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Technical Report Documentation Page

1. Report No.

FHWA-SA-15-089

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

4. Title and Subtitle

Applying Safety Data and Analysis to Performance-Based 

Transportation Planning

5. Report Date

November 2015

6. Performing Organization Code

7. Author(s)

Nicole Waldheim, Elizabeth Wemple, P.E., Joseph Fish

8. Performing Organization 

Report No.

9. Performing Organization Name And Address

Cambridge Systematics, Inc.

4800 Hampden Lane, Suite 800

Bethesda, MD 20814

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

DTFH61-10-D-00020-T-14-020

12. Sponsoring Agency Name and Address

U.S. Department of Transportation

Federal Highway Administration

Office of Safety

1200 New Jersey Avenue, SE

Washington, DC 20590

13. Type of Report and Period 

Covered

Technical Report, September 2014

through October 2015

14. Sponsoring Agency Code

FHWA

15. Supplementary Notes

FHWA Project Manager (COTM): Chimai Ngo

Technical Panel: Dave Harris, Esther Strawder, and Jim Thorne

Additional FHWA Reviewers: Rob Ritter, James Garland, Ray Krammes, Lorrie Lau, Tameka Macon, 

Michelle Noch, Kevin Burgess, Rob Ayers, Keith Harrison, Gene Amparano, Bob Pollack, Danielle Betkey, 

Marc Starnes, and Stuart Thompson.

The FHWA Division Offices also provided inputs at the beginning of the project.

16. Abstract

This guidebook provides State departments of transportation (DOT) and metropolitan planning organization 

(MPO) planners with a framework for navigating the fundamentals and advanced methods of safety data 

collection and analysis. It also demonstrates how the results of that analysis can be applied to the performancebased transportation planning process to develop safety goals, objectives, performance measures, and targets; 

identify and prioritize projects; and evaluate progress towards safety priorities.

17. Key Words 

Transportation safety planning, crash data, data 

collection, data analysis, performance-based 

planning

18. Distribution Statement

No restrictions

19. Security Classif. 

(of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

100

22. Price

N/A

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

Applying Safety Data and Analysis to Performance-Based Transportation Planning

i 

Table of Contents

1.0 Introduction ....................................................................................................... 1

2.0 Audience, Purpose, and Guidebook Structure ..................................................... 3

2.1 Who Should Use this Guidebook? ..................................................................... 3

2.2 Why the Guidebook is a Useful Tool? ................................................................ 3

2.3 Guidebook Components .................................................................................. 4

2.3.1 Performance-Based Planning Process ...................................................... 4

2.3.2 Getting Started with Transportation Safety Planning—Data Collection ......... 4

2.3.3 Safety Analysis Questions and Tools ....................................................... 4

2.3.4 Applying Safety Data and Analysis to Inform Decisionmaking .................... 5

3.0 Performance-Based Planning Processes ............................................................. 7

3.1 The Transportation Planning Process................................................................. 7

3.1.1 Data Collection and Analysis .................................................................. 9

3.1.2 Goals and Objectives ............................................................................ 9

3.1.3 Performance Measures and Targets ........................................................ 9

3.1.4 Project Prioritization and Programming ................................................... 9

3.1.5 Evaluation ........................................................................................... 9

3.2 The Strategic Highway Safety Planning Process................................................10

3.2.1 The SHSP Data-Driven Planning Process................................................10

3.2.2 SHSPs and Transportation Plans...........................................................11

3.3 Integrating Safety during the Transportation Planning Process...........................12

4.0 Getting Started with Transportation Safety Planning—Data Collection ............. 15

4.1 Institutional Considerations ...........................................................................15

4.1.1 Collaboration and Coordination ............................................................15

4.1.2 Organizational Capacity ......................................................................16

4.1.3 Funding ............................................................................................16

4.1.4 Liability.............................................................................................17

4.2 Common Types of Safety Data and Application to Planning Processes .................17

4.2.1 Crash Data ........................................................................................18

4.2.2 Roadway Characteristics .....................................................................21

4.2.3 Traffic Volume ...................................................................................22
Applying Safety Data and Analysis to Performance-Based Transportation Planning

ii

4.2.4 Integrating Crash, Roadway, and Volume Data ......................................24

4.2.5 Other Safety Datasets.........................................................................24

4.3 Data Quality ................................................................................................25

4.3.1 Timeliness.........................................................................................25

4.3.2 Accuracy ...........................................................................................26

4.3.3 Completeness ....................................................................................26

4.3.4 Consistency/Uniformity .......................................................................26

4.3.5 Integration ........................................................................................26

4.3.6 Accessibility.......................................................................................27

4.4 Obtaining Safety Data...................................................................................27

4.4.1 Raw Data ..........................................................................................27

4.4.2 Generated Reports .............................................................................28

4.4.3 Web Interfaces and Tools ....................................................................29

4.4.4 Custom Inquiries................................................................................30

5.0 Using Safety Analyses for Planning .................................................................. 31

5.1 Benchmarking..............................................................................................32

5.1.1 Methods for Benchmarking ..................................................................32

5.2 Identify Crash Trends and Contributing Factors................................................34

5.2.1 Methods for Identifying Crash Trends and Contributing Factors ................34

5.3 Identify and Evaluate Focus Crash Types.........................................................37

5.3.1 Methods for Identifying and Evaluating Focus Crash Types ......................38

5.4 Network Screening—Identify Sites for Safety Improvements..............................40

5.4.1 Methods for Network Screening............................................................41

5.5 Systemic Analysis—Identify Safety Risk Factors ...............................................43

5.5.1 FHWA Systemic Safety Project Selection Tool ........................................44

5.6 Corridor and Intersection Planning Safety Analysis ...........................................45

5.6.1 Crash Diagrams .................................................................................46

5.6.2 Crash Modification Factors...................................................................47

5.6.3 AASHTO HSM Predictive Method...........................................................47

6.0 Applying Safety Data and Analysis to Inform Decisionmaking ......................... 49

6.1 Institutional Considerations ...........................................................................49

6.1.1 Legislation.........................................................................................49

6.1.2 Collaboration and Coordination ............................................................49
Applying Safety Data and Analysis to Performance-Based Transportation Planning

iii

6.1.3 Organizational Capacity ......................................................................51

6.1.4 Funding ............................................................................................51

6.2 Using Safety Data and Analysis to Develop Goals and Objectives .......................52

6.2.1 Qualitative Safety Goals......................................................................52

6.2.2 Data-Driven Safety Goals ....................................................................53

6.2.3 Data-Driven Safety Objectives .............................................................57

6.3 Using Safety Data and Analysis to Develop Performance Measures and 

Targets .......................................................................................................62

6.3.1 Performance Measures........................................................................62

6.3.2 Performance Targets ..........................................................................64

6.3.3 Evaluating System Performance ...........................................................66

6.4 Using Safety Data and Analysis for Project Prioritization and Programming..........68

6.4.1 Transportation Projects Integrating Safety ............................................69

6.4.2 Safety Projects ..................................................................................71

6.4.3 Evaluating Projects.............................................................................74

7.0 Conclusions ...................................................................................................... 77

Appendix A. Tools and Resources ...................................................................... 79

Appendix B. Safety Analysis Objectives and Methods ........................................ 83

Appendix C. Risk Ratio ....................................................................................... 85

Appendix D. Regression to the Mean .................................................................. 87

Applying Safety Data and Analysis to Performance-Based Transportation Planning

v 

List of Tables

Table 3.1 Safety Integration in the Transportation Planning Process .............................13

Table 4.1 Raw Crash Data Sample............................................................................28

Table 5.1 Safety Analysis Categories and Questions....................................................31

Table 6.1 Network Screening Safety Goal Setting .......................................................57

Table 6.2 Sample Safety Goal and Nationally Required Performance Measures ...............62

Table 6.3 Relationship between Performance Measures and Goals and Objectives..........64

Table 6.4 Relationship between Goals, Performance Measures, and Targets...................64

Table 6.5 Data-Driven Performance Targets Related to Safety Goal ..............................65

Table 6.6 Data-Driven Performance Targets Related to Safety Goal ..............................66

Table A.1 Safety Data, Analysis, and Application Resources and Tools...........................79

Table B.1 Safety Analysis Categories, Questions, Tools, and Data Needs .......................83

Table C.1 Risk Ratio Data for Crashes in Rural Areas...................................................85

Table C.2 Risk Ratio Data for DUI Crashes................................................................. 86

Table C.3 Risk Ratio Data for Rural DUI Crashes.........................................................86

Applying Safety Data and Analysis to Performance-Based Transportation Planning

vii

List of Figures

Figure 2.1 Flowchart. Guidebook Outline ...................................................................... 3

Figure 3.1 Flowchart. Federal Highway Administration (FHWA) Performance-Based 

Planning and Programming Framework ........................................................... 8

Figure 3.2 Flowchart. Planning Process for Montana Safety Plans...................................11

Figure 4.1 Relationship Diagram. Types of Safety Data ................................................18

Figure 4.2 Graph. Linear Referencing Conceptual Diagram............................................22

Figure 4.3 Chart. Crash Distribution by Average Daily Traffic Example ...........................23

Figure 4.4 Screenshot. Ohio DOT’s Geographic Crash Analysis Tool (GCAT) Query 

Form and Map .........................................................................................30

Figure 5.1 Chart. Fatalities and Serious Injuries per Year .............................................32

Figure 5.2 Chart. Comparison of Fatalities by Region ...................................................33

Figure 5.3 Chart. Distribution of Total and Severe Injury Crashes by Time of Day...........35

Figure 5.4 Chart. Distribution of Total and Severe Injury Crashes by Age .......................36

Figure 5.5 Chart. Distribution of Total Crashes by Gender.............................................36

Figure 5.6 Chart. Distribution of Severe Injury Crashes by Gender ................................37

Figure 5.7 Map. Distribution of Roadway Departure Crashes by Transportation 

Analysis Zone ..........................................................................................38

Figure 5.8 Scatterplot. Crash Types by Frequency and Severity Ranking ........................39

Figure 5.9 Chart. Overrepresentation of Severe Crashes among Select Crash Types ........40

Figure 5.10 Heat Map. Density of Crashes per Unit Area.................................................43

Figure 5.11 Flowchart. Example Crash Tree Analysis......................................................45

Figure 5.12 Graphic. Example Simplified Collision Diagram.............................................46

Figure 6.1 Chart. Trends Safety Goal Setting ..............................................................54

Figure 6.2 Chart. Contributing Factors Safety Goal Setting ...........................................55

Figure 6.3 Chart. Functional Class Goal Setting ...........................................................56

Figure 6.4 Screenshot. Defining Safety Goals with Measurable and Specific Objectives.....58

Figure 6.5 Screenshot. Adopting Objectives/Strategies from Other Planning 

Documents..............................................................................................59

Figure 6.6 Chart. Using the Results of Analysis to Inform Objectives..............................61

Figure 6.7 Chart. Tracking National Performance Measures Fatalities, 2008-2012 ............63

Figure 6.8 Chart. Tracking National Performance Measures Major Injuries, 2008-2012.....63

Figure 6.9 Chart. Data-Driven Performance Targets Related to Safety Goal.....................66

Figure 6.10 Graphic. Example Evaluation Report Card....................................................67
Applying Safety Data and Analysis to Performance-Based Transportation Planning

viii

Figure 6.11 Flowchart. Relationship between Data-Driven Planning Tasks and 

Programs/Projects....................................................................................68

Figure 6.12 Screenshot. Incorporating Safety into Project Prioritization............................69

Figure 6.13 Screenshot. Incorporating Safety into Project Prioritization............................70

Figure 6.14 Flowchart. Relationship between the SHSP and HSIP ....................................72

Figure 6.15 Graphic. Data-Driven Safety Actions ...........................................................73

Figure 6.16 Chart. Before and After Studies..................................................................75

Figure C.1 Equation. Risk Ratio .................................................................................85

Figure C.2 Equation. Severe Crash Risk Ratio for Rural Areas........................................85

Figure C.3 Equation. Severe Crash Risk Ratio for DUI Crashes.......................................86

Figure C.4 Equation. Severe Crash Risk Ratio for DUI Crashes in Rural Areas ..................86

Figure D.1 Chart. Example of Regression to the Mean ..................................................87
1.0 INTRODUCTION

1

1.0 Introduction

This guidebook provides State departments of transportation (DOT) and metropolitan planning 

organization (MPO) planners with a framework for navigating the fundamentals and advanced 

methods of safety data collection and analysis. It also demonstrates how the results of that 

analysis can be applied to the performance-based transportation planning process to develop 

safety goals, objectives, performance measures, and targets; identify and prioritize projects; 

and evaluate progress towards safety priorities. 

Performance-based planning is not a new concept—for years transportation agencies have 

been tracking performance metrics, using the results to identify program and project 

investments to positively impact the system. Moving Ahead for Progress in the 21st Century Act 

(MAP-21), continues the focus on performance measurement, requiring State DOTs and MPOs 

to demonstrate progress in meeting seven national goals. One of the national goal areas is 

safety. Planners will track annual performance for number of fatalities and serious injuries and 

fatality and serious injury rate. The process for setting and tracking safety performance 

measures includes the following: 

• Reviewing past, current, and future (if possible) safety trends—where are we now?

• Developing safety goals, objectives, measures, and targets—where do we want to go?

• Identifying transportation safety programs and projects to achieve results—how do we get 

there?

• Monitoring and evaluation—how are we doing?

This approach to safety fits within the context of the traditional transportation planning 

process, which agencies already use to set goals and objectives, complete data analyses, 

identify programs and projects, and evaluate progress towards safety priorities. Incorporating 

safety performance into the existing transportation planning process does not need to be 

complicated, but will require planners to understand and have access to safety data and 

analysis tools.

2.0 AUDIENCE, PURPOSE, AND GUIDEBOOK STRUCTURE

3

2.0 Audience, Purpose, and Guidebook Structure

2.1 Who Should Use this Guidebook?

Integrating safety in the transportation planning process requires many different 

considerations, one of which is using qualitative and quantitative analysis to understand the 

safety issues and trends, identify programs and projects, and evaluate the results. This 

guidebook will help transportation planners at DOTs and MPOs understand what types of safety 

data to use and where they can be accessed; analysis techniques to understand the key 

concerns; and opportunities to use the data and analysis to inform planning decisions. 

Practitioner examples are included throughout to demonstrate realistic approaches to 

addressing each of these topics.

2.2 Why the Guidebook is a Useful Tool?

Currently available literature and resources related to safety data, analysis, or planning 

typically focus on certain components of the process, such as types of safety data or how to 

use certain analysis tools. This guidebook provides users with a step-by-step approach for 

putting data and analysis together to inform safety decisions in the transportation planning 

process. Figure 2.1 demonstrates the type of questions this guidebook will help answer.

Figure 2.1 Flowchart. Guidebook Outline

Data Collection

• What types of data 

are available to 

address safety?

• What are data 

limitations and 

opportunities?

• Where can I go to 

obtain data?

Data Analysis

• What safety analysis 

tools and methods 

are available for the 

transportation 

planning process?

• How do they work and 

what do they tell me?

• What are examples of 

tools and methods in 

practice?

Application to 

Transportation 

Planning Process

• How does my agency 

use the results of the 

data analysis to 

develop safety goals, 

objectives, 

performance 

measures, and 

programs/projects?

Source: Cambridge Systematics, Inc.
2.0 AUDIENCE, PURPOSE, AND GUIDEBOOK STRUCTURE

4

2.3 Guidebook Components 

The guidebook contains background information, strategies, and examples to help 

transportation planners obtain data, understand safety analysis tools/methods, and utilize the 

results to inform a data-driven transportation planning process. The following describes the 

contents of the guidebook.

2.3.1 Performance-Based Planning Process

Chapter 3 presents an overview of the performance-based transportation planning process and 

the opportunities to consider safety when setting goals and objectives, developing performance 

measures and targets, and identifying programs and projects. Topics addressed are:

• The transportation planning process;

• Considering safety in the transportation planning process; and

• Strategic Highway Safety Plans (SHSP) and how they serve as a resource.

2.3.2 Getting Started with Transportation Safety Planning—Data Collection

Chapter 4 discusses the opportunities to identify and use available data to consider safety 

during the transportation planning process. Topics addressed are:

• Institutional considerations necessary to initiate and sustain data collection efforts.

• Types of safety data and how they can inform transportation planning.

• Considerations, such as data quality, completeness, gaps, and availability. This also will 

include a discussion on overcoming potential data limitations to provide planners with ideas 

to initiate safety planning with limited data.

• Methods in which agencies can obtain data to initiate data analysis.

2.3.3 Safety Analysis Questions and Tools

Chapter 5 discusses the array of tools, methods, or approaches that planners can utilize to 

analyze safety data for application to the transportation planning process. Topics addressed 

are:

• Institutional considerations necessary to initiate and sustain safety analysis. 

• Planning- and project-level analysis tools and methods and their functionality. With so 

many available tools and methods, this section focuses on those that are practical, 

affordable, and easy to use for planners.
2.0 AUDIENCE, PURPOSE, AND GUIDEBOOK STRUCTURE

5

• Analysis approaches and their relationships to the transportation planning process, 

including several examples from MPOs and DOTs.

2.3.4 Applying Safety Data and Analysis to Inform Decisionmaking

Chapter 6 discusses how the outputs of the data analysis can be used to inform the inclusion of 

safety in the transportation planning process, namely, safety goals, objectives, performance 

measures, and programs and projects. Topics addressed are:

• Institutional considerations necessary to initiate and sustain transportation safety planning; 

and

• How to use data and analysis to:

– Develop safety goals and objectives; 

– Develop safety performance measures; and

– Identify and prioritize transportation safety programs and projects.

3.0 PERFORMANCE-BASED PLANNING PROCESSES

7 

3.0 Performance-Based Planning Processes

A key outcome of this guidebook is to describe how data (crash, roadway characteristics, 

vehicle miles traveled (VMT), etc.) and the outputs of analysis can be used by planners during 

the transportation planning processes to develop safety goals, objectives, performance 

measures, and targets; identify and prioritize projects; and evaluate progress towards safety 

priorities. States often possess robust safety data, and planners have the skills and tools to 

analyze an array of crash information to inform safety-specific plans or safety components of 

transportation plans. However, all too often, data and analysis are not used to inform safety 

considerations in all transportation decisionmaking and project prioritization.

The basics of the transportation planning process and opportunities to incorporate the outputs 

of safety analysis into that process are presented in this section. The goal is to help planners 

develop a performance-based framework for lowering fatalities and serious injuries. This 

section also provides an overview of SHSPs, describing how they may serve as a resource.

3.1 The Transportation Planning Process

Transportation plans come in many different varieties. 

Long-range transportation plans (LRTP) define an 

overarching vision for the future transportation system; 

establish goals and objectives that clarify and 

operationalize that vision; and guide the selection of 

transportation policies, programs, and projects consistent 

with the goals. Modal plans (i.e., bicycle/pedestrian, 

freight) function in the same way as long-range plans, but 

typically are focused on one transportation topic and 

identify short-, mid-, and long-term policies, programs, 

and projects. Corridor plans address a range of 

transportation topics or modal priorities along a certain 

portion of the transportation network and also identify 

short-, mid-, and long-term policies, programs, and 

projects. Regardless of the type of plan, the ultimate goal is the same—use a 

performance-based transportation planning process to identify programmatic, policy, 

and project priorities to address current and future needs. Figure 3.1 outlines a goaldriven process that can be used to construct any transportation planning document.

Why is “Data Driven” 

so Important to the 

Planning Process?

Transportation programs and 

projects need to demonstrate 

how they address the most 

pressing needs. Data allows 

planners to develop goals, 

objectives, performance 

measures, and targets, and 

to quantify the impacts of 

policies, programs, and 

projects.
3.0 PERFORMANCE-BASED PLANNING PROCESSES

8

Figure 3.1 Flowchart. Federal Highway Administration (FHWA) 

Performance-Based Planning and Programming Framework

Source: FHWA Performance-Based Planning and Programming Guidebook, September 2013. 

Agencies may use different terminology or approach performance-based planning in slightly 

different ways than what is illustrated in figure 3.1, but the core planning tasks often include:

• Data collection and analysis to identify needs, priorities, policies, programs, and 

projects;

• Goals and objectives to frame those needs and priorities and establish evaluation 

criteria;

• Performance measures and targets to evaluate alternatives and track progress towards 

the goals and objectives;

• Project prioritization and programming to identify the mix of projects that meet the 

goals and objectives of the plan and contribute progress towards the performance 

target; and
3.0 PERFORMANCE-BASED PLANNING PROCESSES

9 

• Evaluation to understand the extent to which safety performance for the transportation 

system, modes, or behaviors is changing and where future investments can be made.

3.1.1 Data Collection and Analysis

To initiate a planning process, planners obtain data to analyze current and future transportation 

issues and needs. Traditionally, issues and needs relate to capacity constraints, connectivity 

gaps, or system preservation. This analysis leads to the identification of goals and objectives, 

various transportation improvement strategies, and ultimately project priorities and investments 

to address those needs.

3.1.2 Goals and Objectives 

Planners coordinate with stakeholders and the public, and consult data to develop goals and 

objectives. Goals define a desired result, or outcome, while objectives support the goal by 

providing additional details, or strategies, on how the goal will be achieved. Goals and 

objectives provide the framework necessary for planners to identify transportation programs 

and projects.

3.1.3 Performance Measures and Targets

Performance measures are tied to goals and objectives and are used to assess the 

effectiveness of programs and projects that address transportation issues and deficiencies 

(i.e., Will this project/program improve air quality? Will it reduce the number of fatalities? Will 

it increase person throughput?). Performance targets are a numeric goal and describe the 

extent to which an agency will address its goals, taking into account resources and funding 

(i.e., conformity attainment by 2015, 5 percent reduction in fatalities by 2020, 10 percent 

increase in person throughput by 2025).

3.1.4 Project Prioritization and Programming

Project prioritization is an evaluation process to identify the transportation programs and 

projects that best support the overall goals and/or objectives of the plan and help an agency 

make progress towards its performance targets with available resources. Agencies often 

develop a scoring/ranking methodology and identify evaluation criteria in which to assess the 

value and costs of transportation projects.

3.1.5 Evaluation

Transportation systems or specific projects can be evaluated to understand the extent to which 

crashes, fatalities, and/or serious injuries are increasing or decreasing. Many agencies use 

performance measures and targets to track and then evaluate progress towards programmatic 

safety goals and objectives. Some may also assess and evaluate the reduction potential for 

certain projects. Both programmatic and project evaluation provide information on how and 

where to invest limited resources.
3.0 PERFORMANCE-BASED PLANNING PROCESSES

10

Each of these individual planning tasks builds upon one another to form a framework, or 

process, for identifying and programming transportation priorities. The next section goes on to 

discuss how safety can be included during these tasks to lower fatalities and serious injuries.

3.2 The Strategic Highway Safety Planning Process

State DOTs are required to develop Strategic Highway Safety Plans (SHSP) in a cooperative 

process with Local, State, Federal, Tribal, and other safety stakeholders. This includes regional 

and metropolitan transportation planning organizations and county transportation officials. It is 

a data-driven plan that presents a framework for reducing fatalities and serious injuries on all 

public roads in the State. Each State’s SHSP identifies safety problems, as well as key 

emphasis areas that direct safety resources for all public roads. For these plans, crash data 

and analysis must be used to inform selection of safety emphasis areas and strategies. 

Federal, State, and other funds can be used for efforts that support the priorities and 

strategies in the SHSP. For example, HSIP funds are applied to projects and initiatives that are 

consistent with the emphasis areas and strategies found in their State’s SHSP. National 

Highway Traffic Safety Administration (NHTSA) funds (e.g., Section 402 (23 CFR Part 1200) 

and 405 (23 CFR Parts 1200.21, 1200.22, 1200.23, 1200.23(5), 1200.24, 1200.25, 1200.26, 

and 1200.20(e)(3)) also are often used to fund SHSP-related projects, particularly those 

related to behavioral countermeasures. 

The SHSP is intended to be a coordinated planning effort. Legislation encourages coordination 

of the SHSP with various other planning documents (i.e., Highway Safety Plan (HSP), 

Commercial Vehicle Safety Plan (CVSP), local plans, etc.) and the LRTP must integrate directly, 

or by reference, the goals, objectives, performance measures, and targets described in other 

State transportation plans, such as the SHSP. The SHSP is an extremely useful tool, 

complimenting and enhancing safety efforts conducted during the transportation planning 

process. The relationship between the two documents is further described in Section 3.2.1.

3.2.1 The SHSP Data-Driven Planning Process

The SHSP development and update process can be a 

model for planners interested in a data-driven 

approach to identifying safety programs and projects. 

The SHSP Champion’s Guidebook, Second Edition

provides the basic structure for SHSP development, 

including data collection and analysis; SHSP content 

(performance measures, goals and objectives, 

emphasis areas); and SHSP preparation (plan 

format). State and regional agencies interested in 

identifying safety priorities; developing safety goals, 

objectives, and performance measures; and 

prioritizing safety funding can use this framework 

when developing regional safety plans, mode-specific 

Funding Safety Plans

In many instances, the DOT will 

provide funding to MPOs or local 

jurisdictions to complete safety 

plans. However, another source of 

funding can be the State Highway 

Safety Office. The Cheyenne MPO 

in Wyoming coordinated with the 

National Highway Traffic Safety 

Administration and the Wyoming 

Highway Safety Office to complete 

an update to their Safety 

Management Plan. 
3.0 PERFORMANCE-BASED PLANNING PROCESSES

11

safety plans, corridor plans, or integrating safety into other transportation planning 

documents. This SHSP-style planning approach can be seen in practice in Montana. Six 

communities developed community transportation safety plans. Figure 3.2 demonstrates the 

process used to identify emphasis areas, strategies, and performance measures through data 

and analysis.

Figure 3.2 Flowchart. Planning Process for Montana Safety Plans

CTSP Planning Process

Establish TSAC

Review Crash Data

Establish CTSP Goal

Identify Emphasis Areas

Young Driver 

Crashes

Distracted 

Crashes Seatbelt Use Intersection 

Crashes

Safety Strategies

Performance Measures

Implementation Responsibilities

CTSP

Implementation

Source: Bozeman Community Transportation Safety Plan (CTSP), July 2013.

Although the SHSP is an important tool during the transportation planning process, planners 

also need to think beyond the contents of the SHSP and consider medium- to longer-term 

safety considerations during transportation plan development. Section 3.2.2 describes the 

differences between the two planning processes.

3.2.2 SHSPs and Transportation Plans

A common question asked by transportation planners is, “Why does safety need to be 

considered in transportation plans when the topic already is strategically addressed in the 

SHSP?” This should be done because:
3.0 PERFORMANCE-BASED PLANNING PROCESSES

12

• Transportation plans typically look at longer planning horizons than the SHSP and must 

consider how future infrastructure can be planned safer. To do so, safety is addressed in 

the LRTP to meet identified safety goals, objectives, and performance measures. 

• Transportation planners must consider all modes, corridors, and the network as a whole 

during the planning process, whereas the SHSP addresses the most pressing and current 

data-driven safety issues at the statewide level. Planners need to think about the longerterm implications of the emphasis areas outlined in the SHSP, but also need to think 

beyond those and address topics such as freight, community, and transit safety, as well as 

other topics that link to safety, such as complete streets, sustainability, health, 

environment, and more.

• Transportation planning studies are necessary to focus on and pinpoint the range of safety 

issues, project locations, and countermeasures, beyond what would be expected in the 

SHSP. Specific projects, funding sources, or locations where safety needs to be addressed

would be included in state and metropolitan transportation improvement programs 

(S/TIPs). 

SHSPs assume a data-driven approach to identify goals (or emphasis areas), objectives, 

strategies, performance measures, and programs/projects. This process does compliment the 

transportation planning process to help with the identification of data-driven transportation 

safety priorities in LRTPs, modal plans, or other transportation documents. 

3.3 Integrating Safety during the Transportation Planning Process

Planners utilize the transportation planning process as 

a framework for planning, prioritizing, programming 

investments, and advancing policies. Incorporating 

safety into planning does not require an entirely new 

process—it can be easily integrated into the common 

tasks that planners already undertake, including data 

collection and analysis, goal and objective setting, 

performance measures and targets, project 

prioritization and programming, and evaluation. 

Table 3.1 depicts the common transportation planning 

tasks, the opportunities to consider safety during 

those tasks, and MPO and State DOT examples of 

safety integration.

Why is it Important to 

Consider Safety in the 

Transportation Planning 

Process?

Transportation related fatalities 

occur every day. 

Transportation planners have 

an inherent responsibility to 

identify transportation projects 

and programs to meet safety 

goals and work towards 

reducing fatalities and serious 

injuries to zero.
3.0 PERFORMANCE-BASED PLANNING PROCESSES

13

Table 3.1 Safety Integration in the Transportation Planning Process

Transportation 

Planning Process—

Key Planning Task

Safety Integration into 

Key Planning Task Examples

Data Collection and 

Analysis

• Obtain safety data, which can 

include crash data, roadway 

characteristic data, traffic volume 

data, and safety information from 

public/stakeholder input.

• Conduct safety analysis, which 

can range from basic analysis like 

identifying crash frequencies to 

more sophisticated approaches, 

such as network screening.

• In Ohio, crash and roadway data are 

obtained through the Ohio DOT. VMT 

estimates also are available for State 

and regional agencies. Ohio DOT has 

developed user-friendly tools, such 

as the Geographic Information 

System (GIS) Crash Analysis Tool 

(GCAT), which automate the 

analysis.

• In New Mexico, State and regional 

agencies can access safety data 

through the University of New Mexico 

(UNM) Division of Government 

Research (DGR) Web site to access 

published reports, or they can submit 

a request to New Mexico DOT via 

email to the Crash Records reporting 

office (crash.records@state.nm.us) 

to request specific records and/or 

generated reports.

• The Mid-Ohio Regional Planning 

Council (MORPC) analyzes pedestrian 

and bicycle high-crash locations to 

identify areas in need of physical 

safety improvements, as well as 

safety education programs.

Goal and Objective 

Setting

• Use the results of public/

stakeholder input, outputs of data 

analysis, and information in other 

plans such as the SHSP to identify 

safety goals and objectives or 

incorporate safety into 

transportation goals.

• In Missouri, the Mid-America 

Regional Council utilized the results 

of stakeholder input and data 

analysis to identify the top safety 

issues in the region (infrastructure, 

behavioral, and special users) and 

strategies to address them. This 

data-driven approach to goal and 

strategy identification can be found 

in their Destination Safe plan. 

• In California, a number of the 

regional transportation planning 

organizations (RTPO), including the 

Del Norte Local Transportation 

Commission, adopted and 

customized relevant goals and 

strategies from the California SHSP 

for use in their LRTPs.
3.0 PERFORMANCE-BASED PLANNING PROCESSES

14

Transportation 

Planning Process—

Key Planning Task

Safety Integration into 

Key Planning Task Examples

Performance Measures

and Targets

• Establish performance measures 

and targets for fatalities and 

serious injuries and fatality and 

serious injury rates.

• Establish performance measures 

and targets for other 

transportation safety goals, as 

appropriate.

• In Nevada, the Regional 

Transportation Commission (RTC) of 

Washoe County identified safety 

performance measures and targets in 

their most recent LRTP.

• In Pennsylvania, Pennsylvania DOT 

provides Highway Safety Guidance 

Reports to every district, MPO, and 

regional planning organization (RPO) 

detailing region-specific performance 

measures and targets for safety 

goals. The goals, measures, and 

targets are all derived from a datadriven approach.

Project Prioritization

and Programming

• Use results of data analysis to 

identify safety projects eligible for 

Highway Safety Improvement 

Program (HSIP) funds.

• Leverage goals and objectives and 

results of data analysis to develop 

safety evaluation criteria for all 

transportation projects, regardless 

of funding source. 

• In Arizona, the Central Arizona 

Governments (CAG) conducted an 

intersection network screening 

analysis and plans to submit an HSIP 

application to Arizona DOT to fund 

safety improvements at priority 

intersection locations.

• In New Jersey, the South Jersey 

Transportation Planning Organization 

(SJTPO) coordinates a Local Safety 

Program to identify local safety 

projects eligible for HSIP funding.

• In Virginia, the DOT is evaluating 

transportation projects against 

several criteria. In addition to 

demonstrating how a project 

mitigates congestion, improves 

accessibility, etc., it also must show 

how it expects to achieve reductions 

in fatal and serious injuries.

Evaluation • Review safety performance 

measures to identify the extent to 

which safety goals and objectives 

are being met.

• Review safety programs and 

projects to identify the extent to 

which they are reducing fatalities 

and serious injuries.

• The Champaign Urbana Urban Area 

Transportation Study has developed 

a report card to evaluate the safety 

performance measures identified in 

its LRTP.

• Washington DOT regularly evaluates 

its cable median barrier program to 

assess its effectiveness of reducing 

fatalities and serious injuries.

Source: Cambridge Systematics, Inc.
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4.0 Getting Started with Transportation Safety 

Planning—Data Collection

Data collection is one of the first steps in the transportation safety planning process. Data are 

needed to establish reasonable goals, objectives, performance measures and targets, or 

identify programs and projects. Fortunately, the data collection process is continually 

improving, as technology advances and organizational capacity improves. Data collection and 

maintenance nonetheless require an ongoing effort that needs to be carefully planned and 

implemented.

This section of the report provides an overview of safety data sources and considerations that 

transportation planners should be familiar with to get started with safety data analysis.

4.1 Institutional Considerations

Institutional arrangements and relationships among agencies can play a significant role in 

determining how easy or difficult it is for planners to access safety data. Although seemingly 

straightforward, the tasks of collecting, storing, and sharing data across agencies are far from 

trivial. Data standards, business rules, communications protocols, agency missions, legal and 

privacy concerns, and other factors come into play. It is important for DOTs and MPOs, who 

have a stake in transportation safety, to work together to improve the quality and usage of 

safety data.

Under MAP-21, States are required to have a Traffic Records Coordinating Committee (TRCC)

to qualify for Section 405(c) funding. The purpose of the TRCC is to coordinate the activities of 

safety data stakeholders across each State in an effort to improve the timeliness, accuracy, 

completeness, uniformity, accessibility, and integration of the various traffic records systems 

throughout the State. Agencies with an interest in improving traffic safety data from any level 

of government should understand their State’s TRCC structure and process. MAP-21 also 

requires that States employ a data-driven process to improve safety on all public roads. In 

particular, they must have a State safety data system to support problem identification and 

countermeasure analysis, project evaluation, and performance management.

4.1.1 Collaboration and Coordination

States and MPOs with successful transportation safety programs demonstrate collaboration and 

coordination across agencies and levels of government. For example, in Tennessee, the 

Department of Public Safety collects crash data, but works closely with the Long-Range 

Planning section to share the data with safety planning stakeholders. MPOs and RPOs interact 

with staff in the Planning division to access data and conduct safety planning activities. 

Communication and collaboration across agencies is seen as one of the keys to success for 

safety planning in Tennessee.
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This type of cooperative approach is needed to ensure that safety data is collected and utilized 

to its fullest extent. Agencies that manage safety data must be willing to share it with other 

agencies in order for them to effectively address safety problems within their respective 

jurisdictions.

Collaboration goes beyond simply making data available to other agencies. For instance, a 

number of State DOTs ensure data is easily accessible through generated reports, Web

interfaces, or other online tools; and provide educational resources to assist novice data users. 

Examples include Florida’s Signal Four Analytics and Alabama’s Critical Analysis Reporting 

Environment (CARE), which also includes training videos and documentation to assist users.

4.1.2 Organizational Capacity

An organization’s staff capacity and resources go a long way in determining its ability to collect 

and manage safety data. This is true at every level of government, but especially applies to 

MPOs and local agencies, where collection and management of safety data may be considered 

as an optional function within the organization.

It is often the case that an agency’s interest in safety planning and analysis is initiated or 

significantly enhanced through the efforts of a single staff member or a small group of staff. In 

the long term, however, it is important for agencies to dedicate staff resources to the collection 

and maintenance of safety data. This provides continuity in the event of staff turnover, and 

ensures that safety data collection and management are integrated into agency processes. 

MAP-21 safety data requirements institutionalize safety data collection and management at the 

State level, but do not address this need at the MPO and local level.

For those agencies just getting started with transportation safety planning, a full data

collection approach may not be necessary. Instead, planners can coordinate with their State 

DOTs to understand what data already is available and the opportunities to access that 

information. It also might be possible for DOT staff to create annual custom or generated crash 

reports to reduce the burden of data collection efforts.

4.1.3 Funding

At a national level, NHTSA provides 405(c) Traffic Safety Information System Improvement 

Grants for States to develop and implement effective programs that improve the timeliness, 

accuracy, completeness, uniformity, integration, and accessibility of data needed to identify 

traffic safety program priorities. 23 U.S.C. section 405(c) funds are awarded to State highway 

safety offices, which, in turn, distribute funds to partner agencies to link data systems, 

including traffic records and systems that contain medical, roadway, and economic data, 

improve the compatibility and interoperability of State data systems with national data 

systems and the data systems of other States, and enhance the ability to observe and analyze 

trends in crash occurrences.
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NHTSA is not the only source of funds 

that are eligible for safety data 

collection and management. HSIP 

funds also may be used to improve 

safety data collection, management, 

and analysis processes and systems if 

identified as an emphasis area in the 

SHSP. Although not limited to safety, 

State Planning and Research (SPR) 

funds may also be used to fund safety 

studies and to develop and implement 

HSIP requirements. Other Federal 

funds that may be used to support 

safety data collection include FMCSA 

funds (Motor Carrier Safety Assistance 

Program) and metropolitan planning 

(PL) funds. Additionally, State and 

local governments may elect to use 

non-Federal funds for safety data

collection, such as traffic counts or 

collection of inventory data.

Liability Protections

The use of reports, data, or other information 

compiled to meet Federal safety program 

requirements as evidence in Federal or State 

courts is prohibited by 23 U.S.C. § 409 

(section 409). In particular, the law reads: 

“Notwithstanding any other provision of law, 

reports, surveys, schedules, lists, or data compiled 

or collected for the purpose of identifying, 

evaluating, or planning the safety enhancement of 

potential accident sites, hazardous roadway 

conditions, or rail-way-highway crossings, 

pursuant to sections 130, 144, and 148 [152] of 

this title or for the purpose of developing any 

highway safety construction improvement project, 

which may be implemented utilizing Federal-aid 

highway funds shall not be subject to discovery or 

admitted into evidence in a Federal or State court 

proceeding or considered for other purposes in any 

action for damages arising from any occurrence at 

a location mentioned or addressed in such reports, 

surveys, schedules, lists, or data.”

Source: FHWA, Office of Safety Programs,

Legal Issues, October 15, 2014. 4.1.4 Liability

States differ with respect to their 

handling of liability concerns related to safety data. In general, State DOTs are protected 

against lawsuits arising from their collection, analysis, and reporting of safety data under 

23 U.S.C. Section 409. 

4.2 Common Types of Safety Data and Application to Planning 

Processes

There are several datasets that are part of the overall traffic records coordination process 

(figure 4.1), including crash data, roadway characteristics, traffic volume, driver and passenger 

information, vehicles, injury control (e.g., EMS response time), citation and adjudication (e.g., 

driver arrest record). For transportation planning purposes, the most commonly used are 

crash, roadway, and traffic volume (exposure) data. These datasets are shown in figure 4.1. 
4.0 GETTING STARTED WITH TRANSPORTATION SAFETY PLANNING—DATA COLLECTION

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Figure 4.1 Relationship Diagram. Types of Safety Data

Crash

Roadway

Traffic 

Volume

Driver and 

Passenger

Vehicle

Injury 

Control

Citation and 

Adjudication

Datasets addressed in detail in this guidebook. 

Other safety datasets that are not addressed in detail in this guidebook. 

Source: Cambridge Systematics, modified from Federal Highway Administration’s Crash Data 

Improvement Guide, April 2010.

4.2.1 Crash Data

Crash data is the foundation of transportation safety planning. For each crash that meets a 

minimum injury or property damage reporting threshold, a large set of information is collected 

and entered into a State database. (Reporting thresholds are set individually by States. In 

most States, crashes with one or more injuries or with a property damage threshold of around 

$1,000 are reported. The property damage threshold in particular can vary by State.)

The specific crash data elements that are collected vary by State, but generally are based on the 

guidelines outlined in the Model Minimum Uniform Crash Criteria (MMUCC). Officers who respond 

to the scene of a crash collect information on the crash itself (e.g., location, number of vehicles, 

type of crash); the vehicles or ‘units’ involved (e.g., model and year, estimated speed); and the 

people involved (e.g., driver, occupant, pedestrian, age, sex, impairment status).
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One of the most important data fields in the crash report is the injury level of each person 

involved in the crash. The KABCO system is a standardized way of coding injury severity using 

the following injury codes: 

• K—fatality;

• A—serious injury;

• B—nonincapacitating injury;

• C—possible injury; and

• O—no injury.

The standardization of injury coding is important for conducting comparisons across States or 

regions; however, the underlying definitions of each injury have varied historically. In a 2014 

rulemaking that outlined HSIP performance measure requirements,

1 FHWA proposed to 

standardize the (A) injury level to be consistent with the ‘suspected serious injury’ definition in 

MMUCC (FHWA. MMUCC Guideline: Model Minimum Uniform Crash Criteria. Fourth Edition. 

2012), which is “any injury, other than fatal, which results in one or more of the following:

Severe laceration resulting in exposure of underlying tissues, muscle, organs, or resulting in 

significant loss of blood;

• Broken or distorted extremity (arm or leg);

• Crush injuries;

• Suspected skull, chest, or abdominal injury other than bruises or minor lacerations;

• Significant burns (second- and third-degree burns over 10 percent or more of the body);

• Unconsciousness when taken from the crash scene; or

• Paralysis.

Electronic Reporting and Storage of Crashes

States are moving toward collecting and submitting crash data electronically through the use 

of laptop computers in law enforcement vehicles. In addition to streamlining the data collection 

process, electronic crash reporting can help reduce errors and results in more timely 

submission of reports. This, in turn, allows agencies to more quickly identify and address 

emerging problems.

1

 23 CFR Part 924. Department of Transportation. Highway Safety Improvement Program. Federal 

Register. Vol. 79, No. 60. March 28, 2014.
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Another advantage of electronic crash reporting is that it 

allows for the integration of in-car mapping technologies 

within the crash form completion process. In other words, 

rather than record the crash location with a global 

positioning system (GPS) reading, street address, or 

distance from an intersection, an officer can click on the 

crash location on a digital map and have all of the necessary 

location data automatically entered into the crash report 

(e.g., county, city, latitude and longitude coordinates, 

proximity to intersection, etc.). This is a significant 

improvement, as the process of locating crashes by other 

means requires a substantial amount of staff resources and 

is more prone to errors. Several States are beginning to 

incorporate in-car crash mapping into law enforcement 

vehicles, including Ohio and Alabama.

Once crash data have been collected and submitted to the 

State (through electronic or paper submission), crashes are 

stored in a centralized database. Generally, the data is 

stored using a relational database structure with separate 

tables for the crash, unit, and person information, as 

described above. These tables are linked through identifier 

fields in each table. 

Depending on the institutional arrangements in the State, 

the crash data may be stored in its original form by the DOT, 

the State highway patrol, the Department of Revenue, 

another public agency, or even universities.

Source: FHWA. Model 

Inventory of Roadway 

Elements: Version 1.0. 2010.

MIRE is the corollary to 

MMUCC for roadway 

characteristics. MIRE 

includes a detailed list of 

data elements that are 

recommended for collection 

by transportation agencies 

for the specific purpose of 

evaluating safety.

Many DOTs have found that storing the data in separate tables is not convenient for analysis 

and, thus, create a separate database for this purpose. As part of this process, DOTs may 

conduct a quality control check that addresses inconsistencies or omissions in the data, as 

submitted by the investigating law enforcement agency, assigns coordinates to crashes, and 

supplements, or enhances the crash report based on a review of the crash narrative. It is 

important for agencies which are getting started with safety data analysis to understand what 

information has been added or may be missing relative to the original crash report.

The State DOT’s crash database is likely to contain the most important data for some types of 

analysis, but may not include the full range of information found in the original crash report. 

For example, State DOTs may be less interested in knowing the age of every crash victim than 

a public health department. It is important for agencies that are getting started with safety 

data analysis to understand what information has been added or may be missing relative to 

the original crash report.
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Relevance to Planners

As a DOT or MPO planner, the first step is to identify where crash data is housed in your State, 

and then work with the data manager to understand what information is available for planning 

purposes and how to obtain it. The State DOT’s crash database is likely to contain the most 

important data for planners. Crash data can be used to develop performance measures, 

identify trends and contributing factors, and create crash maps or other visualizations. State 

DOTs and MPOs may perform these analyses when they update their long-range plans, or for 

corridor- or project-level studies.

4.2.2 Roadway Characteristics

Roadway characteristics data refers to the set of information that describes the physical 

attributes and conditions of the street network. While some roadway characteristics are 

collected by law enforcement through the crash reporting process, a more comprehensive and 

reliable set of information is needed to fully evaluate the safety performance of the network.

Developing and maintaining a roadway inventory database is a complex and expensive task. 

This is true for State-maintained routes, but it is even more challenging to collect roadway 

characteristics on local street networks, which account for around 20 percent of fatalities 

nationwide (FHWA Assessment of Local Road Safety Funding, Training, and Technical 

Assistance, August 2013). Nonetheless, some States have developed databases that include 

certain data elements on all State and locally maintained roads. For example, Tennessee DOT 

collects a consistent set of roadway attributes and volume estimates for all public roads since 

2012.

Roadway characteristics can be stored in various ways. Many DOTs use linear referencing, 

which allows roadway attributes, such as shoulders or speed limit, to be stored individually and 

to be defined by the route, along with the start and end points. Crashes also can be referenced 

using the same system.

The primary advantage of linear referencing is that it allows for a very detailed delineation of 

features along a route without breaking the route into very small segments (figure 4.2). A 

potential downside is that analyzing data stored in a linear referencing system requires a 

relatively high level of technical expertise.
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Figure 4.2 Graph. Linear Referencing Conceptual Diagram

Source: Maryland State Highway Administration, One Maryland One Centerline Linear Referencing. 

Roadway characteristics also may be associated with segments that begin and end at 

intersections (e.g., Main Street from Washington Street to Lincoln Street). This approach is 

more common at the local level. While intuitively appealing, a drawback of this segmentation 

scheme is that features relevant to safety may vary over the course of the segment. For 

example, sidewalks may be present on only one-half of the segment length. This is less likely 

in urban areas, but is not uncommon in suburban and rural areas with longer distances 

between intersections.

Regardless of how roadway characteristics data is organized, the relevant features must 

ultimately be associated with crashes. This association enables analysts to characterize crashes 

by roadway features. For example, a State or MPO may report the number of crashes per year 

by roadway functional class, number of traffic lanes, speed limit, or average daily traffic, 

among other factors.

Relevance to Planners

Roadway characteristics data provides context for crashes and allows planners to identify crash 

risk factors. Additionally, organizing crashes by roadway characteristics allows analysts to 

understand the relative performance of different facility types (e.g., two-lane versus four-lane 

rural roads). This type of information is needed to most effectively target countermeasures to 

observed crash patterns and also is necessary for more advanced methods of analysis, 

including crash prediction.

4.2.3 Traffic Volume

All States are required to collect and submit traffic count data through the FHWA’s Highway 

Performance Monitoring System (HPMS). The HPMS requires data to be collected on a sample 

of roads so that State- and county-level traffic volume estimates can be made. State DOTs and 

other agencies typically also conduct traffic counts beyond these requirements. HPMS data can 

be obtained through the FHWA HPMS Web site. 
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The relationship between crashes and traffic 

volume can be expressed in a few different ways, 

depending on the analysis questions at hand. For 

intersections, volume is often expressed as million 

entering vehicles (MEV). For each intersection, the 

number of vehicles that enter the intersection is 

calculated on an annual or multiple-year basis. 

Crashes are then associated with the same 

intersection (often using a distance threshold such 

as 250 feet), and the number of crashes is divided 

by the traffic volume to determine the rate of 

crashes per entering vehicles, typically expressed 

as crashes per 100 million entering vehicles.

The process for calculating crash rates on 

segments is different than that used for 

intersections. Traffic counts conducted along 

segments are first converted to volume estimates 

by multiplying the count at a single location by the 

segment length. From there, the number of 

crashes along the segment is divided by the traffic 

volume to determine the number of crashes per 

million vehicle miles traveled (VMT). Calculating 

the crash rate at a regional or State level follows a similar process.

All Roads Network of 

Linear-Referenced Data

In 2012, FHWA announced a new 

requirement that States must submit 

a complete Linear-Referencing 

System for all public roads in their 

State. This dataset is referred to as 

the All Roads Network of LinearReferenced Data (ARNOLD). The 2014 

ARNOLD Reference Guide describes 

how this requirement can be met in 

different States. Once implemented, 

ARNOLD will greatly facilitate the 

process of locating crashes on local 

roads, which account for a substantial 

portion of fatalities and injuries. 

Further, it will provide a consistent 

linear-referencing system for the 

entire U.S.

Source: FHWA. Arnold Reference 

Manual: All Public Roads Geospatial 

Reference Study. 2014.

Figure 4.3 Chart. Crash Distribution by Average Daily Traffic Example

12% 14% 15% 18% 8% 12% 8% 13%

14%

17% 16%

15%

7%

10%

10%

11%

0 to 10k 10k to 20k 20k to 30k 30k to 40k 40k to 50k 50k to 75k 75k to 236k Unknown

ADT Range

Percent of Total Crashes Percent of Fatalities & Serious Injuries

Source: Sample Data, Cambridge Systematics, Inc., 2015.
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Relevance to Planners

Traffic volume data are essential to understanding the safety risk based on the amount of 

travel. For instance, if planners are conducting a safety review of intersections, they may 

discover that intersections with the same number of crashes can have very different risk 

profiles depending on the level of traffic. Like roadway characteristics data, traffic volume data 

also can be used to help characterize the relative safety performance of groups of roadways 

(e.g., what is the crash rate on arterials with more than 20,000 vehicles per day versus 

arterials with less than 20,000 vehicles per day?).

4.2.4 Integrating Crash, Roadway, and Volume Data

State DOTs and their safety partners dedicate a significant amount of resources to the tasks of 

organizing these individual datasets and linking them together. While each is useful on its own, 

linking the three sets of information together provides the greatest insight.

Since safety data analysis ultimately is concerned with addressing the factors that contribute 

to crashes, it is necessary to understand the roadway and traffic volume conditions at the 

locations where crashes have occurred. This requires each crash to be precisely located with 

respect to the roadway inventory.

As the crash data collection and management processes become increasingly automated, one 

of the main advances relates to the ability to more easily and more accurately locate crashes. 

State DOTs differ in the specifics of their approach, but many use automated processes to link 

location information provided in crash reports to roadway and traffic volume inventories.

In addition to linkages that occur at the crash data management stage, planners may use GIS 

processes to link crash data to local road segments or intersections. For example, the Mid-Ohio 

Regional Planning Commission has developed a methodology to assign crashes to intersections 

within a 250-foot buffer (Mid-Ohio Regional Planning Commission Top 40 Regional High-Crash 

Location Methodology, September 2014). 

Once crashes have been linked to roadway or intersection inventories, a rich set of information 

is available for querying. Additionally, crashes along a given segment of road or at a particular 

intersection may then be aggregated to determine what types of crashes occur with the 

greatest frequency, and how each location performs relative to others. The use of advanced 

safety analysis methods, such as those outlined in the Highway Safety Manual (HSM), requires 

that crashes, roadway characteristics, and volume are integrated.

4.2.5 Other Safety Datasets

Citation and adjudication data, injury data, vehicle data, and driver and passenger information

are less commonly used for transportation planning purposes, but are extremely important in 

other contexts. Citation and adjudication data refers to the arrest and conviction records of 

individual drivers for traffic offenses. States are moving toward implementation of centralized 
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citation and adjudication systems which enable analysis of trends and problem identification. 

This capability supports targeted enforcement, which helps to reduce specific crash types such 

as impaired driving crashes and speed-related crashes.

Injury control data is concerned with the health care systems and processes that are involved 

in responding to motor vehicle crashes. Examples include prehospitalization (EMS) data, 

emergency department data, hospital discharge data, trauma registry data, and vital records 

data. Prehospitalization data provides insight into emergency response times, which are critical 

for reducing fatalities in particular. Hospital and trauma data provide a more accurate 

assessment of injury outcomes as compared to law enforcement crash reports. Additionally, 

hospital records include injuries from certain types of crashes that are not captured by most 

State data systems, such as those involving a single bicycle.

Vehicle data provides valuable information to regulatory agencies regarding the safety of 

vehicle technologies as well as any significant trends regarding the types of vehicles involved 

in crashes. Vehicle crash history also is used in some transportation planning analyses, such as 

identifying locations with a high incidence of commercial vehicle crashes or motorcycle crashes. 

Passenger and driver information are frequently used to identify and document behavioral 

safety patterns, such as impaired driving or failure to wear seat belts. Similarly, tracking the 

age and other available demographic information of drivers and passengers involved in crashes 

provides a better overall understanding of traffic safety problems and sheds light on the 

effectiveness of education or legislative action, such as Graduated Driver’s Licensing (GDL). 

4.3 Data Quality

The successful application of safety data to the transportation planning process is contingent 

on the availability of high-quality data. The following six characteristics for evaluating the 

quality of State safety databases have been identified: timeliness, accuracy, completeness, 

consistency/uniformity, integration, and accessibility (FHWA Crash Data Improvement Program 

Guide, April 2010). Each of these factors affects the ability to use or draw conclusions from 

State safety databases. Transportation safety planners should be familiar with these criteria 

and consider how their data performs with respect to each area. A brief of discussion of crash 

data quality characteristics is provided below. 

4.3.1 Timeliness

Timeliness is concerned with how quickly crash reports are entered into the State database and 

become available for analysis. The timely availability of crash data allows planners to identify 

and address emerging safety concerns. A difference of several months could result in several 

crashes being prevented, including some serious injuries or fatalities. Electronic crash reporting 

and better integration of crash data systems have allowed some States to provide access to 

crashes with very short delays, such as a few days.
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4.3.2 Accuracy

The accuracy of crash data has a direct effect on the 

conclusions that can be drawn from the data. It is expected 

that crash databases will have some level of error or missing 

information, but accuracy can be improved substantially 

through the use of ‘business rules.’ Business rules ensure that 

crash data reports submitted to State databases are logical 

and consistent. For example, a crash report that indicates

there were zero vehicles involved would fail a basic validation 

requirement. Incorporating edits and validation rules into data 

entry will result in significant accuracy improvements.

4.3.3 Completeness

Crash data completeness refers to the degree to which each

crash is represented in the database, as well as whether all 

relevant information has been provided for each crash. In both 

cases, incomplete data can hamper the safety planning 

process. For example, if one county fails to report one-half of 

its crashes, it would appear that their roads are much safer 

than is actually the case. Similarly, if a report for a curverelated crash does not indicate that the crash occurred along a 

curve, planners will not be able to determine the role that the 

curve may have played in the crash.

Source: FHWA. Crash Data 

Improvement Program 

Guide. 2010.

FHWA’s Crash Data 

Improvement Program 

Guide provides an indepth 

discussion of the six data 

quality performance 

measures: Timeliness, 

Accuracy, Completeness, 

Consistency, and 

Integration. It is an 

excellent resource for 

understanding the crash 

data collection process 

and considerations.

4.3.4 Consistency/Uniformity

Consistency of crash reporting across agencies is important to 

ensure that differences in reporting practices do not influence safety funding decisions. For 

example, if one law enforcement agency routinely checks for impaired drivers in crashes, while 

another does not, an analysis of impaired driving crashes will report a significant difference in 

impaired driving crashes in these two areas. Injury definitions and application on crash reports 

also must be carefully defined and consistently reported to allow for appropriate comparisons 

between regions or States.

4.3.5 Integration

Integration of safety data applies not only to crash, roadway, and traffic volume data, as 

discussed above, but also to citation, Emergency Medical Service (EMS), and injury data. 

Relating these datasets to crashes and to each other provides a more complete assessment of 

driver risk factors (e.g., previous driving under the influence (DUI) offenses), emergency 

response times, and injury outcomes, with respect to the other information provided in the 

crash data. Full integration of safety datasets is a worthwhile goal, but is challenging due to 
4.0 GETTING STARTED WITH TRANSPORTATION SAFETY PLANNING—DATA COLLECTION

27

legal and privacy concerns, institutional challenges, and technical hurdles. States vary with 

respect to the current level of integration of their safety datasets.

Integration of State and local data is another aspect of data quality with relevance to safety 

planning. Some local and regional agencies collect data on roadway features and traffic 

volume, but these data are not always easily integrated with State sources. They may use a 

different spatial reference or data definitions that make it difficult to take advantage of 

information from both sources.

4.3.6 Accessibility

The ease with which safety stakeholders can access and use safety datasets is an important 

consideration for safety data managers. Users beyond State DOTs must be able to access 

crash data to develop their safety-related programs. For example, an MPO interested in 

developing a pedestrian safety campaign may wish to develop safety messages based on 

pedestrian crash data specific to their region and to target their effort to geographic areas or 

populations with a high number of pedestrian crashes.

4.4 Obtaining Safety Data

Knowing the types of safety data available in a State and potential data limitations is 

important—however, the next step is to obtain data to initiate transportation planning 

activities. Safety data comes in many formats and can be accessed in a variety of ways. Raw 

crash data often is needed to conduct customized analysis with the greatest amount of 

flexibility. However, if staff or resources limit the use of raw data, standard reports generated 

by State DOTs, online tools, or custom inquiries or input from stakeholders can be used to 

identify safety problems.

4.4.1 Raw Data

In the context of safety planning and analysis, raw 

data refers to data that has not been aggregated or 

significantly modified from its initial state. Raw crash 

data often is available in text file or similar tabular 

format, where each row of data represents one crash, 

and columns represent the attributes or characteristics 

of the crash. Similarly, roadway characteristics data 

may be provided in tabular format, where each row 

corresponds to a roadway segment, and columns 

represent the characteristics of the road. Raw data 

often is provided as a spatial file, or contains the 

information needed to develop a spatial file based on 

the records in a tabular file.

Raw Data in a Nutshell

Working with raw data affords 

planners the greatest opportunity 

to dive into the safety data for 

their region. With raw data it is 

possible to investigate a wide 

variety of questions that may 

arise during the planning process. 

Additionally, it is possible to 

account for combinations of crash 

factors that provide a more 

nuanced understanding of the 

circumstances that are 

contributing to crashes and 

injuries. Sophisticated online tools 

can provide similar functionality, 

but are expensive and timeconsuming to develop.
4.0 GETTING STARTED WITH TRANSPORTATION SAFETY PLANNING—DATA COLLECTION

28

Although working with raw data affords the greatest flexibility, it can be time-consuming and 

resource-intensive to work with raw data files. Staff with data management and analysis skills 

are needed to effectively leverage raw data.

Table 4.1 Raw Crash Data Sample

Unique_Crash_

Identifier

seirujnIg_nitaticpaacnIn_oN

hsarC_erutrpaeD_ydwaaoR

aywadoR_denaitnMai_TOD

seirujnIg_nitaticpaacnI

epy_Tnoitaco_LhsCra

detaleR_noitcesretnI

edCo_epy_ThsCra

ssalC_lanoitcnuF

seirujnI_eblissoP

ecnatsiD_tesffO

noitceriD_tesffO

ed_CoytrieveS

sielitataF

1138927103 5 7 1 0.03 N 1 0 0 0 Y 5 1 0 

2520002700 4 14 1 0.2 S 0 1 0 0 N 3 1 0 

4878061929 3 6 1 0.3 E 0 0 2 0 N 5 0 1 

7448081765 4 11 3 0 – 0 2 0 0 Y 7 0 0 

5085793336 4 9 1 0.22 N 0 1 1 0 N 7 0 0 

8605042833 2 7 1 0.05 W 0 0 0 1 N 5 0 0 

5853315093 2 15 2 0.01 E 0 0 0 2 Y 4 0 0 

8669234119 3 12 3 – – 0 0 1 0 Y 3 1 0 

9418456907 2 16 1 0.1 N 0 0 0 1 N 5 1 1 

3565407865 2 10 1 0.2 S 0 0 0 1 N 7 0 1 

Source: Sample Data, Cambridge Systematics, Inc., 2015.

4.4.2 Generated Reports

The easiest way to learn about basic safety 

statistics for a State, region, or county is through 

reports that already have been prepared. Many 

State DOTs or other agencies prepare summary 

reports on a regular basis. Additionally, the NHTSA 

Fatality Analysis Reporting System (FARS) Web site 

has indepth State-level reports on fatalities.

FARS

The Fatality Analysis Reporting 

System (FARS) is a national 

database of motor vehicle traffic 

fatalities. It includes detailed 

information such as drivers, vehicles, 

and locations; and are available to 

the public. Fatalities reported 

through FARS may differ slightly 

from other State reports due to 

definitional differences.
4.0 GETTING STARTED WITH TRANSPORTATION SAFETY PLANNING—DATA COLLECTION

29

Reports generated by State agencies are likely to provide an overall understanding of crash 

trends at the given reporting level. For example, they may report on fatality and serious injury 

trends, provide an indication of the most prevalent crash types or contributing factors in an 

area, or identify high-crash locations. For planners who do not have the time or resources to 

analyze raw data, these reports provide a basic amount of information to initiate transportation 

safety planning. For example, Louisiana DOT, through the Highway Research Group, provides 

its regional transportation coalitions with annual data on basic trends, contributing factors, and 

high-crash segments and intersections. Pennsylvania DOT provides all its districts, MPOs, and 

RPOs a biannual report on fatality and serious injury trends, performance target data for 

contributing factors, and a list of high-crash locations with GIS functionality.

Generated reports may provide enough information to identify general causes or areas of 

concern, which can lead to the development of safety goals and objectives. They are less likely 

to answer questions about where and why specific crash problems exist in an area. Further 

analysis, such as systemic safety analysis, network screening, or road safety assessments, can 

provide more insight into project and program identification.

4.4.3 Web Interfaces and Tools

Several State DOTs provide access to crash data and 

other datasets for safety stakeholders through Web

interfaces. This is a convenient format that makes it 

easy for planners to access data, while also reducing 

the need for data owners to respond to data requests.

It is common for some level of analysis capabilities to 

be incorporated into these data access tools. Users may 

have the ability to filter data based on criteria such as 

year, type of crash, injury severity, geographic location, 

or other factors. From there, they can download the 

raw data or generated reports based on the selected 

criteria.

Montana DOT Statistics

and Data Web Site

(Montana DOT Statistics 

and Data) 

The Montana DOT provides upto-date crash data summaries 

that are accessible to the public 

via the Montana DOT Statistics 

and Data Web site. Users can 

download an Excel spreadsheet 

that allows them to view crash 

totals based on their selected 

county, city, or Tribal 

reservation. Category reports 

are available for each emphasis 

area identified in the SHSP.
4.0 GETTING STARTED WITH TRANSPORTATION SAFETY PLANNING—DATA COLLECTION

30

Figure 4.4 Screenshot. Ohio DOT’s Geographic Crash Analysis Tool 

(GCAT) Query Form and Map

Source: Ohio DOT GIS Crash Analysis Tool. 

Web interfaces and tools are meant to enhance transportation safety planning activities, 

providing data and analysis in a user-friendly way, but a primary limitation for planners is the 

lack of training or knowledge on the tool. A number of States do offer trainings to overcome 

this barrier. For instance, training on the Crash Mapping Analysis Tool (CMAT), a software 

program that provides convenient access to crash data in Iowa, is offered regularly and free of 

charge to cities, counties, State employees, consultants, and researchers in Iowa.

4.4.4 Custom Inquiries

An alternative to using Web interfaces is for safety stakeholders to request data on an asneeded basis. Such arrangements make sense where a Web interface has not been provided, 

or data users do not have the capacity to access the data electronically.

Custom inquiries should be limited and address a specific question (e.g., how many run-offroad crashes were there along a specific corridor over a given three-year period?). In these 

cases, going through the process of analyzing raw data would be too time-consuming; 

whereas, the data owner is likely able to answer the question with minimal effort.
5.0 USING SAFETY ANALYSES FOR PLANNING

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5.0 Using Safety Analyses for Planning

For many transportation planning organizations, the biggest barrier to integrating quantitative 

safety analysis into the planning process is staff time and expertise. While this can be a significant barrier, agencies can begin to address safety with a low level of effort. First and foremost, 

planners should coordinate with data managers in their States to learn about data availability, 

analyses already complete, and/or options for analytical support specific to the planning jurisdiction. For example, the State SHSP may include data analysis and/or safety emphasis areas 

that are relevant to the planning agency. Funding for transportation safety analysis, research, 

and/or project implementation may be available through the State DOT HSIP; or the State 

TRCC may have resources available for data collection, analysis, or evaluation projects.

Another way to overcome these barriers is to start small. Many of the analyses using 

descriptive statistics can be conducted using common spreadsheet tools. Summarizing the

who, what, when, where, and why of crashes will provide an excellent starting point to 

understanding safety conditions in the community. This information can serve as talking points 

to elected officials and local partners and raise the importance of safety in the community.

This section provides an overview of the basic safety analysis categories, questions answered 

in each category, how this can be included in transportation planning, and analysis methods to 

answer these questions. The topics covered are presented in table 5.1. This guidebook focuses 

on basic analysis methods. As data, expertise, resources, and interest grows, more advanced 

methods should be considered. A more detailed version of table 5.1, including methods, data 

needs and tools is included in appendix B. 

Table 5.1 Safety Analysis Categories and Questions

Analysis Category Analysis Question

Benchmarking • How many fatalities and serious injuries are occurring in my area?

• How does this compare to other areas or my State?

Identify Crash Trends and 

Contributing Factors

• Who is involved in crashes?

• When are the crashes occurring?

• What are the major contributing factors to crashes?

Identify and Evaluate Focus 

Crash Types

• What are the most common crash types?

• What are the most common contributing factors?

• What are the characteristics of the over representation?

Network Screening—Identify 

Sites for Safety Improvement

• What locations (intersections or segments) show the most potential 

for safety improvements?

Systemic Analysis—Identify 

Safety Risk Factors

• What are the common characteristics of locations with crashes?

• What are the countermeasures to address these characteristics?

• How should we prioritize systemwide implementation?

Corridor and Intersection 

Planning Safety Analysis

• What are the safety effects of alternative roadway or intersection 

cross sections?

Source: Cambridge Systematics, Inc.
5.0 USING SAFETY ANALYSES FOR PLANNING

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5.1 Benchmarking 

Integrating safety analysis into planning- and project-level activities starts with understanding 

the scope and scale of safety concerns in the planning area. Initially, planners need to 

understand performance measures such as: number of fatalities; number of serious injuries; 

rate of fatalities; and rate of serious injuries.

Benchmarking the area’s safety performance for a particular period is useful in the long-range 

planning process as part of setting plan vision and goals and establishing performance 

measures and evaluation criteria for the plan. Fundamentally, benchmarking like this makes it 

possible to monitor safety performance within the area, as well as assess performance of the 

system relative to other comparable areas and/or the State. At the highest level, these 

performance measures quantify the number of people killed or seriously injured over time in 

the area. Monitored annually, this will provide the agency with information about overall 

effectiveness and safety planning and programming in the area and will help transportation 

agencies determine the appropriate safety focus areas moving forward.

5.1.1 Methods for Benchmarking

In descriptive analyses for benchmarking, areawide crash frequency and crash severity per 

year are tallied for a period of years to develop a simple trend summary. This trend can be 

summarized for the area only to evaluate current performance to past years, or performance in 

a specific year can be compared to similar data from other areas to compare performance 

across areas. Figure 5.1 shows annual total crash fatalities and serious injuries for a community

for the years 2009 to 2013. Figure 5.2 shows a comparison of fatalities by DOT region. 

Figure 5.1 Chart. Fatalities and Serious Injuries per Year

329 319

276

413

294

121

90

99

136

100

2009 2010 2011 2012 2013

Serious Injuries Fatalities Trend

Source: Sample data, Cambridge Systematics, Inc., 2015.
5.0 USING SAFETY ANALYSES FOR PLANNING

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Figure 5.2 Chart. Comparison of Fatalities by Region

55

25

51

40

72

DOT Region 1

DOT Region 2

DOT Region 3

DOT Region 4

DOT Region 5

Source: Sample data, Cambridge Systematics, Inc., 2015.

Forecasting Long-Range Safety Performance

An advanced method for integrating safety into transportation planning is to develop 

models that predict long-range (20-year) safety performance of transportation networks as 

a function of traditional transportation planning data, such as land use, population, VMT, 

and roadway. While not yet common, long-range safety planning models could be used to 

predict long-term safety performance as part of long-range planning alternatives evaluation 

or scenario testing to select alternative transportation networks.
5.0 USING SAFETY ANALYSES FOR PLANNING

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5.2 Identify Crash Trends and Contributing Factors

The next category of safety analysis is conducted to 

identify major crash trends and contributing factors in 

a community. The crash trends and contributing factors 

tell the safety “story” of who, what, when, where, and 

why people are involved or injured in crashes:

• Who? Age distribution and gender of crash victims.

• What? Number and type of vehicles (single or 

multivehicle crashes, commercial vehicles or 

passenger vehicles), pedestrians, motorcyclists, 

bicyclists, etc., involved in the crash.

• When? Year, month, day, and hours of crashes.

• Where? Crash location by roadway functional 

classification, intersection or roadway segment, 

urban or rural environment, transportation analysis 

zone, or subdistrict within the community.

• Why? Behavioral and environmental factors, such as driver impairment, driver distraction, 

speeding, pavement condition, or road curvature. 

Contributing Factors and 

Countermeasures Defined

Crash-contributing factors are 

driver behaviors, events, or 

roadway infrastructure 

characteristics that contribute to 

the occurrence of the crash. 

Examples include texting while 

driving, low roadway friction 

around a curve, sight distance 

constraints, or inadequate 

lighting. Crashes typically have 

multiple contributing factors. 

Countermeasures/treatments 

refer to strategies implemented 

to reduce a specific crash type or 

crash severity.

The objective of this analysis is to understand the major safety trends in a community and 

identify if there are crash types or contributing factors that are more common than expected; 

and, as a result, should be a focus of project planning, policy or programming, and 

prioritization. Analyses like these can be conducted for safety-specific plans, or can be 

conducted as part of an existing conditions assessment in a long-range or corridor plan.

Knowing crash trends and contributing factors can help transportation agencies determine 

appropriate safety countermeasures during these planning processes.

5.2.1 Methods for Identifying Crash Trends and Contributing Factors

Descriptive statistics count and compare the number 

(i.e., frequency), type, severity of crashes, and/or 

contributing factors that have occurred historically. 

Typically, this is done for the most recent three- to 

five-year period at a site, along a corridor or in an 

area. As described in the bullets above, there are many 

possible contributing factors and categories to count. 

As such, it is advisable to start with a small number of 

categories to keep the process manageable. As specific 

concerns arise within any given category, it may be 

necessary to dig deeper into the data.

Descriptive Analysis Examples

New Mexico DOT provides 

descriptive statistics reports and 

maps for communities and 

counties in the State.

Utah DOT also provides an online 

Web-based tool summarizing 

basic descriptive crash data for 

communities in the State.
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Figures 5.3 through 5.6 show example analyses. Figure 5.3 shows for a one-year period, the 

percentage of all crashes occurring during each hour of a day and the percent of severe 

crashes by hour of day. As shown, in this data set, the greatest percentage of severe crashes 

is occurring between noon and 1:00 p.m. Considering all crashes, 3:00 to 4:00 p.m. is the 

most common period for crashes.

Figure 5.3 Chart. Distribution of Total and Severe Injury Crashes

by Time of Day

12AM-1AM

1AM-2AM2AM-3AM3AM-4AM4AM-5AM5AM-6AM6AM-7AM7AM-8AM8AM-9AM

9AM-10AM

10AM-11AM

11AM-12PM

12PM-1PM

1PM-2PM2PM-3PM3PM-4PM4PM-5PM5PM-6PM6PM-7PM7PM-8PM8PM-9PM

9PM-10PM

10PM-11PM

11PM-12AM

Percent of Total Crashes Percent of Severe Crashes

Source: Sample data, Cambridge Systematics, Inc., 2015.

Figures 5.4 through 5.6 show crash distribution by age and gender. In this data set, 25- to 34-

year-olds have the most crashes, severe and total. This figure also shows that approximately 

half of all crashes and nearly two-thirds of all severe injury crashes involve a male.
5.0 USING SAFETY ANALYSES FOR PLANNING

36

Figure 5.4 Chart. Distribution of Total and Severe Injury Crashes

by Age

9% 10% 13% 20% 17% 14% 8% 5% 3%

<15

15-1718-2021-2425-3435-4445-5455-6465-7475-84

85+

At-Fault Driver Age

Percent of Total Crashes Percent of Severe Crashes

Source: Sample data, Cambridge Systematics, Inc., 2015.

Figure 5.5 Chart. Distribution of Total Crashes by Gender

Female

Male 48%

52%

Total Crashes

Source: Sample data, Cambridge Systematics, Inc., 2015.
5.0 USING SAFETY ANALYSES FOR PLANNING

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Figure 5.6 Chart. Distribution of Severe Injury Crashes by Gender

Female

40%

Male

60%

Severe Crashes

Source: Sample data, Cambridge Systematics, Inc., 2015.

5.3 Identify and Evaluate Focus Crash Types

With an understanding of the major crash trends and contributing factors, the planning agency 

may select one or more of the more prominent crash trends or contributing factors as a focus 

for planning and programming activities. For example, the crash trend assessment may show 

more pedestrian or bicycle crashes than expected for a particular area of the community. As a 

result, a pedestrian/bicycle safety action plan could be developed for the particular area, or the 

community may find roadway departure crashes in the rural part of the community are 

overrepresented. In this analysis, the planner would review and summarize crash data to 

understand such topics as:

• What is the manner of collision? Rear-end, angle, roadway departure, head-on? Was a 

pedestrian or bicycle involved? 

• What is the crash severity? Which crash types are most severe and where are they 

occurring?

• What crash types or contributing factors are overrepresented?

• What is the geographic distribution of the focus crash type?

• What are common roadway features?

As an outcome of this analysis, the transportation planner would understand the categories of 

crashes by type, severity, contributing factor, or geography that may be a focus for planning, 

programming, and countermeasure identification; or the types of crashes or contributing 

factors that should be a consideration in non-safety-specific projects. 
5.0 USING SAFETY ANALYSES FOR PLANNING

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For example, figure 5.7 considers crash distribution by Transportation Analysis Zone (TAZ). 

The figure shows the percentage of roadway departure crashes per TAZ as a total of all crashes 

in each TAZ. As shown, roadway departure crashes are more common on the east side of the 

region, particularly in the southeast. 

Figure 5.7 Map. Distribution of Roadway Departure Crashes by 

Transportation Analysis Zone

Source: Cambridge Systematics, Inc., unpublished, prepared for Alabama Department of Transportation.

5.3.1 Methods for Identifying and Evaluating Focus Crash Types

Scatterplot

The scatterplot (figure 5.8) illustrates a simple method for evaluating the relative occurrence of 

various crash types in terms of frequency and severity. The x-axis represents the crash type 

frequency rank, while the y-axis indicates the crash type severity rank (percentage of crashes 

that result in a severe injury). In this example, the single-vehicle (RD) crash type stands out 

as being highly ranked in both frequency and severity. At the other extreme, backing and 

other crashes are ranked in the bottom in both frequency and severity and, therefore, are 

relatively unimportant. Depending on the interest of the MPO, greater emphasis could be 

placed on frequency or severity.
5.0 USING SAFETY ANALYSES FOR PLANNING

39

Figure 5.8 Scatterplot. Crash Types by Frequency and Severity Ranking

Ped

Other

Backing

Head-On

Unknown

Single Vehicle 

(Other)

Sideswipe 

(Opposite)

Angle (90 Deg.)

Angle (Other)

Angle (Left Turn)

Sideswipe (Same)

Single Vehicle (RD)

Rear-End

Severity Rank

Frequency Rank

Source: Sample Data, Cambridge Systematics, Inc., 2015.

Overrepresentation

Overrepresentation is another measure of whether a crash type or contributing factor should 

be prioritized as a safety issue in the planning area. One way to visualize overrepresentation is 

to compare the percentage of all crashes accounted for by a given factor with the percentage 

of severe crashes (those resulting in a fatal or serious injury) accounted for by that same 

factor. For example, figure 5.9 shows 15 percent of all crashes are single vehicle roadway 

departure crashes, yet 33 percent of all severe crashes are roadway departure crashes. 
5.0 USING SAFETY ANALYSES FOR PLANNING

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Figure 5.9 Chart. Overrepresentation of Severe Crashes among Select 

Crash Types

Source: Sample Data, Cambridge Systematics, Inc., 2015.

Risk Ratio

37%

15%

10%

9%

6% 5%

Rear-End Single Vehicle (RD) Sideswipe (Same

Direction)

Angle (Left Turn) Angle (Other) Angle (90 Deg.)

 Percent of Total Crashes Percent of Severe Crashes

Another method for identifying if a particular crash type, contributing factor, or severity should 

be considered as a focus for the area is called risk ratio. The risk ratio compares the severity of 

crashes associated with a particular factor to the severity of all other crashes. Using the risk 

ratio analysis method shown in appendix C, it is possible to learn if a particular crash type in a 

given situation is over represented. Crash types or factors with a risk ratio greater than 1 are 

overrepresented with respect to severe crashes and could be considered as a focus crash type 

for the agency. For example the risk ratio calculation could show that crashes in rural areas are 

2.7 times more likely to result in a fatality or serious injury than those in urban areas.

5.4 Network Screening—Identify Sites for Safety Improvements

Some transportation planning organizations may choose to identify and prioritize specific 

locations (also known as sites) for safety improvements. This analysis, also called network 

screening, identifies locations that are experiencing more crashes than would be expected for 

comparable sites. Historically, this has been called a list of “hot spots” or “black spots.” 

Intersections (stop or signal controlled) and roadway segments can be considered sites. From 

this analysis, the agency learns what specific locations may benefit from safety improvements 

and, with more detailed analysis, the specific modifications for any given site. For example, 

New Hampshire DOT imports the safety data into AASHTOWare Safety AnalystTM and 

distributes the tool to MPOs to use in their analysis. Ohio DOT has approached FHWA for 

assistance in integrating their State and MPO data and are striving to provide this information 

to MPOs in Ohio. This analysis can support an existing conditions assessment of a long-range 
5.0 USING SAFETY ANALYSES FOR PLANNING

41

Using Safety Analyst for Planning

The AASHTO software Safety Analyst conducts statewide network screening, site 

prioritization, countermeasure identification, and benefit-cost analysis. It applies network 

screening methods from the HSM. The level of effort to deploy Safety Analyst is 

substantial; however, once functional it is a powerful tool for conducting network screening 

and prioritization analysis. Ohio, Washington State, and New Hampshire are leaders in the 

development and deployment of Safety Analyst. If available, Safety Analyst results can be 

used at the regional level.

plan or corridor planning analysis; could be used to help transportation agencies determine 

appropriate countermeasures at locations for a safety plan; or it could be integrated into a 

prioritization process by giving a scoring benefit to projects or programs, which also address a 

site with potential for safety improvements.

Chapter 4: Network Screening of the AASHTO HSM provides detailed explanations of many 

different network screening methods. The simplest methods are frequency, crash rate, and 

equivalent property damage only. There are strengths and weaknesses to each of these 

methods; however, if facilities are organized into groups of comparable facility type and traffic 

volume, many of the common challenges are overcome.

5.4.1 Methods for Network Screening

Crash Frequency

The crash frequency method for network screening 

counts the number of crashes that have occurred 

at an intersection or roadway segment over a 

specified time period, typically three to five years. 

The locations are ranked from highest to lowest 

crash frequency. Locations with relatively higher 

crash frequency are selected as possible sites for 

detailed investigation and subsequent safety 

improvement. 

Crash frequency is an attractive quantitative 

screening technique because the only data 

required are crashes and their physical locations. 

Other data like traffic volume and roadway 

features are not necessary for using this 

technique, making it relatively quick and easy. 

However, it does have shortcomings. The crash 

frequency method does not take traffic volumes or 

roadway elements into account. Because higher-volume locations are likely to have more 

crashes than lower volume locations, this method has an intrinsic bias toward higher-volume 

locations. 

Network Screening Methods

Chapter 4 of the AASHTO HSM also 

includes network screening methods 

to compare observed site crash 

frequency to “expected” crash 

frequency for comparable sites. The 

expected crash frequency is a more 

reliable estimate of long-term safety 

performance at a site than estimates 

based on a three-year average. 

Calibrated Safety Performance 

Functions (SPF) are needed to 

calculate expected crash frequency 

or severity. Many State DOTs are 

developing calibration factors and/or 

State-specific SPFs. Be sure to check 

with your State DOT colleagues to 

determine if these are available. It 

may also be possible for your State 

partners to conduct the network 

screening analysis in your area.
5.0 USING SAFETY ANALYSES FOR PLANNING

42

Crash frequency also is subject to issues associated with regression to the mean. If regression 

to the mean is not accounted for, a site might be selected for study because the annual 

number of crashes that occurred was higher than “usual” due to a random fluctuation in the 

data. Conversely, a site that should be selected for study might be overlooked because an 

unusually low number of annual crashes occurred there. To reduce the influence of regression 

to the mean the agency should calculate the average of the most recent three to five years of 

crash data to determine the average crash frequencies. This minimizes, but does not entirely 

overcome, the year-to-year fluctuations in data and is appropriate if site conditions (e.g., 

traffic volume, land use, driveway access, and roadway configuration) have not changed. 

A more detailed explanation of regression to the mean can be found in appendix D. 

Crash Rate

Crash rates describe the number of crashes in a given period as compared to some measure of 

exposure. Crash rates are calculated by dividing the total number of crashes at a given 

roadway section or intersection over a specified time period (typically three to five years) by a 

measure of exposure. While traffic volume is the most typically used measure of exposure, 

others such as population, lane, or roadway miles, and licensed drivers within a community 

also can be used. The locations are then ranked from high to low by crash rate. Crash rate 

screening is able to identify low-volume, high-crash risk locations that do not necessarily 

experience a high total number of crashes.

It is important to note that crash rates also are influenced by regression to the mean and tend 

to overemphasize sites with lower traffic volumes. It is best to use crash rates as a comparison 

tool only for sites that have similar functional classifications, number of lanes, surrounding land 

uses, and traffic volume.

Equivalent Property Damage Only

In the equivalent property damage only (EPDO) method, weighting factors related to the 

societal costs of fatal, injury, and property damage-only crashes are assigned to crashes by 

severity (typically, at a given location over three to five years) to develop an EPDO score that 

considers frequency and severity of crashes. The sites are ranked from high to low EPDO 

score. Those sites at the upper end of the list may be selected for investigation. To apply the 

EPDO method for ranking sites, it is necessary to know the number of crashes per year and the 

severity of crashes per year per site. In this method, all injury crashes (incapacitating, 

nonincapacitating, minor injury) are grouped together.

Heat Map

Heat maps show the density of crashes per unit area (e.g., crashes per square mile) on the 

roadway system. Crash data must be geolocated; and then using GIS tools, the crash density 

can be plotted. As shown in figure 5.10, heat maps are useful for crash data visualization as it 

can be difficult to decipher patterns based on a map of individual crashes. They can help 

planners to focus their analysis on areas with higher crash concentrations. They also can 
5.0 USING SAFETY ANALYSES FOR PLANNING

43

quickly reveal corridors that may be worthy of attention; whereas, analyzing corridors using 

other techniques can be quite challenging. Based on the result from a heat mapping exercise, 

field investigations could be conducted at the locations with a higher crash density to identify if 

there is potential for safety improvement.

Figure 5.10 Heat Map. Density of Crashes per Unit Area

Source: Cambridge Systematics, Inc., unpublished, Central Arizona Governments.

5.5 Systemic Analysis—Identify Safety Risk Factors

Another form of safety analysis is called systemic analysis. The systemic approach to reducing 

crash frequency and severity involves wide implementation of low-cost safety improvements to 

address high-risk roadway features correlated with specific severe crash types. The approach 

provides a more comprehensive method for safety planning and implementation and 

compliments site-specific analysis.
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Systemic analysis identifies if there are the 

transportation system characteristics that can be 

commonly associated with particular types of

crashes. These characteristics are called risk 

factors. For example, if roadway departure 

crashes are most frequently occurring on twolane roads with a particular curve radius, this 

combination of characteristics (i.e., two-lane 

roads with specific curve radii) can be 

considered risk factors. The transportation 

system is then evaluated to identify all the 

locations where these characteristics exist. The 

locations are subsequently prioritized to develop 

a list of locations for implementing low-cost 

safety treatments.

With an understanding of the risk factors 

associated with particular crash types and the 

countermeasures addressing the particular risk 

factors, the transportation planning organization 

can consider these risk factors and potential treatments as part of other corridor planning or 

site-specific projects; or in the prioritization process, if a project includes addressing known 

risk factors, it could be given additional scoring benefits. For example, several DOTs have 

installed cable median barriers to address cross-median crashes, which often result in severe 

injuries. Ohio has installed over 300 miles on its roadway network and has found the 

technology to be a cost-effective solution when applied in the appropriate context. 

Proven Safety Countermeasures

FHWA Office of Safety maintains a Web 

site of proven safety countermeasures. 

These countermeasures are research 

proven but not yet widely implemented. 

The FHWA Web site describes each of 

these countermeasures and provides 

background, guidance, and resources 

for each countermeasure. The 

countermeasures are: roundabouts, 

corridor access management, 

backplates with retroreflective borders, 

longitudinal rumble strips and stripes 

on two-lane roads, enhanced 

delineation and friction for horizontal 

curves, safety edge, medians and 

pedestrian crossing islands in urban 

and suburban areas, pedestrian hybrid 

beacon, and road diets.

5.5.1 FHWA Systemic Safety Project Selection Tool

The FHWA guidebook The Systemic Safety Project Selection Tool provides the following:

• A step-by-step process for conducting systemic safety planning;

• Considerations for determining a balance between spot and systemic safety improvements; 

and

• Analytical techniques for quantifying the benefits of a systemic safety program.

The guidebook can be downloaded from the FHWA Systemic Safety Analysis Web site. Missouri 

DOT and Minnesota DOT have been leaders in systemic analysis for many years. Missouri DOT 

started their systemic safety efforts in the mid-2000s. More recently, Minnesota DOT has 

conducted systemic analysis for every county in the State. Figure 5.11 shows an example 

crash tree analysis (hypothetical data), which is a common step in systemic analysis. This 

figure shows that of the 191,000 statewide urban crashes, 3,000 are bicycle related and 280 

are fatal and serious injury crashes. Fatal and serious injury bicycle crashes are most common 
5.0 USING SAFETY ANALYSES FOR PLANNING

45

on Principal Arterials, and on the Principal Arterials the fatal and serious injury crashes are 

roughly equally distributed between intersection and nonintersection crashes. A crash tree 

allows the user to identify trends per mode and facility type.

Figure 5.11 Flowchart. Example Crash Tree Analysis 

Urban 

Crashes

191,000

4,000

Pedestrian

3,000 (1.5)

560 (14.0)

Bicycle

3,000 (1.5)

280 (7.0)

Motorcycle

5,000 (2.6)

680 (17.0)

Commercial 

Vehicle

10,000 (5.2)

160 (4.0)

Two or More 

Vehicles

140,000 

(73.3)

1,760 (44.0)

Single 

Vehicle

30,000 (15.7)

560 (14.0)

Local Street

660 (22.0)

72 (26.0)

Collector

600 20.0)

48 (17.0)

Minor 

Arterial

720 (24.0)

67 (24.0)

Not 

IntersectionRelated

297 (45.0)

28 (40.0)

IntersectionRelated

363 (55.0)

44 (20.0)

Not 

IntersectionRelated

208 (32.0)

17 (35.0)

IntersectionRelated

408 (68.0)

31 (65.0)

Not 

IntersectionRelated

201 (28.0)

20 (30.0)

IntersectionRelated

518 (72.0)

47 (70.0)

Interstate

90 (3.0)

8 (3.0)

Principal 

Arterial

930 (31.0)

84 (30.0)

Not 

IntersectionRelated

316 (34.0)

44 (45.0)

IntersectionRelated

614 (66.0)

47 (55.0)

Legend

Crash Type

Total Crashes (% of Parent Category)

Fatal and Serious Injury Crashes (Percent of Category)

Source: Sample data, Cambridge Systematics, Inc., 2015.

5.6 Corridor and Intersection Planning Safety Analysis

Typical corridor or intersection planning projects will evaluate the impact different facility cross

section alternatives have on mobility, reliability, environmental impacts, or construction costs. 

These projects can and should include an evaluation of changes in crash frequency or severity 

that can be associated with various roadway cross sectional features. Traffic volume and 

roadway features, such as the number of lanes, form of intersection control, lighting, shoulder 

type and width, horizontal curvature, and many other features, influence the expected crash 

frequency and severity at an intersection or along a roadway segment. The inclusion of these 

variables in the analysis greatly improves the ability to predict future safety outcomes.

Evaluating alternatives that address safety performance can help agencies determine 

appropriate short- or long-term safety goals, objectives, and countermeasures. 
5.0 USING SAFETY ANALYSES FOR PLANNING

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5.6.1 Crash Diagrams

Crash diagrams are hand-drawn or computer-generated sketches of the type and severity of 

crashes at a site. The site (e.g., roadway segment or intersection) is sketched in plan view. 

Each crash is sketched onto the drawing in the approximate location where the crash occurred. 

Arrows and other common symbols are used to represent each crash type. The diagram makes 

it possible to visualize the location, type, and number of crashes of each type to see if there 

are any trends. Figure 5.12 is a simplified crash diagram for a hypothetical intersection. In this 

example, there are a five of rear-end crashes at the south approach to the intersection, two 

left-turning crashes, and one right angle crash. Additional notes could be added to the 

diagrams to include severity of the crashes, time of day, weather, or lighting conditions. 

Figure 5.12 Graphic. Example Simplified Collision Diagram

Source: Sample data, Cambridge Systematics, Inc., 2015.
5.0 USING SAFETY ANALYSES FOR PLANNING

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5.6.2 Crash Modification Factors

A crash modification factor (CMF) is a multiplicative factor used to compute the expected 

number of crashes at a site after implementing a given countermeasure. The expected (or 

observed) crash frequency at the site without treatment is multiplied by the value of the CMF 

to estimate the new number of crashes at the site after implementing the treatment. A CMF 

greater than 1.0 indicates an expected increase in crashes, while a value less than 1.0 

indicates an expected reduction in crashes. For example, a CMF of 0.8 indicates an expected 

safety benefit; specifically, a 20 percent reduction in crashes. A CMF of 1.2 indicates an 

expected degradation in safety; specifically, a 20 percent expected increase in crashes.

The FHWA CMF Clearinghouse is one of the current tools available for identifying and selecting 

countermeasures. The CMF Clearinghouse serves as a central online repository of CMFs. Users 

are able to query the Clearinghouse’ database to identify treatments, the crash type and 

severity the treatment will address, and the CMF associated with the treatment. For each CMF, 

the database provides users with published information, such as how it was developed, the 

research quality behind the CMF, and a link to the publication from which the CMF was 

extracted. Based on this, users are able to determine the most applicable CMF for their 

condition.

The Clearinghouse is updated regularly to incorporate the latest safety research. The CMF 

Clearinghouse also reports which CMFs are included in the HSM; these CMFs typically have a 

higher quality rating given the strict HSM inclusion criteria.

In the planning process as alternative roadway configurations for a site or corridor are 

considered, the CMFs for various treatments can be included in the investigation to consider 

the potential safety effects of different features and again include a quantitative safety 

evaluation criterion as part of the analysis.

5.6.3 AASHTO HSM Predictive Method

The AASHTO HSM predictive method calculates an expected number and severity of crashes at 

sites with similar geometric and operational characteristics for one or more of the following: 

existing conditions, future conditions, or roadway design alternatives.

The predictive method provides a quantitative measure of expected average crash frequency 

under both existing conditions and conditions that have not yet occurred. This allows proposed 

roadway conditions to be quantitatively assessed along with other considerations, such as 

community needs, capacity, delay, cost, right-of-way, and environmental considerations.

The predictive method can be used for evaluating and comparing the expected average crash 

frequency of situations, such as the following:

• Existing facilities under past or future traffic volumes;
5.0 USING SAFETY ANALYSES FOR PLANNING

48

• Alternative designs for an existing facility under past or future traffic volumes;

• Designs for a new facility under future (forecast) traffic volumes;

• The estimated effectiveness of countermeasures after a period of implementation; and

• The estimated effectiveness of proposed countermeasures on an existing facility (prior to 

implementation).

Part C of the AASHTO HSM presents the detailed 

methodology for applying the predictive method 

on two-lane rural highways, rural multilane 

highways, urban and suburban arterials, and 

freeway facilities. The HSM predictive method is 

based on safety performance functions (SPF), 

crash modification factors and calibration factors. 

SPFs are equations used calculate predicted crash frequency as a function of traffic volume and 

roadway characteristics. Crash modification factors and calibration factors are used to modify 

the prediction to reflect local conditions. The Interactive Highway Design Model (IHSDM) is a 

software available at no cost from FHWA, which can be used to apply the predictive method 

from the HSM. Florida, Washington, Utah, Illinois, and Ohio DOTs have been very active in 

training and deploying HSM predictive methods. Planners can reach out to the safety analysis 

division within the DOT to initiate or obtain assistance on these more advanced safety analysis 

techniques. Spreadsheets also are available for applying the HSM predictive method 

(NCHRP 17-38 HSM Predictive Method Spreadsheets). 

Interactive Highway Design Model

IHSDM is a safety decision support tool 

that provides estimates of a highway 

design's expected safety and operational 

performance.
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6.0 Applying Safety Data and Analysis to Inform 

Decisionmaking

Chapter 4.0 and chapter 5.0 provide planners with an understanding of the types of safety 

data and analysis techniques available for use in the transportation planning process. 

Chapter 6.0 describes how to use the information to develop data-driven safety goals, 

objectives, performance measures, and projects.

6.1 Institutional Considerations

6.1.1 Legislation

Transportation legislation dating back to the Intermodal Surface Transportation Efficiency Act 

(ISTEA) and continuing through MAP-21 makes clear the importance of safety in transportation 

planning. Safety has long been one of the factors transportation planners are required to 

consider during the transportation planning process and reflected in statewide and regional 

transportation plans. More recent requirements 

have looked to strengthen the link between SHSPs 

and other transportation planning processes and 

documents. As a result, planners are developing 

transportation safety goals and objectives based 

on the results of data and analysis as well as by 

adopting or customizing safety goals identified in 

other planning documents, such as the SHSP.

6.1.2 Collaboration and Coordination

The development of transportation safety goals, 

objectives, performance measures/targets, and 

projects/programs relies on obtaining crash data 

and conducting analysis. Crash databases, data 

owners, and analysis tools differ across States, but 

a critical step in the planning process is to 

collaborate across State and regional agencies to 

understand where the data is housed, how it can 

be obtained, and what technical resources exist to 

analyze the information.

Examples of Collaborating 

on Safety Planning

Where Data is Housed: In 

Alabama, the DOT informs all 

transportation planning agencies of 

the CARE system, which provides 

convenient access to crash data.

How to Obtain Data: In Louisiana, 

transportation planners know to 

coordinate with the DOTD Highway 

Safety Section staff for safety data 

and analysis. In New Mexico, 

planners submit an email request to 

the New Mexico DOT Crash Records 

reporting office.

What Technical Resources Exist: 

Transportation agencies in Ohio use 

the Geographic Crash Analysis Tool 

(GCAT). To ensure planners can 

utilize the tool, Ohio DOT offers 

frequent training opportunities.
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An opportunity for coordination can come through 

multidisciplinary collaboration. As part of the 

transportation planning process, committees are 

formed to provide input into a plan. To ensure 

safety interests are represented during a plan 

update, a transportation agency can choose to form 

a safety subcommittee or invite safety stakeholders 

to participate.

The SHSP and TRCC planning, update, and/or 

implementation processes also are essential 

processes planners should be engaged in for 

purposes of information sharing, and coordination. 

By being actively involved, planners will:

• Gain exposure to a data-driven safety planning 

process, which could be replicated during their 

transportation planning processes;

• Gain access to and better understand available 

crash, roadway, and volume data and tools to 

use it;

• Connect with other transportation safety 

stakeholders;

• Understand the safety emphasis areas and 

proven strategies, which could be adopted and 

customized for other transportation planning 

documents; 

• Influence and coordinate safety goals and 

objectives in order to integrate the processes 

(e.g., SHSP and transportation planning); and

• Understand the SHSP which is a strategic 

document and does not include projects, but 

planners will still gain an understanding of the 

various funding and prioritization processes to 

better position themselves to leverage limited 

safety improvement resources.

Committees

For a recent LRTP update, the York 

MPO in Pennsylvania formed a safety 

committee to provide input into the

Plan. The committee included 

representation from MPO staff, local 

law enforcement, PennDOT District 

staff, the County Center for Traffic 

Safety, and the local Bicycle Council.

Other agencies incorporate safety 

stakeholders into transportation 

focused committees. For an 

Interchange Area Management Plan 

in Oregon, the DOT invited State 

traffic safety designers as well as the 

local police and fire departments to 

be part of the committee, to inform 

safety considerations in the 

transportation plan.

Participation in Committees

In Florida, State DOT planners and 

MPOs are encouraged to participate 

in the SHSP planning and 

implementation processes. As a 

result of this engagement, planners 

are able to effectively utilize Statedeveloped data to incorporate the 

SHSP goals and performance 

measures into their processes. The 

MPOs also provide their local data to 

the State and report activities that 

relate to SHSP to the State via a 

database entry system.

In both Michigan and Vermont, a 

high level of coordination exists 

between the TRCC’s strategic 

planning efforts and the SHSP effort. 

This arrangement ensures planners 

can address any data-related issues 

related to safety planning in a 

timely manner. 
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6.1.3 Organizational Capacity

Planners often wear many different hats, dealing with an array of transportation topics. 

Because of this, they may not have the staff or resources to adequately address safety, instead 

relying on the State SHSP to address all safety needs and priorities in the State. However, as 

mentioned in section 3.2.2, the SHSP does not necessarily address all the statewide or regional 

transportation safety issues and needs. Opportunities to begin dedicating resources to study 

transportation safety include the following:

• Weave safety into other plans. Considering safety in the planning process does not 

necessarily entail the development of a stand-alone safety plan. Some agencies identify 

efficiencies by considering safety within the context of other planning documents. For 

example, the Hillsborough MPO in Florida has integrated crash analysis into the congestion 

management process. Other examples could be related to freight planning, bike and

pedestrian plans, or corridor planning.

• Develop reports or other technical assistance. Many State DOTs and some MPOs 

create custom crash data reports to reduce the burden of agencies completing their own 

analysis. For instance, Pennsylvania DOT creates a high-crash location list in GIS for each 

of its MPOs and RPOs every two years. They use these lists during planning and project 

prioritization processes. Other agencies will identify opportunities to provide safety 

technical assistance—for instance, Louisiana DOTD relies on its local technical assistance 

program (LTAP) to assist local jurisdictions with the identification of safety issues and 

priorities.

• Invest in tools that can advance analysis. A number of tools and approaches exist to 

conduct crash data analysis, but some need to be purchased and all require staff resources 

to run and manage. Consider which tool or tools might make sense to your agency and 

during budget cycles, and identify what opportunities exist to leverage resources to support 

safety analysis.

• Hire consultants. Without in-house staff expertise, some agencies hire consultants to 

prepare crash analysis and assist with program/project identification.

• Enlist University assistance. State DOTs and MPOs may rely on students or programs at 

universities and colleges to perform safety analysis activities.

• Add safety staff or make safety part of someone’s job responsibility. If feasible, 

agencies may create a position for a safety planner or, at a minimum, ensure it is 25 to 

50 percent of an appropriate technical representative’s job responsibilities.

6.1.4 Funding

Transportation safety planning activities can be funded using FHWA statewide or metropolitan 

planning (PL), HSIP, SPR, NHTSA 402 and 405, or FMCSA funds. Some States also may have 

discretionary funds for planning activities that could be used for safety. For example, Arizona 
6.0 APPLYING SAFETY DATA AND ANALYSIS TO INFORM DECISIONMAKING

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DOT administers the Planning Assistance for Rural Areas (PARA) programs, which funds 

multimodal planning studies, some of which have addressed safety issues and needs. 

6.2 Using Safety Data and Analysis to Develop Goals and

Objectives

The purpose of setting goals and objectives during 

the planning process is to identify the desired 

outcomes for the transportation system and how 

those outcomes can be achieved. 

6.2.1 Qualitative Safety Goals

Safety goals can be developed in a number of ways. 

A primary focus of Section 6.2.2 is to provide 

examples of data-driven goals, but it is clear that 

not all goal setting occurs in a quantitative manner. 

Qualitative goal setting can be just as effective 

because, at a minimum, it establishes safety as a 

priority during the planning process and sets the stage for the identification of data-driven 

objectives, performance measures and targets, and projects to help meet that safety goal. 

Types of qualitative goal setting include:

Safety Vision

Prior to establishing goals and 

objectives, many agencies will 

develop a long-term vision for the 

transportation system to guide 

programs, policies, and projects. 

Some vision statements are 

transportation focused but 

incorporate elements of safety. 

Other agencies have developed 

safety-specific vision statements, 

such as Towards Zero Deaths (TZD). 

The Mid-America Regional Council

has taken this latter approach. 

• Safety Planning Factor: It is common for transportation agencies to reference the 

Federally required planning factors as their transportation goals. When it comes to safety, 

“increase the safety of the transportation system for motorized and nonmotorized users,” 

or something similar, can be utilized as the safety goal for a planning document.

• Public/Stakeholder Input: Another common 

approach is to identify transportation goals 

through committee, stakeholder, and/or public 

input. Information can be obtained either 

through surveys, comment cards, open houses, 

committee meetings, mapping tools, or other. 

This type of input can vary drastically 

depending on stakeholders or public 

participants, but presenting the same 

information to everyone and asking pointed 

questions can reduce the possibility of wide 

variations. Planners can utilize the information 

to inform a single or multiple goals. The goal 

could be safety specific or safety could be 

woven into other goals. 

Example of Safety Goal Setting—

Public and Stakeholder Input

During a committee meeting for the 

development of their Community 

Safety Transportation Plan, the City 

of Hamilton (Montana) asked 

committee members to discuss their 

safety goals. Input included increase 

education regarding texting and 

driving, address increased speed 

around schools, continue safe routes 

to school, and many more. From 

this input, the following safety goal 

was created: preserve and enhance 

the quality of life by improving 

transportation safety for all users.
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• Goals in Other Plans: Another qualitative approach to safety goal setting is to review and 

adopt applicable goals from other planning documents. Documents to review include the 

SHSP, HSP, Commercial Motor Vehicle Safety Plan, State and MPO LRTPs and Modal Plans, 

and Comprehensive Plans. Ideally, planners should have a sense, based on public/

stakeholder input or preliminary analysis, as to what the key safety issues/needs are, so 

only relevant goals will be adopted.

6.2.2 Data-Driven Safety Goals

The results of data analysis identify general as well as 

specific safety issues and needs and can be used to 

develop transportation goals. The data used to develop 

safety goals can range from basic analysis, such as 

reviewing the results of crash frequency to more 

sophisticated analysis, like network screening to identify 

more specific goals.

SHSP Goals

MAP-21 requires that the 

transportation planning 

process must integrate directly 

or by reference, the goals, 

objectives, performance 

measures, and targets 

described in other State 

transportation plans, such as 

the SHSP.

Trend Analysis

Many agencies use basic time trend analysis to understand how safety fatalities and serious 

injuries have changed over the years. Reviewing trends on an annual basis can encourage an 

agency to consider safety more prominently as a goal area. For instance, if safety trends 

demonstrate a high number of crashes or increases over time, safety should be recognized as 

a priority goal area over the long term. By looking at the trend data in figure 6.1, an agency 

could conclude that both serious injuries and fatalities are a concern based on the numbers

and a safety goal would be appropriate to develop. How the goals are stated can vary, but 

based on this amount of data, agencies could likely develop a broad safety goal, such as: 

“Increase safety for all users by reducing transportation-related fatalities and serious injuries.”
6.0 APPLYING SAFETY DATA AND ANALYSIS TO INFORM DECISIONMAKING

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Figure 6.1 Chart. Trends

Safety Goal Setting

1,693 1,641

1,495

1,292

1,247 1,223 1,199

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

2006 2007 2008 2009 2010 2011 2012

Serious Injuries Fatalities

Serious Injuries Fatalities

Source: Sample data, Cambridge Systematics, Inc., 2015. 

Contributing Factors

For every vehicle crash, there are numerous factors contributing to its severity. Many agencies 

will review and analyze the different elements (i.e., speeding, alcohol, unbelted) that played a 

role in the crash to draw conclusions regarding program and project investments. This 

information also can be used to establish safety goals. Figure 6.2 shows data reviewed by the 

Capital Region Safety Coalition in Louisiana during the development of a regional safety plan. 

Based on this data, the coalition decided to establish four safety-specific goals, which were: 

• Reduce roadway departure fatalities;

• Reduce impaired driving fatalities;

• Reduced occupant protection-related fatalities; and

• Reduce young driver fatalities.

However, goal statements based on contributing factor data, can vary. For instance, an agency 

may still wish to draw broad safety goals based on this data. Different text options could be: 

• Increase safety for all users by reducing transportation-related fatalities; or
6.0 APPLYING SAFETY DATA AND ANALYSIS TO INFORM DECISIONMAKING

55

• Improve safety by reducing the prevalence of infrastructure, impaired driving, occupant 

protection, and young driver-related fatalities.

Figure 6.2 Chart. Contributing Factors

Safety Goal Setting

Source: Louisiana Highway Safety Research Group, Capital Region Transportation Safety Coalition 

Level II Data. 

Other Characteristics

Agencies review crash data in a multitude of ways, more than can be presented in this section; 

however, other ways planners may look at data, which can be extrapolated into safety goals is 

by geography (rural and urban), mode of travel (single vehicle, commercial vehicle, 

motorcycle, etc.), or functional class. Figure 6.3 examines functional class, showing that a 

higher proportion of crashes are occurring on principal arterials. As a result, an agency may 

decide to create a specific safety goal, to focus on reducing severe crashes on principal 

arterials. The goal could read as: “Improve multimodal safety by reducing crashes on principal 

arterials throughout the State.” This same type of approach—reviewing data and developing 

goals—could be done when looking at data by geography and mode of travel.
6.0 APPLYING SAFETY DATA AND ANALYSIS TO INFORM DECISIONMAKING

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Figure 6.3 Chart. Functional Class

Goal Setting

15%

12%

16%

33%

24%

18%

14%

17%

35%

16%

Local Streets Collector Streets Minor Arterial Principal Arterial Interstate

Percent of Total Crashes Percent of Severe Crashes

Source: Sample data, Cambridge Systematics, Inc., 2015.

Advanced Analysis

The results of more sophisticated analysis, such as network screening or systemic analysis also 

can provide useful information for goal setting. Network screening, for instance, provides 

planners with information on specific segments or intersections that have a safety record

higher or lower than expected. Table 6.1 shows sample high-priority intersections for a region. 

Based on this data, a general safety goal could be developed to capture the entirety of the 

network screening process or a specific goal could be identified to consider intersection safety. 

Possible safety goals stemming from a network screening analysis include:

• General Goal: Increase safety for all users by reducing transportation-related fatalities 

and serious injuries at sites with the most potential for safety improvements; or

• Specific Goal: Improve safety by reducing fatalities and serious injuries at intersections.
6.0 APPLYING SAFETY DATA AND ANALYSIS TO INFORM DECISIONMAKING

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Table 6.1 Network Screening

Safety Goal Setting

Final 

Rank Intersection

Frequency 

Rank

Crash Rate 

Rank

EPDO 

Rank

Composite 

Rank

1 U.S. Highway 60 at Radanovich Boulevard 4 3 2 9 

2 SR 87/Beeline Highway at Longhorn Road 

at U.S. Highway 260

1 1 9 11

3 SR 260 Valley Road at Highline Drive 4 5 12 21

3 SR 87/Beeline Highway at Bonita Street 10 4 7 21

5 SR 188/Apache Trail at U.S. Highway 60

at Russell Road

2 10 10 22

6 U.S. Highway 60/Ash Street at Hill Street 7 11 8 26

7 U.S. Highway 60/Ash Street at Hill Street 6 7 15 28

8 U.S. Highway 60 at Escudilla Drive at 

Main Street

3 2 24 29

9 SR 347/John Wayne Parkway at 

Papago Road

12 18 3 33

10 SR 87/Beeline Highway at Main Street 7 26 5 38

Source: Cambridge Systematics, Inc., unpublished, Central Arizona Governments.

Developing a safety goal or goals may not be entirely data-driven, but when possible, available 

safety analysis results, either qualitative or quantitative, can be used to inform this initial 

portion of the planning process.

6.2.3 Data-Driven Safety Objectives

Regardless of the approach used to establish transportation safety goals, objectives are 

necessary to define how the goals will be met. Ultimately, objectives should provide enough 

specificity to help planners identify programs and projects that will meet the goals of the 

planning document. Although objectives can be identified in a qualitative fashion, such as 

through public/stakeholder input or adopted from other planning documents, elements of data 

analysis should still be included to ensure objectives are specific and measurable and progress 

towards the goals can be tracked. An example of this is found in the South Carolina Multimodal 

Transportation Plan shown in figure 6.4. The safety goal itself is general, but the objectives are 

descriptive and measurable to ensure the South Carolina DOT understands exactly how to 

achieve its safety goal. 
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Figure 6.4 Screenshot. Defining Safety Goals with Measurable and 

Specific Objectives

Source: South Carolina Department of Transportation 2040 Multimodal Transportation Plan, 

December 2014.

Public and Stakeholder Input

Public and stakeholder input can be used to set 

objectives, but as described in the goals section, 

this type of input has the potential to yield a 

number of different priorities. When relying on this 

information to develop objectives, it is important to 

share data results and priorities in advance to 

better shape the input public and stakeholders 

provide. For instance, if bicycle and pedestrian 

safety has been identified as an issue in your State 

or region, available crash data trends and 

information about potential treatments (i.e., 

Countermeasures that Work (CTW), or FHWA CMF

Clearinghouse) should be shared with the public and stakeholders to guide the input. Doing 

this will increase the chances that objectives, and eventually strategies/actions, are developed 

based on data versus perceptions.

Objective Setting—

Public and Stakeholder Input

The Capital Region Transportation 

Safety Coalition in Louisiana utilized 

data to identify four safety goals. 

Based on this, stakeholders 

developed specific objectives to 

achieve the goals. Stakeholders were 

provided with a list of 

countermeasures that work and 

other proven strategies to assist 

them in the selection of data-driven 

objectives.

Customizing Objectives From Other Plans

Transportation planning documents typically include specific objectives to achieve the goals of 

a plan. In developing or updating a plan, it is not always necessary to start from scratch, but 

instead review other objectives already developed in other plans, such as the SHSP. This 
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59

approach to objective setting can be quantitative. For example, an RPO in California, the 

Del Norte Local Transportation Commission, identified the safety issues and needs for their 

region based on data and stakeholder input. Equipped with this knowledge, agency planners 

were better able to review and customize the goals and objectives outlined in the California 

SHSP and customize those to meet the needs in their own planning environment, as shown in 

figure 6.5. When reviewing the goals or objectives from other plans try to review statewide, 

regional, or local crash data first to have a better understanding of what objectives would be 

relevant to your transportation plan. 

Figure 6.5 Screenshot. Adopting Objectives/Strategies from Other 

Planning Documents

Source: Del Norte Local Transportation Commission Regional Transportation Plan, June 2011. 

Crash Analyses

The results of crash analyses also play a large role in objective setting. Data can assist with 

setting numeric or specific objectives, outlining how the safety goals will be achieved. For 

example, by reviewing rolling five-year average crash data trends, it is possible to identify: 

1) a baseline for fatalities and serious injuries by modal or topic area (i.e., roadways, bicycle, 

freight, transit, intersections, segments, etc.); and 2) the extent to which fatalities and serious 

injuries are increasing or decreasing overall, or by specific mode or topic.
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If the baseline data shows roadway crashes are an issue and the trend data shows that these 

crashes have been steadily increasing over the previous five years, safety goals and objectives 

may be:

Goal—Increase the safety of the transportation system for all users.

• Potential objectives: 

– Reduce the total number of crashes on roadways in the State (or region); or

– Reduce the total number of crashes by five percent by 2020.

If the baseline data shows motorcycle crashes as an area of concern, goals and objectives may

be:

• Potential goal: 

– Increase the safety of the transportation system for all users; or

– Improve motorcycle safety throughout the transportation network.

• Potential objectives: 

– Reduce motorcycle fatalities and serious injuries in the State (or region); or

– Reduce the number of motorcycle fatalities and serious injuries by five percent by 2030.

If additional data is available beyond the basic trend information, it is possible to specify 

objectives even further. For example, if the majority of crashes are known to take place on 

major arterials or are the result of people running off the road, more specific objectives could 

be:

• Identify systemic, low-cost countermeasures to implement to reduce roadway departure 

fatalities and serious injuries; and

• Identify the major arterials with high-crash severity indices to determine the need for road 

safety assessments and safety improvements.

The results of other analyses, besides trend analysis, also can help shape safety objectives. 

Figure 6.6 shows the results of a systemic analysis (total crashes are shown in the left bar and 

severe crashes are shown in the right bar). This data tells planners that pedestrian, bicycle, 

and motorcycle crashes are substantially overrepresented among severe crashes. 
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Figure 6.6 Chart. Using the Results of Analysis to Inform Objectives

Source: Sample data, Cambridge Systematics, Inc., 2015.

Equipped with this information, safety goals and objectives may be:

Goal—Reduce fatalities and serious injuries on the transportation system for all users.

• Objective: Reduce bicycle crashes.

• Strategies: 

– Identify low-cost bicycle safety improvements for local roads;

– Promote bicycle public education campaigns, including the shared use of roadways; and

– Facilitate coordination among jurisdictions and business to address missing bicycle 

links.

Another option may be:

Goal—Reduce bicycle crashes.

• Objective: 

– Reduce the number of crashes involving bicyclists by five percent; or

– Implement 5 to 10 percent of the safety projects in the bicycle plan.

2% 1% 2%

5%

16%

75%

16%

8%

18%

4%

15%

39%

Pedestrian Bicycle Motorcycle Commercial

Vehicle

Single Vehicle Two or More

Vehicles

Percent of Total Crashes Percent of Severe Crashes
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The development of data-driven objectives provides planners with specific information for how 

they can accomplish their safety goal.

6.3 Using Safety Data and Analysis to Develop Performance 

Measures and Targets

The purpose of setting performance measures and targets during the planning process is to 

have a means to track and evaluate progress towards transportation goals and objectives. If 

targets are not being met, it provides planners the opportunity to reevaluate programs and 

projects to identify how to invest differently.

6.3.1 Performance Measures

Performance measures are a useful tool to understand programmatic progress towards 

transportation goals. Every DOT and MPO will eventually need to adopt the national 

performance measures, which include number and rate of fatalities and serious injuries. These 

measures will help transportation agencies track progress towards their safety goal(s). 

Table 6.2 depicts an example of what this could look like in practice.

Table 6.2 Sample Safety Goal and Nationally Required Performance 

Measures

Goal Objective

Performance 

Measure Data

Achieve a significant reduction in 

traffic fatalities and serious injuries 

on all public roads

Reduce fatalities Number of fatalities 

per year

FARS

Achieve a significant reduction in 

traffic fatalities and serious injuries 

on all public roads

Reduce serious 

injuries

Number of injuries 

per year

State Data

Achieve a significant reduction in 

traffic fatalities and serious injuries 

on all public roads

Reduce fatality rates Fatality rate 

100 million VMT

FARS, HPMS

Achieve a significant reduction in 

traffic fatalities and serious injuries 

on all public roads

Reduce serious 

injury rates

Serious injury rate 

100 million VMT

State Data, HPMS 

Source: Sample text, Cambridge Systematics, Inc., 2015.

To track performance measures on a regular basis, agencies will utilize annual or average data 

(combining a certain number of years of data into an average for a single year) from FARS or 

the State crash database. An example of annual performance tracking is shown in figures 6.7 

and 6.8 from the Lehigh Valley Planning Commission in Pennsylvania. 
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Figure 6.7 Chart. Tracking National Performance Measures

Fatalities, 2008-2012

Source: Lehigh Valley Planning Commission Traffic Safety Plan for the Lehigh Valley 2008 to 2012. 

Figure 6.8 Chart. Tracking National Performance Measures

Major Injuries, 2008-2012

Source: Lehigh Valley Planning Commission Traffic Safety Plan for the Lehigh Valley 2008 to 2012. 

Other agencies may want to set performance measures beyond what is nationally required. To 

identify other performance measures, the first step is to review the goals and objectives in a 

transportation plan and identify which performance measures will accurately track their 

progress. If goals and objectives were developed based on data, data also should be available 

to track performance. Table 6.3 provides an example of the direct relationship between goals, 

objectives, performance measures, and data. 
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Table 6.3 Relationship between Performance Measures 

and Goals and Objectives

Goal Objective Performance Measure Data Sources

Increase the safety of the 

transportation system for 

all users

Reduce roadway 

fatalities

Number of roadway 

fatalities per year

FARS

Increase the safety of the 

transportation system for 

all users

Reduce bicycle crashes Number of bicycle 

crashes per year

Local law enforcement 

crash database

Increase the safety of the 

transportation system for 

all users

Reduce transit crashes Number of preventable 

transit crashes per 

100,000 miles

National Transit 

Database

Source: Sample text, Cambridge Systematics, Inc., 2015.

6.3.2 Performance Targets

Performance targets are numeric and describe the extent to which an agency will address its 

performance measures, taking into account resources and funding. They should be developed 

in relationship to the goals, objectives, and performance measures. Whereas performance 

measures are a tool to help planners and communities assess progress towards goals and 

objectives, targets specify what your agency would like to achieve in those goal/objective 

areas. Table 6.4, from the RTC of Washoe County in Nevada, illustrates an example of the 

connectivity between goals, measures, and targets.

Table 6.4 Relationship between Goals, Performance Measures, 

and Targets

Transportation Plan Goal Annual Performance Measure Target

Improve Safety Preventable transit accidents per 100,000 

miles of service

0 

Improve Safety Number of crashes and number of crashes 

per VMT

Reduce by 50% by 2020

Improve Safety Number of serious injuries per VMT Reduce by 50% by 2020

Improve Safety Number of fatalities and fatalities per VMT 0; Reduce by 50% by 

2020

Improve Safety Miles of bicycle lane added and percent of 

Bicycle Pedestrian Master Plan completed

3% to 7% of plan 

implemented per year

Improve Safety Miles of sidewalk added or enhanced and 

percent of the Americans with Disabilities Act 

(ADA) Transition Plan completed

3% to 7% of plan 

implemented per year

Source: RTC of Washoe County Annual Report, 2013.
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Some DOTs and MPOs have begun setting targets for 

the national performance measures (number and rate 

of fatalities and serious injuries) and other measures, 

as interested (as shown in the RTC example). 

Although a number of different target-setting 

approaches have been identified, at the core, is data 

and analysis. One of the primary data-driven ways to 

set targets is through trend analysis. Using this 

approach, multiple years of data can be reviewed to 

establish a baseline, and then targets can be set based on:

Target Setting Resource

Further information on the state 

of the practice in safety target 

setting as well as ideas for 

developing or updating 

transportation safety targets, can 

be found in the FHWA Safety 

Target Setting Final Report.

• Previous annual or average trend reductions (staying the course); and

• A prediction based on the expected safety benefits of programs and projects (this would 

entail an understanding of the crash reduction factors associated with types of 

transportation projects and the extent to which they would be implemented.)

Table 6.5 demonstrates how data is identified and trends are analyzed to set safety 

performance targets.

Table 6.5 Data-Driven Performance Targets Related to Safety Goal

Goal

Performance 

Measure Baseline Target Data Source

Increase the safety 

and security of the 

transportation system 

for motorized and 

nonmotorized users

Decrease five-year 

average fatalities

125 

(2007 to 2011)

Decrease fatalities

by 5% by 2020 

FARS

Increase the safety 

and security of the 

transportation system 

for motorized and 

nonmotorized users

Decrease five-year 

average serious

injury crashes

243 

(2007 to 2011)

Decrease serious

injury crashes by 

8% by 2020

State DOT 

database

Increase the safety 

and security of the 

transportation system 

for motorized and 

nonmotorized users

Decrease five-year 

average 

pedestrian and 

bicycle crashrelated injuries

36 

(2007 to 2011)

Decrease 

pedestrian and 

bicycle crashrelated injuries by 

3% by 2020 

Local law 

enforcement crash 

data

Source: Sample text, Cambridge Systematics, Inc., 2015.

Table 6.6 and figure 6.9 demonstrate another example of how trend data can be utilized to 

establish data-driven safety targets for identified goals and objectives. The recommended 

target is to reduce fatalities by five percent by 2020, but the graphic demonstrates the range 

of target options based on previous years trends. 
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Table 6.6 Data-Driven Performance Targets Related to Safety Goal

Goal Objective

Performance 

Measure

Performance 

Target Data Source

Improve safety Reduce impaired

driving fatalities

Number of 

impaired driving 

fatalities

Reduce impaired 

driving fatalities by 

5% by 2020 based 

on five-year 

averages.

State DOT 

database

Source: Sample data, Cambridge Systematics, Inc., 2015. 

Figure 6.9 Chart. Data-Driven Performance Targets Related to 

Safety Goal

44 45 43 40 36 32 31 29 28 26 25 24 23

26

19

0

10

20

30

40

50

60

2004-20082005-20092006-20102007-20112008-20122009-20132010-20142011-20152012-20162013-20172014-20182015-20192016-2020

Fatalities per Year

Impaired Driving Fatalities (5-Yr. Avg.)

Recommended Impaired Driving Target (5% Annual Reduction)

Annual Impaired Driving Fatalities

3% Reduction

7% Reduction

Fatality Trend (5-Yr. Avg.)

Source: Sample data, Cambridge Systematics, Inc., 2015.

6.3.3 Evaluating System Performance

With limited resources, safety performance measures and targets help planners identify the 

extent to which safety goals and objectives are being met. Monitoring crash trends and targets 

over time will demonstrate whether crash numbers have increased or decreased. An increase 

would trigger a review of goals and objectives to determine where future funding could better 
6.0 APPLYING SAFETY DATA AND ANALYSIS TO INFORM DECISIONMAKING

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be utilized to improve performance. Decreases would suggest that safety goals and objectives

are working and would help determine whether to maintain future funding levels or direct 

resources to other safety issues. To evaluate performance, agencies may produce an annual 

report, report card, or utilize performance tracking information. For example, the Nevada DOT 

publishes a Performance Management Report on an annual basis. A portion of the 2014 Report

focuses on the goal of reducing crashes, discussing current and future performance, what 

strategies have been initiated and worked to reduce crashes, those that have not been 

successful, and future strategies that have the potential to lower crash numbers. This annual 

evaluation process allows the Nevada DOT to review progress towards performance goals and 

targets to re-evaluate programmatic investments. The Champaign Urbana Urbanized Area 

Transportation Study, an MPO in Illinois, produces an annual LRTP Report Card, which details 

the progress made on the goals and objectives in the document. Figure 6.10 demonstrates 

tracking dials, which provide a quick snapshot of system-level performance. This information is 

used by the MPO to adjust performance information, if necessary and revisit objectives and 

strategies for meeting safety goals. 

Figure 6.10 Graphic. Example Evaluation Report Card

Source: Champaign Urbana Urbanized Transportation Study 2014 LRTP Report Card, April 2015. 
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6.4 Using Safety Data and Analysis for Project Prioritization and 

Programming 

Tying together goals, objectives, performance measures and targets, are transportation and 

safety projects and programs. With limited resources, programs and projects should be 

identified, evaluated, and prioritized based on whether or not they address (or have the 

likelihood to address) the goals in the plan and the extent to which they contribute to meeting 

performance targets. Over time, it is possible to see the effect programs and projects have on 

the goals of the plan. These should be reevaluated regularly to ensure they are consistent with 

project and program outcomes. Figure 6.11 shows the relationship between the already 

discussed planning tasks and programs/projects.

Figure 6.11 Flowchart. Relationship between Data-Driven Planning 

Tasks and Programs/Projects

Goal: Improve transportation safety for all users

Objectives:

Reduce intersections fatalities and serious injuries

Reduce pedestrian fatalities and serious injuries

Target:

Reduce intersection fatalities and serious injuries by 

3% by 2030

Reduce pedestrian fatalities and serious injuries by 

3% by 2030

Programs and 

Projects:

Does this transportation or 

safety project help meet 

the data-driven goals, 

objectives, performance 

measures, or targets 

outlined in the plan?

In what ways?

To what extent?

Do goals, objectives, 

performance measures, 

and targets need to be 

reevaluated based on 

project/programmatic 

success or issues?

Performance Measures: 

Number of intersection fatalities and serious injuries

Number of pedestrian fatalities and serious injuries

Source: Cambridge Systematics, Inc.

To get to this point in the planning process, data have been utilized to pinpoint the key goals, 

objectives, and a reliable means to measure success. Now, it is time to decide how programs 

and projects can contribute solutions to the identified issues. There are two opportunities to do 

this—one is to incorporate safety evaluation criteria into the scoring approach for all 

transportation projects; and the other is to identify safety projects (i.e., crash reduction 

factors, countermeasures).
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6.4.1 Transportation Projects Integrating Safety

Many common evaluation criteria for transportation 

projects, such as mobility, congestion, and air quality, 

can be generated by travel demand model results. 

A common challenge for safety is the difficulty in 

predicting how transportation projects will influence 

safety over the medium and long term. The HSM is a 

tool that can assist planners identify and assess safety 

benefits for specific projects, which is summarized here, 

but described in detail in Section 5.6. However, basic 

data analysis also can be used to identify the safety 

benefits for transportation projects, helping to meet the 

goals outlined in the plan.

A range of data can be used during the transportation project prioritization process to help 

determine the safety benefits of a project. For instance, some States, including Utah, use a 

severity index to rank segments or intersections, determining where on the transportation 

system the safety issues lie. Planners then use this information when evaluating and 

prioritizing their transportation projects. If a potential transportation improvement is in a 

location with a high safety index or a comparable area, the opportunity exists to consider 

safety improvements within the context of the transportation project. As such, the project 

would score higher because, in addition to meeting other transportation goals, it also presents 

the opportunity to lower fatalities and serious injuries. Some States combine severity with 

other factors, use high-crash location lists, the results of network screening, or systemic 

analysis to consider how to incorporate safety considerations in the context of all their 

transportation projects. Figure 6.12 depicts the safety project prioritization criteria for highway 

and State bridge projects in the North Jersey Transportation Planning Agency metropolitan 

region. Figure 6.13 shows how the North Carolina DOT evaluates safety criteria for capacity 

projects to determine the need for future safety improvements with project limits.

Safety Index

Utah DOT has a safety index on 

State routes, including a 

mapping tool, which represents 

the degree of risk to the driver, 

in terms of both crash rate and 

severity. This tool has been 

used during corridor and other 

planning efforts to evaluate 

how to meet transportation 

safety goals and targets.

Figure 6.12 Screenshot. Incorporating Safety into Project Prioritization

Source: NJTPA Project Prioritization Criteria, January 2007.
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Figure 6.13 Screenshot. Incorporating Safety into Project Prioritization

Source: North Carolina DOT Strategic Prioritization Process. 

Another example of using safety analysis during 

transportation project prioritization comes from the 

Virginia DOT. Legislation requires Virginia DOT to 

develop and implement a quantifiable prioritization 

process for their transportation projects. Safety 

evaluation criterion is considered very highly in the 

scoring process for transportation projects. Each 

project must demonstrate the expected reductions in 

fatalities and serious injuries and rate. This is 

calculated by summing the annual number of crashes 

where a project is located, and multiplying it by the 

expected crash modification factor (this will be based 

on FHWA and Virginia-specific CMF). This type of prioritization attempts to identify appropriate 

safety improvements in correlation with the project prioritization instead of waiting until the 

scoping or design phase to officially address any potential safety improvements.

In Louisiana, the DOTD and all the MPOs must complete a Stage 0 Preliminary Scope and 

Budget Checklist for highway projects. To advance to Stage 1, Planning and Environmental, a 

number of criteria must be identified and addressed, including the results of any safety 

analyses performed and whether abnormal crash locations or overrepresented crash types 

Additional Prioritization 

Approaches

Examples from other agencies that 

incorporate safety criteria into their 

prioritization process to help meet 

the safety goals and objectives in 

their planning documents include: 

Erie County, Harrisburg Area 

Transportation Study, Indian 

Nations Council of Governments, 

and Centre County MPO. 
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exist within the project limits. This early review of projects ensures safety issues are captured 

and can be factored into project planning and design.

States also are starting to use the HSM during corridor planning and alternatives analysis to 

predict the safety performance of a roadway or intersection project based on physical 

characteristics. Part C of the HSM allows planners to quantify the safety effects of alternatives 

and compare those with other project criteria, such as capacity, delay, community needs, and 

others.

6.4.2 Safety Projects

Chapter 5.0 outlines the range of analysis options that can be undertaken to identify safety 

programs and projects. However, these programs and projects should be identified based on 

how well they meet the safety goals, objectives, performance measures, and targets identified 

earlier in the planning process.

The SHSP planning process and HSIP prioritization process provide a good example of this 

linkage. At the statewide level, significant reductions in traffic fatalities and serious injuries on 

public roads are meant to be accomplished through the development and implementation of 

the SHSP. The SHSP, a strategic document, outlines a framework for addressing safety using 

goals, emphasis areas, and strategies. However, it does not typically identify safety projects. 

Instead, additional analysis is conducted within the context of the SHSP goal and emphasis 

areas to drive the States’ HSIP investment decisions. Figure 6.14 describes the relationship 

between the SHSP and HSIP process. A number of States also have developed HSIP project 

prioritization manuals to ensure planners understand how to identify safety projects—one such 

example is from the Ohio DOT. 
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Figure 6.14 Flowchart. Relationship between the SHSP and HSIP

Source: FHWA Highway Safety Improvement Program Manual, January 2010.

This same approach also can work to identify and prioritize safety projects during the 

transportation planning process. Similar to the SHSP, the LRTP outlines strategic goals, 

objectives, and policies, which are used to guide decisionmaking for transportation 

investments. From here, additional analysis is typically needed to identify transportation safety 

programs and projects that support this framework. The following example from the Lee 

County MPO demonstrates the link between strategic transportation safety goals and 

objectives with the identification and development of safety programs/projects:

• LRTP Goals: For the 2035 Collier and Lee County LRTP update, planners identified the 

following safety goal: A transportation system that is safe and secure for existing 

and future residents, visitors, and businesses.

• LRTP Objectives: To support this goal, a number of objectives were developed, but two of 

particular note are: Safety planning shall be consistent with and reflect the goals 

and objectives of the State’s SHSP; and Reduce crash rates that involve conflicts 

among different modes of transportation through engineering and public 

education (autos, trucks, buses, trains, motorcycles, pedestrians and bicyclists).
6.0 APPLYING SAFETY DATA AND ANALYSIS TO INFORM DECISIONMAKING

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• From here, the question became how can safety in the region be enhanced and programs/

projects identified to make progress towards these established goal and objectives? This is 

where additional plans or studies can be used to analyze data further, identify potential 

countermeasures, and prioritize and select projects. The Lee County MPO took this 

approach during the development of a Bicycle and Pedestrian Safety Action Plan. The Plan 

was initiated to further explore and support the bicycle and pedestrian safety goals outlined 

in the Florida SHSP and the Lee County LRTP.

• Using crash data sources from the Florida Department of Highway Safety and Motor 

Vehicles as well as the FDOT Crash Analysis Reporting System, Lee County was able to 

identify a specific set of actions (figure 6.15), which included programs and projects, to 

support the overarching bicycle and pedestrian goals for the region. 

Figure 6.15 Graphic. Data-Driven Safety Actions

Source: Lee County Bicycle and Pedestrian Safety Action Plan, September 2013. 
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Departments of Transportation and some MPOs and 

other agencies use a similar approach to meet SHSP 

or LRTP goals, but do so by specifically identifying 

projects for HSIP funding. For example, the North 

Central Pennsylvania Regional Planning and 

Development Commission developed a goal in their 

LRTP to increase safety for roadway users, especially 

on their Core System Roadways. To implement this 

goal, they developed the North Central Regional 

Safety Study, which utilizes a data-driven approach to 

identify and prioritize safety projects throughout the region. The analysis included a 

combination of data from PennDOT, including, but not limited to, high-crash locations, crash 

clusters, and public input. This was used to identify locations, investigate the safety issues 

further at those locations, and eventually identify countermeasures to implement. From there, 

they prioritized locations based on a cost-benefit analysis and came up with a list of 45 safety 

improvements. Many of the priority projects were then included in the TIP for funding. 

FHWA Highway Safety 

Improvement Program Manual

Describes the relationship 

between the SHSP and HSIP and 

presents the HSIP’s four basic 

steps—analyze data, identify 

potential countermeasures, 

prioritize and select projects, and 

determine effectiveness. 

Another example where data and analysis are being used to identify safety countermeasures 

for HSIP funding is the South Jersey Transportation Planning Organization (SJTPO). The MPO 

administers a Local Safety Program, consisting of a five-step data-driven process. SJTPO 

shares the results of network screening and systemic analyses with local jurisdictions to 

identify priority locations. Once locations are identified, road safety audits are conducted to 

better understand the problems and possible solutions. Based on the results of the audits, 

safety countermeasures are identified and a benefit costs analysis is run to understand the 

effectiveness of each improvement. As a last step, a technical committee reviews the projects. 

This process of data review; data analysis; and safety program/project (countermeasure) 

selection can be utilized by any agency wishing to identify transportation safety projects. 

6.4.3 Evaluating Projects

With limited resources, programs and projects should be evaluated to identify if they address 

the goals in the plan and the extent to which they contribute to lowering fatalities and serious 

injuries. Options to better understand the contribution of a program or project to lowering 

fatalities and serious injuries is conducting before and after studies and employing proven 

countermeasures or crash modification factors whenever possible. 

Before and after studies provide planners with information on the extent to which investment 

decisions are meeting expectations. For safety improvements, planners would expect to 

understand how well individual projects or programs of projects, such as systemic 

improvements, are performing to lower fatalities and serious injuries. If positive changes are 

not being seen, planner can refocus investments to other options. As an example, Washington 

DOT has studied and evaluated its cable median barrier program since 2007 to understand the 

effects of the program and how significantly it improves safety. In addition to reviewing the 

program systemwide, they also monitor and evaluate installations for specific locations. As a 
6.0 APPLYING SAFETY DATA AND ANALYSIS TO INFORM DECISIONMAKING

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result of the ongoing before and after evaluation, Washington DOT has identified value in the 

cable median barrier program and plans to continue implementing it to save lives (figure 6.16).

Figure 6.16 Chart. Before and After Studies

Source: Cable Median Barrier Program in Washington State, June 2013. 

In addition to before and after studies, proven safety countermeasures can be considered an 

evaluation tool. When implemented appropriately, countermeasures increase the chances of 

lowering fatalities and serious injuries. For example, in Florida, the implementation of 

longitudinal rumble strips and stripes in the center of two-lane urban roads has reduced head 

on collisions by 64 percent. Tracking the results of implemented countermeasures in a State or 

region and then sharing the results can increase the use of certain types of safety projects, 

yielding positive evaluation results. Resources for countermeasure selection include 

Countermeasures That Work, PEDBIKESAFE, FHWA Proven Countermeasures, and the CMF 

Clearinghouse. Some States, like Oregon, have identified State-specific countermeasures.

7.0 CONCLUSIONS

77

7.0 Conclusions

This guidebook describes safety data collection and safety analysis approaches, with the goal 

of assisting State DOTs and MPOs apply the results to the performance-based transportation 

planning process. Soon, state and regional planning agencies will need to demonstrate how 

plans, programs, and projects are achieving progress towards meeting seven national goals, 

including safety. To do so will require planners to understand crash trends (where are we now)

and expected crashes (what are the future priorities); conduct safety analyses (what are the 

impacts of transportation safety in our State or region); and identify safety goals, objectives, 

measures and targets, and projects in planning documents (what is our framework for 

achieving a safer future). Current literature typically focuses on each of these tasks (data 

collection, analysis, and plan integration) individually, but this Guidebook provides a step-bystep approach for incorporating the results of safety data and analysis into existing 

transportation planning processes. Answers to the above questions are provided throughout 

the Guidebook, including both basic and advanced examples. 

APPENDIX A. TOOLS AND RESOURCES

79

Appendix A. Tools and Resources

The table below presents other available resources to learn more about crash data collection, 

safety analysis, and the integration of safety data in the transportation planning process.

Table A.1 Safety Data, Analysis, and Application Resources and Tools

Title Description

Data and Analysis 

Resources and Tools:

FHWA Roadway Safety Data 

Program Toolbox

This Web link includes an extensive list of 68 tools, including software, 

application guides, and information guides to help users navigate the 

many intricacies of data and analysis. Brief descriptions for each tool 

are provided, which includes many of the resources listed in this 

guidebook, such as the HSM, Safety Analyst, GIS, HSIP Manual, MIRE, 

MMUCC, systemic analysis, network screening, usRAP, and more. 

Data and Analysis 

Resources and Tools:

Roadway Safety Data Program 

(RSDP) Web site

The RSDP Web site provides information and resources that can help 

an agency improve its roadway safety data. Data and analysis are two 

areas of RSDP’s comprehensive safety program. Resources on the Web

site include: noteworthy practices, access to technical assistance, 

webinar recordings, case studies, and information on trainings.

Transportation Safety 

Planning Resources:

National Cooperative Highway

Research Program (NCHRP) 

Report 05-46, Incorporating 

Safety into Long-Range 

Transportation Planning, 2006

Report 546 was one of the first publications to provide MPO and DOT 

transportation planners with an approach to integrate safety in the 

planning process. It discusses opportunities to incorporate safety into 

goal and objectives setting and performance measures. Discussion of 

data collection approaches is limited, but the safety analysis section is 

robust. It includes a discussion of the fundamental concepts of safety 

analysis, appendix C lists a number of safety analysis tools, and 

appendix D discusses a planning-level forecasting model.

Transportation Safety 

Planning Resources:

NCHRP Report 08-76, 

Institutionalizing Safety in the 

Transportation Planning 

Process, 2011

Report 876 was the second in a NCHRP series discussing opportunities 

to integrate safety into the planning process. The document outlines a 

seven-principle transportation safety planning framework 

(Transportation Safety Planning (TSP) Framework) and describes a set 

number of specific strategies, instead of general concepts, to 

implement the Framework. The strategies were based on extensive 

practitioner input (surveys, interview, and focus groups). The report 

introduces the concept of using crash data to develop transportation 

safety goals, objectives, and performance measures; and includes basic 

ideas to get started with crash data collection and analysis to inform 

transportation plans. The report is limited to the fundamental steps a 

planner would need to take to get started with crash data and analysis.

Transportation Safety

Planning Resources:

NCHRP Report 811, 

Institutionalizing Safety in 

Transportation Planning 

Processes: Techniques, 

Tactics, and Strategies, 2015

Report 811 is based on input from five lead States and two peer States 

that tested the TSP Framework, developed for the original report. 

Transportation and safety planners in each State participated in a 

workshop to identify strategies, approaches, tools, and challenges for 

integrating safety throughout the transportation planning process in 

their own unique planning environments. The report captures these 

ideas and offers a number of approaches for planners to address safety 

in the planning process during committee meetings, data collection and 

analysis, goal and objective setting and performance measurement, 

and project prioritization and programming.
APPENDIX A. TOOLS AND RESOURCES

80

Title Description

Transportation Safety 

Planning Resources:

FHWA Integrating Safety in 

the Rural Transportation 

Planning Process, 2015

This report identifies opportunities for RPOs to incorporate safety into 

the different tasks that constitute the planning process. It addresses 

topics such as where to retrieve crash data, opportunities to analyze 

the information, and how the outputs of the analysis can be used to 

establish goals, objectives and performance measures. It also has a 

short section on steps to develop a stand-alone safety plan.

Transportation Safety 

Planning Resources:

FHWA Developing Safety 

Plans: A Manual for Local Rural 

Road Owners, 2012

This manual provides local rural road practitioners with a process and 

high-level information to develop a safety plan, including sections on 

data collection and analysis, and identifying data-driven emphasis 

areas, strategies, and priorities. These sections do not provide much 

“how to” information, but do reinforce the importance of data in safety 

planning. There also is a section on common issues, which recognizes 

the reality of data limitations and offers resources and strategies to 

collect other types of safety data (i.e., road safety audits or the 

development of an emphasis area on data collection). These strategies 

would be useful to highlight or reference in the e-handbook.

Transportation Safety 

Planning Resources:

FHWA Strategic Highway 

Safety Plans—A Champion’s 

Guidebook to Saving Lives, 

Second Edition, 2013

This guidebook reviews the basic principles and important 

considerations concerning the development of a Strategic Highway 

Safety Plan (SHSP). This document outlines the basic processes for 

data collection, analysis, and application to emphasis areas, strategies, 

and performance measures. The process used to develop an SHSP is 

transferable to other transportation planning processes to address 

safety.

Transportation Safety 

Planning Resources:

NCHRP Report 500, 

Volume 21: Safety Data and 

Analysis in Developing 

Emphasis Area Plans, 2008

This document addresses a number of items, but most relevant to the 

e-handbook are the sections on crash data and process. The crash data 

section explains the types of data that are necessary for making good 

safety decisions, as well as the data that are helpful, but not required, 

to develop and implement a safety plan. The process section introduces 

a three-stage approach for identifying a target emphasis area, setting 

an appropriate injury (and fatality) reduction goal, and defining the 

treatments that will allow the jurisdiction to reach that goal.

Performance-Based 

Planning Resources:

FHWA Transportation 

Performance Management 

Web site

This Web site provides a comprehensive list of resources to support 

target setting practices at State DOTs and MPOs. Resources include: 

Safety Targets Setting Final Report, A Compendium of State and 

Regional Target Setting Practices, the results of a Safety Target Setting 

Peer Exchange, Target Setting Literature Review, and the Urbanized 

and Nonurbanized Safety Target Setting Final Report.

Performance-Based 

Planning Resources: 

FHWA A Primer on Safety 

Performance Measures for the 

Transportation Planning 

Process, 2009

This primer is a tool to help State and local practitioners, transportation 

planners, and decisionmakers identify, select, and use safety 

performance measures as a part of the transportation planning 

process. It describes types of data and how to use it to develop 

performance measures for goals and objectives.

Performance-Based 

Planning Resources: 

FHWA Performance-Based 

Planning and Programming 

Guidebook, 2013

This guidebook presents a process for incorporating performance into 

the transportation planning process. It discusses the steps to a 

performance-based planning process (PBPP), which includes the 

development of goals and objectives, performance measures, planning 

analysis, trends and targets, strategies and alternatives, and 

identification of priorities. Data and analyses are key components of 

this process; and although it does not address safety directly, the PBPP 

can be adopted and used by planners to identify safety goals, 

objectives, performance measures, and targets.
APPENDIX A. TOOLS AND RESOURCES

81

Title Description

Performance-Based 

Planning Resources:

NHTSA Traffic Safety 

Performance Measures for 

State and Federal Agencies, 

2008

This publication explains the minimum set of safety performance 

measures, which are required by States in the development and 

implementation of behavioral highway safety plans and programs. The 

14 (now 15) measures must be reported in Highway Safety Plans and 

Annual Reports. The measures are based on available data for each 

State and also could be used/referenced by other agencies (MPO/

council of governments (COG), RPO) in a State when identifying/

developing safety performance measures and targets.

Performance-Based 

Planning Resources: 

FHWA Strategic Highway 

Safety Plan Evaluation Process 

Model, 2013

This document is meant to assist safety professionals with program 

evaluation of an SHSP. However, evaluating the performance of safety 

goals and objectives is a key component to any planning process. 

Conducting an evaluation requires data to establish performance 

measures and monitor the results over time. This report discusses the 

basics of collecting data, establishing output and outcome performance 

measures and continuous evaluation.

APPENDIX B. SAFETY ANALYSIS OBJECTIVES AND METHODS

83

Appendix B. Safety Analysis Objectives and 

Methods

Table B.1 Safety Analysis Categories, Questions, Tools, 

and Data Needs

Analysis Category Safety Analysis Question

What Tools are 

Available? Data Needs

Benchmarking • How many fatalities and 

serious injuries are 

occurring in my area?

• How does this compare to 

other areas or my State? 

• Descriptive 

Statistics

• FARS data

• Total crashes

• Total fatalities and serious injuries

• High-level roadway data—roadway 

ownership, functional classification

• Agency geographic boundary 

information

Identify Crash Trends 

and Contributing 

Factors

• Who is involved in 

crashes?

• When are the crashes 

occurring?

• What are the major 

contributing factors to 

crashes?

• Descriptive 

Statistics

• Trend analysis

• Crash severity—fatality, injury type, 

property damage, only

• Crash incidence data—time of day, 

day, month, weather, etc.

• Crash type—road departure, 

intersection, head-on, angle, etc.

• Contributing factors—age, impairment, 

seatbelt usage, speed, etc.

Identify and Evaluate 

Focus Crash Types

• What are the most 

common crash types?

• What are the most 

common contributing 

factors?

• What are the 

characteristics of the 

overrepresentation?

• Descriptive 

Statistics

• GIS Mapping

• Scatterplot

• Overrepresentation

• Risk Ratio

• Crash severity—fatality, injury type, 

property damage, only

• Crash incidence data—time of day, 

day, month, weather, etc.

• Crash type—road departure, 

intersection, head-on, angle, etc.

• Contributing factors—age, impairment, 

seatbelt usage, speed, etc.

Network Screening—

Identify Sites for 

Safety Improvement

• What locations 

(intersections or 

segments) show the most 

potential for safety 

improvements?

• AASHTO HSM 

Part B Network 

Screening—

Includes 

descriptive and 

predictive 

methods

• AASHTOWare 

Safety AnalystTM 

• GIS Heat 

Mapping

• Crash severity

• Crash location

• Roadway and roadside 

characteristics—intersection control, 

number of lanes, presence and type of 

shoulder, presence and type of 

median, posted speed, horizontal and 

vertical alignment, etc.

• Traffic volume data—intersection total 

entering traffic volume, roadway 

segment volume per million vehicle 

miles

• Calibrated safety performance 

functions, if predictive methods are 

used
APPENDIX B. SAFETY ANALYSIS OBJECTIVES AND METHODS

84

Analysis Category Safety Analysis Question

What Tools are 

Available? Data Needs

Systemic Analysis—

Identify Safety Risk 

Factors

• What are the common 

characteristics of locations

with crashes?

• What are the 

countermeasures to 

address these 

characteristics?

• How should we prioritize 

systemwide

implementation?

• FHWA Systemic 

Safety Project 

Selection Tool

• Crash severity

• Crash location

• Roadway and roadside 

characteristics—intersection control, 

number of lanes, presence and type of 

shoulder, presence and type of 

median, posted speed, horizontal and 

vertical alignment, etc.

• Traffic volume data—intersection total 

entering traffic volume, roadway 

segment volume per million vehicle 

miles

Corridor and 

Intersection Planning 

Safety Analysis

• What are the safety 

effects of alternative 

roadway or intersection 

cross sections?

• AASHTO HSM 

Part C 

Predictive 

Method and 

NCHRP 17-38 

Spreadsheets

• Interactive 

Highway Safety 

Design Model 

(IHSDM)

• Crash 

Modification 

Factors (e.g., 

FHWA Crash 

Modification 

Factor 

Clearinghouse)

• Collision 

Diagrams

• Crash severity

• Crash location

• Roadway and roadside 

characteristics—intersection control, 

number of lanes, presence and type of 

shoulder, presence and type of 

median, posted speed, horizontal and 

vertical alignment, etc.

• Traffic volume data—intersection total 

entering traffic volume, roadway 

segment volume per million vehicle 

miles

• Calibrated safety performance 

functions if predictive methods are 

used
APPENDIX C. RISK RATIO

85

Appendix C. Risk Ratio

The risk ratio compares the severity of crashes associated with a particular factor to the 

severity of all other crashes (e.g., the percentage of angle crashes that result in a serious 

injury or fatality divided by the percentage among all other crashes, excluding angle crashes). 

Crash types or factors with a risk ratio greater than 1 are overrepresented with respect to 

severe crashes. Formally, the risk ratio is defined by the following equation.

Figure C.1 Equation. Risk Ratio

Where:

A = the number of severe crashes of a particular type or emphasis area; 

B = the total number of nonsevere crashes of the same type as in A; 

C = the number of severe crashes, excluding those of the same type as in A; and

D = the total number of nonsevere crashes, excluding those of the same type as in A.

To illustrate this concept further, a few examples are provided below. Conventionally, data 

used to compute the risk ratio (variables A, B, C, and D) are arranged in a 22 matrix, where 

the first row corresponds to the numerator values in the formula above, and the second row 

corresponds to the denominator values.

Table C.1 Risk Ratio Data for Crashes in Rural Areas

Severe Crash Not a Severe Crash Total Crashes

Rural Area 523 (A) 5,768 (B) 6,291 (A+B)

Not a Rural Area (Urban Area) 700 (C) 24,396 (D) 25,096 (C+D)

Source: Sample data, Cambridge Systematics, Inc., 2015. 

Given this data, the formula to calculate the risk ratio is as follows:

Figure C.2 Equation. Severe Crash Risk Ratio for Rural Areas

Based on this calculation, crashes in rural areas are around three times more likely to result in 

a fatality or serious injury than those in urban areas.
APPENDIX C. RISK RATIO

86

A similar example for DUI crashes is provided here:

Table C.2 Risk Ratio Data for DUI Crashes

Severe Crash Not a Severe Crash Total Crashes

DUI 201 (A) 1,589 (B) 1,790 (A+B)

Not a DUI 1,022 (C) 28,575 (D) 29,597 (C+D)

Source: Sample data, Cambridge Systematics, Inc., 2015. 

Figure C.3 Equation. Severe Crash Risk Ratio for DUI Crashes

A risk ratio can also be developed for a combination of factors. An example for DUI crashes in 

rural areas is shown here:

Table C.3 Risk Ratio Data for Rural DUI Crashes

Severe Crash Not a Severe Crash Total Crashes

Rural DUI Crash 93 (A) 597 (B) 690 (A+B)

Not a Rural DUI Crash 1,130 (C) 29,567 (D) 30,697 (C+D)

Source: Sample data, Cambridge Systematics, Inc., 2015. 

Figure C.4 Equation. Severe Crash Risk Ratio for DUI Crashes in 

Rural Areas

As an outcome of this step, the transportation planner would understand the categories of 

crashes by type, severity, contributing factor, or geography that may be a focus for planning 

and programming or that should be a consideration in nonsafety-specific projects. 
APPENDIX D. REGRESSION TO THE MEAN 

87

Appendix D. Regression to the Mean

From year to year, the number of crashes at a site will randomly fluctuate up and down. 

Overtime, however, this random fluctuation will balance out to what can be considered the 

long-term expected average number of crashes at the site. Figure D.1 demonstrates regression 

to the mean and the effects of average crash frequency across multiple years. The ‘Crashes’

line shows hypothetical 1990 to 2010 annual crash frequency at a site. The crash frequency 

varies up and down from year to year. The ‘Mean’ line represents the long-term average crash 

frequency at the same hypothetical site. As shown, the five-year rolling average stabilizes at 

approximately 14 crashes per year. For example, the first five-year average is from 1990 to 

1994 and is plotted in 1994, the second is from 1991 to 1995 and plotted on 1995. The fiveyear rolling average more closely approximates the long-term average then the annual crash 

frequency alone. 

Figure D.1 Chart. Example of Regression to the Mean

Source: Federal Highway Administration. Improving Safety on Rural Local and Tribal Roads: 

Safety Toolkit. August 2014.

If regression to the mean is not accounted for, a site might be selected for study because the 

annual number of crashes that occurred was higher than “usual” due to a random fluctuation in 

the data. Conversely, a site that should be selected for study might be overlooked because an 

unusually low number of annual crashes occurred there.

To reduce the influence of regression to the mean, the agency should calculate the average of 

the most recent three to five years of crash data to determine the average crash frequencies. 

This minimizes year-to-year fluctuations in data and is appropriate if site conditions (e.g., 

traffic volume, land use, driveway access, and roadway configuration) have not changed. 

However, if site conditions have changed significantly during the analysis period, it may be 

more appropriate to monitor the site and evaluate safety after conditions have stabilized.