Reliability of Safety 

Management Methods 

Systemic Safety Programs 

FHWA-SA-16-041 September 2016
 

http://safety.fhwa.dot.gov 
 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

NOTICE

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

Transportation in the interest of information exchange. The U.S. Government assumes no 

liability for the use of the information contained in this document. This report does not 

constitute a standard, specification, or regulation. 

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. 

ii 
1. Report No.

FHWA-SA-16-041

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

4. Title and Subtitle

Reliability of Safety Management Methods: Systemic Safety Programs

5. Report Date

September 2016

6. Performing Organization Code

7. Author(s)

Frank Gross, Tim Harmon, Geni Bahar, and Kara Peach

8. Performing Organization Report No.

9. Performing Organization Name and Address

VHB

8300 Boone Boulevard

Suite 700

Vienna, VA 22182

10. Work Unit No.

11. Contract or Grant No.

DTFH61-10-D-00022-T-13005

12. Sponsoring Agency Name and Address

Federal Highway Administration Office of Safety

1200 New Jersey Ave., SE

Washington, DC 20590

13. Type of Report and Period

Final Report, August 2016 

14. Sponsoring Agency Code

FHWA

15. Supplementary Notes

The Contracting Officer’s Task Manager (COTM) was Stuart Thompson.

16. Abstract

High quality data and reliable analytical methods are the foundation of data-driven decision-making. The Reliability of Safety Management 

Methods series includes five information guides that identify opportunities to employ more reliable methods to support decisions

throughout the roadway safety management process. Four of the guides focus on specific components of the roadway safety

management process: network screening, diagnosis, countermeasure selection, and safety effectiveness evaluation. The fifth gu ide focuses

on the systemic approach to safety management, which describes a complementary approach to the methods described in the network

screening, diagnosis, and countermeasure selection guides. The purpose of the Reliability of Safety Management Metho ds series is to

demonstrate the value of more reliable methods in these activities, and demonstrate limitations of traditional (less reliable) methods.

The Reliability of Safety Management Methods: Systemic Safety Programs guide describes the state-of-the-practice and the latest tools to 

support systemic safety analysis. The target audience includes program managers, project managers, and data analysts involved in 

projects that impact highway safety. The objectives of this guide are to: 1) raise awareness of the systemic approach to safety 

management, 2) characterize typical projects identified and implemented through a comprehensive safety management program, 3) 

demonstrate the value of integrating systemic approaches as part of a comprehensive safety management program, and 4) provide 

information on allocating funding to systemic projects within a comprehensive safety management program. 

This guide includes six sections and an appendix. The first section introduces roadway safety management and the purpose of safety 

programs. The second section provides an overview of two general approaches that support a comprehensive safety program, including 

a discussion of the high-level strengths and limitations. The third section demonstrates the value of projects implemented through 

various safety programs. Empirical examples lead to cost-effectiveness estimates and information on integrating the systemic approach 

within a comprehensive safety program. The next sections summarize the data requirements to employ, and available tools and 

resources to support, a comprehensive approach to safety management. The final section describes future research needs to enhance 

the state of the knowledge on the systemic approach . An appendix provides detailed information related to the methods and examples 

presented throughout the guide. 

17. Key Words:

Roadway, Safety, Data, Analysis, Systemic, 

Comprehensive, Program

18. Distribution Statement

No restrictions.

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

45

22. Price

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

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

TECHNICAL DOCUMENTATION PAGE
 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

ACKNOWLEDGMENTS

The project team would like to thank the following individuals who served as members on the

Technical Working Group for this effort. 

Technical Working Group 

Stuart Thompson, FHWA Office of Safety 

Ray Krammes, FHWA Office of Safety 

Yanira Rivera, FHWA Office of Safety 

Karen Scurry, FHWA Office of Safety 

Marc Starnes, FHWA Office of Safety 

Craig Thor, FHWA Office of Safety Research and Development 

Derek Leuer, Minnesota Department of Transportation 

Brian Porter, Wisconsin Department of Transportation 

Kevin Scopoline, Wisconsin Department of Transportation 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

TABLE OF CONTENTS

1. Introduction to Roadway Safety Management...................................................................................1
 

2. Overview of Safety Management Approaches...................................................................................2
 

Crash-Based Approach................................................................................................................................2



Systemic Approach.......................................................................................................................................4



Systemic Variations in Practice..............................................................................................................7
 

Policy-Based Method ................................................................................................................................ 10
 

Summary of Crash-Based and Systemic Approaches ........................................................................ 11
 

3. Demonstrating the Value of Integrating Systemic Approaches in a Comprehensive Safety

Program ........................................................................................................................................................... 12
 

Value of Crash-Based Projects ............................................................................................................... 13
 

Value of Systemic Projects ...................................................................................................................... 16
 

Comparison of Crash-Based and Systemic Projects.......................................................................... 19
 

Crash-based and Systemic Projects within a Comprehensive Safety Program ........................... 21
 

Allocating Funds to Crash-Based and Systemic Projects.................................................................. 23
 

Development of a Breakeven Crash Frequency Equation ........................................................... 23
 

Example Application of the Breakeven Equation ........................................................................... 26
 

Considerations for Applying the Breakeven Equation.................................................................. 28
 

Summary...................................................................................................................................................... 30
 

4. Data Requirements for Crash-Based and Systemic Approaches................................................ 32
 

Crash-Based Approach............................................................................................................................. 32
 

Systemic Approach.................................................................................................................................... 33
 

5. Tools and Resources for Systemic Approaches............................................................................. 35
 

Using the Roadway Safety Data and Analysis Toolbox..................................................................... 35
 

6. Future Research Needs ....................................................................................................................... 37
 

References....................................................................................................................................................... 38
 

Appendix: Crash-Based and Systemic Project Details........................................................................... 39
 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

LIST OF TABLES

Table 1. Summary of variations to the systemic approach......................................................................7
 

Table 2. Comprehensive crash costs by maximum reported severity. ............................................. 12
 

Table 3. Crash-based countermeasure data. ........................................................................................... 14
 

Table 4. Crash-based project cost-effectiveness. ................................................................................... 15
 

Table 5. Systemic countermeasure data................................................................................................... 17
 

Table 6. Systemic project cost-effectiveness. .......................................................................................... 18
 

Table 7. Comparison of crash-based and systemic economic measures. ......................................... 19
 

Table 8. Weighted average CMF and costs by project type................................................................ 27
 

Table 9. CMFs and project costs for intersection improvement example. ...................................... 29
 

Table 10. Data needs for the crash-based approach to safety management.................................... 32
 

Table 11. Crash-based crashes per site-year before treatment.......................................................... 39
 

Table 12. Crash-based crashes per site-year after treatment. ............................................................ 39
 

Table 13. Systemic crashes per site-year before treatment................................................................. 40
 

Table 14. Systemic crashes per site-year after treatment.................................................................... 40
 

Table 15. Crash-based project benefits. ................................................................................................... 41
 

Table 16. Systemic project benefits........................................................................................................... 41
 

Table 17. Typical crash cost matrix........................................................................................................... 42
 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

LIST OF FIGURES

Figure 1. Chart. High-level overview of roadway safety management process..................................1
 

Figure 2. Chart. Schematic of crash-based roadway safety management process.............................3
 

Figure 3. Graph. Statewide distribution of intersection safety performance. .................................. 22
 

Figure 4. Equation. General equation for net benefits of a project.................................................... 23
 

Figure 5. Equation. Net benefits in terms of crash frequency, crash cost, and project cost........ 24
 

Figure 6. Equation. Net benefits in terms of before-period crashes, project effectiveness, crash 

cost, and project cost. .................................................................................................................................. 24
 

Figure 7. Equation. Simplified equation for net benefits of a project. ................................................ 24
 

Figure 8. Chart. Optimizing investments in high-cost and low-cost improvements....................... 25
 

Figure 9. Equation. Equality criterion for calculation of breakeven of net benefits........................ 25
 

Figure 10. Equation. Breakeven crash frequency equation................................................................... 25
 

Figure 11. Equation. Application of the breakeven equation. .............................................................. 27
 

Figure 12. Chart. Optimizing investments in high-cost and low-cost improvements. ................... 28
 

Figure 13. Equation. Application of the breakeven equation. .............................................................. 29
 

Figure 14. Screenshot. Roadway Safety Data and Analysis Toolbox. ................................................ 35
 

Figure 15. Screenshot. Advanced search feature.................................................................................... 36
 

Figure 16. Screenshot. Filter options from advanced search page. .................................................... 36
 

Figure 17. Equation. Average project cost per site................................................................................ 42
 

Figure 18. Equation. Project coverage. ..................................................................................................... 43
 

Figure 19. Equation. Average cost per crash........................................................................................... 43
 

Figure 20. Equation. Net benefit per site for crashes by severity. ..................................................... 44
 

Figure 21. Equation. Net benefit per site for total crashes.................................................................. 44
 

Figure 22. Equation. Net benefit for whole program. ........................................................................... 45
 

Figure 23. Equation. Net benefits per site................................................................................................ 45
 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

LIST OF ACRONYMS

CMF Crash Modification Factor 

DOT Department of Transportation 

EB Empirical Bayes 

FHWA Federal Highway Administration 

HFST High Friction Surface Treatment

HSIP Highway Safety Improvement Program 

MIRE FDE Model Inventory Roadway Elements—Fundamental Data Elements 

MUTCD Manual on Uniform Traffic Control Devices 

SHSP Strategic Highway Safety Plan 

SPF Safety Performance Function 

TRID Transport Research International Documentation 

viii 
 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

PREFACE
 

High quality data and reliable analytical methods are the foundation of data-driven decisionmaking. The Reliability of Safety Management Methods series includes five information guides 

that identify opportunities to employ more reliable methods to support decisions throughout 

the roadway safety management process. Four of the guides focus on specific components of 

the roadway safety management process: network screening, diagnosis, countermeasure 

selection, and safety effectiveness evaluation. The fifth guide focuses on the systemic approach 

to safety management, which describes a complementary approach to the methods described in 

the network screening, diagnosis, and countermeasure selection guides. The purpose of the 

Reliability of Safety Management Methods series is to demonstrate the value of more reliable 

methods in these activities, and demonstrate limitations of traditional (less reliable) methods. 

The Reliability of Safety Management Methods: Systemic Safety Programs guide describes the 

state-of-the-practice and the latest tools to support systemic safety analysis. The target 

audience includes program managers, project managers, and data analysts involved in projects 

that impact highway safety. The objectives of this guide are to: 1) raise awareness of the 

systemic approach to safety management, 2) characterize typical projects identified and 

implemented through a comprehensive safety management program, 3) demonstrate the value 

of integrating systemic approaches as part of a comprehensive safety management program, and 

4) provide information on allocating funding to systemic projects within a comprehensive safety

management program.

This guide includes six sections and an appendix. The first section introduces roadway safety 

management and the purpose of safety programs. The second section provides an overview of 

two general approaches that support a comprehensive safety program, including a discussion of 

the high-level strengths and limitations. The third section demonstrates the value of projects 

implemented through various safety programs. Empirical examples lead to cost-effectiveness 

estimates and information on integrating the systemic approach within a comprehensive safety 

program. The next sections summarize the data requirements to employ, and available tools 

and resources to support, a comprehensive approach to safety management. The final section 

describes future research needs to enhance the state of the knowledge on the systemic 

approach. An appendix provides detailed information related to the methods and examples 

presented throughout the guide. 

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1. INTRODUCTION TO ROADWAY SAFETY MANAGEMENT

At the most basic level, the roadway safety management process is a three-step process as 

shown in Figure 1 and outlined in the Highway Safety Improvement Program (HSIP) Manual.(1) 

The intent of this process is to identify and improve sites expected to benefit the most from 

targeted, cost-effective treatments. This aligns with the purpose of the Federal HSIP, which is to 

achieve a significant reduction in fatalities and serious injuries on all public roads.

(2) To achieve 

this goal, the safety management process should maximize the opportunity to improve safety; 

otherwise, agencies may allocate resources inefficiently to sites with less potential for 

improvement while locations with a higher potential for cost-effective safety improvement 

remain untreated. 

There are two general approaches to safety management: 1) selecting and treating sites based 

on site-specific crashes (referred to as the crash-based approach for this guide), and 2) selecting 

and treating sites based on site-specific geometric and operational attributes known to increase 

crash risk (referred to as the systemic approach for this guide). These two approaches are 

complementary and support a comprehensive approach to safety management. The primary 

difference is the way in which analysts identify issues and develop projects in the planning stage. 

In either case, it is important to use reliable, data-driven methods to inform decisions. The 

Highway Safety Manual presents a predictive method to relate crash frequency to roadway 

design and operational characteristics through statistical models or safety performance 

functions (SPFs). A predictive approach based on a combination of historical crash, exposure, 

and roadway data is more reliable than approaches based on crash frequency alone or ad hoc 

analysis of geometric and operational attributes that may increase risk. 

Figure 1. Chart. High-level overview of roadway safety management process. 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

2. OVERVIEW OF SAFETY MANAGEMENT APPROACHES 

This section describes three approaches to safety management: crash-based, systemic, and 

policy-based. 

CRASH-BASED APPROACH 

The crash-based approach to roadway safety management is represented by the six-step 

process shown in Figure 2 and outlined in the Highway Safety Manual.(3) Most agencies employ 

at least the first three steps of this process: 1) network screening, 2) diagnosis, and 3) 

countermeasure selection. These three steps differentiate the crash-based approach from the 

systemic approach. The following is an overview of the crash-based approach. 

1.	 Network screening: In the crash-based approach, analysts first identify sites based on 

site-specific, crash-based performance measures. For example, analysts may conduct 

crash-based network screening to identify candidate locations for safety projects with 

the highest frequency of crashes, highest potential for safety improvement, or worst 

safety performance. Refer to the Reliability of Safety Management Methods: Network 

Screening for further discussion of network screening.(4) 

2.	 Diagnosis: Once an agency identifies a list of sites, diagnostic analyses serve to hone in 

on safety concerns at each site. The analyst (preferably a multidisciplinary analysis team) 

reviews the site-specific crash history and site characteristics (e.g., geometry, traffic 

operations, road users, and adjacent land use) in detail to understand and identify 

collision patterns and crash contributing factors. This provides the foundation for the 

identification and selection of appropriate countermeasures to mitigate the specific 

safety issues (e.g., crash patterns and contributing factors) at each site. Refer to the 

Reliability of Safety Management Methods: Diagnosis for further discussion of diagnosis.(5) 

3.	 Countermeasure selection: Given a list of specific safety issues based on diagnosis, 

an agency can identify, assess, and select appropriate countermeasures. Appropriate 

countermeasures should directly target the underlying crash contributing factors, and 

may include engineering, education, enforcement, and EMS-related measures (i.e., the 4E 

approach). Refer to the Reliability of Safety Management Methods: Countermeasure Selection 

for further information and considerations related to countermeasure selection.(6) 

The following points provide a general characterization of the crash-based approach: 

•	 Agencies use the crash-based approach as an effective means to identify sites and 

implement treatments at those sites with the highest potential for site-specific safety 

improvement. Agencies may refer to these locations as hotspots, blackspots, or sites 

with potential for improvement. 

•	 The underlying safety issue typically varies at each site (i.e., agencies are not focused on 

addressing a specific issue unless the screening is carried out for a specific crash type). 

•	 Projects can range from relatively simple and low-cost improvements (e.g., enhancing 

signing or striping, trimming vegetation, or modifying signal phasing) to substantial capital 

improvement projects (e.g., constructing a roundabout, modifying the skew angle of an 

intersection, or realigning a horizontal curve). 

•	 There is an opportunity to achieve reductions in crash frequency and severity at treated 

locations given the focus on site-specific issues and targeted treatments. 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Potential limitations of the crash-based approach include the need for site-specific data, the 

inability to efficiently address highly-dispersed crashes, and the potential for high-cost 

improvements at spot locations. 

•	 Site-specific data: The crash-based approach uses site-specific crash data to identify 

sites with potential for improvement. Other site-specific data such as geometric and 

operational characteristics can enhance the reliability of crash-based network screening. 

•	 Highly-dispersed crashes: It is difficult to address a high percentage of highlydispersed crashes with the crash-based approach because this would require projects at 

many sites. Using the crash-based approach, it is difficult for an agency to objectively 

establish priorities for treatment among the many locations that have few, if any, crashes 

each but which cumulatively account for a large percentage of crashes in a jurisdiction. 

•	 Potential for high-cost improvements: High-cost projects represent a higher 

financial risk in terms of contributing to the effectiveness of an agency’s safety program. 

Dedicating large amounts of funds to a safety project at one location represents the 

identification of a problem and a commitment to fix it; however, if the project does not 

adequately address the problem, revisiting the location with another project within a 

few years can be difficult to justify from funding and public relations perspectives. 

Further, agencies can only treat a limited number of sites with high-cost improvements 

given a fixed budget. These projects may have a notable safety benefit at the improved 

locations, and on the system as a whole when the majority of crashes occur at relatively 

few locations. For crashes more distributed across the network, such as fatal and severe 

injury crashes or crashes on rural and local roads, high-cost projects have limited 

capacity to impact the safety performance of the system as a whole. 

Figure 2. Chart. Schematic of crash-based roadway safety management process. 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

SYSTEMIC APPROACH 

In the systemic approach, analysts identify sites based on site-specific geometric and operational 

attributes rather than observed crashes. The first three steps involved in the planning 

component of the systemic approach are: 1) identify focus crash types, facility types, and risk 

factors, 2) screen and prioritize candidate locations, and 3) select countermeasures. These 

steps are similar to the first three steps of the crash-based approach shown in Figure 2, but in a 

different order. The following is an overview of these three general steps: 

1.	 Identify focus crash types, facility types, and risk factors: The first step in the 

systemic approach is to select focus crash type(s), facility types, and risk factors. This is 

similar to the second step in the crash-based approach (diagnosis). Focus crash types 

typically reflect prevalent severe crash types for a given jurisdiction. As noted in the 

Federal Highway Administration (FHWA) Systemic Safety Project Selection Tool, State and 

regional strategic highway safety plans (SHSPs) are a good starting point to identify focus 

crash types.(7) Focus facility types typically include the locations where the target crash 

types are most prevalent (e.g., rural, two-lane, undivided segments or urban, four-leg, 

signalized intersections). Risk factors are site-specific attributes common across 

locations with the focus crash type(s), and associated with an increased risk of the focus 

crashes. Risk factors may include site-specific crash history (if available) and geometric 

and operational attributes. For example, sharp horizontal curves are a common feature 

associated with roadway departure crashes. Analysts identify risk factors and the relative 

risk by analyzing crash data associated with the focus crash type and facility type from 

their jurisdiction or by reviewing previous research studies. Refer to the Systemic Safety 

Project Selection Tool for further information on the identification of focus crash types, 

focus facility types, and risk factors.

(7) 

2.	 Screen and prioritize candidate locations: The second step of this approach is to 

develop a prioritized list of potential locations for systemic improvement. This is similar 

to step one in the crash-based approach (network screening). Using risk factors as a 

guide, analysts identify sites on the focus facility types with these specific geometric and 

operational characteristics as candidate locations. To prioritize candidate locations, 

analysts assign a level of risk to each site based on the site-specific geometric and 

operational characteristics and crash history. Analysts can also apply thresholds or 

weights to each risk factor to reduce the list of sites based on available resources and 

program objectives. Refer to the Systemic Safety Project Selection Tool for further 

information related to the screening and prioritization of candidate locations.

(7) 

3.	 Select countermeasures: Given the list of risk factors for the focus crash type(s), an 

agency can develop targeted treatments to address or mitigate the specific risk factors 

at the specific locations across the network. This is similar to the third step in the crashbased approach (countermeasure selection). Refer to the Systemic Safety Project Selection 

Tool for further information related to the selection of countermeasures.(7) Analysts can 

refer to the CMF Clearinghouse for estimates of the effectiveness of countermeasures. 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

The following points provide a general characterization of the systemic approach: 

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

SHSP. Targeting common underlying safety issues across sites, agencies can implement 

similar projects across a network to address high priority crash types and risk factors. 

•	 Agencies use the systemic approach as an effective means to identify sites and 

implement treatments at those sites with the highest risk across a road network. 

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

countermeasures on relatively high-risk sites identified by the presence of risk factors 

rather than site-specific crash history. 

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

when the average crash frequency at individual sites is relatively low (i.e., highlydispersed crashes). 

•	 Given the typical extent of improvements (i.e., many improved sites), systemic projects 

are generally low-cost improvements (e.g., enhancing signing or striping, installing 

rumble strips, or upgrading signal heads). Higher-cost improvements are also candidates 

for the systemic approach, but the improvement should be highly effective to justify the 

increased cost. 

•	 Agencies may begin with the intent to implement proven, low-cost countermeasures, 

and then continue to identify appropriate treatment locations based on risk factors. In 

general, the use of proven, low-cost countermeasures for systemic improvements will 

result in a positive return on investment; however, a benefit-cost analysis is useful to 

determine the most effective (i.e., greatest expected reduction in severe crashes) and 

most cost-effective (i.e., greatest return on investment) alternatives. 

•	 There is an opportunity to achieve reductions in crash frequency and severity across a 

large portion of the system given the focus on priority crash types and risk factors 

rather than site-specific crash history. For example, consider a $3M safety program and 

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

roundabouts at an average cost of $1M per site with an average crash history of 20 

crashes per year and assuming a 40 percent reduction in crashes as the average 

treatment effect. The second option is to install intersection improvement packages at 

500 sites at an average cost of $6000 per site with an average crash history of 3 crashes 

per year and assuming a 5 percent reduction in crashes as the average treatment effect. 

The system benefit for the first option is a reduction of 24 crashes per year and the 

system benefit for the second option is a 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. Chapter 3 provides examples of such comparisons, 

including a method to allocate funding between crash-based and systemic approaches. 

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

data. Rather than analyzing crashes at specific locations, analysts investigate prevalent severe 

crash types across the focus facility type to correlate risk factors (e.g., geometric and 

operational roadway characteristics) with the crash type of interest. Agencies then use those 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

high-risk roadway characteristics as a basis for implementing countermeasures to address the 

focus crash types. Beyond the presence of risk factors, analysts may identify thresholds at which 

the characteristic becomes problematic. For example, rather than simply identifying sites with 

horizontal curves, the analyst may specify the degree of curve or radius at which risk increases. 

Analysts can also apply weights to these risk factors to prioritize sites for countermeasure 

implementation. For example, risk factors for roadway departure crashes may include lane 

width, shoulder width, and horizontal curvature; however, sharper horizontal curves may 

increase crash risk more than narrow lanes. If this is the case, the analyst may place more 

weight on the curve-related risk factor and less weight on the lane width factor. 

The systemic approach is a preventative approach because it applies countermeasures to 

locations with features correlated with crashes, but the sites are not required to have a history 

of crashes to receive treatment. This 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 lower 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 crash-based approach due to the low density of 

crashes and typical data limitations associated with local and rural roads. The systemic approach 

helps to overcome these limitations by focusing on the underlying risk factors across the 

network as opposed to crash history at individual locations. In Minnesota, hotspot locations 

represent approximately 10 percent of severe crashes statewide. As such, managing safety with 

the crash-based approach alone would overlook approximately 90 percent of severe crashes. 

Minnesota employs the crash-based approach to address select high-crash locations, and uses 

the systemic approach to address the remaining 90 percent of severe crashes. 

Example: 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. They noted these crashes were most prevalent on 

rural, two-lane roads and selected this as the focus facility type for head-on crashes (i.e., the focus crash 

type). The agency reviewed the data for all head-on crashes on rural, two-lane roads and determined 

that common roadway features (potential risk factors) include narrow cross-section, narrow or no 

median, and no median barrier. Alternatives to address the underlying risk factors include installing 

centerline rumble strips, widening the cross-section, widening the median, or installing a median barrier. 

The agency deemed the latter three options cost prohibitive for wide-scale deployment. As such, they 

selected centerline rumble strips as an appropriate measure to address the underlying risk factors. At 

this point, the agency would consider installing centerline rumble strips on all rural, two-lane, undivided 

roads. If the agency does not have available funds to install centerline rumble strips on all rural, twolane, undivided roads, then it becomes necessary to establish a threshold for implementation. 

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

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

the safety effectiveness of improvements that are 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 safety effect of projects implemented based on 

the crash-based approach or countermeasures that require substantial engineering work prior 

to implementation at each site. It is generally unknown if the systemic application will result in 

6
 
 

 

 

 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

the same 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 

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

depending on the treatment 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 higher-cost countermeasures. As such, it is important to consider the life-cycle 

costs prior to implementation. 

Systemic Variations in Practice 

Based on a review of agency practices, there are several variations of the systemic approach. 

The following are two variations of the systemic approach in practice, identified during this 

research effort. These variations are not completely consistent with the FHWA Systemic Safety 

Project Selection Tool, but each variation serves a specific purpose, using different levels of data 

and analysis. As a result, the variations are associated with varying levels of reliability and may 

produce different countermeasures and overall benefits from the approach described in the 

Systemic Safety Project Selection Tool. Table 1 provides a high-level summary of the variations, and 

the remainder of this section describes each in detail with examples. 

Table 1. Summary of variations to the systemic approach. 

Method Approach Benefits 

Benefit-Cost 

Threshold 

Begins with crash-based or systemic 

approach, but adds site-based crash 

threshold to achieve minimum desired 

benefit-cost ratio. 

Helps to maintain a minimum 

benefit-cost ratio. 

Potential for a higher return 

on investment. 

Hybrid Systemic 

and Crash-Based 

Combines the crash-based and systemic 

approach to identify candidate locations 

based on safety performance. 

Identifies sites with potential 

for improvement based on 

observed or expected safety 

performance. 

Benefit-Cost Threshold Variation 

It is common for agencies to specify minimum benefit-cost ratios for crash-based projects. For 

example, an agency may not fund any projects that do not result in an estimated benefit-cost 

ratio of at least 2.0. Agencies can apply similar thresholds to the systemic approach based on 

site-specific crash or exposure data. As described in the Systemic Safety Project Selection Tool, 

applying minimum thresholds can help to prioritize and select locations for treatment.

(7) 

Minimum thresholds can also help to maintain a minimum benefit-cost ratio, considering all sites 

treated with the countermeasure(s), to ensure a higher return on investment. For example, 

using the average implementation cost, CMF, and average crash cost reduction for the 

countermeasure of interest, the analyst can establish a minimum crash threshold to improve the 

chance of a positive return on investment. See the appendix for details on estimating benefits. 

7 
 

 

 

 

 

 

 

 

 

 

 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Example: Consider the same scenario as described previously in the systemic approach. Using the risk 

factor-based method, an agency selected centerline rumble strips to address head-on crashes on rural, 

two-lane, undivided roads. The agency did not have sufficient funds to install centerline rumble strips on 

all candidate roads, so they applied a traffic volume and corridor-level crash threshold to prioritize sites. 

Further analysis of the crash data suggested sites with higher traffic volumes have an increased risk of 

head-on crashes, and the statewide average is 0.01 head-on crashes per mile for rural, two-lane, 

undivided roads. Using this information, the agency prioritized sites with more than 5,000 vehicles per 

day and more than 0.01 head-on crashes per mile for installing centerline rumble strips. To compete 

for funding with other safety improvement projects, the agency also required a minimum benefit-cost 

ratio of 2.0. Assuming an average installation cost of $2,500 per mile, a CMF of 0.70, an average crash 

cost of $400,000 per head-on crash reduced, a service life of 10 years, and a discount rate of 3.0 

percent, the agency estimated the benefit-cost ratio. With these assumptions, and a minimum corridorlevel crash threshold of 0.01 head-on crashes per mile, the benefit-cost ratio for installing centerline 

rumble strips is at least 4.0, which exceeds the agencies minimum threshold. Had the benefit-cost ratio 

been less than 2.0, then the agency could increase the crash threshold to achieve the desired minimum. 

The benefit of this method is establishing a threshold to improve the chance of a positive return 

on investment. The difficulty in applying this method is determining an appropriate threshold. 

To apply crash-based thresholds, there is a need for crash data by site or at least by corridor. 

Further, there are multiple options for establishing crash-based thresholds (e.g., crash 

frequency, crash rate, predicted crashes, and expected crashes), and some measures are more 

reliable than others. Predicted and expected crashes are more reliable than crash frequency and 

crash rate for estimating the long-term safety performance of a site. Refer to the Reliability of 

Safety Management Methods: Network Screening for further discussion on the strengths and 

limitations of these measures. 

While a positive return on investment is desirable, it does not guarantee the most effective use 

of funds. For example, allocating the funds to another project may result in a more costeffective use of funding and resources. Refer to chapter 3, Demonstrating the Value of Integrating 

Systemic Approaches in a Comprehensive Safety Program, for further discussion of estimating 

benefit-cost ratios and allocating funds among different project types. 

Hybrid Systemic and Crash-Based Variation 

The hybrid method begins by identifying a focus crash type, similar to the systemic approach. 

Then, the analyst screens sites similar to crash-based network screening, using performance 

measures such as excess expected crash frequency of the focus crash type to prioritize sites for 

improvement. Again, some performance measures (predicted and expected crashes) are more 

reliable than others (crash frequency and crash rate) for screening sites. Refer to the Reliability 

of Safety Management Methods: Network Screening for further discussion on performance 

measures for screening. 

The next step is to diagnose underlying safety issues and select appropriate countermeasures to 

mitigate the specific issues. One option is to analyze crash patterns, contributing factors, and 

distributions for the list of top sites from the screening. This is similar to the crash-based 

8
 
 

 

 

 

 

 

 

 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

approach, but diagnosis focuses on a group of sites simultaneously to identify commonalities 

rather than focusing on individual locations in isolation. In essence, the analyst applies the 

systemic approach to the list of sites with potential for improvement rather than all sites. 

Example: Consider a scenario where an agency identified roadway departure crashes as the focus crash 

type. Using excess expected roadway departure crashes as the performance measure for network 

screening, the agency identified potential locations for treatment. Upon further investigation of the 

candidate sites, the agency determined common characteristics among these sites: horizontal curvature 

and lack of advance and in-curve warning signs. Based on this information, the agency selected a 

countermeasure package to include the installation of advance warning signs (i.e., curve or turn ahead) 

and in-curve warning signs (i.e., chevrons or large arrow boards) as appropriate. 

Another option is to select a proven countermeasure to target the focus crash type, and then 

determine where it would be most cost-effective. In this method, an analyst selects a 

countermeasure for implementation based on the focus crash type, and then uses the crashbased method to identify candidate locations. Agencies commonly use this option to employ 

proven countermeasures when the countermeasure addresses an emphasis area in its SHSP and 

past research shows the countermeasure to be universally cost-effective. 

Example: An agency recently learned of the potential safety benefits of installing a high-friction surface 

treatment (HFST) on horizontal curves to address roadway departure crashes. Based on the literature, 

many agencies identify candidate curves based on crash frequency (e.g., greater than expected number 

of severe roadway departure crashes or greater than expected wet-weather crashes), low pavement 

friction, large speed differential between tangent and curve, small curve radii, and deficient 

superelevation. In an effort to address the roadway departure emphasis area of its SHSP, the agency 

identified curves throughout the State for implementation of HFST. The agency applied the following 

factors to screen and prioritize candidate locations: excess expected severe roadway departure crashes, 

pavement friction, and differential between posted and advisory speed. 

A strength of this method is identifying sites with potential for improvement based at least in 

part on past crash experience and safety performance, as opposed to relying solely on 

geometric and operational risk factors. Countermeasures deployed in these projects can range 

from low to medium unit cost, with the higher crash risk serving as a justification for more 

expensive countermeasures that may produce greater benefits. Both low-cost and high-cost 

countermeasures can fit within projects identified and selected by the hybrid method. For 

example, the consideration of safety performance measures is popular among States developing 

systemic intersection safety improvement plans. Through these plans, States implement a 

number of countermeasures at a wide range of sites where the treatments are appropriate. To 

use this method, there is a need for detailed crash data (and possibly exposure data) at the site 

level. This method has similar limitations to the crash-based method, such as when there is a 

small sample of crashes. In these cases, it will be difficult to control for the random fluctuation 

in crashes from site to site over time. If there is an issue with small sample size or no crash data 

available at the site level, then it is more appropriate to employ the systemic approach. 

9
 
 

 

 

 

 

 

 

 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

POLICY-BASED METHOD 

The policy-based method serves to bring design or operational features up to a standard or 

policy. Agencies often implement policy-based countermeasures aiming to reduce liability as 

well as crash risk. In some cases, policies reflect national standards such as improving the 

retroreflectivity of all curve warning signs to meet the Manual on Uniform Traffic Control 

Devices (MUTCD) criteria. In other cases, agencies create new policies based on past success. 

New safety policies generally stem from successful crash-based and systemic improvements. As 

new safety concepts arise, agencies may try these improvements to address issues at a few sitespecific locations. If a new safety concept proves effective at reducing crashes at these locations, 

agencies may implement the concept more widely through the systemic approach. The agency 

may then conduct an analysis to understand the countermeasure effectiveness. Finally, if the 

research proves the concept is effective, agencies may develop a policy to implement the 

proven countermeasure as part of their regular design, construction, operations, and 

maintenance practices. 

For example, analyzing risk factors, an agency may identify an elevated risk of head-on crashes 

on divided highways with a given median width and traffic volume. Based on prior research, the 

agency understands the potential safety benefits of cable median barrier on divided highways 

with unprotected medians. As a result, the agency may develop a policy to install cable median 

barrier on all divided highways with a specific median width and traffic volume. This example 

reflects the use of the systemic approach to develop a policy for cable median barrier. 

Using the policy-based approach, agencies upgrade features or install countermeasures at all 

applicable locations regardless of substantive risk. This includes all new construction and may 

include installation or upgrades on existing facilities to the extent possible. For example, an 

agency may create a new policy to install retroreflective backplates on all new signal 

installations as well as signal upgrades. 

While many standards help to reduce risk and protect against liability, a standard is not a 

guarantee of safety. When developing standards, an agency should consider the costs and 

benefits of alternatives, including conditions without the treatment of interest. Continuing with 

the example of retroreflective backplates, an agency would consider the cost of installing 

backplates on all new signals and signal upgrades compared to the expected benefits (i.e., safety 

performance with and without backplates). 

Given the need for cost-effective measures, policy-based safety improvements typically include 

proven countermeasures that are highly effective or relatively low cost to justify the installation 

on a large scale. Refer to FHWA’s Proven Safety Countermeasures for opportunities to create 

policy-based safety improvements. The following are examples of policy-based safety projects 

that are also included in FHWA’s Proven Safety Countermeasures: 

• Install retroreflective backplates on all new signal installations and signal upgrades.

• Improve the retroreflectivity of curve warning signs to enhance delineation on

horizontal curves.

• Install longitudinal rumble strips and stripes on two-lane roads.

• Install SafetyEdgeSM for all asphalt paving projects without curbs.

10 
 

 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

SUMMARY OF CRASH-BASED AND SYSTEMIC APPROACHES 

The crash-based and systemic approaches are complementary and support a comprehensive 

approach to safety management. The primary difference is the way in which analysts identify 

issues and develop projects. In the crash-based approach, analysts select sites and develop 

projects based on site-specific crashes. In the systemic approach, analysts focus on site-specific 

geometric and operational attributes known to increase crash risk. 

While there are differences in the application of the approaches, both approaches focus on 

preventing future crashes and reducing fatalities and injuries. Another commonality is focusing 

on sites with the greatest potential for safety improvement. In either case, it is important to use 

reliable, data-driven methods to inform these decisions. A predictive approach based on a 

combination of historical crash, exposure, and roadway data is more reliable than an approach 

based on crash frequency alone or ad hoc analysis of geometric and operational attributes that 

may increase risk. 

Finally, there is not an intrinsic link between the project cost and analysis approach. While 

systemic projects are generally low-cost and widely implemented, no countermeasures are 

exclusive to the systemic approach. For example, agencies may install lower unit cost 

countermeasures at a single site as a standalone low-cost project. 

11 
 

 

 

 

 

 

 

 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

3. DEMONSTRATING THE VALUE OF INTEGRATING SYSTEMIC

APPROACHES IN A COMPREHENSIVE SAFETY PROGRAM 

This section presents a framework for characterizing the cost-effectiveness of and allocating 

funds to crash-based and systemic projects. In an attempt to characterize typical crash-based 

and systemic projects, the research team identified a sample of projects to represent both 

project types. Separate sections present the characteristics of the sample of crash-based and 

systemic projects, including average project costs and benefits, average benefit-cost ratios, and 

net benefits given a fixed program budget. 

Table 2 shows the crash cost values used in this guide based on the Highway Safety Manual and 

expressed in 2016 dollars.(3) This guide uses weighted crash costs and average total crashes for 

the examples. Agencies should consider the potential impact of fatal crashes in estimating 

project benefits. Even one fatal crash can skew the estimated project benefits. Consider using 

expected crashes as the basis for estimating the long-term safety performance and weighted 

crash costs in estimating project benefits. 

Table 2. Comprehensive crash costs by maximum reported severity. 

Maximum Crash Severity Cost 

Fatal $5,715,100 

Incapacitating Injury $302,400 

Non-incapacitating Injury $110,400 

Possible Injury $62,200 

Property Damage Only $10,000 

While agencies implement some countermeasures such as median barrier, signal retiming, or 

sight distance improvements with either the crash-based or systemic approach depending on 

the project, a review of the 2014 HSIP annual reports indicated some projects are more 

common to one approach or the other. This guide includes six sample countermeasures 

representing the crash-based approach: left turn lanes, high friction surface treatments, 

intersection reconfigurations, reduction of intersection skew, road diets, and roundabouts. It 

also includes six sample countermeasures representing the systemic approach: cable median 

barriers, centerline and shoulder rumble strips, ramp curve signage, chevron curve warning 

signs, and low-cost intersection improvements at signalized and stop-controlled intersections. 

The following sections present the potential value of crash-based and systemic projects. Note 

the results reflect a sample of safety projects and a hypothetical safety program budget of 

$10,000,000. While all States receive more than $10,000,000 annually for safety programs, this 

value is for illustrative purposes and is easily scalable to larger values. Agencies could replicate 

the process to customize the results based on local experience. They could also generalize 

these results to an available portion of a larger budget. Following the cost-effectiveness analyses 

is a discussion of several noted strengths, limitations, and key considerations for the crashbased and systemic approaches. There is also information for program managers on how to 

incorporate both types of projects (crash-based and systemic) and allocate funding within a 

comprehensive safety improvement program. 

12 
RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

VALUE OF CRASH-BASED PROJECTS 

Crash-based projects deploy countermeasures with the potential to yield reductions in crash 

frequency and severity at the specific site. Table 3 presents data for six countermeasures 

representing crash-based projects, including the service life, average crashes before treatment, 

CMF, and average cost. The numbers in the table represent data from various research reports 

and from State DOTs. The countermeasures represent the primary treatment implemented in 

the project; however, minor improvements may have accompanied the primary treatments in 

some cases. The following is a brief summary of the data elements in Table 3. 

• Countermeasure: The table presents data for six countermeasures selected to

represent projects associated with a crash-based approach. For road diets, the table

includes two versions; one assuming resurfacing and restriping, and the other assuming

milling old pavement markings and restriping as a new configuration.

• State(s): The table includes data from California, Iowa, Rhode Island, South Carolina,

and Washington. The table indicates the State(s) represented for each countermeasure.

• Service life: The table presents the assumed service life (in years) for each

countermeasure based on research reports and State documentation. The service life

ranges from 10 years (high friction surface treatment) to 20 years (add left turn lanes,

reconfigure intersection, reduce intersection skew and add left turn lanes, road diets,

and roundabouts).

• Average crash frequency before treatment: The table presents the average crash

frequency before treatment based on research reports and State documentation. While

the average crash frequency is one measure of the opportunity for improvement, the

expected crashes from the Empirical Bayes (EB) method provides a more reliable

measure of the potential for improvement in the long-term.

• CMF: The table presents the total crash CMF for each countermeasure based on

existing documentation or data provided by the States. The appendix provides detailed

information on project effectiveness by crash severity.

• Study method: The table presents the method used to develop the CMF for each

countermeasure. For road diets, the CMF is from an EB before-after analysis

documented in an existing report. For the other countermeasures, the CMF is from a

simple before-after analysis of projects provided by the States.

• Similar CMFs from the CMF Clearinghouse: The table presents the existing CMF

(or range of CMFs) from the CMF Clearinghouse. This provides a point of reference for

comparing the CMFs based on limited project data directly from the States. In general,

the CMFs assumed for this study are comparable to those from the CMF Clearinghouse.

• Average cost per mile or per site: The table presents the average countermeasure

cost based on research reports and State documentation. The costs range from

$100,000 per mile (road diets without resurfacing) to $1,106,000 per intersection

(reduce intersection skew and add left turn lanes).

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Table 3. Crash-based countermeasure data. 

Countermeasure State(s) 

Service 

Life 

(years) 

Average Crash 

Frequency Before 

Treatment1 

CMF Study 

Method2

Similar CMFs 

from the CMF 

Clearinghouse 

(CMF ID#) 

Average Cost 

Per Mile or 

Per Site 

Add Left Turn Lanes SC 20 5.0 per intersection 0.59 Simple 

Before-After 

0.69 

(7853) $706,000 

High Friction Surface 

Treatment RI 10 5.4 per site 0.85 Simple Before-After 

0.76 

(194) $100,000

Reconfigure Intersection3

SC 20 4.2 per intersection 0.66 Simple 

Before-After N/A $822,000 

Reduce Intersection Skew 

and Add Left Turn Lanes SC 20 3.8 per intersection 0.48 Simple Before-After N/A $1,106,000 

Road Diet Without 

Resurfacing4

IA, CA, 

WA 20 26.2 per mile 0.71 EB BeforeAfter 

0.63 

(874) $100,000

Road Diet Including 

Resurfacing Costs4

IA, CA, 

WA 20 26.2 per mile 0.71 EB BeforeAfter 

0.63 

(874) $1,000,000

Roundabout SC 20 4.6 per intersection 0.28 Simple 

Before-After 

0.21-0.32 

(2122, 2123) $739,000 

1. All crash frequencies expressed as crashes per mile-year or crashes per site-year.

2. CMFs from simple before-after studies are generally less reliable than CMFs from EB before-after studies. As such,

there is more uncertainty in the estimates from simple before-after studies.

3. Includes various treatments such as reducing skew, removing slip ramps, and teeing up a scissors-type intersection.

4. Information for road diets is from the following sources:

a. Incorporating On-Road Bicycle Networks into Resurfacing Projects

b. Florida District 3 Preliminary Estimates Section Transportation Costs

c. Evaluation of Lane Reduction "Road Diet" Measures on Crashes

14 

Under 23 United States Code - Section 409, this data cannot be used in discovery or as evidence 

at trial in any action for damages against the respective State DOT or the individual States. 
 

 

 

 

 

 

 

 

 

 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Given the countermeasure data in Table 3 and the appendix, Table 4 presents the benefit-cost 

ratio of theoretical projects, representing the potential coverage and benefits of implementing 

each countermeasure within a budget of $10,000,000. The table presents project costs and net 

safety benefits in terms of present dollar value for each countermeasure as well as the average 

of all countermeasures. For road diets, the table includes two analyses using the same crash 

data; one includes reconstruction and resurfacing costs, and the other assumes milling old 

pavement markings and restriping as a new configuration. The appendix provides further details. 

Table 4. Crash-based project cost-effectiveness. 

Countermeasure Coverage1 Project 

Costs 

Net Safety 

Benefits 

Benefit 

Cost Ratio 

Add Left Turn Lanes 14 intersections $9,884,000 $62,386,011 6.3 

High Friction Surface 

Treatment 100 sites $10,000,000 $498,263,771 49.8 

Reconfigure Intersection 12 intersections $9,864,000 $134,293,525 13.6 

Reduce Intersection Skew 

and Add Left Turn Lanes 9 intersections $9,954,000 $83,931,637 8.4 

Road Diet Without 

Resurfacing 100 miles $10,000,000 $631,888,312 63.2 

Road Diet Including 

Reconstruction and 

Resurfacing Costs 

10 miles $10,000,000 $63,188,831 6.3 

Roundabout 13 intersections $9,607,000 $111,682,769 11.6 

Average 37 sites $9,901,286 $226,519,265 23.0 

1. Assumes one mile, one curve, and one intersection are equivalent to a single site.

Benefit-cost ratios greater than 1.0 represent a positive return on investment. While benefitcost ratios in Table 3 are all well above 1.0 and are economically justifiable projects, this sample 

of projects is associated with relatively high costs and high investment risks in the context of 

the overall safety program. With high-cost projects, agencies can address relatively few sites 

annually given a fixed budget. While this sample of projects developed through a crash-based 

approach has relatively high costs, there is not an intrinsic link between the project cost and 

analysis approach. With respect to investment risk, if a high-cost project does not yield the 

expected benefits, and results in a benefit-cost ratio less than 1.0, then the agency could have 

allocated this portion of the safety budget more effectively elsewhere. This is a particular 

concern when the estimated benefit-cost ratio prior to treatment is close to 1.0 because slight 

overruns in project costs can result in a benefit-cost ratio less than 1.0. High-cost projects may 

also include additional costs related to resurfacing, drainage, and other elements required to 

implement the safety-related aspects of a more substantial project. These costs are required to 

facilitate the overall project construction, but do not necessarily contribute to the expected 

safety benefit. To mitigate this issue, there is an opportunity to integrate efforts from 3R/4R 

condition management with high-cost safety improvements. 

15
 
 

 

 

 

 

 

 

 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

VALUE OF SYSTEMIC PROJECTS 

Agencies commonly install systemic projects at many sites or along longer corridors within a 

single project. As such, there are economies of scale and systemic projects are often associated 

with lower unit costs and low economic risk compared to high-cost projects. While systemic 

projects are generally low-cost and widely implemented, no countermeasures are exclusive to 

the systemic approach. For example, agencies may install lower unit cost countermeasures at a 

single site as a standalone project. Agencies are less likely to program high-cost projects with 

the systemic approach for a number of reasons, including budget limitations, but this does not 

preclude higher cost countermeasures from systemic implementation. 

Table 5 presents data for a six countermeasures representing systemic projects, including the 

service life, average crashes before treatment, CMF, and average cost. The numbers in the table 

represent data from various research reports and from State DOTs. The following is a brief 

summary of the data elements in Table 5. 

• Countermeasure: The table presents data for six countermeasures selected to

represent projects associated with a systemic approach.

• State(s): The table includes data from Connecticut, Kentucky, Michigan, Missouri,

Pennsylvania, Rhode Island, South Carolina, and Washington. The table indicates the

State(s) represented for each countermeasure.

• Service life: The table presents the assumed service life for each countermeasure

based on research reports and State documentation. The service life ranges from five

years for general signing improvements to 13 years for cable median barrier.

• Average crash frequency before treatment: The table presents the average crash

frequency before treatment based on research reports and State documentation. While

the average crash frequency is one measure of the opportunity for improvement, the

expected crashes from the Empirical Bayes (EB) method provides a more reliable

measure of the potential for improvement in the long-term.

• CMF: The table presents the total crash CMF for each countermeasure based on

existing documentation or data provided by the States. The appendix provides detailed

information on project effectiveness by crash severity.

• Study method: The table presents the method used to estimate the safety effect for

each countermeasure. For most countermeasures, the CMF is from an EB before-after

analysis documented in an existing report. For ramp curve signage, the CMF is from a

simple before-after analysis of projects provided by Rhode Island.

• Similar CMFs from the CMF Clearinghouse: The table presents the existing CMF

(or range of CMFs) from the CMF Clearinghouse. This provides a point of reference for

comparing the CMFs based on limited project data directly from the States. In general,

the CMFs assumed for this study are comparable to those from the CMF Clearinghouse.

• Average cost per mile or per site: The table presents the average countermeasure

cost based on research reports and State documentation. The costs range from $1,600

per site for curve warning signs to $196,000 per mile for cable median barrier. The

research team included maintenance cost for cable median barrier at a three percent

discount rate; otherwise, maintenance costs are negligible over the service life.

16
 
 

 

 

 

 

 

 

 

 

 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Table 5. Systemic countermeasure data. 

Countermeasure State(s) 

Service 

Life 

(years) 

Average Crash 

Frequency 

Before 

Treatment1 

CMF Study 

Method2

Similar CMFs 

from the CMF 

Clearinghouse 

(CMF ID#) 

Average Cost 

Per Mile or 

Per Site 

Cable Median Barrier3

MI 13 1.97 

2.14 

0.95 for KABC 

crashes 

EB BeforeAfter 

1.91 (5442) 

0.79 for KABC 

crashes (6129) 

$196,000 

Centerline and 

Shoulder Rumble Strips4

KY, MO, PA 7 0.91 0.80 EB BeforeAfter 

0.80 

(6850) $5,000 

Ramp Curve Signage RI 5 15.2 0.74 Simple 

Before- After 

0.59-0.69 

(1905, 1907, 1909) $10,000 

Curve Warning 

Signage (Chevrons)5

WA, CT 5 6.2 0.94 EB BeforeAfter 

0.63-0.72 

(1898, 7268) $1,600 

Low Cost Intersection 

Improvements – 

Signal6

SC 7 12.5 0.96 EB BeforeAfter N/A $7,000 

Low Cost Intersection 

Improvements –Stop7

SC 7 3.5 0.92 EB BeforeAfter N/A $6,000 

17 

 1. All crash frequencies are expressed as crashes per mile-year or crashes per site-year.

2. CMFs from simple before-after studies are generally less reliable than CMFs from EB before-after studies. As such, there is more

uncertainty in the estimates from simple before-after studies.

3. Guidance on the application of cable median barrier: tradeoffs between crash frequency, crash severity, and agency costs

4. Safety Evaluation of Centerline Plus Shoulder Rumble Strips

5. Safety Evaluation of Improved Curve Delineation

6. Includes doubling and oversizing advance warning signs, fluorescent yellow sheeting for warning signs, retroreflective sign posts,

refreshing existing pavement markings, one signal per lane, retroreflective backplates, and 12-inch LED lenses, with each installed only

where appropriate.

7. Includes doubling and oversizing advance warning signs, fluorescent yellow sheeting for warning signs, retroreflective sign posts,

refreshing existing pavement markings, and stop bar markings on cross streets, with each installed only where appropriate.

Under 23 United States Code - Section 409, this data cannot be used in discovery or as evidence 

at trial in any action for damages against the respective State DOT or the individual States. 
 

 

 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Given the countermeasure data in Table 5 and the appendix, Table 6 presents the benefit-cost 

ratio of theoretical projects, representing the potential coverage and benefits of implementing 

each countermeasure within a budget of $10,000,000. The table presents project costs and net 

safety benefits in terms of present dollar value for each countermeasure as well as the average 

of all countermeasures. The appendix provides further details on these calculations. 

Table 6. Systemic project cost-effectiveness. 

Countermeasure Coverage1 Project Cost Net Safety 

Benefits 

Benefit Cost 

Ratio 

Cable Median Barrier 51 miles $9,996,000 $58,006,096 5.8 

Centerline and Shoulder 

Rumble Strips 2,000 miles $10,000,000 $126,771,305 12.7 

Ramp Curve Signage 1,000 curves $10,000,000 $2,928,925,502 292.9 

Curve Warning Signage 

(Chevrons) 6,250 curves $10,000,000 $640,014,079 64.0 

Low Cost Intersection 

Improvements - Signal 

1,428 

intersections 

$9,996,000 $279,526,340 28.0 

Low Cost Intersection 

Improvements - Stop 

1,666 

intersections $9,996,000 $168,073,055 16.8 

Average 2,066 sites $9,998,000 $700,219,396 70.0 

1. Assumes one mile, one curve, and one intersection are equivalent to a single site.

The benefit-cost ratios of the systemic projects in Table 5 are all well above 1.0 and are 

economically justifiable projects. While the systemic approach appears to hold great promise, 

the approach also has specific limitations. First, many agencies are not as familiar or 

experienced with the project delivery and analysis methods to identify and plan systemic 

projects. Second, some jurisdictions have found difficulties in managing and administering 

systemic projects when there is a requirement for detailed plans or surveys for construction, 

which can add considerable costs to otherwise low-cost projects. Additionally, there are 

limitations to address some crash types with systemic projects because proven, low-cost 

countermeasures are not available for targeting all severe crash types. For example, 

roundabouts are effective at reducing severe, right-angle crashes, but roundabouts are not a 

viable systemic improvement. Finally, although systemic projects may yield high net benefits, 

agencies still have an obligation to address the highest risk sites, which include those with a 

history of severe crashes. 

18 
 

 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

COMPARISON OF CRASH-BASED AND SYSTEMIC PROJECTS 

Table 4 and Table 6 present the results of simulated safety programs for crash-based and 

systemic projects, respectively. Table 7 lists the average results for the crash-based and 

systemic countermeasure programs. Note there are seven crash-based programs and six 

systemic programs represented in Table 7. While each hypothetical program is $10M, the 

research team assumed an agency can only install whole projects. For example, it is not possible 

to install 3.5 roundabouts. 

Table 7. Comparison of crash-based and systemic economic measures. 

Economic Measure Crash Based Systemic 

Total Cost $9,901,286 $9,998,000 

Total Benefit $226,519,265 $700,219,396 

Overall Benefit-Cost Ratio 23.0 70.0 

The results for the crash-based countermeasure program show an average cost of $9,901,286, 

average benefit of $226,519,265, and average benefit-cost ratio of 23.0 based on seven projects. 

The results for the systemic countermeasure program shows an average cost of $9,998,000, 

average benefit of $700,219,396, and average benefit-cost ratio of 70.0 based on six projects. 

There are a number of considerations for interpreting these results. The research team 

selected studies for this analysis with available data for at least before period crashes, project 

cost and coverage, and the countermeasure effectiveness (CMF). There may be a level of bias 

associated with this limitation. For example, agencies tend to implement proven (i.e., effective) 

countermeasures, and research tends to focus on the most prevalent countermeasures. As 

such, those countermeasures with available CMFs may reflect more effective measures. Further, 

there is limited availability of crash-based evaluations of systemic projects, and there is limited 

information on, and variability in, the methods used to plan systemic projects, identify sites for 

implementation, and evaluate the results. Agencies should use caution in applying these results. 

The analysis in this guide reflects the average effectiveness of a countermeasure. There is a 

standard error associated with each estimate. While many agencies use the average CMF in 

benefit calculations, the recommended practice is to consider the standard error and 

confidence interval associated with the estimates. However, given the relatively high benefitcost ratios in Table 4 and Table 6, there is a low probability these hypothetical projects would 

result in benefit-cost ratios less than 1.0. The research team did not analyze whether there are 

significant differences, accounting for the confidence interval, between crash-based and systemic 

projects. For more information on CMFs and confidence intervals, refer to the Reliability of 

Safety Management Methods: Countermeasure Selection.

(6) 

The FHWA Office of Safety identifies all but two of the crash-based countermeasures in this 

analysis as proven countermeasures (exceptions are reconfiguring intersections and reducing 

intersection skew).(8) While the proven countermeasures are associated with a demonstrated 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

capability to provide cost-effective safety benefits, agencies should still confirm that a proven 

countermeasure will not trigger other crashes due to specific conditions not considered by 

CMFs associated with total crashes. 

While the benefit-cost ratios and net benefits in Table 4 are relatively high, the coverage within 

a budget of $10,000,000 is limited given the relatively high cost of the countermeasures. High 

friction surface treatment and road diets without resurfacing are relatively lower cost crashbased projects, resulting in higher coverage and higher net benefit than other crash-based 

countermeasures. This guide uses a $10,000,000 budget for comparison, and the results 

represent average projects based on available information. See the appendix for details related 

to the individual projects represented in these averages. It is safe to assume the sites used as a 

basis for this analysis were some of the better candidates in a State for implementing these 

treatments. As agencies address locations with the highest potential for improvement, they may 

realize diminishing returns and relatively smaller benefits from additional implementation of the 

same measure. However, it takes many years to address all notable concerns and other sites 

may emerge as safety concerns due to new developments or changes in the nature of the site. 

The sample of systemic projects show a higher ceiling of net benefit and higher coverage overall 

(i.e., ability to treat more sites with the same budget as shown in Table 6) than the crash-based 

projects (see Table 4). The FHWA Office of Safety identifies all but two of the systemic 

countermeasures in this analysis as proven countermeasures (exceptions are the low-cost 

intersection improvements at signalized and stop-controlled intersections).(8) The systemic or 

systematic implementation of countermeasures helps to streamline or forego the site-specific 

diagnostic considerations in a crash-based safety management process. The systemic process 

can start with the selection of a countermeasure based on the focus crash type, which 

precludes the opportunity to improve a site beyond the implementation of the systemic 

countermeasure. However, it is necessary for agencies to consider the potential for sites to 

exhibit other safety concerns not addressed during the implementation of a single systemic 

project due to the limited diagnosis. 

By nature of the approach, agencies implement systemic projects at multiple sites. When 

implemented at many sites as part of a single contract, this helps to distribute engineering and 

construction costs. As such, these countermeasures are associated with lower unit costs and 

potentially higher system benefits. Similar to the crash-based projects, there is potential for 

diminishing returns of implementing additional systemic projects as agencies address locations 

with the highest potential for improvement. 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

CRASH-BASED AND SYSTEMIC PROJECTS WITHIN A COMPREHENSIVE 

SAFETY PROGRAM 

The ultimate purpose of the HSIP is to achieve a significant reduction in traffic fatalities and 

serious injuries on all public roads. Safety program managers administer funds to maximize the 

reduction in fatal and serious crashes, which could be expressed in terms of maximizing the net 

economic benefits of projects. This task requires selecting projects with the best chance to 

achieve these goals while ensuring that funds do not lapse and programs are not overcommitted (i.e., planning sufficient projects, but not planning excessive financial commitments 

relative to the estimated budget). 

The analysis and discussion in the previous sections demonstrate the value of both crash-based 

and systemic projects. Sites with the highest potential for improvement are often high profile 

locations with a notable history of severe crashes. The public expects agencies to address such 

problematic sites, and it is often beneficial to do so with the right countermeasures. Systemic 

projects may not adequately address crash problems at the highest crash sites, but show the 

potential to address targeted issues across a larger portion of the network, particularly highlydispersed crashes across a network. 

The number of sites representing high quality candidates for crash-based safety projects is small 

relative to the entire network of sites. Additionally, crash-based projects usually represent 

solutions requiring more effort to plan, program, and design, and may require right-of-way 

acquisition. These projects are generally not flexible within programs due to larger construction 

efforts and are not as scalable as systemic projects. Given these factors, and considering the 

average return on investment may be lower than systemic projects as suggested in Table 7, a 

program built entirely of crash-based projects is likely not optimal. 

A logical conclusion is that crash-based and systemic safety projects are complementary, serving 

different purposes within an overall safety management program. Figure 3 illustrates a typical 

distribution of expected fatal and injury crash frequency at approximately 1,400 intersections 

across a network. These sites represent those three-legged and four-legged, stop-controlled 

and signalized intersections in New Hampshire with available traffic volume for all approaches. 

Based on the screening measures employed, these sites represent relatively larger intersections. 

A distribution including all intersections will skew further toward lower frequency sites. 

The few sites with the highest expected crash frequency (e.g., the top 0.5 percentile) are sparse 

outliers, and the top five percent of sites have substantially higher frequencies than the rest of 

the sites on average. This is typical of most road networks. There is a need to implement crashbased projects to address the sites with the highest potential for improvement. Beyond the 

sites representing the steep slope of the distribution (e.g., top five percent), the potential return 

is fairly constant and relatively low. As such, diagnosing and treating the lower frequency sites 

one by one is not feasible within safety budgets and resource constraints. 

Systemic projects can provide an effective way to address the safety concerns at the majority of 

sites with countermeasures representing generally lower risk, potentially more cost-effective, 

and scalable projects. Widespread implementation of similar countermeasures within a single 

systemic project can also save costs during design and construction, and the low-cost, low21
 
 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

impact nature of systemic countermeasures often does not trigger right-of-way and 

environmental impacts that can increase project costs. However, preliminary engineering can 

constitute a greater proportion of systemic projects due to the planning and coordination 

involved in developing the project. Additionally, systemic projects do not realize the potential 

for greater improvements at the highest crash sites. 

Figure 3. Graph. Statewide distribution of intersection safety performance. 

22 
RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

ALLOCATING FUNDS TO CRASH-BASED AND SYSTEMIC PROJECTS 

The question of how to allocate funds in a safety program for crash-based and systemic projects 

is not necessarily a question of complementing the two safety management approaches. A more 

applicable question for program managers is how to balance the implementation of high-cost 

and low-cost countermeasures. 

Based on the sample analysis in this study, the results in Table 7 show the potential costeffectiveness of both crash-based and systemic projects. In this guide, the sample of projects 

seem to reflect an association between the project cost and approach: the sample of crashbased projects are relatively high-cost and the sample of systemic projects are relatively lowcost. Again, there is not an intrinsic link between the project cost and analysis approach. As 

such, the remainder of this guide discusses high-cost and low-cost projects in addition to crashbased and systemic projects. 

Safety programs are like an investment portfolio in the sense that it is helpful to diversify risk 

and optimize return on investment. Consider the crash frequency distribution in Figure 3 in this 

context. The goal of a program is to reduce the area under the curve. High-cost projects may 

be a sound investment in the highest crash sites when there is a clear opportunity for a large 

crash reduction. High-cost investments in sites with lower crash frequencies do not present the 

same potential return, and a lower level of investment with modest return may be appropriate. 

Agencies can address the wide-ranging, but lower magnitude, safety concerns across the 

network with relatively low-cost, low-risk countermeasures. These types of countermeasures 

typically offer lower potential return on investment at individual sites, but represent a large 

potential benefit considering the widespread implementation. An optimization function can 

demonstrate the breakeven points along the crash frequency distribution using the information 

from the cost-effectiveness analysis presented earlier. 

The following section describes a process for determining the optimal allocation of funds 

between two types of projects or two countermeasures. 

Development of a Breakeven Crash Frequency Equation 

Figure 4 presents the equation for calculating the net benefits of some safety improvement. 

Figure 4. Equation. General equation for net benefits of a project. 

Where: 

NB = net annual safety benefits. 

AVB = annualized value of project safety benefits. 

AVC = annualized value of project costs. 

The economic benefits of a safety project are the product of multiplying the estimated crash 

reduction by average crash costs. If the estimated crash reduction is the difference between the 

estimated crash frequency with and without the treatment, then the previous equation can be 

rewritten as shown in Figure 5. 

23 
RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Figure 5. Equation. Net benefits in terms of crash frequency, crash cost, and 

project cost. 

Where: 

ACFwithout = average annual crash frequency without treatment. 

ACFwith = average annual crash frequency with treatment. 

CC = average estimated economic cost per crash. 

The average crash frequency before treatment is an approximation of the average annual crash 

frequency without treatment. The Highway Safety Manual presents a predictive method to 

estimate average annual crash frequency without treatment. Note a predictive approach based 

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

approaches based on crash frequency alone. The annual crash frequency with treatment is the 

annual crash frequency without treatment multiplied by a CMF for the treatment. The crash 

costs, crash frequency, and CMF must all be in terms of the same crash types and severities. 

Figure 6 reflects the expanded equation, and simplifies to the equation shown in Figure 7. Note 

analysts can calculate the net benefits of multiple crash types and severities separately, and then 

sum the results. 

Figure 6. Equation. Net benefits in terms of before-period crashes, project 

effectiveness, crash cost, and project cost. 

Figure 7. Equation. Simplified equation for net benefits of a project. 

Where: 

CMF = crash modification factor for a given safety treatment. 

A general goal of safety improvement programs is to maximize the net safety benefits of the 

overall program of safety projects. A common tradeoff in project planning and countermeasure 

selection is whether it is more appropriate to select a more expensive treatment that is more 

likely to reduce a relatively greater number of crashes per site, or to select a less expensive 

treatment that may reduce a relatively lower number of crashes per site. Given that some sites 

experience a much higher crash frequency than others, it is usually more appropriate and 

beneficial to implement higher cost and more effective treatments at sites with higher crash 

frequency, and lower cost treatments at sites with relatively lower crash frequency. There is 

then a certain crash frequency where the benefits of these two types of projects are equivalent, 

yielding a breakeven point where either approach is warranted. In other words, there is a 

minimum crash frequency below which a high-cost investment is no longer worth the 

expenditure. Above the minimum threshold, it is possible to realize a return on investment 

from a high-cost strategy. Figure 8 illustrates this optimization problem where the dashed line 

represents the breakeven threshold. 

24 
 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Figure 8. Chart. Optimizing investments in high-cost and low-cost improvements. 

By determining the breakeven crash frequency (ACFwithout), program managers can determine 

the sites within a roadway network that warrant higher investments and similarly those that 

warrant lower cost improvements. Analysts can determine the breakeven crash frequency by 

setting the net benefits equal for crash-based and systemic projects, using Figure 9, and 

characterizing the net benefits and crash frequency for the two approaches by representative 

project costs and CMFs. 

Figure 9. Equation. Equality criterion for calculation of breakeven of net benefits. 

Where: 

NBC = net safety benefits of a crash-based treatment. 

NBS = net safety benefits of a systemic treatment. 

Substituting the net benefit notation from Figure 7 into the equality in Figure 9, and using 

algebra to solve for ACFwithout, Figure 10 shows the equation to calculate the breakeven crash 

frequency. 

Figure 10. Equation. Breakeven crash frequency equation. 

25 
 

 

 

 

 

 

 

 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Where: 

ACFwithout = crash frequency before treatment representing a breakeven between 

hotspot and systemic treatments. 

AVCC = annualized value of project costs for a crash-based treatment. 

AVCS = annualized value of project costs for a systemic treatment. 

CC = average estimated economic cost per crash. 

CMFS = crash modification factor for a systemic treatment. 

CMFC = crash modification factor for a crash-based treatment. 

Assuming: 

CMFS > CMFC 

AVCC > AVCS 

Crash cost, crash frequency, and CMF are determined for same crash type and severity. 

Using the equation in Figure 10 and substituting the average costs and CMFs for each type of 

project, analysts can solve for the breakeven crash frequency for crash-based and systemic 

projects across the roadway network. The application of this equation is to determine the 

breakeven threshold, and then assess whether the crash frequency for a given site is above or 

below that threshold. Crash-based projects are likely more appropriate at sites with a crash 

frequency higher than the breakeven threshold, and systemic projects are likely more 

appropriate at sites with a crash frequency below the threshold. The crash frequency, ACFwithout, 

should represent the average observed crash frequency or the expected crash frequency with 

EB adjustment for the entire area of the project. 

If such a situation arises where CMFC > CMFS and AVCC > AVCS (or vice versa), it is not 

necessary to undertake this analysis of tradeoffs. In this case, the treatment with lower cost and 

greater effectiveness (i.e., lower CMF) will result in the optimal solution. 

Example Application of the Breakeven Equation 

Analysts can use the equation to calculate the breakeven crash frequency for applying the 

results of crash-based and systemic projects in Table 4 and Table 6. Table 8 presents the 

weighted average CMF and annualized cost for the crash-based and systemic projects over the 

service life. The average data for systemic projects excludes cable median barrier due to the 

large increase in total crashes and maintenance cost that limited the application in this simple 

analysis of total crashes. Note cable median barrier is highly-effective at reducing severe headon crashes, but can increase total crashes. 

26 
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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Table 8. Weighted average CMF and costs by project type. 

Economic Measure Crash Based Systemic 

Average CMF 0.73 0.90 

Average Project Cost Per Site 

(Intersection, Curve, or Mile) Per Year $20,000 $750 

This analysis used an average crash cost for total crashes of $55,900. This value is from the 

average crash costs presented in Table 2 and an assumed crash severity distribution. See the 

appendix for further discussion of the assumed crash severity distribution and calculation of the 

average crash cost of $55,900. With these inputs, the breakeven equation in Figure 10 yields a 

breakeven crash frequency threshold of 2.0 as shown in Figure 11. 

Figure 11. Equation. Application of the breakeven equation. 

The resulting breakeven crash frequency for the average crash-based and systemic projects in 

this example is 2.0 total crashes per site per year. For intersection-related improvements, a site 

represents one intersection. For segment-related improvements, a site represents one mile. As 

discussed previously, higher-cost projects may be more appropriate at sites with an average 

crash frequency higher than the breakeven threshold, and lower-cost projects may be more 

appropriate at sites with an average crash frequency below the threshold. In this case, sites with 

estimated total crashes higher than 2.0 crashes per site per year are more fitting locations for a 

crash-based approach and countermeasures, and sites with estimated total crashes lower than 

2.0 crashes per site per year are more appropriate for systemic countermeasures. If applied to 

the distribution in Figure 3, the top 15 percent of sites are potentially more appropriate for 

some type of crash-based countermeasure, and the remaining 85 percent of sites are more 

fitting for systemic countermeasures. 

Figure 12 illustrates the results of the breakeven analysis. Again, the hypothetical program 

budget is $10M. The average cost per site and average benefit reflect the numbers in Table 8 

based on the sample of projects included in this study. Based on these results, the higher-cost 

projects and lower-cost projects produce similar benefits when assigned to sites with more 

than 2.0 and less than 2.0 crashes per year, respectively. 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Figure 12. Chart. Optimizing investments in high-cost and low-cost improvements. 

Note this is a basic example of how practitioners can apply the equation in Figure 10. Analysts 

should consider the applicability of the average projects included in this research before 

applying the results of this example to actual safety programs. It is desirable to generate agencyspecific estimates for the average cost and CMF of crash-based and systemic-based projects. 

Considerations for Applying the Breakeven Equation 

Analysts should consider a number of factors to appropriately apply the breakeven equation. 

First, it is desirable to apply the equation to fatal and injury or fatal and severe injury crashes 

rather than total crashes as shown in the example. In either case, analysts should use the 

weighted average crash cost for crashes of that severity level and the CMF for crashes of that 

severity level. The resulting breakeven crash frequency reflects those conditions (e.g., the 

breakeven fatal and injury crashes or breakeven total crashes). Similarly, analysts could input a 

crash cost and CMF for a specific crash type. Note the analysis should focus on a single crash 

type or severity using corresponding crash costs and CMFs as inputs. 

Another consideration is the mix of projects considered in the analysis. Ideally, analysts would 

consider segment and intersection projects separately. The previous example application mixes 

projects along segments, intersections, and curves to estimate the average project cost and 

effectiveness. It may be more appropriate to consider segments, intersections, and curves 

separately, particularly when allocating funds within a targeted program such as a roadway 

departure program or an intersection improvement program. 

Practitioners could apply this equation in a number of ways to help inform project planning and 

programming decisions. For example, analysts could apply the equation to assess the tradeoff 

and selection of specific treatments for a certain site, rather than average project costs and 

effectiveness estimates for typical projects within a program. 

28 
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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Given these additional considerations, the remainder of this section presents an example of 

how an agency could apply the equation to an intersection improvement program. Let’s assume 

an agency is developing an intersection improvement program, focusing on fatal and injury 

crashes. They have narrowed the focus to stop-controlled intersections, and are considering 

how to allocate funding between crash-based and systemic improvements. The proposed crashbased projects include the conversion of stop-controlled intersections to roundabouts. The 

proposed systemic projects include enhanced signing and marking packages. 

Table 9 presents the assumed CMF and average annualized cost for the two improvements 

over the assumed service life. The CMFs apply to fatal and injury crashes, and reflect the 

average effectiveness over rural and urban areas. The average project cost for roundabouts and 

signs and markings are from Table 3 and Table 5, respectively. The assumed service life is 20 

years for roundabouts and seven years for signing and marking packages. The average crash 

cost for fatal and injury crashes is approximately $160,000.(9) 

Table 9. CMFs and project costs for intersection improvement example. 

Economic Measure Crash Based 

(Roundabout) 

Systemic 

(Signs and Markings) 

CMF (fatal and injury crashes) 0.151 0.902 

Average Project Cost Per 

Intersection Per Year $739,000 $6,000 

1. The CMF for roundabouts is an average of the CMF for fatal and injury crashes in urban areas (CMF = 0.12; 

http://cmfclearinghouse.org/detail.cfm?facid=210) and the CMF for fatal and injury crashes in rural areas (CMF = 

0.18; http://cmfclearinghouse.org/detail.cfm?facid=211). 

2. The CMF for signing and marking packages is from the following paper: Le, T., F. Gross, and T. Harmon. Safety 

Effects of Low-Cost Systemic Safety Improvements at Signalized and Stop-Controlled Intersections. 96th Annual 

Meeting of the Transportation Research Board Compendium of Papers, January 8 – 12, 2017. 

With these inputs, the breakeven equation in Figure 10 yields a breakeven crash frequency 

threshold of 6.1 fatal and injury crashes per intersection per year as shown in Figure 13. In this 

case, stop-controlled intersections with more than 6.1 fatal and injury crashes per year are 

more fitting locations for roundabouts, and stop-controlled intersections with less than 6.1 fatal 

and injury crashes per year are more appropriate for the signing and marking package. 

Figure 13. Equation. Application of the breakeven equation. 

29 
 

 

 

 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

SUMMARY 

These analyses and other considerations demonstrate the value of complementing crash-based 

and systemic approaches to safety management within a comprehensive safety program. While 

States currently allocate approximately 75 percent of HSIP funds to crash-based projects, the 

analysis results and breakeven crash frequency threshold calculation provide evidence of the 

potential to improve the cost-effectiveness of safety improvements through increased systemic 

projects. Incorporating more systemic projects into a safety program has the potential to 

address safety problems on a broader scale and enhance the overall effectiveness of a program. 

In complementing crash-based projects with systemic projects, it is important to understand 

the strengths and limitations of each approach. The crash-based approach is useful to identify 

and mitigate safety issues at sites with high potential for improvement. While projects 

implemented under the crash-based approach have an opportunity to produce great local 

benefits, the associated project costs are typically high. As such, there are limited system 

benefits because agencies can treat only a limited number of sites. Further, the projects are 

higher risk in terms of contributing to the effectiveness of an agency’s safety program. 

The systemic approach is useful to identify and address widespread safety issues distributed 

across many segments and intersections. It is difficult to address these sites with the crashbased approach due to the low density of crashes. The systemic approach overcomes these 

limitations by focusing on the underlying risk factors across the network as opposed to crash 

history at individual locations. While systemic projects typically represent lower-cost and 

lower-risk countermeasures, the site-specific benefits are typically not as attractive as crashbased projects, and it may be difficult for agencies to justify the allocation of resources to sites 

without a history of crashes. 

In either case, it is important to use reliable, data-driven methods to inform decisions. The 

Highway Safety Manual presents a predictive method to relate crash frequency to roadway 

design and operational characteristics through statistical models or SPFs. A predictive approach 

based on the combination of historical crash, exposure, and roadway data is more reliable than 

approaches based on crash frequency alone or ad hoc analysis of geometric and operational 

characteristics to approximate risk. The following is a brief summary of using the predictive 

method in crash-based and systemic approaches to safety management. 

•	 Crash-based approach: Agencies can employ predictive models to estimate the 

average safety performance given specific site conditions (e.g., traffic volume, geometric, 

and operational attributes). They can also incorporate the observed crash history with 

the average crash predictions to estimate the long-term crash propensity for a given 

site. Sites with higher expected crashes over the long-term (compared to the average 

safety performance for those conditions) indicate a higher potential for improvement. 

•	 Systemic approach: Agencies can use the results from predictive models to identify 

the most critical risk factors or combination of features that increase risk for a given 

crash type. They can use these risk factors to identify high risk locations with or without 

a history of crashes. While the systemic approach is still useful when data are limited, 

agencies should use crash and traffic volume data when it is available throughout 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

network screening, diagnosis, and countermeasure selection to the extent possible. The 

use of low-cost countermeasures in systemic projects helps to limit the uncertainty of 

using site-based geometric and operational data (i.e., risk factors) for site selection in 

the absence of site-specific observed crash or traffic volume data. 

Crash-based performance measures and exposure are eligible, appropriate, and possibly 

preferred risk factors that analysts can employ in the systemic approach. This is not common 

practice at this time and was not mentioned in any reports reviewed during the data collection 

effort for the analysis in this guide. However, AASHTOWare Safety AnalystTM employs crashbased screening performance measures in the systemic approach and usRAP employs a 

systemic approach in which exposure is a risk factor. Other tools may have similar capabilities. 

It is clear through the development of the current state of the art in SPFs, and specifically in 

several papers and in the Highway Safety Manual, that crash-based performance measures and 

exposure are superior predictors of risk compared to other geometric and operational factors. 

When crash and exposure data are adequate and available, analysts should incorporate these 

data in the systemic approach. Doing so will help to improve the reliability of the results and 

potentially improve the benefits of the approach compared to the crash-based approach. 

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4. DATA REQUIREMENTS FOR CRASH-BASED AND SYSTEMIC 

APPROACHES 

The following is a brief overview of the data requirements for crash-based and systemic 

approaches to safety management. 

CRASH-BASED APPROACH 

The crash-based approach comprises a safety management process with six steps: network 

screening, diagnosis, countermeasure selection, economic appraisal, project prioritization, and 

safety effectiveness evaluation. Table 10 provides a summary description of the data needs for 

various components of the crash-based approach to safety management, excluding project 

prioritization as this is an internal process that can include many different factors. While the 

table presents the data elements separately, there is a need to link crash, roadway, and traffic 

volume data geospatially to use the predictive crash-based approaches. Refer to the Model 

Inventory Roadway Elements—Fundamental Data Elements (MIRE FDE) for further discussion 

of basic data elements required for crash-based network screening and beyond. 

Table 10. Data needs for the crash-based approach to safety management. 

Component Crash Exposure Roadway Other 

Network 

screening 

Crash counts by 

severity at the site 

level (intersections 

and segments) 

Traffic volume 

and segment 

length 

Area type (rural or 

urban), number of 

lanes, median type, 

intersection control, 

and number of legs 

Safety performance 

functions (SPFs) or 

other thresholds by 

facility type 

Diagnosis Three to five years 

of police crash 

reports and details 

for each location 

Traffic volume 

and turning 

movement 

counts 

Traffic operations, 

roadway design, and 

roadside design 

features 

Adjacent land use, 

road user behavior, 

and road user 

demographics 

Countermeasure 

selection 

Three to five years 

of police crash 

reports and details 

for each location 

Traffic volume 

and turning 

movement 

counts 

Traffic operations, 

roadway design, and 

roadside design 

features 

List of crash 

contributing factors 

and countermeasure 

details 

Economic 

appraisal 

Expected change in 

crashes due to 

treatment 

Current and 

future traffic 

volume 

Site characteristics 

to identify suitable 

crash modification 

factors (CMFs) 

Applicable CMFs, 

average crash costs, 

and service life of 

treatment 

Safety 

effectiveness 

evaluation 

Crash counts by 

severity before and 

after treatment for 

each site 

Traffic volume 

before and after 

treatment for 

each site 

Site characteristics 

to define a suitable 

reference group or 

comparison group 

Treatment details, 

including location 

and implementation 

date; SPFs 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

SYSTEMIC APPROACH 

The systemic approach begins with the identification of focus crash types based on crashes at 

the network level. For example, an agency may identify roadway departure crashes as a focus 

crash type because these crashes present the majority of fatal and injury crashes across their 

network. Given a focus crash type, the next step is to determine risk factors related to the 

focus crash type. Once an agency determines the risk factors associated with a focus crash type, 

the next step is to determine appropriate countermeasures to target the underlying issue(s). 

Next, the agency must identify sites to implement the treatment. Finally, there is a need to 

evaluate the safety effectiveness of the treatment. 

The following is a brief summary of the data requirements for each step of the systemic safety 

management process. Note many of the data requirements are similar to the crash-based 

approach; however, agencies can apply the systemic approach without site-level crash and 

exposure data or when the average crash frequency at individual sites is relatively low. Both of 

these conditions present issues in applying the crash-based approach. 

•	 Identify focus crash types and facility types: The data requirements include a 

summary of crashes by facility type, often by severity, at the network level. There is no 

need to match crashes with individual locations. 

•	 Determine risk factors: This requires statistical modeling or cross-tabulations, and 

the association of specific roadway data with each crash type. If an agency lacks the data 

or expertise to determine risk factors for the focus crash type, then they may search for 

related results from national or state research reports to inform the analysis. Refer to 

the National Cooperative Highway Research Program Report 500 to identify risk 

factors related to specific crash types. Refer to the CMF Clearinghouse and review 

CMFs to understand the level of risk associated with specific roadway features. The 

following are common segment and intersection features to define risk factors. 

o	 Segment features: number of lanes, lane width, shoulder type and width, median 

type and width, road edge features and quality, number and type of access 

points, radius and superelevation of horizontal curves, speed limit, speed 

differential between curves and tangents, roadside hazards, and pavement 

condition and friction. 

o	 Intersection features: number of approaches, number of approach lanes, traffic 

control devices, skew, proximity to horizontal and vertical curves, signal timing, 

proximity to railroad crossing, presence of street lighting, proximity to nearby 

access points, and presence of commercial developments. 

•	 Select countermeasures: This step requires information related to the applicability, 

cost, and effectiveness of potential countermeasures. It is important to select measures 

that directly target the underlying risk factor(s). The Highway Safety Manual and CMF 

Clearinghouse provide CMFs and associated standard errors for various measures. If 

available from the underlying study, these sources indicate the applicability of the CMFs 

with respect to site conditions (e.g., area type, number of lanes, median type, and traffic 

volume), crash type, and crash severity. 

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

• Screen network for suitable locations: This step requires roadway data for the

network of interest. For example, if the agency is focusing on angle crashes at rural,

four-legged, two-way stop-controlled intersections, then they would need data for this

facility type. Specific data needs will vary, but there is a need for at least basic

information to identify the presence of risk factors at those locations. Refer to the MIRE

FDE for further discussion of basic data elements required for network screening. If

there is incomplete data for a portion of the network or for specific risk factors, then

the agency may choose to collect the required data, screen the portion of the network

with complete data, or screen the entire network with incomplete risk factor data.

• Evaluate safety effects: The data requirements to evaluate the safety effectiveness of

systemic treatments are identical to the data requirements to evaluate treatments

implemented though the crash-based approach. Refer to Table 10 for details. There are

several potential methods for evaluating the safety effects of both crash-based and

systemic projects, and the Empirical Bayes before-after method is generally preferred.

Refer to A Guide to Developing Quality CMFs for further details related to appropriate

evaluation methods. Potential issues related to the evaluation of systemic improvements

include small sample sizes, many treated sites with no recent crashes, and the lack of

site-specific crash data. If the sample size is relatively small, it may not be possible to

detect changes in safety performance at the desired level of statistical significance.

Further, if there are many sites with few or no crashes in the before period, then even

one or two crashes at these sites in the after period can indicate an increase in crashes.

As such, it is important to evaluate systemic projects as a system rather than as

individual sites. For example, if an agency installs shoulder rumble strips on all two-lane,

rural roads with a minimum shoulder width of five feet, then it is appropriate to evaluate

the safety effectiveness of shoulder rumble strips at the system level (i.e., all treated

two-lane, rural roads) rather than evaluating individual sites or corridors. Finally, if the

average crash frequency per site is relatively small (i.e., low sample mean), then it may

be necessary to rely on more sophisticated methods (e.g., Full Bayes before-after) to

evaluate the impact of these countermeasures.

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

5. TOOLS AND RESOURCES FOR SYSTEMIC APPROACHES 

Tools and resources are available to support systemic approaches, including guides and 

software. Some guides provide a discussion of the systemic approach, while other tools relate 

to specific components of the systemic process. For example, selecting targeted 

countermeasures to address systemic safety issues requires information related to potential 

countermeasures. Tools such as the National Cooperative Highway Research Program Report 

500 series can help users identify risk factors and appropriate countermeasures for a given 

safety issue or focus crash type. The CMF Clearinghouse can help users identify and apply CMFs 

to estimate the expected benefits of countermeasures. 

The FHWA Roadway Safety Data and Analysis Toolbox is a web-based repository of safety data 

and analysis tools. Use the Toolbox to identify an appropriate tool for your systemic safety 

management needs. A Primer is available to understand the overall scope and functionality of 

the Toolbox as well as the roles, responsibilities, and tasks supported by tools in the Toolbox. 

USING THE ROADWAY SAFETY DATA AND ANALYSIS TOOLBOX 

There are two primary options for searching the Toolbox. The first is a predefined query using 

the four large icons in the upper right of Figure 14 (Manage, Analyze, Collect, and Research). 

The second is an advanced search option where users can search keywords and apply filters to 

customize their search as shown in the lower left of Figure 14. 

Figure 14. Screenshot. Roadway Safety Data and Analysis Toolbox. 

The following is a brief demonstration of the stepwise process to identify an appropriate tool 

to support the systemic approach. 

1.	 Click the ‘Advanced Search’ icon, highlighted in the lower left of Figure 14. 

2.	 From the advanced search page (Figure 15), enter the word ‘systemic’ in the keyword 

search and click the search button. This returns a list of tools related to systemic safety 

management. 

35 
 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Figure 15. Screenshot. Advanced search feature. 

Using the advanced search, the Toolbox returns guides such as the Systemic Safety Project 

Selection Tool, Manual for Selecting Safety Improvements on High Risk Rural Roads, and 

Integrating Safety in the Rural Transportation Planning Process. Related software tools include 

AASHTOWare Safety AnalystTM and usRAP. 

To identify appropriate tools to support specific aspects of the systemic approach (e.g., 

countermeasure selection or economic appraisal), use the following stepwise process. 

1.	 From the advanced search page (Figure 15), leave the keyword blank and click the 

search button. This returns a list of all tools in the Toolbox. 

2.	 Click the ‘Show/Hide Filters’ button, highlighted in the upper left of Figure 16. This 

reveals a list of filters to refine the general search. 

3.	 Use the ‘Safety Management Process’ filter to select ‘Countermeasure Selection’ or 

other primary area of interest as shown in Figure 16. Apply additional filters as needed 

to refine the results. For example, apply the ‘Tool Type’ filter to narrow the list of tools 

to application guides, information guides, software, information sources, or databases. 

Figure 16. Screenshot. Filter options from advanced search page. 

36 
 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

6. FUTURE RESEARCH NEEDS
 

This guide presents an initial framework for estimating the value of and allocating funds 

between two complementary approaches to safety management: crash-based and systemic. 

While this work represents one potential method for comparing crash-based and systemic 

approaches, there is considerable research needed to test and validate the method and 

underlying assumptions. The following is a list of opportunities to enhance the information 

presented in this guide: 

•	 There is limited information on the prevalence of systemic countermeasures. As such, 

there is a need for agencies to track, and specifically identify, systemic projects. 

•	 There is limited information on the safety effectiveness of systemic countermeasures. 

Many CMFs to date reflect the safety effectiveness of crash-based projects. It is 

unknown if these countermeasures will have the same level of effectiveness when 

applied systemically. It is assumed that the Empirical Bayes before-after method is 

appropriate to evaluate the safety effects of systemic improvements, but future research 

should validate this approach. 

•	 Many of the estimates presented in this guide reflect the safety effectiveness of a limited 

number of projects based on simple before-after studies. It is necessary to increase the 

sample size and employ more reliable methods to obtain more reliable estimates of the 

average safety effectiveness of various project types. 

•	 The results presented in this guide reflect the safety benefits in terms of all crash types 

and severities. A similar analysis should focus on fatal and serious injury crash reductions 

for the calculation of benefits. 

•	 There is a need to expand the analysis to include more types of crash-based and 

systemic projects as more information becomes available on the cost and effectiveness. 

•	 There is a need to test the application of the framework for allocating funds to crashbased and systemic projects. This framework should be tested in real-world scenarios 

and under various conditions (e.g., HSIP program level, subprogram level, and project 

level to identify potential strengths, limitations, challenges, and opportunities). 

37 
RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

REFERENCES 

1. Herbel, S., L. Laing, and C. McGovern. Highway Safety Improvement Program (HSIP)

Manual, Report No. FHWA-SA-09-029, Federal Highway Administration, Washington,

D.C., January 2010.

2. Fixing America's Surface Transportation Act, Highway Safety Improvement Program [23

U.S.C. 148(b)].

3. American Association of State Highway and Transportation Officials (AASHTO).

Highway Safety Manual, First Edition, Washington, DC, 2010.

4. Srinivasan, R., F. Gross, B. Lan, and G. Bahar. Reliability of Safety Management Methods:

Network Screening, Report No. FHWA-SA-16-037, Federal Highway Administration,

Washington, D.C., October 2016.

5. Srinivasan, R., G. Bahar, and F. Gross. Reliability of Safety Management Methods: Diagnosis,

Report No. FHWA-SA-16-038, Federal Highway Administration, Washington, D.C.,

October 2016.

6. Bahar, G., R. Srinivasan, and F. Gross. Reliability of Safety Management Methods:

Countermeasure Selection, Report No. FHWA-SA-16-039, Federal Highway

Administration, Washington, D.C., August 2016.

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

Report No. FHWA-SA-13-019, Federal Highway Administration, Washington, D.C., July

2013.

8. FHWA Proven Countermeasures. http://safety.fhwa.dot.gov/provencountermeasures/

9. Council, F., Zaloshnja, E., Miller, T., and Persaud, B. Crash Cost Estimates by Maximum

Police-Reported Injury Severity within Selected Crash Geometries. Publication FHWA-HRT05- 051, Federal Highway Administration, McLean, VA, 2005.

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

APPENDIX: CRASH-BASED AND SYSTEMIC PROJECT DETAILS 

Table 11 through Table 14 present crashes per site-year for improvements associated with the 

crash-based and systemic approaches. The tables present crashes by severity where available 

and for separate periods before and after treatment. When possible, the benefits included in 

this guide reflect the change in crashes by severity, accounting for situations where crashes may 

increase for certain severities (e.g., PDO crashes) and decrease for other severities. For cases 

when crashes by severity are unavailable, the research team used applicable CMFs to estimate 

the change in crashes for all severities. For treatments with data from multiple States or studies, 

the research team weighted the average crashes using the proportion of mile-years or siteyears contributed by each State or study. 

Table 11. Crash-based crashes per site-year before treatment. 

Treatment State(s) CMF Total K A B C PDO 

Add Left Turns SC 0.59 5.02 0.03 0.28 0.49 1.21 3.01 

High Friction Surface Treatment RI 0.85 5.37 0.09 0.11 0.14 1.46 3.57 

Reconfigure Intersection SC 0.66 4.22 0.12 0.15 0.50 0.84 2.61 

Reduce Intersection Skew and 

Add Left Turn Lanes 

SC 0.48 3.76 0.13 0.17 0.29 1.04 2.14 

Road Diet Without Resurfacing IA, CA, 

WA 

0.71 26.20 - - - - -

Road Diet With Reconstruction

and Resurfacing 

IA, CA, 

WA 

0.71 26.20 - - - - -

Roundabout SC 0.28 4.61 0.07 0.13 0.74 1.15 2.52 

Table 12. Crash-based crashes per site-year after treatment. 

Treatment State(s) CMF Total K A B C PDO 

Add Left Turns SC 0.59 2.95 0.00 0.06 0.10 0.83 1.97 

High Friction Surface Treatment RI 0.85 4.57 0.00 0.00 0.14 0.43 4.00 

Reconfigure Intersection SC 0.66 2.78 0.00 0.06 0.26 0.81 1.65 

Reduce Intersection Skew and 

Add Left Turn Lanes 

SC 0.48 1.80 0.03 0.06 0.17 0.34 1.19 

Road Diet Without Resurfacing IA, CA, 

WA 

0.71 18.60* - - - - -

Road Diet With Reconstruction

and Resurfacing 

IA, CA, 

WA 

0.71 18.60* - - - - -

Roundabout SC 0.28 1.27 0.00 0.00 0.19 0.29 0.79 

*After-period crash data not given and estimated using the CMF from the report.

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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Table 13. Systemic crashes per site-year before treatment. 

Treatment State(s) CMF Total K A B C PDO 

Cable Median Barrier MI 2.14 (0.95) 1.97 0.03 0.12 0.22 0.34 1.26 

Centerline and Shoulder 

Rumble Strips 

KY, MO, 

PA 

0.80 0.91 - - - - -

Ramp Curve Signage RI 0.74 15.21 0.08 0.50 1.12 3.13 10.38 

Curve Warning Signs 

(Chevrons) 

WA, CT 0.94 6.19 - - - - -

Low Cost Intersection 

Improvements –Signal 

SC 0.96 12.49 - - - - -

Low Cost Intersection 

Improvements –Stop 

SC 0.92 3.49 - - - - -

Table 14. Systemic crashes per site-year after treatment. 

Treatment State(s) CMF Total K A B C PDO 

Cable Median Barrier MI 2.14 (0.95) 4.38 0.01 0.06 0.18 0.44 3.69 

Centerline and Shoulder 

Rumble Strips 

KY, MO, 

PA 

0.80 0.73* - - - - -

Ramp Curve Signage RI 0.74 11.18 0.00 0.27 1.18 2.03 7.70 

Curve Warning Signs 

(Chevrons) 

WA, CT 0.94 5.79 - - - - -

Low Cost Intersection 

Improvements –Signal 

SC 0.96 11.93 

* 

- - - - -

Low Cost Intersection 

Improvements –Stop 

SC 0.92 3.20* - - - - -

* After-period crash data not given and estimated using the CMF from the report.

Table 15 and Table 16 present the costs and benefits associated with crash-based and systemic 

improvements. Maintenance for all countermeasures over the service life was considered 

negligible with the exception of cable median barrier. Benefits reflect the economic impact of 

the difference in crashes (by severity, when applicable) before and after treatment. When 

crashes by severity were unavailable, the benefits reflect the difference in total crashes. 

40 
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RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Table 15. Crash-based project benefits. 

Treatment Average 

Construction 

Cost 

(per mile/site) 

Average 

Maintenance 

Cost 

(per mile/site) 

Project 

Coverage 

(miles/sites) 

Service Life 

(years) 

Net Benefits 

per Site 

Net Benefits 

for Program 

Benefit 

Cost 

Ratio 

Add Left Turns $706,000 - 14 20 $4,456,144 $62,386,011 6.3 

High Friction Surface Treatment $100,000 - 100 10 $4,982,638 $498,263,771 49.8 

Reconfigure Intersection $822,000 - 12 20 $11,191,127 $134,293,525 13.6 

Reduce Intersection Skew and 

Add Left Turn Lanes $1,106,000 - 9 20 $9,325,737 $83,931,637 8.4 

Road Diet Without Resurfacing $100,000 - 100 20 $6,318,883 $631,888,312 63.2 

Road Diet With Reconstruction 

and Resurfacing 

$1,000,000 - 10 20 $6,318,883 $63,188,831 6.3 

Roundabout $739,000 - 13 20 $8,590,982 $111,682,769 11.6 

Table 16. Systemic project benefits. 

Treatment Average 

Construction 

Cost 

(per mile/site) 

Average 

Maintenance 

Cost 

(per mile/site) 

Project 

Coverage 

(miles/sites) 

Service 

Life 

(years) 

Net 

Benefits 

per Site 

Net Benefits 

for Program 

Benefit 

Cost 

Ratio 

Cable Median Barrier $156,000 $40,000* 51 13 $1,137,374 $58,006,096 5.8 

Centerline and Shoulder Rumble Strips $5,000 - 2,000 7 $63,386 $126,771,305 12.7 

Ramp Curve Signage $10,000 - 1,000 5 $2,928,926 $2,928,925,502 292.9 

Curve Warning Signs (Chevrons) $1,600 - 6,250 5 $102,402 $640,014,079 64.0 

Low Cost Intersection Improvements –Signal $7,000 - 1,428 7 $195,747 $279,526,340 28.0 

Low Cost Intersection Improvements –Stop $6,000 - 1,666 7 $100,884 $168,073,055 16.8 

*Assumes $848.58 repair cost per crash, 4.38 crashes per mile per year, and a 13-year service life at a discount rate of 3 percent.

41 
 

 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Table 17 presents the crash severity distribution and associated average crash costs used in the 

benefit-cost analysis. When information was available for crashes by severity, the benefits 

reflect the crash costs by severity. When information was not available for crashes by severity, 

the benefits reflect the total crash cost ($55,900). 

Table 17. Typical crash cost matrix. 

Injury Percent of Total Cost per Crash 

K-Killed 0.38% $5,715,100 

A-Incapacitating 1.69% $302,400 

B-Non-Incapacitating 13.50% $110,400 

C-Possible Injury 10.89% $62,200 

PDO-No Apparent Injury 73.54% $10,000 

Total 100% $55,900 

Figure 17 through Figure 23 present the equations used to estimate the project benefits and 

compare them to estimated project costs. Each equation is accompanied by two examples, one 

for a road diet with resurfacing (crash-based) and one for cable median barrier (systemic). The 

examples show the differences in calculations for projects with and without annual maintenance 

costs and for projects with and without information by crash severity. 

Figure 17 presents the equation to estimate the average project cost per site. 

Figure 17. Equation. Average project cost per site. 

Where: 

PVCsite = present value of project costs per site. 

PVCconstruction = present value construction cost per site. 

AVCmaintenance = average annual maintenance cost per site. 

y = service life. 

r = discount rate (assumed as 3 percent for this guide). 

Example: The present value construction cost of the road diet (with resurfacing) is $1,000,000 

per mile with no annual maintenance costs. The following shows the calculation of the present 

value cost for the road diet. 

The present value construction cost of the cable median barrier is $156,000 per mile with an 

annual maintenance cost of $3,720, assuming a discount rate of three percent (r = 0.03) and 

service life of 13 years (y = 13). The following shows the calculation of the present value cost 

for the cable median barrier. Note this is rounded to $196,000 for the purpose of this report. 

42 
 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Figure 18 presents the equation to estimate project coverage, which is the number of projects 

an agency could implement given a fixed budget. The research team assumed a $10,000,000 

budget for each countermeasure. The team did not scale projects up to the exact limitations of 

the budget; rather, only whole projects were considered within the budget. The research team 

calculated the number of sites within the budget using the formula in Figure 18, rounded down 

to the nearest whole number of sites. 

Figure 18. Equation. Project coverage. 

Where: 

Nsites = number of sites within budget (i.e., project coverage). 

Example: The following shows the calculation of the project coverage for the road diet, 

assuming a present value cost of $1,000,000 per mile as previously shown. 

The following shows the calculation of the project coverage for the cable median barrier, 

assuming a present value cost of $196,000 per mile as previously shown. Note the value is 

rounded down to the nearest whole project (51 miles) for the purpose of this report. 

Figure 19 presents the equation to estimate average cost per crash using the crash severity 

distribution and associated crash costs presented in Table 17. 

Figure 19. Equation. Average cost per crash. 

Where: 

CC = average total cost per crash. 

Kcost = average cost per fatal crash. 

Acost = average cost per incapacitating crash.
 

Bcost = average cost per non-incapacitating crash.
 

Ccost = average cost per possible injury crash.
 

PDOcost = average cost per no apparent injury crash.
 

Example: The following shows the calculation of the average cost per crash using the crash 

severity distribution and associated crash costs presented in Table 17. Note the value is 

rounded to $55,900 for the purpose of this report. 

43 
 

 

 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Figure 20 presents the equation to estimate the net benefit for a single site based on crashes 

reduced and crash costs by severity. For this analysis, the research team assumed a discount 

rate of three percent. 

Figure 20. Equation. Net benefit per site for crashes by severity. 

Where: 

NBsite = net benefits per site. 

Kreduced = average fatal crashes reduced per site-year. 

Areduced = average incapacitating crashes reduced per site-year. 

Breduced = average non-incapacitating crashes reduced per site-year. 

Creduced = average possible injury crashes reduced per site-year. 

PDOreduced = average no apparent injury crashes reduced per site-year. 

Example: The following shows the calculation of the net benefit per site for the cable median 

barrier, assuming a discount rate of three percent (r = 0.03) and service life of 13 years (y = 

13). Note the benefit is based on the change in crashes by severity from Table 13 and Table 14 

and crash costs by severity from Table 17. For example, the average fatal crashes reduced per 

site-year (Kreduced) is 0.03 – 0.01 = 0.02 from Table 13 and Table 14. 

Figure 21 presents the equation to estimate the net benefit for a single site based on total 

crashes reduced and average total crash costs. 

Figure 21. Equation. Net benefit per site for total crashes. 

Where: 

T = total average crashes reduced. 

Example: The following shows the calculation of the net benefit for the road diet, assuming a 

discount rate of three percent (r = 0.03) and service life of 20 years (y = 20). Note the change 

in crashes by severity was not available, so the benefit is based on the change in total crashes 

from Table 11 and Table 12 and total crash cost from Table 17. 

44 
 

 

RELIABILITY OF SAFETY MANAGEMENT METHODS: SYSTEMIC SAFETY PROGRAMS
 

Figure 22 presents the equation to estimate the total net benefits assuming full implementation 

given a fixed budget. 

Figure 22. Equation. Net benefit for whole program. 

Where: 

NBprogram = total net benefits for program (i.e., all projects within $10,000,000 budget). 

Example: The following shows the calculation of the net benefit for a $10,000,000 budget 

spent entirely on road diets (with resurfacing), assuming a present value cost of $1,000,000 per 

mile and coverage of 10 miles. Note the result is slightly different than the program benefit 

presented in Table 4 due to rounding in Table 11 and Table 12. 

The following shows the calculation of the net benefit for a $10,000,000 budget spent entirely 

on cable median barrier, assuming a present value cost of $196,000 per mile and coverage of 51 

miles. Note the result is slightly different than the net safety benefit presented in Table 6 due to 

rounding in Table 13 and Table 14. 

Figure 23 presents the equation to estimate the benefit-cost ratio. 

Figure 23. Equation. Net benefits per site. 

Where: 

BCR = benefit-cost ratio. 

Example: The following shows the calculation of the benefit-cost ratio for road diets (with 

resurfacing), assuming a present value cost of $1,000,000 per mile and present value benefit of 

$6,320,546. 

The following shows the calculation of the benefit-cost ratio for cable median barrier, assuming 

a present value cost of $196,000 per mile and present value benefit of $1,130,942. 

45 
For More Information: 

Stuart Thompson 

Stuart.Thompson@dot.gov 

202-366-8090 

Federal Highway Administration 

Office of Safety 

1200 New Jersey Avenue SE 

Washington, DC 20590 

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

Publication # FHWA-SA-16-041