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Technical Report Documentation Page

1. Report No.

FHWA-SA-14-073

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

4. Title and Subtitle

Improving Safety on Rural Local and Tribal Roads 

Site Safety Analysis – User Guide #1

5. Report Date

August 2014

6. Performing Organization Code

7. Author(s)

Elizabeth Wemple, P.E.

Timothy Colling, P.E.

8. Performing Organization Report No.

9. Performing Organization Name and Address

Cambridge Systematics, Inc.

555 12th Street, Suite 1600

Oakland, CA 94607

Michigan Technological University

Center for Technology and Training

1400 Townsend Drive

Houghton, MI 49931

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

DTFH61-12-C-00034

12. Sponsoring Agency Name and Address

Department of Transportation

Federal Highway Administration

Office of Safety

400 7th Street S.W.

Washington, DC 20590

13. Type of Report and Period Covered

Covered Technical Manual

14. Sponsoring Agency Code

15. Supplementary Notes

Federal Highway Administration (FHWA) Technical Manager: Rosemarie Anderson, Office of Safety

Technical working group members: Craig Allred (FHWA Resource Center), Galen Balster (Federal Lands Highway), Dave Brand 

(Madison County, Ohio), Victoria Brinkly (Western Federal Lands Highway), Steve Castleberry (Nevada County, California), 

Clayton Chen (FHWA Research, Development, and Technology), Scott Davis (Thurston County, Washington), Kayloe Dawson 

(Chehalis Tribe), Thomas S. Elliot (FHWA National Highway Institute), Tony Giancola (Roadway Safety Foundation), Daniel Holt 

(Federal Lands Highway), Hillary Isebrands (FHWA Resource Center), Robin Lewis (City of Bend, Oregon), Nate Miller 

(Upper Valley Lake Sunapee Regional Planning Commission), Todd Morrison (Kentucky LTAP), Scott Nodes (Arizona DOT), 

Jessica Rich (FHWA Tennessee Division), Karen Timpone (FHWA Office of Safety), Dennis Trusty (Northern Plains TTAP)

16. Abstract

This User Guide presents an example of how rural local and Tribal practitioners can study conditions at a preselected site. 

It demonstrates the step-by-step safety analysis process presented in Improving Safety on Rural Local and Tribal Roads – 

Safety Toolkit (Publication FHWA-SA-14-072). 

The FHWA created the Toolkit and two User Guides to assist local agency and Tribal practitioners in completing traffic safety 

analyses. Each Toolkit step contains a set of tools, examples, and links to resources appropriate to the needs of safety 

practitioners. The User Guides accompanying the Toolkit provide hypothetical yet typical local or Tribal agency safety analysis 

scenarios and step-by-step solutions to the scenarios using materials from the Toolkit.

This report specifically addresses how to study crash conditions at a curve on a rural roadway. The User Guide provides example 

applications of five Toolkit steps: compile data; diagnose site conditions and identify countermeasures; prioritize countermeasures for 

implementation; implement countermeasures; and evaluate effectiveness of implemented countermeasures.

17. Key Words

Safety analysis, local roads, Tribal roads, safety management, network screening, 

site diagnosis, countermeasure selection, safety evaluation

18. Distribution Statement

No restrictions

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

40

22. Price

N/A

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

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Improving Safety on Rural Local and Tribal Roads

Table of Contents

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

What are the User Guides? ..................................................................................................................... 2

2.0 User Guide #1 Scenario............................................................................................................. 3

3.0 Solution ........................................................................................................................................ 4

Step 1. Compile Data............................................................................................................................ 4

Crash Data .......................................................................................................................................... 5

Traffic Volume Data............................................................................................................................10

Roadway Characteristics ...................................................................................................................10

Step 4. Diagnose Site Crash Conditions and Identify Countermeasures............................................12

Crash Data .........................................................................................................................................12

Field Review.......................................................................................................................................14

Identify Countermeasures..................................................................................................................18

Step 5. Prioritize Countermeasures for Implementation..................................................................... 22

Step 6. Implement the Countermeasures ............................................................................................24

Step 7. Evaluate Effectiveness of Implemented Countermeasures.................................................... 28

4.0 Options for Additional Activities............................................................................................. 29

5.0 Conclusions...............................................................................................................................30

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Improving Safety on Rural Local and Tribal Roads

List of Figures

Figure 1. Toolkit Safety Analysis Process ...................................................................................... 1

Figure 2. Scenario Preselected Site ............................................................................................. 3

Figure 3. Example Crash Form from Michigan (UD-10 Form) ............................................................ 8

Figure 4. Example Key for Crash Form from Michigan (UD-10 Form) ................................................. 9

Figure 5. Example Site Conditions Map .......................................................................................11

Figure 6. Incapacitating Injury Crashes ........................................................................................14

Figure 7. CMF Clearinghouse Countermeasure Example

Install Chevrons ......................................................................................................... 20

Figure 8. Potential Treatment

Enhanced Signage .................................................................................................... 21

Figure 9. Potential Treatment

Install Edgeline Rumble Strips ..................................................................................... 21

Figure 10. MUTCD Excerpt on Chevron Sign Spacing .................................................................... 25

Figure 11. Curve Radius Calculation ............................................................................................ 26

List of Tables

Table 1. Quantitative Information for Studying Safety at a Site.......................................................... 5

Table 2. Summary of Crash Data by Year ....................................................................................13

Table 3. Summary of Crash Data by Crash Type ..........................................................................13

Table 4. Summary of Site Inspection Prompt List .........................................................................15

Table 5. CMFs of Potential Treatments ...................................................................................... 20

Table 6. Qualitative Comparison of Potential Treatments ............................................................... 23

Table 7. MUTCD Chevron Sign Spacing Based on Advisory Speed and Curve Radius ...................... 26

Table 8. Example of Comparison of Before-and-After Period Crash Data ........................................ 28

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Improving Safety on Rural Local and Tribal Roads

1.0 Introduction

The Federal Highway Administration (FHWA) Office of Safety created a Toolkit for Rural Local and Tribal 

Roadway Safety Practitioners (referred to hereafter as the Toolkit) to provide a step-by-step process to assist 

local agency and Tribal practitioners in completing traffic safety analyses. Figure 1 shows the safety process 

outlined in the Toolkit. The Toolkit includes an explanation of each step in the process and provides tools, 

examples, guidance, and resources for learning more about each step. The process and tools presented in the 

Toolkit are flexible and can be applied to assist in solving any number of safety situations.

The Toolkit has been developed to provide information about how to study road safety on rural roads under 

the jurisdiction of local or Tribal agencies. There are many different types of staff that could be responsible for 

safety on local and Tribal roads, including maintenance staff, landscapers, planners, engineers, or politicians. 

Throughout the Toolkit and User Guides, these people are referred to as “practitioners” or “staff,” independent 

of whether they work for a local or Tribal road agency. Similarly, the road agency is referred to as the “agency”

or “jurisdiction,” whether it is a Tribal or local agency.

Figure 1. Toolkit Safety Analysis Process

Evaluate

Netwo

r

k

mI plement and Monitor

1. Compile

6. mI p

el m

ent

7. Evaluate

Data

Cou

n

et mr e

a

sures

Effectiveness

Network

Si et s of r

Screening In

v

est gi at

oi n

Select Improvements

Countermeasure

Im

s

plementation

Conditions and Identi

C

fy

ountermeasures for

4. Diagnose Site

5. Prioritize

2. Conduct

3. Se

el ct
- 2 -

Improving Safety on Rural Local and Tribal Roads

What are the User Guides?

The FHWA has developed two User Guides (this document and its counterpart) to provide practitioners with 

examples of applying the tools presented in the Toolkit. Each User Guide presents an example scenario that is 

typical on rural roads and example solutions to the scenario using methods presented in the Toolkit.

The User Guides’ example scenarios show intended use and application of the tools for each toolkit process 

step. The User Guides’ example solutions provide step-by-step procedures for practitioners to apply the 

methods to comparable situations in any community. 

There are two User Guides:

1. User Guide #1 – Improving Safety on Rural Local and Tribal Roads – Site Safety Analysis describes 

a step-by-step analysis for conducting a site-specific safety analysis. This scenario is typical of a situation 

where a site of concern is identified by agency staff, an elected official or someone outside of the agency 

based on site crash history. User Guide #1 demonstrates Step 1 and Steps 4 through 7 in Figure 1.

2. User Guide #2 – Improving Safety on Rural Local and Tribal Roads – Network Safety Analysis 

describes how to conduct a proactive analysis of a component of the transportation network such as all 

two-lane road segments, or all stop-controlled intersections. User Guide #2 demonstrates how to identify 

sites for safety improvement, diagnose conditions, implement selected countermeasures, and evaluate 

countermeasure effectiveness. User Guide #2 demonstrates all of the steps in Figure 1. 

This is User Guide #1 – Site Safety Analysis. The example that follows demonstrates how to study conditions 

at a preselected site. In this hypothetical example, the study site has been identified from community concerns; 

however, the methods are applicable to any situation where one preselected site is under investigation.

Referring again to Figure 1, User Guide #1 provides example applications of:

• Step 1 – Compile Data;

• Step 4 – Diagnose Site Conditions and Identify Countermeasures;

• Step 5 – Prioritize Countermeasures for Implementation;

• Step 6 – Implement Countermeasures; and

• Step 7 – Evaluate Effectiveness of Implemented Countermeasures.

Steps 2 and 3 in this User Guide have already been completed because the site of interest was selected 

because of a public concern; not from a data-driven process.
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Improving Safety on Rural Local and Tribal Roads

2.0 User Guide #1 Scenario

This scenario is set in a rural environment. There are approximately 50 miles of asphalt and gravel roads under 

the agency’s jurisdiction. Community residents have recently voiced concerns about safety at a particular curve 

in the community (see Figure 2). Residents have complained that travel speeds around the curve are too high, 

and there are many near misses on the curve. Residents have brought their complaints to community leaders 

at the agency by speaking at public meetings and calling local officials.

Figure 2. Scenario Preselected Site 

PARK

INDUSTRIAL

LAND

In response to the public concerns, community leaders have asked the manager of the Public Works department to study the location and identify what can be done to reduce public concerns and address any safety 

issues that may be present.

The Public Works department in this scenario has limited resources. While department staff have ample 

experience maintaining and operating roadways in the community, there is not a separate roadway or traffic 

engineering department. The police have the crash record files, but staff have not been maintaining any type 

of annual summary of crashes by location or type. Traffic volume and roadway characteristics data is available 

for locations where there have been recent road construction projects; however, the agency does not have an 

annual program to conduct traffic volume counts at locations throughout the community. As such, there is no 

historic traffic volume data for this site.
- 4 -

Improving Safety on Rural Local and Tribal Roads

Step 1

3.0 Solution

Figure 1 shows the safety process from the Toolkit. To study safety conditions at the curve and identify if countermeasures should be implemented, and what type of countermeasures are appropriate to implement, the 

manager of the Department of Public Works will need to apply:

• Step 1 – Compile data and determine what data is available to help study the site;

• Step 4 – Diagnose site conditions and identify countermeasures;

• Step 5 – Prioritize countermeasures for implementation;

• Step 6 – Implement countermeasures; and

• Step 7 – Evaluate effectiveness of implemented countermeasures.

Each of the analysis steps is described below. Steps 2 and 3 are not necessary because the location of interest 

has been already pinpointed by the public.

Step 1. Compile Data

The first step in conducting the analysis for this scenario is to compile and evaluate the available data. The 

data available influences the type of analyses that can be conducted. Typically, the information available can be 

divided into quantitative information and anecdotal information.

Table 1 summarizes the quantitative information that might be collected for this situation, and shows the data 

types that this scenario assumed are available. More information about sources for and how to work with each 

data type follows in this section.

There also are often regional and state organizations available to provide guidance or data for conducting 

safety analyses. It is useful to get to know staff in the safety group at your state’s DOT or planners or engineers 

at your Council of Governments (COG) or Metropolitan Planning Organization (MPO), as they also could assist 

you in conducting safety analyses. 

Typically, there are statewide documents that may be available to support a site-specific traffic safety study. For 

example, the state Strategic Highway Safety Plan (SHSP) may contain information about crash types that are of 

particular concern in the state and/or countermeasures known to be applicable in the state. Some states have 

plans focusing on specific safety issues such as intersections or run-off-road crashes. These documents also 

can be resources for understanding factors contributing to crashes, possible treatments, and funding sources 

to address the safety concern.
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Improving Safety on Rural Local and Tribal Roads

Step 1

Table 1. Quantitative Information for Studying Safety at a Site

Type of 

Quantitative Data Typical Data Sources and Formats

Data Available in 

this Scenario

Crash Data • Paper crash records from police/sheriff 

about each reported crash at or near 

the site

• Electronic crash reports from state 

department of transportation (DOT), 

summarizing each reported crash at or 

near the site

Paper crash records from 

police/sheriff about each 

reported crash near the site

Average Daily 

Traffic  Volume

• Historic traffic counts available at the

agency (actual or estimated through 

periodic processes)

• Historic traffic counts available from

the DOT (actual or estimated through 

periodic processes)

• New traffic counts conducted specifically

for this analysis

• Perception of traffic volume as average,

high, medium, or low relative to other roads 

in the community

Perception of roadway 

traffic volume as average

relative to other roads in 

the community

Roadway 

Characteristics

• Characteristics information from site visit

• Aerial views from Internet-based 

mapping providers

• As-built documents on file at the agency

or state DOT

• State road video or photo logs if available

Able to conduct site visit 

and view aerial information 

from the Internet

In this scenario, the anecdotal information is gathered from conversations with the community officials, community residents, and road maintenance workers that travel through the curve on a regular basis. The information 

gathered indicates there is a perception that the curve is too sharp, and that drivers are going too fast leading 

into the curve. For instance, residents described 

“near misses” they have experienced and 

helping to tow cars out of the adjacent ditch. 

This type of anecdotal information can be a 

good source of information and clues as to what 

should be studied at the site.

Crash Data

Background

The crash data on printed crash forms can be 

acquired from the local police or sheriff department, or from the state department managing 

the crash data, often the DOT.

Is Anecdotal Data Valuable? 

Many times anecdotal data may provide information 

that is not reflected in the site crash history. This can 

include information relating to minor crashes that are 

below a reporting threshold, near misses, and other 

vehicle conflicts that do not result in a reportable 

crash. This information can be valuable in providing 

clues on where to start a data-driven investigation. 

The challenge with anecdotal data is sorting out what 

issues are the perception of safety issues versus 

actual addressable safety issues.
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Improving Safety on Rural Local and Tribal Roads

Step 1

Local and Tribal police agencies typically only 

hold the crash records that their officers have 

created, so their records may be missing 

crashes if there are other police agencies that 

have jurisdiction in the area, or if the crash is 

not reported at all. Most states only require 

crashes to be reported if the dollar value of damages exceeds a minimum, or an injury occurs. 

Usually, the more severe the crash, the more 

likely the crash is reported to the police.

The state DOT, state police agency, or department of public safety in most states compile and 

hold all crash records from all police agencies in 

the state. Often, one of these organizations will 

publish a yearly summary of crashes in a report 

or database. State databases may not include 

crashes in Tribal areas.

When requesting crash data, it is best to collect 

as much data as possible. At a minimum, the 

practitioner should gather at least three years 

of crash data for a specific site. Many states 

have automated this request process and have 

on-line data request forms, or have a log-in procedure access on-line crash databases.

This Scenario

In this scenario, the crash data is acquired from 

the agency police department and is provided 

in completed paper crash forms. All crash forms 

use abbreviations and notations that can seem 

cryptic or can be misleading without a key to the 

form. To address this, almost every state-level 

crash form also has an accompanying document that details what the form abbreviations 

mean and give criteria for determining how to 

code certain data elements. Figures 3 (Michigan 

Crash Report Form) and 4 (Key for Crash 

Report Form) on pages 8 and 9, respectively, 

illustrate some key fields and their meanings for 

assessing crash data.

What to look for on a Crash Report

Information on a crash report that can provide clues to 

the factors that led to the crash include:

• Date;

• Time;

• Weather conditions;

• Roadway conditions;

• Number and severity of injuries;

• Driver impairment or distraction; and

• Type of crash and vehicle direction of travel. 

The officer’s diagram and written description of the 

crash can also provide invaluable information that 

can assist in understanding what occurred at the 

crash site. Information to be gleaned from these two 

sources include the officer’s opinion on what caused 

the crash and details on the vehicles’ exact path 

when the crash occurred.

Understanding Crash Location

There are many ways to specify and record crash 

location on the crash record or in the crash database. 

One common method is “road on and milepoint 

range.” In this method the crash location is specified by recording the “road on” which the crash 

occurred and a “milepoint range” or distance from a 

beginning point. For example a crash could occur on 

Main Street, 0.20 miles from First Street. 

Recently, many crashes are geocoded. When a crash 

location is geocoded, it is assigned a pair of geographic coordinates such as longitude and latitude. 

Crashes can then be mapped electronically using 

these coordinates.
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Improving Safety on Rural Local and Tribal Roads

Step 1

Example Email Request for Crash Data from a State DOT

Hi Ms. Smith,

My community is studying safety conditions on River Road between Third Avenue and Fir Street. In order 

to complete my analysis, I will need to study the available crash data for this segment. Please provide the 

most recent three calendar years of data you have for crashes in this segment of River Road.

Please provide the information by individual crash record so that we can summarize crashes by type, 

severity, time of day, day of week, and environmental conditions (for example, weather, roadway dry or 

wet). If possible, please provide the data in a spreadsheet so that we can more easily summarize the 

information. If this is not possible, that is fine too.

If the data contains codes to specify information such as crash type, severity, or impairment, please provide me a copy of the document defining the codes. If this is available on-line, please just provide the link 

to the site.

Please confirm that you have received this request and let me know when you will be able to provide the 

information. If you have any questions, please call me to discuss. My contact information is below.

Thanks in advance,

Clark White
- 8 -

Improving Safety on Rural Local and Tribal Roads

Step 1

Figure 3. Example Crash Form from Michigan (UD‐10 Form) 

Source: Michigan Department of Transportation, UD‐10 Traffic Crash Report Manual.

http://www.michigan.gov/documents/UD-10_Manual_2004_91577_7.pdf.
- 9 -

Improving Safety on Rural Local and Tribal Roads

Step 1

Figure 4. Example Key for Crash Form from Michigan (UD‐10 Form) 

Source: Michigan Department of Transportation, UD‐10 Traffic Crash Report Manual.

http://www.michigan.gov/documents/UD-10_Manual_2004_91577_7.pdf.
- 10 -

Improving Safety on Rural Local and Tribal Roads

Step 1

Traffic Volume Data

Background

Quantitative traffic volume data may be available through other work conducted at or near a site. There may be 

an annual traffic counting program, or traffic counts may have been conducted as part of a construction project. 

If not available within the agency, the state DOT, Council of Governments (COG), Local Technical Assistance 

Program (LTAP), or Tribal Technical Assistance Program (TTAP) may have the data or can provide support 

in acquiring the data. If no traffic volume data is available, anecdotal perceptions of traffic volume as “low,”

“average,” or “high” relative to comparable roads in the community can be acquired from local stakeholders 

familiar with the site. This information can be useful to get a perspective on the order of magnitude of exposure 

to the safety concern. 

This Scenario

In this example, the agency does not have access to roadway traffic volume data. Even though exact traffic 

counts are not available, staff indicate that the traffic volume on River Road is “about the same” when compared to other roads in the county. At a minimum, this qualitative assessment of the traffic volume should be 

recorded in the project documentation and can provide some basis for comparison of crash histories between 

this segment and others in the county.

Roadway Characteristics

Background

To the greatest extent possible, a site visit should always be 

part of the safety analysis process to get a feel for site conditions and get an understanding of existing and potential 

safety issues.

The type of roadway characteristics data to collect during a 

site visit includes:

• Number of lanes;

• Road surface conditions; 

• Road geometry;

• Signs and marking;

• Presence of motorcycles, pedestrians, or bicycles;

• Posted speed;

• Observations of travel speed;

• Adjacent land uses and driveways;

• Sight distance; and 

• Evidence of problems.

Possible sources for the roadway characteristics data are roadway design or maintenance staff, state DOT 

roadway databases or as-built drawings, on-line mapping tools such as Google Street ViewTM mapping service, 

and/or an on-site field visit.

Field Visits are Important to Do

It is important for the practitioner to 

make a field visit. Viewing the site 

in-person allows the practitioner to 

observe traffic and other features that 

data or photos alone cannot convey.

The type of data collected during a site 

visit should include number of lanes, 

lane width, shoulder width and type, 

sight distance where it appears limited, 

posted speed limit, and other signage. 

Videotape or photographs are also very 

helpful in documenting conditions.

A field visit after dark is also very 

important to evaluate the signing and 

pavement marking. The Road Safety 

Audit (RSA) Guidebook and Highway 

Safety Manuals have prompt lists that 

can assist in field visit data collection. 

See the Toolkit for more information on 

these resources.
- 11 -

Improving Safety on Rural Local and Tribal Roads

Step 1

This Scenario

Roadway characteristics are used in the scenario analysis 

to support the diagnosis and potential countermeasure 

selection. Roadway characteristics are best collected by 

visiting the site, taking photos, and recording the physical 

site characteristic. The FHWA document, FHWA Road 

Safety Audit Guidelines, provides many resources for 

formal or informal site inspections. The document provides prompt lists, which can act as a field visit outline. 

It may be useful to visit the site after dark. As the safety 

analysis proceeds, it may be useful to visit the site again to help with the diagnosis of crash conditions.

To the greatest extent possible, site data information should be hand drawn on a site conditions map (see 

Figure 5).

Google MapsTM mapping service or Bing® maps, if available, can supplement a site visit. Before the site visit, it 

can be useful to get initial community and local perceptions of the site; and after the site visit, these perceptions 

can be useful reminders of the site’s conditions. 

Figure 5. Example Site Conditions Map 

2-foot-wide gravel shoulder

11-foot-wide lanes

Legend

 Curve Sign

 Vegetation

Other Documents

There may be other agency-specific or statewide documents that contain information useful for the analysis. 

Summary of Data Compilation and Evaluation

The safety analysis in this scenario will be based on the site field investigation information, a summary of the 

crash data, and the qualitative assessment of traffic volume.

Field Evidence Demonstrating 

a Potential Safety Issue

Some very subtle signs of a safety problem 

can be uncovered during a site visit. These 

include skid marks on the road or shoulder, 

scarred or damaged trees, debris from 

damaged vehicles, or damaged signs.
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Improving Safety on Rural Local and Tribal Roads

Step 4

Step 4. Diagnose Site Crash Conditions and 

Identify Countermeasures

With the data compiled and the field visit complete, the next steps in a site-specific safety analysis are to analyze the crash data, traffic volume data, and roadway characteristics data to begin to understand contributing 

factors to the safety concerns at the site. This is called “diagnosis.” As an outcome of the diagnosis, it is possible to identify potential countermeasures for implementation at the site.

Diagnosis

Crash Data

Background

The crash data collected in Step 2 should be 

summarized in tabular form and, if possible, 

crash location also should be mapped. Crashes 

can be mapped at a site manually on a paper 

map, or by using free mapping tools available 

on-line.

This Scenario

This scenario summarizes crash counts by year, 

type, severity, and other environmental factors. 

Table 2 shows a summary of crash count by 

year and severity. This table shows 22 of the 37 

crashes were property damage-only crash, and 

there was one fatal crash in 2007 and another 

in 2010. A summary like Table 2 can show crash 

frequency trends on an annual basis.

Why analyze crash data?

The purpose of analyzing crash data is to determine 

factors that may be common across a number of 

crashes. These patterns can sometimes be evident 

by summarizing data by factors that contribute to the 

safety issue. This can include environmental factors, such as wet/dry roadway, or day/night driving; 

and driver factors, such as distraction, age, or use of 

alcohol/drugs.

Crash Severity KABCO System

Crash Severity: The KABCO Scale is used to classify 

crashes by injury severity. The letters represent injury 

levels as follows:

• K – involves a fatal injury;

• A – incapacitating injury;

• B – non-incapacitating injury;

• C – possible injury;

• O – no injury; and 

• PDO – property damage-only crash.
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Improving Safety on Rural Local and Tribal Roads

Step 4

Table 2. Summary of Crash Data by Year

Year

Fatal and Serious Injury 

Crashes (K, A)

Minor Injury Crashes

(B, C)

Property Damage-Only

Crashes (O)

2011 0 2 5

2010 1 5 3

2009 0 3 7

2008 0 1 3

2007 1 2 4

Total 2 13 22

Table 3 shows the site crash data summarized by year and crash type. This table shows the most common 

crash type is run-off-road crashes, and most of these crashes occurred in 2009. Note that in some situations 

run-off-road crashes also can be fixed-object crashes if an object is hit after the road departure. The crash 

records should be carefully evaluated to confirm that double counting is not occurring.

Table 3. Summary of Crash Data by Crash Type 

Year Run Off The Road Fixed Object Head-On Othe

2011 4 2 0 1

2010 5 2 1 1

2009 7 2 0 1

2008 0 3 0 1

2007 3 3 1 0

Total 19 12 2 4

Figure 6 provides a graphical display of the location of the fatal and serious injury crashes. Alternatively, Google 

Map MakerTM service in Google EarthTM mapping service can be used to create an electronic map of site conditions. Specifically, the Add a Place pushpin function can be used.
- 14 -

Improving Safety on Rural Local and Tribal Roads

Step 4

Figure 6. Incapacitating Injury Crashes 

PARK

INDUSTRIAL

Fatal and Serious Injury Crashes LAND

Field Review

Background

After crash summaries have been developed and studied in the office, a second field visit can be useful to 

reconsider the site with the site’s crash history in mind.

For site inspection to be productive, the person or people conducting the site visit will benefit from understanding 

how field conditions relate to safety issues. This understanding can be developed through knowledge of geometric design standards, the proper use of traffic control devices, and other safety-related topics. The resources 

presented after each step in the Toolkit provide a wealth of information for developing this knowledge base.

The field review also could be conducted as a formal Road Safety Audit (RSA). If an RSA is being conducted, 

agencies should develop a multidisciplinary team of experts to participate in the RSA. FHWA Road Safety Audit 

Guidelines provide guidance on conducting RSAs. Additionally, if needed, staff can seek out technical assistance/expertise from the state DOT, LTAP/TTAP, county engineer, or qualified consultant.

This Scenario

As an outcome of the site visit conducted for this project, the practitioner learned the following, as shown in 

Table 4. This table shows a field review evaluation prompt list and the information recorded during the field visit. 

As described in the resources section of Step 4 of the Toolkit, prompt lists like this one can be found in many 

different resources.
- 15 -

Improving Safety on Rural Local and Tribal Roads

Step 4

Table 4. Summary of Site Inspection Prompt List 

Topic Field Condition

Road 

Function, 

Classification,

Environment

Rural minor collector

Road 

Alignment 

and CrossSection

• Visibility – Sight distance measures more than 500 feet continuously around the 

curve, which is more than the minimum – not an issue

• Design speed – 20 miles per hour (advisory)

• Speed limit/speed zoning – 45 miles per hour

• Passing – Curve is a no-passing zone and is delineated as such

• ‘Readability’ (perception) of the alignment by drivers – Curve has two radii 

(curve gets sharper as drivers progress into it in the eastbound direction). This 

appears to violate what drivers expect and can catch some of them off guard 

as they transition into the “sharp” section of the curve.

• Lane width – 11 feet

• Shoulders – Curbed sections on one side, gravel approximately two feet wide

• Cross-slopes – Appear normal, 2 percent crown or similar

• Side slopes – 1:4 or flatter

• Drains – None present, rural

• Combinations of features – Not Available (NA)

Auxiliary 

Lanes

NA

Intersections NA. No intersections or driveways in this segment

Interchanges NA. No interchanges in this segment of road

Signs and 

Lighting

• Lighting – No overhead lighting

• Sign Inventory – Curve delineation signs missing; this location would benefit from

more of them

• Sign legibility – Signs in place can be seen during daytime, night retroreflectivity

is marginal but within acceptable limit

• Sign supports – Breakaway sign supports in all cases

Marking and 

Delineation

• General issues – Retroreflectivity on pavement markings is poor, but otherwise

markings in good condition

• Centerlines, edgelines, lane lines – Centerlines and edgelines present and 

appear new

• Guideposts and reflectors – NA

• Curve warning and delineation – Existing ‘curve ahead’ sign covered 

by vegetation

Barriers and 

Clear Zones

• Clear zones – Some trees and vegetation may be in the clear zone

• Barriers – NA

• End treatments/crash cushions – NA

• Pedestrian railing – NA

• Visibility of barriers and fences – NA
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Improving Safety on Rural Local and Tribal Roads

Step 4

Topic Field Condition

Traffic Signals NA

Pedestrians 

and Bicyclists

Pedestrian and bike use is minimal and not reflected in the crash data or traffic

volume data

Older Drivers Does not appear to be an issue given the type of site and the fact that less than 

1 percent of crashes included an occupant 60 years or older; however, topic 

should be kept in mind as part of identifying potential solutions. 

Topics that might be particularly relevant to older drivers:

• Turning operations (receiving lane widths, radii);

• Channelization, opposing left-turn lanes;

• Sight triangles;

• Signing, marking, and delineation; and

• Traffic signals.

Bridges and 

Culverts

NA

Pavement • Pavement defects – Pavement is good condition

• Skid resistance – Appears normal (good friction)

• Ponding/icing/snow accumulation – None observed during visit

• Loose stones/material – None

• Manholes – NA

• Parking – Not allowed in this section

Provision 

for Heavy 

Vehicles

• Design issues – None

• Pavement quality – Good

• Gravel shoulder quality – Good

Floodways 

and 

Causeways

NA

Other 

Safety Issues

• Landscaping – Trees and vegetation could be cleared to give more 

sight distance

• Temporary works – NA

• Headlight glare – Glare could be an issue on the curve

• Roadside activities – NA

• Signs of possible problems (pavement, roadside) – NA

• Rest areas – NA

• Environment – NA

• Median curbing – NA

• Ponding, snow, or ice in winter conditions – NA

To identify the contributing factors, feature, or crash type to investigate, crash data is compared and contrasted 

to the results of the field visit and summarized. 

Table 4. Summary of Site Inspection Prompt List (continued)
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Improving Safety on Rural Local and Tribal Roads

Step 4

In this scenario, the site visit and crash data evaluation show:

• The roadway has a compound curve or a curve that starts at one rate of curvature, and then quickly 

becomes sharper. The changing curve radius appears to cause drivers to misjudge how fast they should 

be traversing the curve.

• There are few advanced warning signs to advise drivers of a safe speed for the curve or chevron signs to 

give drivers direction at night and advise them of the road’s curve. Some key existing signs are partially 

covered by vegetation, and retroreflectivity of these signs is marginal.

• There is limited sight distance around the curve, causing drivers to be unaware of vehicles or other road 

obstructions in the road ahead.

• Trees in the clear zone may increase the severity of crashes during run-off-road incidents.

• Of the 37 crashes at the site in the last five years, 19 have been have been run-off-road crashes. There 

have been 22 property damage-only crashes; and 2 fatal and serious injury crashes.

• Crashes appear to be more frequent on this road segment when compared to other curves with similar 

levels of traffic.

Based on the existing crash data and field investigation, the site’s run-off-road crashes included the two fatal 

crashes and were the most frequent crash type. The investigation also showed that existing roadway features 

may not sufficiently inform drivers of upcoming conditions; therefore, safety treatments should focus on the 

roadway departure crashes.

The FHWA Office of Safety web site has a web page focused on roadway departure crashes.1 This web site 

provides information about how common roadway departure crashes, particularly on horizontal curves, and 

provides information about countermeasures to address these types of crashes. 

It is often useful at this stage of the analysis to prepare an existing conditions memorandum/write-up to document the evaluation and current conclusions. A possible outline for documentation of the work through this 

stage of the analysis is shown below.

Introduction

• Description of concerns at the site; and

• Description of approach to analyzing conditions.

Data Collection and Evaluation

• Description of the data that was collected and summary of the data:

– Crash data tables; and

– Roadway characteristics summary or sketches.

Diagnosis Results

• Summary of the evaluation of the existing crash and roadway characteristics data:

– Summary of recommended approach to addressing the issues.

1 http://safety.fhwa.dot.gov/roadway_dept/.
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Improving Safety on Rural Local and Tribal Roads

Step 4

Identify Countermeasures

Background

The most common and readily available 

resources for identifying possible treatments 

(countermeasures) to address a particular crash 

type are the web-based CMF Clearinghouse, 

Part D of the Highway Safety Manual, the 

National Cooperative Highway Research 

Program (NCHRP) 500 reports, and the FHWA 

Office of Safety Proven Countermeasures 

web page. Another useful resource is the 

FHWA document Low-Cost Countermeasures 

for Horizontal Curve Safety. This document is 

available at http://safety.fhwa.dot.gov/roadway_

dept/horicurves/. These and other resources 

are presented in Step 4 of the Toolkit.

The Crash Modification Factors (CMF) Clearinghouse (http://www.cmfclearinghouse.org/) serves as a central 

on-line database of countermeasures and their associated CMFs. The CMF Clearinghouse defines a crash 

modification factor as “a multiplicative factor used to compute the expected number of crashes after implementing a given countermeasure at a specific site.” Users are able to query the Clearinghouse database to 

identify treatments and the associated CMF. 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 information, users are able to determine the most applicable CMF 

for their condition.

The NCHRP 500 consists of multiple reports, each report addresses a specific type of highway crash or contributing factor. Volume 06, A Guide for Addressing Run-Off-Road Collisions is applicable to this situation

Looking for patterns in crash data

Studying the crash type, severity, and environmental 

conditions will provide insights for identifying potential 

crash contributing factors and potential treatments. 

For example, if a site had very high nighttime crash 

frequency, then lighting might be a treatment to 

reduce crash frequency. Or if there were many 

crashes on Friday nights after high school football 

games, education about speeding and distracted 

driving or speed enforcement might be a more useful 

countermeasure. It is important to remember that 

infrastructure will not always address site issues.

What to do if the potential safety issue is not obvious?

Sometimes, there is not an obvious pattern in the data leading to a potential safety issue or treatment. 

This can affect proper diagnosis of the safety issue. Options for dealing with this difficult safety situation 

include the following:

1. Ask a peer from another agency, the TTAP, LTAP, or state to review the site and study results and provide their opinion on the matter.

2. If data is missing that limits the type of study that can be completed, look for ways to collect this data 

over the upcoming years and continue to monitor the site.

3. Do a design check to verify that all minimum design criteria are met. Where possible, consider 

exceeding the minimum on key safety features.

4. Work with the local police departments to get notification of crashes that may occur in areas of concern. Visit crash sites as soon as possible after a crash event to get answers to questions that may 

not be in the crash record.
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Improving Safety on Rural Local and Tribal Roads

Step 4

This document provides information about typical conditions related to run-off-road crashes, strategies for 

addressing the crashes, and guidance for implementing solutions. In this document, the countermeasures are 

reported as “proven,” “tried,” and “experimental.” Proven countermeasures are the preferred countermeasures for implementation. Note that since this series of documents was originally published, new research may 

have been conducted that may have reclassified some countermeasures from “experimental” to “tried,” or from 

“tried” to “proven.”

In the case of identifying countermeasures for a specific crash type at a specific location, it is worthwhile to 

return to the FHWA Office of Safety web site and review the web page dedicated to “proven countermeasures”

(http://safety.fhwa.dot.gov/provencountermeasures/). This web page provides information about countermeasures known to address specific crash types. The web page contains information related to rumble strips and 

stripes, and enhanced delineation, and friction for horizontal curves and the safety edge. Each of these countermeasures addresses run-off-road crashes and may be applicable to the study site.

This Scenario

This scenario’s site diagnosis determined that countermeasures, which may reduce run-off-road crashes, are 

appropriate at the study site. Based on this conclusion, the scenario can identify countermeasures that address 

run-off-road crashes using the aforementioned resources.

To find countermeasures in the CMF Clearinghouse 

database, users query the Clearinghouse for CMFs 

related to a particular treatment or crash type (in 

this case, run-off-road crashes). There are search 

filters provided to help narrow the results. The 

search filters are by star quality or the research 

quality behind the CMF, crash type, crash severity, 

roadway type, area type, intersection type, intersection geometry, traffic control, and whether the countermeasure is in the AASHTO Highway Safety Manual 

(HSM). For this scenario, a search for a treatment related to run-off-road crashes with filters for all star ratings, 

run-off road crash types, any crash severity, and in rural area shows treatments for run-off-road crashes in the 

following categories of potential treatments (countermeasures):

• Roadside;

• Roadway;

• Shoulder treatments; and

• Signs.

Each of these categories contains treatments for reducing run-off-road crashes and these treatments CMF 

developed from research. For example, the countermeasures contained in the Signs category are:

• Install chevron signs on horizontal curves; and

• Install new fluorescent curve signs or upgrade curve signs to fluorescent sheeting.

The information about each of these treatments in the above categories needs to be studied to determine the 

potential application of the treatment to this scenario. For example in Figure 7, the treatment related to install 

chevrons in curves provides five different four-star-rated CMFs.

Countermeasures and Treatments

The terms “countermeasures” and “treatments”

are often used interchangeably to mean a strategy 

or action implemented to reduce the frequency or 

severity of crashes at a site.
- 20 -

Improving Safety on Rural Local and Tribal Roads

Step 4

Figure 7. CMF Clearinghouse Countermeasure Example

Install Chevrons

Source: http://www.cmfclearinghouse.org/.

To select a countermeasure, the possible treatments in each of the categories would be examined to identify 

how applicable the treatment is for the situation at hand. The Clearinghouse provides an option to export the 

query for review and evaluation in Microsoft Excel. In all likelihood, there will not be a perfect match between 

the countermeasures in the Clearinghouse and the specific site under investigation. However, the best available treatment can be selected for application based on good judgment and familiarity with the site conditions. 

Things to consider as part of CMF selection process include specific roadway type, urban, suburban rural 

environment, specific volume range, or addressing a particular crash type or severity. If a CMF’s situation is not 

similar to the site at hand, the same safety effectiveness cannot be expected. Remember, the lower the CMF 

the greater the potential reduction in crashes. However, there may be tradeoffs or barriers to implementing the 

CMF with the lowest value. This is acceptable and part of the judgment process of selecting countermeasures.

If the CMF Clearinghouse does not provide an option for a treatment for the particular scenario, the FHWA 

Office of Safety web site and the NCHRP 500 report may also provide insight, or the state DOT might have a 

list of treatments and CMF values approved for use in the state. 

Following review of the Clearinghouse and the FHWA Office of Safety web site, the treatments in Table 5 

were selected as optional treatments applicable at the site under investigation. Figures 8 and 9 show example 

images of these optional treatments.

Table 5. CMFs of Potential Treatments 

Enhanced Signage

Increase 

Lateral Clearance

Install Edgeline 

Rumble Strips

Safety Effectiveness 

(CMF)

0.84 to Fatal and 

Injury Crashesa

0.49 to Fatal and 

Injury Crashesb

0.85 to All 

Crash Severityc

a FHWA.

b CMF Clearinghouse, does not specify if relevant to curved segments, tangent segments, or both.

c CMF Clearinghouse, specific to principal arterial/other.
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Improving Safety on Rural Local and Tribal Roads

Step 4

Figure 8. Potential Treatment

Enhanced Signage

Source: Scott Davis, Thurston County, Washington. 

Figure 9. Potential Treatment

Install Edgeline Rumble Strips

Source: FHWA.
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Improving Safety on Rural Local and Tribal Roads

Step 5

Step 5. Prioritize Countermeasures for Implementation

Background

The process for prioritizing and selecting countermeasures for implementation can range from a quantitative 

benefit/cost analysis to a qualitative rating process using high, medium, and low (or good, fair, poor ratings); or 

a hybrid of both. The purpose of the countermeasure evaluation and prioritization step is to review the potential 

countermeasures and select the most feasible countermeasure for the site under investigation. The types of 

criteria that may influence the feasibility of a particular countermeasure in a particular situation include:

• Environmental impacts;

• Construction costs;

• Stakeholder input and community preferences;

• Maintenance costs;

• Anticipated safety effectiveness;

• Right-of-way availability; and

• Consistency with other community plans and goals.

This Scenario

The criteria for selecting a countermeasure in this scenario are environmental impacts, safety effectiveness, 

construction costs, maintenance costs, right-of-way impacts, and timeline to implementation. Different criteria 

will be important in different situations and communities, and the Toolkit presents the array of criteria that could 

be considered. 

The results of the qualitative rating process are shown in Table 6. The impacts of each optional countermeasure were compared to the selected evaluation criteria and given a high, medium, or low rating. For example, 

enhanced signage received a “low” rating for environmental impacts because staff are aware that signs could 

easily be placed with limited, if any, impact to vegetation, hillside slopes, or the adjacent creek. In contrast, 

increasing lateral clearance received a “high” rating in the environmental impacts category because trees 

would need to be removed to increase roadside clear zones. The evaluation team also noted the potential negative impacts of edgeline rumble strips on the bicyclists in the area. 
- 23 -

Improving Safety on Rural Local and Tribal Roads

Step 5

Table 6. Qualitative Comparison of Potential Treatments

Evaluation Criteria Enhanced Signage

Increase Lateral 

Clearance

Install Edgeline 

Rumble Strips

Environmental Impacts Low High impact to trees Medium

Safety Effectiveness 

(CMF)

0.84 to Fatal and 

Injury Crashesa

0.49 to Fatal and 

Injury Crashesb

0.85 to All 

Crash Severityc

Construction Costs Low Medium Medium

Maintenance Costs Low Medium Medium

Right-of-Way Impacts Low Medium Low

Timeline to 

Implementation

Low Medium Medium

a FHWA.

b CMF Clearinghouse, does not specify if relevant to curved segments, tangent segments, or both.

c CMF Clearinghouse, specific to principal arterial/other.

As shown above, the impacts of enhanced 

signage are lowest and the CMF is most 

specific to the study site; therefore, this countermeasure is selected for implementation.

At the end of this stage, it is appropriate to 

revisit the summary of existing conditions 

documented at the end of the previous 

step, and expand the memorandum/writeup to include an explanation of the analysis, 

countermeasure prioritization, and recommended treatments. This information also 

could be presented to agency leadership for 

review, input, and approval, if necessary. At 

this stage, the project documentation outline could be:

Introduction

• Description of concerns at the site; and

• Description of approach to analyzing conditions.

Data Collection and Evaluation

• Description of the data that was collected and summary of the data:

– Crash data tables; and

– Roadway characteristics summary or sketches.

Diagnosis Results

• Summary of the evaluation of the existing crash and 

roadway characteristics data; and

• Summary of recommended approach to addressing 

the issues.

Countermeasure Prioritization

• Summary of prioritization process, evaluation criteria 

and results.

Recommendations

• Brief summary of the memorandum explaining 

fundamental conclusions of the analysis and the 

recommended action.
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Improving Safety on Rural Local and Tribal Roads

Step 6

Step 6. Implement the Countermeasures

Background

Obtaining the necessary human and financial 

resources to implement any safety project or 

program is a major consideration. Harnessing 

local funding sources and staff resources is 

often the quickest way to implement projects. 

For example, maintenance or public works staff 

can implement low-cost projects such as maintenance or replacement of signs, maintenance 

of striping, and/or vegetation control as part of 

their regular duties.

In addition to local funds, the Local Technical Assistance Program (LTAP) web site describes the various types 

of local agency support provided by state DOTs – a useful first stop for identifying the resources available by 

state. The LTAP web site is http://www.ltap.org/resources/lpa/state.php.

This Scenario

Implementing enhanced signage is a relatively 

low-cost countermeasure. In some cases, 

enhanced signage could be implemented as 

part of ongoing maintenance activities. The 

Toolkit provides additional information about 

funding opportunities. 

The Manual on Uniform Traffic Control Devices 

(MUTCD) should be consulted for guidance 

and requirements related to sign size, placement, and retroreflectivity (http://mutcd.fhwa.

dot.gov/). Figure 10 below is an incomplete excerpt 2 of Figure 2C2 from the 2009 MUTCD, illustrating the recommended curve delineation sign layout for a horizontal curve. The MUTCD provides detailed information used 

to customize this layout to the specifics of the curve. 

2 Notes and advisory speed signage information are not included in the figure in order to focus on curve delineation.

Seek Technical Assistance if Needed

If in-house expertise to work with the MUTCD or other 

guidelines appropriate for the project is not available, 

technical assistance is always available through the 

LTAP/TTAP, regional or metropolitan planning organization, or the state DOT.

Consider Applying Results from One 

Study to Other Comparable Locations

Based on the results of this assessment, a systemic 

analysis could be conducted to identify locations with 

similar configurations and safety risk. As in this case, 

enhanced signage could be considered for implementation at selected locations throughout the community. 
- 25 -

Improving Safety on Rural Local and Tribal Roads

Step 6

Figure 10. MUTCD Excerpt on Chevron Sign Spacing 

Source: FHWA.

For example, Table 7 from the MUTCD illustrates the spacing of chevron signs based on the radius of the curve 

being delineated. In this scenario, the curve has a radius of 228 feet which results in a chevron sign (W1 8L) 

spacing of 80 feet along the outside of the curve. 
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Improving Safety on Rural Local and Tribal Roads

Step 6

Table 7. MUTCD Chevron Sign Spacing Based on Advisory Speed and 

Curve Radius 

Advisory Speed Curve Radius Sign Spacing

15 miles per hour or less Less than 200 feet 40 feet

20 to 30 miles per hour 200 to 400 feet 80 feet

35 to 45 miles per hour 401 to 700 feet 120 feet

50 to 60 miles per hour 701 to 1,250 feet 160 feet

More than 60 miles per hour More than 1,250 feet 200 feet

Source: MUTCD.

Note: The relationship between the curve radius and the advisory speed shown in this table should not be used to 

determine the advisory speed.

Alternatively, if the curve radius is not known, it can be calculated using the information in Figure 11.

Figure 11. Curve Radius Calculation 

W

Roadway Centerline

H

Radius = + H

2

W2

8H
- 27 -

Improving Safety on Rural Local and Tribal Roads

Step 6

Finally, if other aspects of the project have been documented, it would be useful to add the results of this step 

to the project documentation as well. At this stage, the project documentation outline could be:

Introduction

• Description of concerns at the site; and

• Description of approach to analyzing conditions.

Data Collection and Evaluation

• Description of the data that was collected and summary of the data:

– Crash data tables; and

– Roadway characteristics summary or sketches.

Diagnosis Results

• Summary of the evaluation of the existing crash and 

roadway characteristics data; and

• Summary of identified contributing factors and 

treatment types selected for potentially addressing 

the issues.

Countermeasure Prioritization

• Summary of prioritization process, evaluation criteria, 

and results.

Recommendations

• Brief summary of the memorandum explaining 

fundamental conclusions of the analysis and the 

recommended action. 

Final Comments

• Potential for applying the treatment elsewhere in the 

community; and

• Lessons learned for future application.
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Improving Safety on Rural Local and Tribal Roads

Step 7

Step 7. Evaluate Effectiveness of 

Implemented Countermeasures

Background

If possible, it is useful to conduct a quantitative analysis to see if the crash frequency or severity has changed 

after implementing the treatments. Two to three years after implementing the treatment, agency staff should 

routinely conduct additional analyses to evaluate treatment effectiveness.

This Scenario

In this scenario, assuming traffic volume does not change dramatically, crash records for the three-year period 

after implementing the treatment should be collected, summarized, and compared to the crash data summarized for this analysis. Table 8 shows an example of a tabular comparison of the before-and-after period 

crash data. As shown in the table, the run-off-road crashes decreased after implementing enhanced signage. 

However, because of statistical issues associated with crash data (explained in the Toolkit) it should not be concluded that there was an 88 percent reduction in run-off-road crashes ((19-2)/19 = 89.5%). It can be concluded 

that run-off-road departure crashes have decreased, but this analysis is not statistically rigorous enough to 

quantify the change in crash frequency. 

Note that the crash frequency for fixed-object and other crashes increased in the after-period. It is not possible 

to know if this is due to the treatment installed or a random fluctuation in crashes. 

Table 8. Example of Comparison of Before-and-After Period Crash Dat

Crash Type

Before 

(2009-2011

After 

(2013-2015

Run Off The Road 19 2

Fixed Object 12 8

Head-on 2 2

Other 4 6

Total 37 18

It also is important to note that if traffic volume changes substantially after implementing the treatment at the 

site, this type of simple before-and-after crash analysis will be less valid because the change in traffic volume 

may be influencing the change in crash frequency or severity. For example, a significant decrease in crash frequency recorded in Table 8 may be due partially to the decrease in study area traffic volume.

Documenting the results of the effectiveness analysis in a memo, or for presentation to governing board would 

be useful. This could demonstrate the value of the project in the specific jurisdiction and serve as a resource if 

similar projects are considered in the future. 
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Improving Safety on Rural Local and Tribal Roads

4.0 Options for 

Additional Activities

Looking forward from implementing the particular treatment at one site, there are a number of additional actions 

the agency could take. Staff could:

• Arrange for maintenance staff to review curves throughout 

the community (including night reviews) as part of other 

activities (e.g., vegetation control, pavement management). For those curves that have comparable conditions 

to the site studied in this scenario, staff could develop 

a list for enhanced signage and plan funding to implement the signs, when possible. Step 2 of the Toolkit has 

resources for this activity.

• Collect and summarize crash data for all horizontal 

curves in the community and begin a more quantitative 

process for identifying curves with potential safety treatment needs where the countermeasures outlined in this 

study could be applicable as well. The Toolkit provides a 

description of the systemic analysis.

• Contact the stakeholders that were so concerned about 

the treatment and gauge their interest in developing and 

participating in a community traffic safety committee. This 

committee could study traffic safety in the community, and 

identify potential solutions and activities to encourage 

safer travel in the community.

• Collaborate with police enforcement in the community to enhance speed enforcement in the vicinity of 

horizontal curves as a strategy for managing speeds and driver behavior in the community.

Regression to the Mean

On an annual basis, the number 

of crashes at a site will fluctuate 

up and down. Over time, if nothing 

changed at the site (e.g., traffic 

volume, surrounding land use, 

weather, driver demographics), the 

frequency of crashes at the site 

would converge on an average crash 

frequency. This is called regression to 

the mean. Regression to the mean is 

the tendency for a site to experience 

a period with a comparatively 

high crash frequency followed by 

a period with comparatively low 

crash frequency.
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Improving Safety on Rural Local and Tribal Roads

5.0 Conclusions

This User Guide (User Guide #1) focuses on studying safety conditions at one site. The site could be identified in any variety of ways such as public concern, local official input, or staff familiarity of site conditions. To 

study safety at one site, the practitioner can use a portion of the roadway safety analysis process presented in 

Figure 1. The steps to study safety conditions at one site are:

• Step 1 – Compile Data;

• Step 4 – Diagnose Site Conditions and Identify Countermeasures;

• Step 5 – Prioritize Countermeasures for Implementation;

• Step 6 – Implement Countermeasures; and

• Step 7 – Evaluate Effectiveness of Implemented Countermeasures.

At the conclusion of these activities, the practitioner also should evaluate whether there are other additional 

safety-related activities that can be conducted as part of ongoing work in the agency.

The solutions presented in this User Guide are provided in step-by-step form so that practitioners can apply the 

methods to comparable situations in any community. The scenarios outlined in the User Guide are examples 

to show intended use of the tools and provide examples of how some of the tools for each step are applied.