontal curves; ROR R2L 

Tangent = run-off-road crashes on rural two-lane roads on tangent segments; LD, R2L, Curve = lane-departure crashes on rural two-lane roads on horizontal 

curves; LD R2L Tangent = lane-departure crashes on rural two-lane roads on tangent segments; HO R2L Curve = head-on crashes on rural two-lane roads on 

horizontal curves; HO R2L Tangent = head-on crashes on rural two-lane roads on tangent segments; Angle R2L Tangent = angle crashes on rural two-lane roads 

on tangent segments; RO/OT R2L Curve = rollover/overturn crashes on rural two-lane roads on horizontal curves; RO/OT R2L Tangent = rollover/overturn 

crashes on rural two-lane roads on tangent segments. 

11 

CHAPTER 4. IDENTIFYING TARGETED COUNTERMEASURES

This chapter provides an overview of countermeasures and describes the process of identifying 

potential countermeasures that address the FCFTs and contributing factors in the previous two 

chapters. This chapter includes several potential countermeasures for intersection and 

nonintersection FCFTs, respectively, that State and local transportation agencies can consider as 

part of a systemic approach to road-safety management. 

COUNTERMEASURE SELECTION

The countermeasure selection process provided in this guide consists of six steps, which are 

described in the following subsections. 

Step 1. Identify a Focus Crash Type 

The first step is to identify a focus crash type, which should be based on an analysis of available 

data and the priorities of the transportation agency as outlined in the State or regional SHSP. 

A focus crash type will be defined by the type of maneuver (e.g., run off road), time of day 

(i.e., daytime or nighttime), and type of segment (i.e., curve versus tangent) or type of 

intersection (e.g., four-leg signalized). Readers should refer to chapter 2 of this guide for lists of 

common focus crash types. 

Step 2. Identify Contributing Factors for the Focus Crash Type

The second step is to identify the contributing factors for the focus crash type. Some factors may 

be expected to contribute to the increase of the crash type, such as the presence of an unpaved 

shoulder, whereas others may decrease certain crash types, such as increasing (i.e., flattening) the 

radius of a horizontal curve. Readers should refer to chapter 3 of this guide for more discussion 

on identifying contributing factors. 

Step 3. Assemble a List of Potential Countermeasures That Address the Focus Crash Type 

The third step is to assemble a list of potential countermeasures that address the contributing 

factors of the focus crash type. A wide range of resources, including the following, could be used 

to assemble a list of potential countermeasures:

• NCHRP Report 500 Series.(1)

• Highway Safety Manual.

(7)

• CMF Clearinghouse.(5)

• FHWA Proven Safety Countermeasures.(8)

• Countermeasures that Work: A Highway Safety Countermeasure Guide for State 

Highway Safety Offices.

(9)

• PEDSAFE.

(10)

• BIKESAFE.

(11)

• State-generated list of common countermeasures within a State (i.e., a toolbox). 
12 

This list should contain a wide pool of potential countermeasures, including those that address 

any part of the focus crash type. Readers should refer to the sections Systemic Countermeasures 

for Intersection FCFTs and Systemic Countermeasures for Nonintersection FCFTs in this chapter 

for potential countermeasures. 

Step 4. Identify Countermeasures That Explicitly Address Contributing Factors Associated 

with the Focus Crash Type

The fourth step is to identify countermeasures that explicitly address the contributing factors 

associated with the focus crash type. Compare the information known about each 

countermeasure on the list from step 3 to the contributing factors identified in step 2 to identify 

countermeasures that specifically address one or more of the contributing factors. During this 

process, logical links can be drawn between many countermeasures and contributing factors. For 

the purpose of this process, only a clear, explicit relation to contributing factors should be 

indicated.

Step 5. Identify Countermeasures with CMFs

The fifth step is to use CMF resources to identify which countermeasures on the list from step 3 

have CMFs that quantify the safety effect. A countermeasure with a known effect can be 

compared to other countermeasures in a prioritized selection and can be used to generate a B/C

analysis of proposed alternatives. Countermeasures for which a robust set of CMFs are available 

may have CMFs that address the focus crash type specifically. If this is the case, extra 

consideration should be given to these countermeasures during the final selection.

The most comprehensive and accessible resource of CMF information is the CMF 

Clearinghouse.(5)

 Other sources for CMF information may include State-specific CMF lists.

(12)

Step 6. Select a Countermeasure

The sixth and final step is to select a countermeasure from the pool of eligible countermeasures 

generated in step 3. The selection should consider how well each countermeasure addresses the 

specific contributing factors for the focus crash type as determined in step 4 and the extent to 

which CMFs are available for each countermeasure as determined in step 5. 

SYSTEMIC COUNTERMEASURES FOR INTERSECTION FCFTS

Table 1 summarizes contributing factors associated with intersection FCFTs based on an analysis 

of data from multiple States described in Contributing Factors for Focus Crash and Facility 

Types.

(2) The roadway-related contributing factors include the intersection being located on a 

horizontal curve with a smaller curve radius, wider lane widths, wider median widths, absence of 

mainline left-turn channelization, absence of cross-street right-turn channelization, and higher 

speed limit or design speed. 

Table 3 summarizes countermeasures related to the contributing factors for the intersection 

FCFTs. These countermeasures include left- and right-turn lanes, yellow change intervals, 

backplates with retroreflective borders, application of multiple low-cost countermeasures, and 

advance signs. More detailed information on what each countermeasure is and why and where 
13 

they are used as well as other considerations and related resources are provided in the following 

sections. The first four countermeasures in table 3 and most of the detail provided for each are

from FHWA’s Office of Safety Proven Safety Countermeasures initiative.(8) The last two 

countermeasures and supplemental information for the other four proven countermeasures are 

from the Institute of Transportation Engineers’ Unsignalized Intersection Improvement Guide 

website, FHWA’s Intersection Safety website, and a FHWA brochure, Intersection Safety 

Strategies.

(25–27)

Table 3. Systemic countermeasures for intersection contributing factors.

Countermeasure

Smaller 

Curve Radius 

(Intersection 

on Curve)

Wider 

Mainline

Lane 

Width

Wider 

Mainline 

Median 

Width

Absence of 

Mainline LeftTurn 

Channelization

Absence of 

Minor Street 

Right-Turn 

Channelization 

(Signalized 

Intersections)

Design 

Speed/Higher 

Speed Limit

Left- and rightturn lanes— — — ● ● ●

Yellow change 

intervals

— — — — — ●

Backplates with 

retroreflective 

borders

— ● ● — — ●

Application of 

multiple low-cost 

countermeasures

● ● ● ● ● ●

Advance signs ● ● ● — — ●

●Contributing factor in multiple States.

—Not a contributing factor in any State.
14 

Left- and Right-Turn Lanes

What: Auxiliary lanes for left- or right-turning vehicles provide physical separation between 

slowing or stopped turning traffic and adjacent through traffic at intersection approaches. These 

lanes are also for deceleration prior to a turn and storage of waiting vehicles. 

Why: Crashes occurring at intersections are often related to turning maneuvers. The focus crash 

types include collisions of vehicles turning left across opposing through traffic and rear-end 

collisions of vehicles turning left or right with other vehicles following closely behind. Turn 

lanes help reduce the potential for these types of crashes.

Where: Turn lanes should be considered for major road approaches at both three- and four-leg 

intersections with two-way stop control on the minor road where significant turning volumes 

exist and there is a history of turn-related crashes. 

Considerations: Pedestrian and bicyclist safety and convenience should also be considered 

when adding turn lanes at an intersection. 

Resources: The following resources provide further information about left- and right-turn lanes: 

• Refer to FHWA’s Office of Safety Proven Safety Countermeasures website for additional 

information on the implementation of this countermeasure.(8)

• Refer to the report Safety Effectiveness of Intersection Left- and Right-Turn Lanes for 

more information on the implementation of this countermeasure.(28)

• Refer to the CMF Clearinghouse for the safety effectiveness of this countermeasure.(5)
15 

Yellow Change Intervals 

What: The yellow change interval is the length of time that a yellow signal indication is 

displayed following a green signal indication. The yellow signal provides a warning to drivers of 

impending change in right-of-way. Well-timed yellow change intervals can help improve 

signalized intersection safety and reduce red-light running.

Why: Red-light running is a leading cause of severe crashes at signalized intersections. If the 

yellow change interval is too short, drivers may be unable to stop safely, causing rear-end 

crashes or leading to unintentional red-light running. If the yellow change interval is too long, 

drivers may treat the yellow as an extension of the green phase, inviting intentional red-light 

running. 

Where: Yellow change intervals should be considered at all signalized intersections.

Considerations: Agencies should consider instituting regular evaluation and adjustment 

protocols for existing traffic signal timing.

Resources: The following resources provide further information about yellow change intervals:

• Refer to FHWA’s Office of Safety Proven Safety Countermeasures website for additional 

information on the implementation of this countermeasure.(8)

• Refer to NCHRP Report 731, Guidelines for Timing Yellow and All-Red Intervals at 

Signalized Intersections, for more information on this countermeasure.(29)

• Refer to the CMF Clearinghouse for the safety effectiveness of this countermeasure.(5)
16 

Backplates with Retroreflective Borders

What: Backplates with retroreflective borders are added to traffic signal heads to improve the 

visibility of the illuminated face of the signal by introducing a controlled-contrast background. 

Why: Signal heads that have backplates equipped with retroreflective borders are more 

conspicuous in both daytime and nighttime conditions. This treatment enhances traffic signal 

visibility for both older and color vision–deficient drivers. This countermeasure is also 

advantageous during periods of power outages when the signals would otherwise be dark, 

providing a visible cue for drivers at night. 

Where: This countermeasure could be implemented at all signalized intersections.

Considerations: Agencies should consider adopting this countermeasure as a standard treatment 

for signalized intersections across a jurisdiction.

Resources: The following resources provide further information about backplates with 

retroreflective borders:

• Refer to FHWA’s Office of Safety Proven Safety Countermeasures website for additional 

information on the implementation of this countermeasure.(8)

• Refer to the CMF Clearinghouse for the safety effectiveness of this countermeasure 

(CMF ID 1410).(5)
17 

Application of Multiple Low-Cost Countermeasures

What: The systemic approach to intersection safety involves deploying a group of multiple 

low-cost countermeasures, such as enhanced signing and pavement markings at many 

stop-controlled intersections within a jurisdiction. 

The countermeasures include any combination of the following improvements on through or stop 

approaches:

• Through approach improvements are as follows: 

o Doubled-up (i.e., positioned on the left and right), oversized advance-intersection 

warning signs with street name sign plaques. 

o Enhanced pavement markings that delineate through lane edgelines. 

• Stop approach improvements are as follows: 

o Doubled-up (i.e., positioned on the left and right), oversized advance “Stop Ahead” 

intersection warning signs. 

o Doubled-up (i.e., positioned on the left and right), oversized stop signs. 

o Retroreflective sheeting on sign posts. 

o Properly placed stop bars. 

o Removal of any vegetation, parking, or obstruction that limits sight distance.

o Double-arrow warning sign at stem of T-intersections.

Why: These multiple low-cost countermeasures are designed to increase driver awareness and 

recognition of the intersections, traffic control, and potential conflicts.

Where: These countermeasures could be deployed at all stop-controlled intersections. 

Considerations: Agencies should consider adopting these countermeasures as a common 

treatment for stop-controlled intersections across a jurisdiction.

Resources: The following resources provide further information about multiple low-cost 

countermeasures:

• Refer to FHWA’s Office of Safety Proven Safety Countermeasures website for additional 

information on the implementation of these countermeasures.(8)

• Refer to the TechBrief Safety Evaluation of Multiple Strategies at Stop-Controlled 

Intersections for more information on these countermeasures.

(30)
18 

Advance Signs

What: Advance signs include the following: 

• Advance warning signs (e.g., intersection ahead, signal ahead, and stop ahead). 

• Advance informational signs (e.g., advance street name).

Why: Advance signs provide drivers with advance information and warnings that call attention 

to unexpected conditions on or adjacent to a roadway that might require a reduction of speed or 

an action in the interest of safety and efficient traffic operations.

Where: Refer to the MUTCD for information on the use of specific advance signs at 

unsignalized and signalized intersections.(15) In general, the use of advance signs may depend on 

warrants or may be based on an engineering study or judgment. 

Considerations: Use of advance signs should be kept to a minimum as overuse could jeopardize 

the effectiveness of the countermeasure. In situations where the condition or activity is seasonal 

or temporary, the warning sign should be removed or covered when the condition or activity 

does not exist. Agencies should apply signing devices uniformly based on the characteristics of 

the roadway. 

Resources: The following resources provide further information about advance signs:

• Refer to the brochure Intersection Safety Strategies for additional information on the 

implementation of this countermeasure.(27)

• Refer to chapter 2C of the MUTCD for more information on this countermeasure.

(15)

• Refer to the CMF Clearinghouse for the safety effectiveness of various advance signs.(5)

SYSTEMIC COUNTERMEASURES FOR NONINTERSECTION FCFTS

FCFTs based on an analysis of data from multiple States are described in Contributing Factors 

for Focus Crash and Facility Types and summarized in table 2.

(2) The roadway-related 

contributing factors include larger percent grade, smaller curve radius, narrower surface width, 

narrower shoulder width, presence of unpaved shoulders, higher speed limit, narrower lane 

width, and mountainous terrain. Table 4 summarizes countermeasures related to these

contributing factors for the nonintersection FCFTs. These countermeasures include 

SafetyEdgeSM, rumble strips and stripes, enhanced friction for horizontal curves, enhanced 

delineation for horizontal curves, roadside design improvements at curves, advance markings for 

curves, and advance signs. More detailed information on what each countermeasure is and why 

and where they are used, as well as other considerations and related resources, are provided in 

the following sections. The first five countermeasures in table 4, and much of the detail provided 

for each in the following sections, are drawn from FHWA’s Office of Safety Proven Safety 

Countermeasures initiative.

(8)

 FHWA promotes widespread implementation of these 

countermeasures through transportation agencies to reduce serious injuries and fatalities based 

on proven effectiveness and benefits.(8) The last two countermeasures in table 4 and 

supplemental information for the other five proven countermeasures are from the FHWA report

Low-Cost Treatments for Horizontal Curve Safety.

(13) FHWA’s Roadway Departure Safety 
19 

website provides additional discussion on and tools for strategic approaches to 

roadway-departure safety that fall into three categories:

(14) 

• Keep vehicles on the roadway. 

• Provide for safe recovery. 

• Reduce crash severity.

Table 4. Systemic countermeasures for nonintersection contributing factors.

Countermeasure

Larger 

Percent 

Grade

Narrower 

Lane 

Width

Narrower 

Paved 

Surface 

Width

Narrower 

Shoulder 

Width

Unpaved 

Shoulder

Higher 

Speed 

Limit

Mountainous 

Terrain

Smaller 

Curve 

Radius

SafetyEdge ● ● ● ● ● ● — ●

Rumble strips and 

stripes

— ● ● ● ● ● ● ●

Enhanced friction 

for horizontal 

curves

● — ● — — ● — ●

Enhanced 

delineation for 

horizontal curves

— — ● — — ● — ●

Roadside design 

improvements at 

curves

— — — — — ● — ●

Advance 

markings for 

curves

— ● ● ● ● ● — ●

Advance signs — ● ● ● — ●a ● ● a

Refer to the Manual on Uniform Traffic Control Devices for advance-warning-sign requirements based on speed 

differentials.

(15)

●Contributing factor in multiple States.

—Not a contributing factor in any State. 
20 

SafetyEdge 

What: The edge of the pavement is shaped at approximately 30 degrees from the pavement cross 

slope to eliminate the vertical drop-off. It is installed during the paving process and has a 

minimal effect on pavement project cost.

Why: SafetyEdge gives drivers the opportunity to maintain control of their vehicles and allows 

drifting vehicles to return to the pavement safely.

Where: SafetyEdge may be used in paving and resurfacing projects on both asphalt and 

concrete.

Considerations: This countermeasure is not necessary where curbs are present. The adjacent 

shoulder or slope should be flush with the top of pavement. 

Resources: The following resources provide further information about SafetyEdge: 

• Refer to FHWA’s Office of Safety Proven Safety Countermeasures website and 

SafetyEdge website for additional information on the implementation of this

countermeasure.(8,16)

• Refer to the CMF Clearinghouse for the safety effectiveness of this countermeasure.(5)
21 

Rumble Strips and Stripes

What: Longitudinal rumble strips are milled or raised elements on pavement intended to alert a 

driver through vibration and sound that their vehicle has left the travel lane. The strips can be 

installed on the shoulder, along the edgeline of the travel lane, or at or near the centerline of an 

undivided roadway. Rumble stripes are edgeline or centerline rumble strips where the pavement 

marking is placed over the rumble strip, which result in increased visibility of the pavement 

marking during wet nighttime conditions. 

Why: Rumble strips and stripes are designed to address roadway-departure crashes caused by 

distracted, drowsy, or otherwise inattentive drivers who drift from their lane. These crashes 

account for more than half of the fatal roadway crashes annually in the United States.(14)

Where: Driver error may occur on any road, so a systemic application is recommended.

Considerations: Transportation agencies should consider installing milled rumble strips with 

bicycle gaps.

Resources: The following resources provide further information about rumble strips and stripes:

• Refer to FHWA’s Office of Safety Proven Safety Countermeasures website and Rumble 

Strips and Rumble Stripes website for additional information on the implementation of 

this countermeasure.(8,17)

• Refer to the report State of the Practice for Shoulder and Center Line Rumble Strip 

Implementation on Non-Freeway Facilities for more information on this 

countermeasure.

(18)

• Refer to NCHRP Report 641, Guidance for the Design and Application of Shoulder and 

Centerline Rumble Strips, for more information on this countermeasure.(19)

• Refer to the CMF Clearinghouse for the safety effectiveness of this countermeasure.(5)
22 

Enhanced Friction for Horizontal Curves

What: Enhanced friction treatments include the following: 

• High-friction surface treatment: This treatment involves the application of high-quality 

aggregate to a pavement using a polymer binder to restore and/or maintain pavement 

friction at existing or potentially high-crash areas.

• Pavement grooving: This treatment involves applying longitudinal or transverse cuts 

onto a pavement surface to increase or restore pavement friction.

Why: Enhanced friction treatments compensate for the high-friction demand at curves where 

current pavement friction is not adequate to support operating speeds. 

Where: Enhanced friction treatments should be used at the following locations: 

• Sharp curves. 

• Inadequate cross-slope design. 

• Wet conditions. 

• Polished roadway surfaces. 

Considerations: High-friction surface treatments are not an answer for corridor paving but for 

spot applications. Pavement grooving is only appropriate for concrete pavements. 

Resources: The following resources provide further information about high-friction surface 

treatments: 

• Refer to FHWA’s Office of Safety Proven Safety Countermeasures website, Horizontal 

Curve Safety website, High Friction Surface Treatments website, and report Evaluation 

of Pavement Safety Performance for additional information on the implementation of this

countermeasure.(8,20–22)

• Refer to the report Low-Cost Treatments for Horizontal Curve Safety for additional 

information on this countermeasure.(13)

• Refer to the CMF Clearinghouse for the safety effectiveness of this countermeasure 

(CMF IDs 7900, 7901, 7229, 7234, and 7271).(5) 
23 

Enhanced Delineation for Horizontal Curves

What: Enhanced delineation may include one or more of the following: 

• Pavement markings. 

• Post-mounted delineation. 

• Larger signs and signs with enhanced retroreflectivity (in advance of and/or within the 

curve). 

• Dynamic advance-curve warning signs and sequential curve signs. 

Why: Enhanced delineation can alert drivers to the presence of a curve in advance, which can 

increase driver awareness and improve driver behavior (e.g., selecting the appropriate speed) 

through the curve. 

Where: Horizontal curves may be effective on any facility type. 

Considerations: Enhanced delineation countermeasures can be applied in combination, and 

applications may vary by the severity of the curvature and vehicle operating speed. 

Resources: The following resources provide further information about horizontal curves: 

• Refer to FHWA’s Office of Safety Proven Safety Countermeasures website and 

Horizontal Curve Safety website for additional information on the implementation of this

countermeasure.(8,20)

• Refer to the report Low-Cost Treatments for Horizontal Curve Safety for additional 

information on this countermeasure.(13)

• Refer to the CMF Clearinghouse for the safety effectiveness of this countermeasure 

(CMF IDs 2438 and 2439).(5)
24 

Roadside Design Improvements at Curves

What: The following improvements are designed to increase the chances of safely recovering 

errant vehicles: 

• Providing an unobstructed, traversable area beyond the edge of the through traveled way. 

• Flattening side slopes. 

• Adding or widening shoulders. 

The following improvements are designed to reduce crash severity at locations where departing

the roadway could result in higher chances of severe injury than striking a roadside barrier: 

• Cable barrier: A flexible barrier made from wire rope supported between frangible 

posts. 

• Guardrail: A semirigid barrier, usually either a steel box beam or W-beam.

• Concrete barrier: A rigid barrier that does not deflect.

Why: Clear zone, side slope, and shoulder improvements provide favorable conditions for errant 

vehicles to recover and regain control in the event of a roadway departure. Roadside barriers help 

reduce the severity of the crash event at locations where departing the roadway could result in 

higher chances of severe injury than striking a roadside barrier. 

Where: Roadside design improvements can be implemented alone or in combination at 

horizontal curves and locations with a higher percentage of roadway-departure fatalities. 

Considerations: Concrete barriers are typically reserved for use on divided roadways. 

Guardrails deflect less than flexible barriers, so they can be located closer to objects where space 

is limited.

Resources: The following resources provide further information about roadside improvements at 

curves:

• Refer to FHWA’s Office of Safety Proven Safety Countermeasures website and Clear 

Zones website for additional information on the implementation of this

countermeasure.(8,23)

• Refer to the CMF Clearinghouse for the safety effectiveness of this countermeasure.(5)
25 

Advance Markings for Curves

What: Advance markings for curves include the following: 

• Speed advisory marking in lane: This treatment includes the use of word, symbol, or 

arrow markings to supplement advance-curve warning signs and advisory speed plaques. 

The markings supplement the curve warning sign with an advisory speed plaque by 

providing the same information in the driver’s direct line of sight and emphasizing the 

message to the driver. 

• Optical speed bars (speed-reduction markings): These bars are transverse stripes 

spaced at gradually decreasing distances in the direction of travel. The intent of this 

treatment is to increase the driver’s awareness of their speed, causing them to slow down. 

Why: Pavement markings in advance of horizontal curves provide conspicuous, supplementary 

warning information about the presence of horizontal curves in the driver’s direct line of sight. 

Where: Speed advisory markings may be more appropriate for high-speed roads where the curve 

advisory speed is significantly lower than the posted speed, curves where crash reports indicate 

speed-related issues, and corridors where speed studies indicate excessive speeding. Optical 

speed bars should be reserved for unexpected curves. Overuse of optical speed bars could 

jeopardize the visual effect of the countermeasure, and this countermeasure has been shown to be 

most effective at locations that have higher volumes of unfamiliar drivers.

Considerations: Advance markings for curves should supplement, not substitute, for appropriate 

warning signs and may be appropriate at locations where signs alone have proved ineffective. 

The advance distance at which such markings are applied depends on both the approach speed 

and design speed of the curve. Durable marking materials are preferred because of the exposure 

to traffic volume over time.

Resources: The following resources provide further information about advance markings for 

curves:

• Refer to FHWA’s Horizontal Curve Safety website for additional information on the 

implementation of this countermeasure.(20)

• Refer to the report Low-Cost Treatments for Horizontal Curve Safety for additional 

information on this countermeasure.(13)

• Refer to the Manual on Uniform Traffic Control Devices (MUTCD) for design and 

application criteria of this countermeasure.

(15)

• Refer to NCHRP Report 600, Human Factors Guidelines for Road Systems, for 

information on which markings are more or less effective at reducing speeds on 

horizontal curves.(24) 
26 

Advance Signs

What: Advance signs include the following: 

• Advance warning signs (e.g., curves, narrow roads, and advisory speeds). 

• Advance informational signs (e.g., percent grade signs). 

Why: Advance signs provide drivers with advance information and warnings that call attention 

to unexpected conditions on or adjacent to a roadway. These signs alert drivers to conditions that 

might call for a reduction of speed or an action in the interest of safety and efficient traffic 

operations. 

Where: Refer to the MUTCD for information on the use of specific advance signs.(15) In general, 

the use of advance signs may depend on warrants or be based on an engineering study or 

judgment. 

Considerations: Overuse of advance signs could jeopardize the effectiveness of the 

countermeasure. In situations where the condition or activity is seasonal or temporary, the 

warning sign should be removed or covered when the condition or activity does not exist. 

Agencies should apply signing devices uniformly based on the characteristics of the roadway. 

Resources: The following resources provide further information about advance signs:

• Refer to FHWA’s Horizontal Curve Safety website for additional information on the 

implementation of this countermeasure.(20)

• Refer to the report Low-Cost Treatments for Horizontal Curve Safety for additional 

information on this countermeasure.(13)

• Refer to chapter 2C of the MUTCD for additional information on this countermeasure.(15)

• Refer to the CMF Clearinghouse for the safety effectiveness of various types of advance 

signs.(5)
27 

CHAPTER 5. SUMMARY AND CONCLUSIONS 

This quick reference guide is for transportation professionals in State and local agencies 

interested in applying a systemic approach to road-safety management. It provided brief 

overviews of a systemic approach, common target crash types and their associated facility types, 

and contributing factors. It also described a step-by-step process to select countermeasures and 

included lists of potential countermeasures for intersections and nonintersections that could 

mitigate the presence of specific contributing factors. 

A systemic approach to road-safety management relies on identifying and addressing 

contributing factors rather than crash history. The relatively low costs associated with this 

approach allow for the opportunity to achieve safety benefits across the system or a large portion 

of the system. Even with a modest crash reduction per site, a well-implemented systemic 

approach can have a significant impact on safety.

Identifying FCFTs is key to selecting appropriate countermeasures. This guide included a brief 

discussion of the tools and resources that agencies can use for their jurisdiction. The guide also 

detailed a six-step process to identify countermeasures as well as descriptions of potential 

countermeasures for common FCFTs. The vast majority of these countermeasures are from 

FHWA’s Office of Safety Proven Safety Countermeasures website.

(8) Readers with limited data 

or analysis capabilities can also find lists of potential FCFTs for intersections and 

nonintersections, which were developed based on an analysis of national and State datasets, in 

Contributing Factors for Focus Crash and Facility Types.

(2)

 Finally, the guide also detailed

contributing factors associated with those FCFTs based on the same analysis of national and 

State datasets.

This guide is not meant to provide complete lists of contributing factors or countermeasures but 

to be a quick reference for agencies interested in applying systemic safety approaches to the most 

common FCFTs. This guide may be particularly useful for agencies without sufficient data and 

analysis capabilities; they can reference the factors developed in this research to help identify 

countermeasures and prioritize sites for systemic safety improvements. Agencies with sufficient 

data and analysis capabilities can refer to FHWA’s Systemic Safety Project Selection Tool for 

discussions on how to analyze data to identify FCFTs and contributing factors for specific crash 

types.(3)

29 

REFERENCES 

1. AASHTO. 2003. NCHRP Report 500: Guidance for Implementation of the AASHTO 

Strategic Highway Safety Plan. Washington, DC: National Cooperative Highway Safety 

Research Program. Accessed February 16, 2018. 

http://www.trb.org/Main/Blurbs/152868.aspx. 

2. Saleem, T., R. Porter, R. Srinivasan, D. Carter, S. Himes, and T. Le. 2020. Contributing 

Factors for Focus Crash and Facility Types. Report No. FHWA-HRT-20-052. 

Washington, DC: Federal Highway Administration.

3. Preston, H., R. Storm, J. D. Bennett, and B. Wemple. 2013. Systemic Safety Project Selection 

Tool Report. Report No. FHWA-SA-13-019. Washington, DC: Federal Highway 

Administration. Accessed February 16, 2018. 

https://safety.fhwa.dot.gov/systemic/fhwasa13019. 

4. 23U.S.C. 148(b). 2015. Fixing America’s Surface Transportation Act Highway Safety 

Improvement Program. Washington, DC: 114th United States Congress. Accessed 

February 16, 2020. https://www.govinfo.gov/content/pkg/PLAW-114publ94/html/PLAW114publ94.htm. 

5. FHWA. n.d. “CMF Clearinghouse.” (website). Accessed December 14, 2017.

http://www.cmfclearinghouse.org. 

6. Gross, F., T. Harmon, G. Bahar, and K. Peach. 2016. Reliability of Safety Management 

Methods: Systemic Safety Program. Report No. FHWA-SA-16-041. Washington, DC: 

Federal Highway Administration. Accessed February 16, 2018. 

https://safety.fhwa.dot.gov/rsdp/downloads/fhwasa16041.pdf. 

7. AASHTO. 2010. Highway Safety Manual. Washington, DC: American Association of State 

Highway and Transportation Officials. Accessed February 16, 2020. 

http://www.highwaysafetymanual.org/Pages/default.aspx. 

8. FHWA. 2018. “Office of Safety Proven Safety Countermeasures.” (website). Accessed 

December 14, 2017. https://safety.fhwa.dot.gov/provencountermeasures. 

9. Goodwin, A., L. Thomas, B. Kirley, W. Hall, N. O’Brien, and K. Hill. 2015. 

Countermeasures that Work: A Highway Safety Countermeasure Guide for State Highway 

Safety Offices. 8th ed. Report No. DOT HS 812 202. Washington, DC: National Highway 

Traffic Safety Administration. Accessed February 16, 2018. 

https://www.nhtsa.gov/sites/nhtsa.dot.gov/files/documents/812202-

countermeasuresthatwork8th.pdf. 

10. FHWA. n.d. “PEDSAFE: Pedestrian Safety Guide and Countermeasure Selection System.” 

(website). Accessed February 16, 2018. http://www.pedbikesafe.org/PEDSAFE. 
30 

11. FHWA. n.d. “BIKESAFE: Bicycle Safety Guide and Countermeasure Selection System.” 

(website). Accessed February 16, 2018. http://www.pedbikesafe.org/bikesafe. 

12. FHWA. n.d. “Crash Modification Factors Clearinghouse State Selected CMF Lists.” 

(website). Accessed February 16, 2018. 

http://www.cmfclearinghouse.org/stateselectedlist.cfm. 

13. Albin, R., V. Brinkly, J. Cheung, F. Julian, C. Satterfield, W. Stein, E. Donnell, et al. 2016. 

Low-Cost Treatments for Horizontal Curve Safety. Report No. FHWA-SA-15-084. 

Washington, DC: Federal Highway Administration. 

14. FHWA. (019. “Roadway Departure Safety.” (website). Accessed February 16, 2018. 

https://safety.fhwa.dot.gov/roadway_dept. 

15. FHWA. 2012. Manual on Uniform Traffic Control Devices for Streets and Highways 2009 

Edition. Washington, DC: Federal Highway Administration. Accessed May 22, 2020. 

https://mutcd.fhwa.dot.gov/pdfs/2009r1r2/pdf_index.htm. 

16. FHWA. 2017. “SafetyEdgeSM.” (website). Accessed February 16, 2018. 

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

17. FHWA. 2017. “Rumble Strips and Rumble Stripes.” (website). Accessed February 16, 2018. 

https://safety.fhwa.dot.gov/roadway_dept/pavement/rumble_strips. 

18. Himes, S., H. McGee, S. Levin, and T. Zhou. 2017. State of the Practice for Shoulder and 

Center Line Rumble Strip Implementation on Non-Freeway Facilities. Report No. FHWAHRT-17-026. Washington, DC: Federal Highway Administration. Accessed February 16, 

2018. https://www.fhwa.dot.gov/publications/research/safety/17026/17026.pdf. 

19. Jenks, C., C. Jencks, C. Niessner, E. Delaney, B. Cottrell, D. Bachman, and R. Pain. 2009. 

Guidance for the Design and Application of Shoulder and Centerline Rumble Strips. Report 

No. 641. Washington, DC: National Cooperative Highway Safety Research Program. 

Accessed February 16, 2018. https://www.nap.edu/read/14323/chapter/1. 

20. FHWA. 2019. “Horizontal Curve Safety.” (website). Accessed February 16, 2018. 

https://safety.fhwa.dot.gov/roadway_dept/countermeasures/horicurves. 

21. FHWA. 2019. “High Friction Surface Treatments (HFST).” (website). Accessed 

February 16, 2018. 

https://safety.fhwa.dot.gov/roadway_dept/pavement_friction/high_friction/index.cfm. 

22. Merritt, D., C. Lyon, B. and Persaud. 2015. Evaluation of Pavement Safety Performance. 

Report No. FHWA-HRT-14-065. Washington, DC: Federal Highway Administration. 

Accessed February 16, 2018. 

https://www.fhwa.dot.gov/publications/research/safety/14065/14065.pdf. 

23. FHWA. “Clear Zones.” (website). Accessed February 16, 2018. 

https://safety.fhwa.dot.gov/roadway_dept/countermeasures/safe_recovery/clear_zones. 
31 

24. Campbell, J., M. Lichty, J. Browne, C. Richard, J. Graving, J. Graham, and D. Harwood. 

2012. Human Factors Guidelines for Road Systems. NCHRP Report 600. Washington, DC: 

National Cooperative Highway Research Program. Accessed February 16, 2018. 

http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_600Second.pdf.

25. Institute of Transportation Engineers. 2017. “Unsignalized Intersection Improvement Guide.” 

(website). Accessed February 16, 2018. http://toolkits.ite.org/uiig. 

26. FHWA. 2018. “Intersection Safety.” (website). Accessed December 14, 2017.

https://safety.fhwa.dot.gov/intersection. 

27. FHWA. 2017. Intersection Safety Strategies. 2nd ed. Report No. FHWA-SA-15-085. 

Washington, DC: U.S. Department of Transportation. Accessed December 14, 2017. 

https://safety.fhwa.dot.gov/intersection/conventional/signalized/FHWA-SA-15-

085_Strategies_2.pdf. 

28. Harwood, D., K. Bauer, I. Potts, D. Torbic, K. Richard, E. Kohlman Rabbani, and 

L. Elefteriadou. 2002. Safety Effectiveness of Intersection Left- and Right-Turn Lanes. Report 

No. FHWA-RD-02-089. Washington, DC: Federal Highway Administration. Accessed 

February 16, 2018. https://www.fhwa.dot.gov/publications/research/safety/02089/02089.pdf. 

29. McGee, H., K. Moriarty, K. Eccles, M. Liu, T. Gates, and R. Retting. 2012. Guidelines for 

Timing Yellow and All-Red Intervals at Signalized Intersections. NCHRP Report 731. 

Washington, DC: National Cooperative Highway Research Program. Accessed February 16, 

2018. https://dx.doi.org/10.17226/22700. 

30. Amjadi, R. 2017. Safety Evaluation of Multiple Strategies at Stop-Controlled Intersections. 

Report No. FHWA-HRT-17-087. Washington, DC: Federal Highway Administration. 

Accessed February 16, 2020. 

https://www.fhwa.dot.gov/publications/research/safety/17087/17087.pdf. 




HRDS-20/11-20(300)E Recycled

Recyclable