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Technical Report Documentation Page

1. Report No.

FHWA-SA-14-074

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

4. Title and Subtitle

Improving Safety on Rural Local and Tribal Roads 

Network Safety Analysis – User Guide #2

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

FHWA COTM: Rosemarie Anderson, Office of Safety

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

Ohio), Victoria Brinkly (Western Federal Lands), Steve Castleberry (Nevada County, California), Clayton Chen (FHWA), Scott Davis 

(Thurston County, Washington), Kayloe Dawson (Chehalis Tribe), Tom Elliot (National Highway Institute), Tony Giancola 

(Roadway Safety Foundation), Daniel Holt (Federal Lands), Hillary Isebrands (FHWA), Robin Lewis (Bend, Oregon), Nate Miller 

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

Jessica Rich (FHWA), Karen Timpone (FHWA), Dennis Trusty (Northern Plains TTAP)

16. Abstract

Rural roadway safety is an important issue for communities throughout the country and presents a challenge for local and Tribal 

agencies. The FHWA created a Toolkit and two User Guides to help rural local and Tribal roadway safety practitioners address 

these challenges. The Toolkit provides a step-by-step process 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 is Improving Safety on Rural Local and Tribal Roads, Network Safety Analysis – User Guide #2. This report presents 

an example scenario and step-by-step solution for studying safety conditions and identifying potential treatments at unsignalized intersections on a network. This User Guide demonstrates how to conduct network screening, select sites for further 

investigation, conduct safety diagnosis, select countermeasures, and prioritize and implement improvements. The User Guide 

provides example applications of all seven steps in the Improving Safety on Rural Local and Tribal Roads – Safety Toolkit 

(FHWA-SA-14-072): compile data; conduct network screening; select sites for investigation; 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

48

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 #2 Scenario............................................................................................................. 3

3.0 Solution ........................................................................................................................................ 5

Step 1. Compile Data............................................................................................................................ 5

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

Traffic Volume Data............................................................................................................................. 9

Roadway Characteristics .................................................................................................................... 9

Other Documents ...............................................................................................................................11

Step 2. Conduct Network Screening ...................................................................................................12

Network Screening Using Crash Frequency......................................................................................12

Network Screening Using Equivalent Property Damage-Only Method .............................................13

Network Screening Using Systemic Analysis ....................................................................................15

Step 3. Select Sites For Investigation..................................................................................................18

Step 4. Diagnose Site Crash Conditions and Identify Countermeasures........................................... 20

Identify Countermeasures..................................................................................................................24

Step 5. Prioritize Countermeasures for Implementation..................................................................... 28

Step 6. Implement The Countermeasures.......................................................................................... 34

Step 7. Evaluate Effectiveness ........................................................................................................... 36

4.0 Options for Additional Activities.............................................................................................38

5.0 Conclusions............................................................................................................................... 39

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Improving Safety on Rural Local and Tribal Roads

List of Figures

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

Figure 2. Schematic of Town Roadway System............................................................................... 3

Figure 3. Map of Intersection Crashes – 2010 to 2012...................................................................... 8

Figure 4. Evaluation of Roadway Functional Class as a Potential Risk Factor......................................17

Figure 5. Collision Diagram for Intersection L (First Street and Main Street) – 2010 to 2012 .................. 21

Figure 6. Condition Diagram for Intersection L (First Street and Main Street) ..................................... 22

Figure 7. Intersection Sight Distance Triangle .............................................................................. 26

Figure 8. Increase Sight Distance Triangle From CMF Clearinghouse .............................................. 27

Figure 9. FHWA’s Vegetation Control for Safety Guide – Sight Triangle Diagram ............................... 34

List of Tables

Table 1. Quantitative Data for Safety Analysis ............................................................................... 6

Table 2. Subset of 2010-2012 Crash Records for Intersection of First Street/Main Street 

(Intersection L in Table 3)............................................................................................... 7

Table 3. Intersection Crash Data Summary – 2010 to 2012.............................................................. 8

Table 4. Roadway Characteristics ............................................................................................. 10

Table 5. Two-Way Stop-Controlled Intersections Ranked by Crash Frequency and Severity – 

2010 to 2012...............................................................................................................13

Table 6. Two-Way Stop-Controlled Intersections Crashes Ranked by EPDO – 2010 to 2012.................15

Table 7. Network Screening Results and Site Selection for Further Investigation ............................... 19

Table 8. Intersection L: Crash Type Summary – 2010 to 2012 ........................................................ 20

Table 9. Haddon Matrix for Intersection L (First Street and Main Street) ........................................... 23

Table 10. Countermeasures Identified for Intersection L (First Street and Main Street) ......................... 25

Table 11. Summary of Benefit/Cost Analysis for Vegetation Control for Intersection L (First Street 

and Main Street)......................................................................................................... 31

Table 12. Summary of Benefit/Cost Analysis................................................................................. 32

Table 13. Example of Comparison of Before-and-After Period Crash Data ......................................... 36

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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 Safety Toolkit for Improving Rural Tribal 

and Local Roads (referred to hereafter as the Toolkit) to provide a step-by-step process to assist local agency 

and Tribal practitioners in completing traffic safety processes. Figure 1 shows the safety process outlined in 

the Toolkit. For each step in the process, the Toolkit includes an explanation of the step and 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, and 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

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mI plement and Monitor

1. Compile

6. mI p

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7. Evaluate

Data

Cou

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Effectiveness

Network

Si et s of r

Screening In

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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
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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 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 presented 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 staff at the agency, an elected official or someone outside the 

agency based on 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 #2 – Network Safety Analysis. The hypothetical scenario that follows presents a situation 

where the agency has decided to study safety at many locations.

User Guide #2 demonstrates how to screen and select sites for safety investigation given a large pool of sites, 

identify specific sites for investigation, diagnose site conditions, implement selected countermeasures, and 

evaluate countermeasure effectiveness. User Guide #2 demonstrates all steps in the Toolkit process shown in 

Figure 1.

• Step 1 – Compile Data;

• Step 2 – Conduct Network Screening;

• Step 3 – Select Sites for Investigation;

• 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.

See User Guide #1 to review an example application of tools to study safety at a preselected location.
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Improving Safety on Rural Local and Tribal Roads

2.0 User Guide #2 Scenario

This scenario is set in a small, rural town. The Roadway Manager in this community is responsible for approximately 50 miles of roads. About six months ago, a teenager died in a fatal car crash at an intersection in town. 

During the annual public works briefing regarding future road projects, one of the town commissioners asked if 

there are projects on the list that will improve intersection safety, or if there is a process for identifying sites that 

may need safety improvements. As an outcome of the discussion, the Roadway Manager was asked to develop 

an intersection safety plan to identify and prioritize safety improvements.

The intersection safety plan will document the evaluation of all 15 two-way stop-controlled intersections in town, 

identify intersections for detailed evaluation, diagnose conditions at these locations, and identify and prioritize 

countermeasures for implementation. Figure 2 is a schematic of the town roadway system and identifies all of 

the two-way stop-controlled intersections that will be evaluated.

Figure 2. Schematic of Town Roadway System

Park

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Cemetary

Stop Sign

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Improving Safety on Rural Local and Tribal Roads

The Roadway Manager and staff have ample experience managing and maintaining the road system in their 

community. For studying this situation, they will:

1. Compile crash reports from the police department;

2. Conduct network screening;

3. Select sites for investigation;

4. Diagnose conditions and identify countermeasures using resources identified in the Toolkit;

5. Conduct a benefit/cost analysis to prioritize countermeasures;

6. Implement the selected treatment using guidance from national safety manuals presented in the Toolkit; and

7. Evaluate the effectiveness of the implemented treatment.
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Improving Safety on Rural Local and Tribal Roads

Step 1

3.0 Solution

In this scenario, the Roadways Manager will be studying road safety at the two-way stop-controlled intersections in town, and identifying if anything should be implemented to address safety concerns. As such, this 

scenario will conduct all of the steps in Figure 1.

Step 1. Compile Data

The first step in studying the two-way stop-controlled intersections is compiling and evaluating the available 

data. The data available influences the type of analyses that can be conducted. Typically, the information available can be divided into anecdotal information and quantitative information.

In this scenario, the anecdotal information is gathered from 

the town commissioners and concerned residents. For many 

years, residents and commissioners alike have expressed concerns about vehicles making left turns onto and off of the main 

roads at intersections in town. While different intersections 

have different issues, in summary residents have expressed 

concerns about:

• Higher-speed vehicle through-movements making it difficult to turn left from both the minor and major street;

• Sight distance constraints making it difficult to make a 

turn from the minor street onto the major street; and

• Difficulty seeing intersections at nighttime.

These concerns can be a good source of information and provide useful clues as to what should be studied at 

sites; however, this type of information should be supported with quantitative data when possible to separate 

perception from fact.

Table 1 shows the types of quantitative data that can be used for this type of safety analysis, and shows the 

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

each data type follows in this section.

Crash Data

Background

The crash summary data and printed crash records can be acquired from the local law enforcement agency or 

from the state department managing the crash data.

Local law enforcement agencies typically only hold crash records created by their officers, so crash records 

may be missing if there are other police agencies that have jurisdiction in the area. Only reported crashes will 

be in the official records. Also, most states require crashes to be reported when the dollar value of damages 

exceeds a minimum threshold or if there is an injury. Crashes that result in limited vehicle property damage 

may not be reported to police. Usually, the more severe the crash, the more likely the crash gets reported to 

the police.

Is Anecdotal Data Valuable? 

Anecdotal data may provide information that is not shown in the crash 

reports. 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 perceptions of safety issues versus actual 

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

Step 1

Table 1. Quantitative Data for Safety Analysis

Type of 

Quantitative Data Data Source and Format Available in this Scenario

Crash Data • Paper crash records from police/sheriff

• Electronic crash reports from local database 

or state Department of Transportation (DOT)

• Spreadsheet of crash data

Average Daily 

Traffic Volume

• Historic traffic counts available at the 

agency (actual or estimated through 

periodic process)

• Historic traffic counts available from 

the DOT (actual or estimated through 

periodic process)

• New traffic counts conducted specifically 

for this analysis

• If needed, staff can conduct traffic 

counts

Roadway 

Characteristics

• Characteristics information from 

field evaluations

• Aerial views from Internet-based 

mapping providers

• As-built documents on file at the agency 

or state DOT

• Field evaluations and aerial views 

from Internet are available

Other Documents • State Strategic Highway Safety Plan (SHSP) 

and/or Focus/Emphasis Area Team Plans

• The state has an SHSP in which rural 

intersection crashes have been 

identified as an emphasis area

• The Roadway Manager recently 

attended a Highway Safety 

Manual Training session provided 

by the Local Technical Assistance 

Program (LTAP)

Depending on what data sources are available, 

compiling data may be a step that is completed 

before or with the network screening activity. 

Agencies that have data in electronic formats, such 

as GIS databases, can compile and report on data 

with little effort. As such, compiling crash summaries for every intersection in the road network is 

quick and easy; however, agencies that have to 

manually compile data may only create summary 

tables for locations identified in the screening step 

due to the effort involved.

This Scenario

In this example, the Roadway Manager and staff 

have been maintaining a crash data spreadsheet 

for the town’s intersections for many years. Each 

year, they acquire the intersection crash data from local law enforcement, and record each intersection’s crash 

data in a spreadsheet. The type of information they record for each crash includes:

What is a GIS Layer? 

Geographic Information Systems (GIS) can be 

thought of as a map combined with a database. 

All the information contained in the database 

is related to a physical location contained in a 

map. GIS users can apply a legend or a theme to 

present specific data on the map as a data layer. 

Various layers of data items can be overlaid to 

visualize relationships. 

Examples: A road layer can be overlaid with a land 

use layer, or a bridge location layer (or both), and 

then crash locations can be also added. 
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Improving Safety on Rural Local and Tribal Roads

Step 1

• Type. Angle, rear-end, sideswipe, or fixed object;

• Severity. Fatality, incapacitating injury, nonincapacitating injury, possible injury, or property 

damage only;

• Environmental Conditions. Day, night, dry, snowy/

icy, or wet road; and

• Driver Conditions. Impaired or not impaired.

Crash data can be summarized from individual crash 

records and then all of the crash records for a given location 

can be summarized. Table 2 shows an example of summary 

details from individual crash records at one of the intersections – First Street and Main Street. Table 3 shows how all 

crash data for all of the locations can be summarized. 

Although crash record forms vary from state to state, 

Table 2 shows an example of the common information that 

might be compiled from a crash record form. This information can provide clues to crash contributing factors in later 

diagnosis steps in the process. 

Table 2. Subset of 2010-2012 Crash Records for Intersection of First Street/

Main Street (Intersection L in Table 3)

Crash 

ID Year Collision Type

Crash 

Severity

Collision 

Type

Surface 

Condition

Light 

Condition Description

1 2010 Angle NB Main Street 

to WB First 

Street colliding 

with EB First 

Street Vehicle

Injury – C Angle Dry Daylight Did not yield 

right-of-way

2 2011 Rear-end WB First Street 

Approach

PDO Rear-end Wet Daylight Driving 

too fast for 

conditions

3 2012 Head-on NB/SB Main 

Street through 

movements

Fatal Head-on Dry Night Opposing 

direction 

vehicles 

collided in 

the center 

of the 

intersection

4 2012 Angle SB Main Street 

traveling 

to EB First 

Street struck 

by vehicle 

traveling NB 

on First Street 

PDO Angle Dry Daylight Left turn 

from First 

did not see 

oncoming 

vehicles

Crash Severity KABCO System

The KABCO Scale to classify crashes 

by injury severity. The letters represent 

injury levels:

• K – Involves a fatal injury,

• A – Incapacitating injury,

• B – Non-incapacitating injury,

• C – Possible injury, and

• O – No injury or a PDO – property 

damage-only crash.

The severity of a crash is based on the 

greatest level of severity of injury occurring 

in the crash. For example: If someone is 

killed in a crash, the crash is labeled as a 

“K” or fatal crash.
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Improving Safety on Rural Local and Tribal Roads

Step 1

Table 3. Intersection Crash Data Summary – 2010 to 2012

Int Total

Severity Type

Fatal Injury PDO Run-Off

Single 

Vehicle Angle

HeadOnRearEnd Sideswipe Other

A 16 0 6 10 2 0 7 1 4 2 0

B 12 1 4 7 0 1 5 1 3 1 1

C 22 0 9 13 3 1 9 1 5 2 1

D 12 0 3 9 2 0 5 1 3 1 0

E 19 1 6 12 2 0 8 1 5 2 1

F 2 0 1 1 0 0 1 0 1 0 0

G 12 0 5 7 1 0 5 1 3 1 1

H 8 0 3 5 1 0 3 1 2 1 0

I 16 0 7 9 2 0 7 1 4 1 1

J 18 1 7 10 2 0 8 1 4 2 1

K 11 0 5 6 1 0 5 0 3 1 1

L 19 1 7 11 2 0 8 1 5 2 1

M 5 0 2 3 1 0 2 0 1 0 1

N 13 0 4 9 2 0 6 1 3 1 0

O 15 1 7 7 2 0 6 1 4 2 0

In this scenario, a mapping tool is available; therefore, the crash data also can be summarized as demonstrated in Figure 3. This map shows total number of crashes at the two-way stop-controlled intersections in this 

analysis. The size of the dot is scaled to the total number of crashes at each intersection for the study period. 

However, as discussed in the Toolkit, a map like this could alternatively show the summary of crashes by type 

or severity at the study intersections, or distribution of crashes by year.

Figure 3. Map of Intersection Crashes – 2010 to 2012

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Improving Safety on Rural Local and Tribal Roads

Step 1

Traffic Volume Data

Background

The availability of major and minor street average daily traffic 

(ADT) volume data allows the practitioner to conduct network 

screening analyses using crash rate or critical crash rate 

methods. Chapter 4 of the Highway Safety Manual presents 

these methods. However, Annual Average Daily Traffic (AADT) 

volumes are not always available because of the expense of 

a regular traffic counting program. For most studies, ADT collected at the study sites on any day is used to estimate AADT.

Often, the ADT at intersections is converted to Total Entering 

Volume (TEV). The TEV is the sum of all traffic entering an 

intersection. TEV of the study intersections can be mapped 

using a GIS database or can be summarized in a table.

This Scenario

For this network screening scenario traffic volume data will 

not be used. 

Roadway Characteristics

Background

As described in the Toolkit, roadway characteristics data may be available in-house from the engineering team, 

or externally from the state DOT roadway databases or as-built drawings, on-line mapping tools such as Google 

Street ViewTM mapping service and/or site field visits. To the greatest extent possible, a site visit should always 

be part of the safety analysis process. 

The types of roadway characteristics that can be collected in the field site visit are:

• Number of and type of vehicle lanes;

• Adjacent land use and driveways;

• Presence of bike lanes;

• Presence of sidewalks;

• Type of intersection control;

• Sight distance; and

• Posted speed limits.

More information about the type of roadway characteristics data to collect is included in Step 1 of the Toolkit.

Consideration When 

Applying Crash Rate 

Network Screening Method

Crash rate network screening is useful 

because:

• It is based on data that is relatively 

easy to acquire – traffic volume and 

crash data; 

• It is easy to calculate – crashes 

divided by traffic volume; and 

• It makes it possible to compare 

safety performance of locations.

However, if multiple sites have the same 

number of crashes, the lower volume 

locations will always show higher crash 

rates. So, crash rates should only be 

used to compare sites with traffic volumes in the same range. 
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Improving Safety on Rural Local and Tribal Roads

Step 1

This Scenario

Intersection characteristics information will be used in this scenario as part of the site investigation and diagnosis. The type of information that will be used includes:

• Lanes. Number of lanes approaching each leg of the intersection and number of turning lanes at the 

intersection (e.g., number of left-turn lanes, number of through-lanes, and number of right-turn lanes).

• Traffic Control. All study intersections have stop-control on the lower volume (i.e., minor) approach 

to the intersection. Traffic on the higher volume (i.e., major) approach to the intersection does not stop 

when traveling through the intersection.

• Speed Limits on both streets.

• Crosswalks. Availability of crosswalks at the intersection.

• Driveways and Access Control in the vicinity of the intersection.

Table 4 demonstrates how this type of information might be summarized in a table and what this data set might 

look like for a subset of intersections from Table 3.

Table 4. Roadway Characteristics

Intersection

Approach Lanes Lane Configurations

Crosswalks 

(North, 

South/East, 

West)

Driveways within 

250 Feet of 

Intersection

Major 

Street

Minor 

Street

Major Street – Lane 

Configuration 

(Lt/Th/Rt)

Minor Street – Lane 

Configuration 

(Lt/Th/Rt)

Yes (Y)/

No (N)

Major 

Street

Minor 

Street

A 1 1 Lt-Th-Rt Lt-Th-Rtb (Y, Y/N, N) 1 1

B 2 1 Lt/Th-Rta Lt-Th-Rt (Y,Y/Y, Y) 3 2

C 2 1 Lt/Th-Rt Lt-Th-Rt (N, N/N, N) 0 1

D 1 1 Lt-Th-Rt Lt-Th-Rt (Y, Y/Y, Y) 2 1

E 2 1 Lt/Th-Rt Lt-Th-Rt (Y, Y/N, N) 3 1

a Lt/Th-Rt – Both directions of the approach to the intersection are striped with one left-turn lane and one combined through 

and right-turn lane. 

b Lt-Th-Rt – Both directions of the approach to the intersection are striped with one lane to accommodate left turns, through 

movements, and right turns. 

Table 4 includes information about the number of driveways within 250 feet of the intersection. Depending on 

traffic volume and pedestrian and bicycle traffic, often as the number of driveways increases, rear-end crashes 

will increase with the amount of activity along and across the roadway. So, the number of driveways can be 

useful in understanding crash contributing factors near intersections. This information is not often collected and 

maintained in a database, but it can be collected using recent aerial photos, an on-line tool like Google Street 

ViewTM mapping service or during the field visits.
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Improving Safety on Rural Local and Tribal Roads

Step 1

Other Documents

Background

Finally, there may be other agency-specific or statewide documents that contain information useful for the analysis. For example, the state SHSP may contain information about the characteristics of intersection crashes in 

state and preferred actions to address these strategies. Additionally, if the state is an intersection focus state, 

the state DOT may have an intersection plan that can be useful in providing information on identifying and 

addressing intersection safety issues.

This Scenario

The state’s SHSP has identified that intersection crashes are a focus area. As such, there are strategies and 

actions available to assist with addressing intersection crashes. The following are some of these strategies and 

actions:

• Implement geometric improvements;

• Increase awareness of safety issues at intersections;

• Improve operating characteristics of intersections to reduce conflicts – possibly through signing and 

pavement marking modifications;

• Follow the principles of access management at intersections; and

• Conduct intersection enforcement.

The state also recently provided Highway Safety Manual training that included information about network 

screening. This information was drawn largely from the FHWA Highway Safety Manual training available on-line 

(http://safety.fhwa.dot.gov/hsm/training/).
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Improving Safety on Rural Local and Tribal Roads

Step 2

Step 2. Conduct Network 

Screening

When applying any network screening program, it is 

often useful to apply more than one network screening 

method to compare and contrast the results and draw yet 

more conclusions from the findings. Based on the data 

and resources available, this example scenario applied 

frequency-based and equivalent property damage-only 

(EPDO) network screening methods. Step 2 of the Toolkit 

provides more information about this and other network 

screening methods.

Network Screening Using Crash Frequency

Background

Crash frequency is one of the most basic network screening methods. In this method, the intersections are 

grouped, evaluated, and compared according to categories of traffic control; number of approach legs; and traffic 

volume range (e.g., higher-volume intersections separated from lower-volume intersections). For example, a 

network screening program could consider all three-legged 

signalized intersections in one group, and all four-legged 

two-way stop-controlled intersections in another group (as 

in this scenario).

The crash frequency measure is the total number of crashes 

over the analysis period or average number of crashes 

per year for the study intersections. The intersections are 

ranked from highest to lowest total crash frequency over 

the analysis period or average crash frequency per year. 

The crash frequency measure can be applied to total 

crashes, fatal and serious injury only crash severities, or 

by a particular crash type.

This Scenario

Table 5 illustrates how intersections could be ranked 

according to crash frequency. The sites are ordered by total 

crash frequency; the severity data is provided for reference.

Crash Rate Analysis

If traffic volumes at the intersections were 

available, a crash rate analysis could also 

be conducted. Crash rate (crashes divided 

by traffic volume) could be conducted on 

total crashes, fatal and serious injury only 

crashes, or a particular crash type. 

If using crash rates, be sure to subdivide 

the sites into categories with comparable 

traffic volumes. For example:

• Category 1 – less than 1,000 ADT;

• Category 2 – 1,000 to 5,000 ADT; and

• Category 3 – greater than 5,000 ADT.

Threshold of Performance

A challenge with frequency-based network 

screening is that there are no specific indications as to whether the observed crash frequencies should be considered high, typical, 

or low for the particular study intersection 

group. There is no threshold or performance measure that says if the frequency 

is greater than x, the site has potential for 

safety improvement.
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Improving Safety on Rural Local and Tribal Roads

Step 2

Table 5. Two-Way Stop-Controlled Intersections Ranked by Crash Frequency 

and Severity – 2010 to 2012

Intersection Total

Severity

Fatal Injury PDO

C 22 0 9 13

L 19 1 7 11

E 19 1 6 12

J 18 1 7 10

A 16 0 6 10

I 16 0 7 9

O 15 1 7 7

N 13 0 4 9

D 12 0 3 9

G 12 0 5 7

B 12 1 4 7

K 11 0 5 6

H 8 0 3 5

M 5 0 2 3

F 2 0 1 1

Network Screening Using Equivalent Property Damage-Only Method

Background

The equivalent property damage-only (EPDO) method is documented in the Highway Safety Manual. In this 

method, weighting factors related to the societal costs of fatal, injury, and property damage-only crashes are 

assigned to crashes by severity to develop an equivalent property damage-only 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 can be selected for investigation.

The major steps in this method are:

• Compile crash severity cost data. The Highway Safety Manual provides the following crash costs by 

crash severity:

Severity Comprehensive Crash Costa

Fatal $4,008,900

Injury A, B, and C $82,600

Property Damage Only $7,400

a AASHTO, Highway Safety Manual 2010, Chapter 7.
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Improving Safety on Rural Local and Tribal Roads

Step 2

• Calculate the severity weighting factors:

The crash severity weighting factors are calculated as a function of the PDO crash cost. The fatal EPDO 

weighting factor is:

The injury EPDO weighting factor is:

The property damage only (PDO) weighting factor is: 

• Calculate the EPDO score for each site. The EPDO score is:

For example, the EPDO score at Intersection A is:

This Scenario

Table 6 shows the EPDO score for each intersection. Ranked by EPDO, the top three intersections are 

Intersections L, J, and O; however, ranked by frequency the top three intersections are C, L, and E (see again 

Table 5).
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Improving Safety on Rural Local and Tribal Roads

Step 2

Table 6. Two-Way Stop-Controlled Intersections Crashes Ranked by EPDO – 

2010 to 2012

Intersection

Severity

Fatal Injury (A-C) PDO Total EPDO

L 1 7 11 19 631

J 1 7 10 18 630

O 1 7 7 15 627

E 1 6 12 19 621

B 1 4 7 12 593

C 0 9 13 22 113

I 0 7 9 16 87

A 0 6 10 16 77

G 0 5 7 12 63

K 0 5 6 11 62

N 0 4 9 13 54

D 0 3 9 12 42

H 0 3 5 8 38

M 0 2 3 5 25

F 0 1 1 2 12

Network Screening Using Systemic Analysis

Background

Systemic Analysis is another approach for network screening that is useful in the rural local and Tribal context. 

In the scenario presented here, the practitioner is evaluating safety conditions at spot-specific locations. The 

systemic approach analyzes crash history on an aggregate basis to identify:

• Facility types that have similar high-risk roadway characteristics; 

• Countermeasures to address the roadway characteristics; and 

• A prioritized implementation plan.

A systemic safety approach works by identifying which roadway characteristics (such as road width, shoulder 

width, posted speed, intersection control, urban or rural environment, or number of intersection approaches) 

are included at a large proportion of the road network’s crash sites. Once these problematic roadway characteristics are known, locations with these characteristics can be identified, and countermeasures targeting them 

implemented so that crash risks are reduced across the road network.

The major steps in the systemic process are:

• Identify focus crash types and risk factors:

– Select focus crash types;

– Select focus facilities; and

– Identify and evaluate risk factors.
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Improving Safety on Rural Local and Tribal Roads

Step 2

• Screen and prioritize candidate locations:

– Identify network characteristics to analyze;

– Conduct risk assessment; and

– Prioritize focus characteristics.

• Select countermeasures:

– Assemble comprehensive list of countermeasures;

– Evaluate and screen countermeasures; and

– Select countermeasures for deployment.

• Prioritize projects:

– Create a decision process for countermeasure selection;

– Develop safety projects; and

– Prioritize project implementation.

The FHWA Systemic Safety Project Selection Tool, published in 2013, thoroughly describes these steps. See 

the resources section for more information. 

As an outcome of a systemic analysis the agency will be able to understand roadway and roadside features that 

show higher risk than other features, have a list of treatment types that can potentially address risk, and have 

a list of sites for potential treatment. 

For example, Figure 4 is taken from the FHWA Systemic Safety Project Selection Tool. In this case study, 

Thurston County Public Works in Washington State compared the proportion of severe curve-related roadway 

departure crashes on various functional classifications of roadways to the proportion those functional classifications represent of the entire County roadway system. The data show that the focus crash type – roadway 

departure crashes – occurs on roadways with a Rural Major Collector functional classification in a greater proportion than this roadway type represents for the County system. Based on this descriptive statistics analysis, 

Thurston County chose Rural Major Collector functional classification as a risk factor. 
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Improving Safety on Rural Local and Tribal Roads

Step 2

Figure 4. Evaluation of Roadway Functional Class as a Potential Risk Factor

Source: FHWA.

At the conclusion of this step, it would be useful to start the process of documenting the project analysis. 

An example document outline through this stage of the analysis is shown below.

Introduction

• Description of concerns; and

• Description of approach to analyzing conditions.

Data Collection and Evaluation

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

– Crash data tables;

– Traffic volume data;

– Roadway characteristics summary or sketches; and

– Other agency-specific or statewide documents.

Network Screening Results

• Summary of crash frequency network screening method and site ranking results; and

• Summary of EPDO network screening method and site ranking results.
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Improving Safety on Rural Local and Tribal Roads

Step 3

Step 3. Select Sites For Investigation

Background

In this step, a subset of the sites evaluated in the network screening process is selected for detailed investigation. Step 3 of the Toolkit provides more information about the process and reasons for selecting or not selecting 

sites for more detailed investigation. 

Sites can be eliminated from the remainder of the analysis for a variety of reasons, including:

• Recent construction at the site has modified conditions that may make the crash record nonrepresentative of current conditions;

• The screening results do not indicate a need to study the site in more detail;

• The issues and potential solutions for the site already are known, and documented elsewhere, and/or 

there already are plans to address the issues; and

• The issues at the site are known and potential solutions are cost prohibitive. No improvements can be 

implemented until funding is acquired and programmed.

Alternatively, sites can be selected for analysis if future development or construction is anticipated that could 

substantively change conditions. In this case, the site could be investigated for enhancements to implement 

with other upcoming changes. 

This Scenario

Table 7 shows crash severity, total crash frequency, and the EPDO score for each intersection. The table 

also shows which intersections were selected for more detailed investigation and why. As shown, of the 

15 sites included in the stop-controlled intersection safety plan, three have been selected for more detailed 

site investigation:

• Intersection L, because it has the highest EPDO score, a high crash frequency, and one of the fatal crashes;

• Intersection O, because it has a high EPDO score, high crash frequency, and one of the fatal crashes; and

• Intersection E, because it has a high EPDO score, high crash frequency, and one of the fatal crashes.

Note that even though Intersection J has a high EPDO score, high crash frequency, and one of the fatal 

crashes, it was not selected for investigation because there already are plans to signalize the intersection – this 

should address the issues at this location.

Intersection B was not selected for analysis either. It has a relatively high EPDO, and one of the fatalities 

occurred here. However, the issues at the location are known and have been previously studied. 

In the next phase of the analysis, each of the selected sites will be studied in more detail to understand crash 

characteristics, potential contributing factors, and to identify possible countermeasures. 
- 19 -

Improving Safety on Rural Local and Tribal Roads

Step 3

Table 7. Network Screening Results and Site Selection for Further Investigation

Int

Severity

Fatal Injury PDO Total EPDO Selected for Detailed Investigation?

L 1 7 11 19 631 Yes – High frequency and high EPDO score.

J 1 7 10 18 630 No – Community already has plans to signalize this intersection 

in next fiscal year. No need for further investigation at this time.

O 1 7 7 15 627 Yes – High frequency, severity, and high EPDO score.

E 1 6 12 19 621 Yes – High frequency, severity, and high EPDO score.

B 1 4 7 12 593 No – Issues at the site are known and solutions have been 

identified previously; however, funding is not available 

for the preferred solution. No action until funding can be 

programmed.

C 0 9 13 22 113 No – Although frequency is high, severity is low, and the EPDO 

score is low.

I 0 7 9 16 87 No – Low severity and low EPDO.

A 0 6 10 16 77 No – Issues have been previously identified and sight distance 

maintenance is planned beginning next fiscal year.

G 0 5 7 12 63 No – Frequency and severity are low.

K 0 5 6 11 62 No – Frequency and severity are low.

N 0 4 9 13 54 No – Frequency and severity are low.

D 0 3 9 12 42 No – Frequency and severity are low.

H 0 3 5 8 38 No – Frequency and severity are low.

M 0 2 3 5 25 No – Frequency and severity are low.

F 0 1 1 2 12 No – Frequency and severity are low.

At the conclusion of this 

step, the practitioner should 

continue documenting the 

analysis results and the 

reasons for selecting sites 

for detailed investigation. At 

this stage, there is an additional step to the document 

outline – Site Selection for 

Detailed Investigation.

Introduction

• Description of concerns; and

• Description of approach to 

analyzing conditions.

Data Collection and Evaluation

• Description of the data 

collected and summary of 

the data:

– Crash data tables;

– Traffic volume data;

– Roadway characteristics 

summary or sketches; and

– Other agency-specific or 

statewide documents.

Network Screening Results

• Summary of crash frequency 

network screening method 

and site ranking results; and

• Summary of EPDO network 

screening method and site 

ranking results.

Site Selection for 

Detailed Investigation

• Summary of method 

of identifying sites for 

detailed investigation and 

documentation of sites 

selected for investigation.
- 20 -

Improving Safety on Rural Local and Tribal Roads

Step 4

Step 4. Diagnose Site Crash Conditions and 

Identify Countermeasures

Diagnosis

Background

In this step, the sites identified for further evaluation are studied in more detail. The purpose of the detailed analysis at this stage is to identify potential crash contributing factors and identify potential treatments to address 

the identified safety concerns. The diagnosis steps and methods for identifying countermeasures are the same 

for each site under investigation. The issues and results of the analysis differ by site; however, the process for 

conducting this analysis does not change. Therefore, in this example, the process of diagnosis and selecting 

countermeasures is shown for one intersection only: Intersection L – First Street and Main Street. In practice, 

this process would be repeated for each site selected for detailed analysis identifying specific solutions for 

each site.

The Toolkit provides many different resources and tools for 

site diagnosis and countermeasures selection. A field visit 

is a very important step in conducting a site diagnosis. As 

described in the Toolkit, the field visit should be conducted 

in daylight and, if possible, under dark conditions. The 

field visit also could be conducted in the context of a Road 

Safety Audit (RSA), as described in the Toolkit. 

Three tools that are integrated into field visits and RSAs 

and are useful in identifying potential crash contributing 

factors and countermeasures are collision diagrams, condition diagrams, and the Haddon Matrix. These tools are 

described below.

This Scenario

In this scenario, collision diagram, site condition diagram, 

and Haddon Matrix are developed for Intersection L (Main 

Street and First Street). These tools can be similarly applied 

for all intersections selected for detailed site investigation.

Table 8 shows the crash type summary table for 

Intersection L. Figure 5 shows the collision diagram for 

Intersection L. 

Table 8. Intersection L: Crash Type Summary – 2010 to 2012

Total 

(2010-2012) 

Crashes

Crash Type

Run-Off

Single 

Vehicle Angle Head-On Rear-End Sideswipe Other

Int. L 19 2 0 8 1 5 2 1

Field Visit 

It is important for the analyst to make a 

field visit if possible. They should view 

the site first hand and 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 shoulder type, sight 

distance where it appears limited, posted 

speed limit, and other signage. Videotape 

or photographs are also very helpful in 

documenting conditions.

A nighttime field visit is very important 

to evaluate the signing and pavement 

marking in dark conditions. The 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.
- 21 -

Improving Safety on Rural Local and Tribal Roads

Step 4

Figure 5. Collision Diagram for Intersection L (First Street and Main Street) – 

2010 to 2012

Driveway Sidewalk

Legend

F

I

P

D

Fatal

Injury

(A, B, C)

Property

Damage 

Only

Darkness

Run-off

Angle

Rear-end

Sideswipe

Four crashes occurred in Head-on

dark conditions. 

All other crashes in the daytime 

and under clear and dry conditions.

N

First St. Main St.

P

P

P P

P

I

P

I

P I

I

ID

P

PD

FD

I

PD I

Reviewing the table and the diagram shows:

• Angle crashes are the most common crashes. Three occurred at the eastbound approach to the intersection and five occurred at the northbound approach to the intersection.

• Rear-end crashes are the next most common crashes. In the three-year period, there were five rear-end 

crashes. The rear-end crashes occurred at the northbound, southbound, and westbound approach to 

the intersection.
- 22 -

Improving Safety on Rural Local and Tribal Roads

Step 4

• The most severe crash was the head-on collision which resulted in a fatality. This crash also occurred 

at nighttime (without illumination).

• Both run-off-road crashes occurred at the eastbound approach to the intersection.

Figure 6 shows the site condition diagram. As shown, during the field review, staff noted that the intersection 

approaches have thick vegetation on the northwest and southeast corners of the intersections and there is no 

illumination on all four intersection corners. Furthermore, the intersection is at the crest of the vertical curve 

along the Main Street alignment. There also are two driveways off First Street – a residential driveway off westbound First Street located 50 feet east of the intersection, and a school driveway off eastbound First Street 

located 100 feet west of the intersection.

Figure 6. Condition Diagram for Intersection L (First Street and Main Street) 

School

100 Feet

Residential Open

Space

50 Feet

N

First St. Main St.
- 23 -

Improving Safety on Rural Local and Tribal Roads

Step 4

Table 9 shows the Haddon Matrix developed from the study intersection’s crash records. As described in the 

Toolkit, the Haddon Matrix provides a framework for reviewing crash records and understanding potential contributing factors in the context of the time of events: before the crash, during the crash, and after the crash. The 

time of events is divided into the three major categories of contributing factors: the human, the vehicle, or the 

environment. For the most part, information and clues for the type of engineering solutions that might be useful 

can be drawn from the physical environment column.

Table 9. Haddon Matrix for Intersection L (First Street and Main Street)

Time of 

Events Human Vehicle/Equipment Physical Environment

Precrash • Poor vision, speeding

• Risk-taking, follow too closely

• Cell phone use

• Failure to stop completely at 

stop sign

• Failed brakes

• Malfunctioning headlight

• Vegetation/trees blocking 

sight distance as drivers 

approach the intersection

• No streetlights at 

the intersection

• High left-turn volumes from 

Main Street onto First Street

Crash • Failure to use seat belt

• Poor reaction time

• Driving under the influence 

of alcohol

• Seat belt and 

airbag malfunction

• Low-friction pavement surface

Postcrash • Crash victim had previous 

medical condition

NA

This Scenario

The field visit, crash data summary, and evaluation, collision diagram, condition diagram, and Haddon 

Matrix show:

• In the three-year period from 2010 to 2012, there have been 19 crashes at the intersection of First Street 

and Main Street, 8 of these are angle crashes. There has been 1 fatal collision at the intersection.

• Of the 19 crashes, 3 occurred at night with no streetlights.

• The collision diagram indicates that angle crashes are occurring between motorists turning from eastbound First Street onto Main Street, and motorists turning from northbound Main Street onto First Street.

• The angle crashes occurring from northbound Main Street onto westbound First Street may be caused by 

difficulty in judging gaps in southbound Main Street traffic flow – possibly due to the crest vertical curve.

• The condition diagram shows trees and shrubs within close proximity of the intersection’s northwest 

and the southeast corners. This is possibly creating a sight distance constraint for motorists turning from 

eastbound First Street onto northbound Main Street.

Based on this summary, the left turn crashes from eastbound First Street onto Main Street and northbound 

Main Street onto First Street are the most critical and concerning; therefore, safety treatments will focus on 

reducing frequency and severity of these angle crashes.
- 24 -

Improving Safety on Rural Local and Tribal Roads

Step 4

Identify Countermeasures

Background

The resources available to identify countermeasures are summarized in Step 4 of the Toolkit. These 

resources are the same whether one site or many 

sites are being investigated: the web-based CMF 

Clearinghouse, Part D of the Highway Safety Manual, 

the NCHRP 500 Reports, and the FHWA Office of 

Safety Proven Countermeasures web page. Step 4 

of the Toolkit provides detailed information about 

each of these resources. This scenario uses the CMF 

Clearinghouse and the Highway Safety Manual as 

resources for identifying possible countermeasures to 

address angle crashes at the intersection.

This Scenario

Table 10 shows countermeasures identified as possible treatments to address the scenario’s turning 

movement and nighttime crashes. The potential 

countermeasures address sight distance constraints, 

lighting concerns, and angle crashes. The table also 

shows the CMF values and construction costs estimates1

 for the countermeasures.

1 Construction costs for these countermeasures are based on 2013 average unit price for Michigan Department 

of Transportation.

Summary of Crash Modification 

Factors (CMF)

A CMF is a multiplicative factor used to compute 

the expected number of crashes after implementing a given countermeasure at a specific 

site. The CMF is multiplied by the expected 

crash frequency without treatment to show the 

expected crash frequency with 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 

after implementation of a given countermeasure. For example, a CMF of 0.8 indicates an 

expected safety benefit; specifically, a 20 percent expected reduction in crashes. A CMF of 

1.2 indicates an expected degradation in safety; 

specifically, a 20 percent expected increase 

in crashes.

CMFs for several countermeasures can be multiplied to reflect the application of multiple safety 

countermeasures at the same location.
- 25 -

Improving Safety on Rural Local and Tribal Roads

Step 4

Table 10. Countermeasures Identified for Intersection L (First Street and 

Main Street)

Contributing 

Factor Countermeasure CMF Costa Source

Vegetation/

trees limiting sight 

distance as drivers 

approach the 

intersection

Clear sight 

triangles at the 

northwest corner 

of intersection 

• 0.44 – Fatal Crashes

• 0.53 – Serious and Minor 

Injury Crashes

• 0.89 – PDO Crashes

• $3,800 to $4,500 

per acre

CMF 

Clearinghouse

Dark intersection 

with no street lights

Provide 

intersection 

illumination

• 0.62 – Nighttime Serious 

and Minor Injury Crashes

• 0.23 – All Crash Types – 

Fatal Crashes

• 0.5 – All Crash Types – 

Serious and Minor 

Injury Crashes

• 0.52 – All Crash Types – 

PDO Crashes

• 30-foot light 

with 15-foot arm 

and concrete 

foundation: 

$2,900 each

• $50 per month of 

operating cost

CMF 

Clearinghouse

High left-turn 

volumes from 

northbound 

Main Street 

and eastbound 

First Street

Convert 

intersection from 

stop-controlled 

to signalcontrolledb

• 0.56 – All Crash Types – 

All severities

• Box span, pedestrian timer, and 

update crosswalk 

markings: $115,000

• $50 per month 

operating cost

Highway Safety 

Manual

a Costs are for illustrative purposes only and should not be used for any jurisdiction-specific calculations. 

b Subject to meeting MUTCD warrants.

Vegetation Control. Through vegetation control, maintenance staff can remove plants, clear tree branches, 

and trim brushes that block a driver’s line of sight at an intersection. Drivers approaching an intersection need a 

clear line of sight to the intersection and along the crossing roadway to perceive and react to potential conflicting 

vehicles, bicyclists, and/or pedestrians. The sight lines required for drivers to see approaching traffic form a 

sight triangle over an intersection corner, as shown in Figure 7.

Intersection Illumination. Intersection illumination can provide lighting for drivers, pedestrians, bicyclists, and 

other road users to see each other approaching the intersection. Streetlights also can illuminate intersection 

characteristics for users such as signage, striping, and shoulder. In rural situations, intersection illumination can 

act as a point of reference or landmark for drivers so they can see the intersection that they are approaching 

well in advance of their arrival. This helps in navigation.

Signalization. A traffic signal warrant is an analysis used to determine whether conditions warrant traffic signal 

installation at an intersection. If traffic signal warrants are met, converting an intersection from stop-controlled 

to signal-controlled provides specific signal phases for turning and through vehicles at the intersection, thereby 

reducing the number of possible collisions. The Manual on Uniform Traffic Control Devices (MUTCD) should be 

used to conduct the traffic signal warrant analysis. 
- 26 -

Improving Safety on Rural Local and Tribal Roads

Step 4

Figure 7. Intersection Sight Distance Triangle 

Leg A Distance

Leg B Distance

Source: Vegetation Control for Safety, A Guide for Local Highway and Street Maintenance Personnel, FHWA Office of Safety.

When choosing a CMF for a particular countermeasure, it is common to have to select one value among many. 

To select a CMF, the practitioner should consider:

• The quality of the research in calculating the CMF;

• Consistency between the site under investigation and site/research conditions provided in the research 

description of the CMF; and

• Crash severity or crash type under investigation.

For example, as shown in Figure 8 the CMF Clearinghouse provides six different CMFs for the countermeasure 

“Increase Triangle Sight Distance.” Differences in these CMFs include:

• Variation in star quality ratings (quality of research);

• Application to specific crash severities (i.e., fatal, severe injury, or PDO); and

• Application to specific area types (e.g., roundabouts or stop-controlled intersections). 

The practitioner will have to review the Clearinghouse’s detailed information to select conditions most applicable to the site under investigation. In this example, Table 10 also shows the three sight distance triangle 

CMFs with the highest star rating and most applicable to our site conditions.
- 27 -

Improving Safety on Rural Local and Tribal Roads

Step 4

Figure 8. Increase Sight Distance Triangle From CMF Clearinghouse 

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

At the conclusion of this step, the agency will have identified potential countermeasures for each site selected 

for investigation in Step 3. At this stage, the project documentation could be updated to include the diagnosis 

results and selection of potential countermeasures. An example of the documentation outline is shown below.

Introduction

• Description of concerns; and

• Description of approach to 

analyzing conditions.

Data Collection and Evaluation

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

– Crash data tables;

– Traffic volume data;

– Roadway characteristics summary or 

sketches; and

– Other agency-specific or statewide documents.

Network Screening Results

• Summary of crash frequency network 

screening method and site ranking 

results; and

• Summary of EPDO network screening 

method and site ranking results.

Site Selection for Detailed Investigation

• Documentation of sites selected for 

detailed investigation.

Diagnose Results and 

Selection of Countermeasures

• Summary of existing site conditions, crash, 

and roadway characteristics; and

• Summary of analysis and countermeasures 

selected for possible implementation.
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Improving Safety on Rural Local and Tribal Roads

Step 5

Step 5. Prioritize Countermeasures for Implementation

Background

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 process for prioritizing 

and selecting countermeasures among a number of optional countermeasures for one site 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 criteria that influence the quantitative or qualitative analysis will vary from agency to agency. Some typical 

criteria are:

• 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.

Step 5 of the Toolkit and User Guide #1 provide an example of a countermeasure selection process applying a 

qualitative ranking process.

This User Guide uses a quantitative benefit/cost analysis to identify the most feasible treatment at the site. 

Conceptually, in a benefit/cost analysis, the benefits and costs of implementing a countermeasure are converted to a present-year dollar value. The total present dollar value of the benefits is divided by the total present 

dollar value of the costs. If the ratio exceeds 1.0, the treatment is considered economically feasible. The higher 

the benefit/cost ratio, the greater the value of the project under consideration. Step 5 of the Toolkit presents 

more information about benefit/cost analysis.

This Scenario

The calculation steps for benefit/cost ratio are the same for all countermeasures; although actual benefits and 

costs of each countermeasure vary. As such the benefit/cost ratio calculations for only one of the three possible countermeasures identified for Intersection L – Main Street and First Street – vegetation control is shown. 

Table 11 summarizes the results of the all three B/C calculations.

The major steps in this benefit/cost analysis are:

1. Estimate the potential annual savings in crashes by severity that can be attributed to clearing vegetation and maintaining sight distance.

a. Calculate existing annual crashes per year by crash severity.

i. The crash diagram in Figure 5 showed three angle crashes from 2010 to 2012, which are likely to 

respond to vegetation control in the northeast corner of the intersection.
- 29 -

Improving Safety on Rural Local and Tribal Roads

Step 5

ii. Crashes per year that may respond to the treatment:

b. Calculate possible annual crashes per year by severity after clearing sight triangles.

i. All three angle crashes were injury crashes. There were no fatal or property damage-only crashes.

ii. The number of injury crashes per year that may respond to the improvements:

2. Estimate the savings in crashes per year by severity.

Vegetation Control CMF by Severity CMF

Fatal Crash 0.44

Injury Crash 0.53

PDO Crash 0.89 

a. The number of crashes per year by severity that can be potentially saved by clearing and maintaining sight distance at the intersection is equal to:

b. There are no fatal or property damage-only crashes at the intersection that may be avoided with 

clearing and maintenance of sight distance.

3. Calculate the net present value of the crash benefits of clearing and maintaining sight distance 

triangles.

a. Convert the estimated savings in 

crashes per year by severity from crash 

frequency to a dollar value per year. 

From the Highway Safety Manual, 

Chapter 7 the societal cost of crashes 

is as follows:

i. Fatal (K) = $4,008,900;

ii. Injury (A, B, and C) = $82,600; and

iii. PDO (O) = $7,400.

Societal Cost 

There are costs to society of a death or injury occurring in a crash. Costs include (defined by National 

Safety Council): wage and productivity losses, 

medical expenses, administrative expenses, motor 

vehicle damage, and employers’ uninsured costs.
- 30 -

Improving Safety on Rural Local and Tribal Roads

Step 5

If there were crashes with other severity types, the potential savings per year would be calculated 

in a similar fashion: the dollar value of the crash severity type multiplied by the potential savings 

in crash severity type per year.

b. Estimate the duration of effectiveness of the improvement. 

i. In this scenario, assume the sight distance triangle would be cleared and maintained for 20 years.

c. Calculate the net present value of the benefits of clearing the sight triangle. Net present value is 

the value of benefits or costs in a “future” year recalculated to a “present” value in the current 

year. So in this scenario, there are 20 years of potential benefits and 20 years of costs. The “net 

present value” is the sum of each present value of the benefits over 20 years or the sum of each 

of the present value of costs over 20 years.

This step calculates the net present value factor for calculating the potential benefits in every year. 

The equation for net present value factor is:

i = Minimum attractive rate of return or discount rate (this scenario assumes a return rate of 

4 percent or i = 0.04)

y = Year in the service life of the countermeasure, one calculation for each year of life.

For example, in Year 10, the present value factor is:

Table 11 shows the present value of the benefits and costs for each year of effectiveness of 

the vegetation control. As shown, saving $38,822 (today’s dollars) in injury crashes per year in 

Year 10 has a present value of $314,881.

4. Calculate the net present value of the costs of clearing and maintaining sight distance at the intersection for 20 years.

a. Calculate the annual costs of maintaining sight distance at the northwest corner of the intersection 

for 20 years.
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Improving Safety on Rural Local and Tribal Roads

Step 5

b. Calculate the net present value of the costs of clearing and maintaining the sight distance at the 

intersection for 20 years.

This scenario assumes it costs $4,500 per acre to clear sight triangles plus $500 per year to maintain 

conditions. This scenario further assumes that every third year, the more expensive sight distance 

maintenance will be required. These costs are for this example only and should not be applied to any 

jurisdiction-specific analyses. In this scenario it is necessary to clear one-half acre of vegetation from 

the northwest corner of the intersection.

Table 11 also shows the net present value of the costs to maintain sight distance at the intersection 

for 20 years. As shown, the present value of spending $2,750 in Year 10 is $22,305; and the total net 

present value for all 20 years to maintain sight distance is $200,548.

Table 11. Summary of Benefit/Cost Analysis for Vegetation Control for 

Intersection L (First Street and Main Street)

Year Fatal Injury A-C PDO

Total 

Benefits ($)

Net Present 

Value 

Benefits

Cost Per 

Yeara

Net Present 

Value Cost

1 $ – $38,822 $ – $38,822 $38,822 $2,750 $2,750

2 $ – $38,822 $ – $38,822 $73,222 $500 $943

3 $ – $38,822 $ – $38,822 $107,735 $500 $1,388

4 $ – $38,822 $ – $38,822 $140,920 $2,750 $9,982

5 $ – $38,822 $ – $38,822 $172,829 $500 $2,226

6 $ – $38,822 $ – $38,822 $203,510 $500 $2,621

7 $ – $38,822 $ – $38,822 $233,012 $2,750 $16,506

8 $ – $38,822 $ – $38,822 $261,379 $500 $3,366

9 $ – $38,822 $ – $38,822 $288,655 $500 $3,718

10 $ – $38,822 $ – $38,822 $314,881 $2,750 $22,305

11 $ – $38,822 $ – $38,822 $340,099 $500 $4,380

12 $ – $38,822 $ – $38,822 $364,347 $500 $4,693

13 $ – $38,822 $ – $38,822 $387,663 $2,750 $27,461

14 $ – $38,822 $ – $38,822 $410,082 $500 $5,282

15 $ – $38,822 $ – $38,822 $431,638 $500 $5,559

16 $ – $38,822 $ – $38,822 $452,365 $2,750 $32,044

17 $ – $38,822 $ – $38,822 $472,296 $500 $6,083

18 $ – $38,822 $ – $38,822 $491,459 $500 $6,330

19 $ – $38,822 $ – $38,822 $509,886 $2,750 $36,118

20 $ – $38,822 $ – $38,822 $527,604 $500 $6,795

Net Present Value $6,222,404 $200,548

a Costs are for illustrative purposes only.
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Improving Safety on Rural Local and Tribal Roads

Step 5

5. Calculate the benefit/cost ratio.

In practice, Steps 1 through 4 would be conducted for each countermeasure being considered for 

implementation.

Table 12 shows summary-level results of this calculation for each countermeasure. The benefit/cost ratio 

is the net present value of the benefits divided by the net present value of the costs. As shown, the benefit/

cost ratio (B/C) for vegetation control is:

Table 12. Summary of Benefit/Cost Analysis

Treatment

Crash Savings Per Year

Fatal NPV Benefits NPV Costs B/C Ratio

Injury 

A, B, and C PDO

Vegetation Control 0.00 0.47 0.00 $6,222,404 $200,548 31.03

Illumination 0.00 0.13 0.21 $2,545,358 $167,080 15.23

Signalize 0.00 0.73 0.44 $13,865,663 $565,560 24.52

The results of this analysis show that implementing vegetation control has the highest benefit/cost analysis, 

assuming the sight distance clearance is maintained at all times for 20 years. Therefore, this treatment is 

selected to be implemented and maintained at the intersection.

There also is a relatively high benefit/cost ratio associated with signalizing the intersection. If traffic signal warrants are met at the intersection and initial construction costs are available, this also could be considered a 

beneficial modification to the intersection. 
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Improving Safety on Rural Local and Tribal Roads

Step 5

At the end of this stage, it is appropriate to expand the project documentation again to include an explanation of 

the analysis, 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; and

• Description of approach to 

analyzing conditions.

Data Collection and Evaluation

• Description of the data collected and 

summary of the data:

– Crash data tables;

– Traffic volume data;

– Roadway characteristics summary or 

sketches; and

– Other agency-specific or 

statewide documents.

Network Screening Results

• Summary of crash frequency network 

screening method and site ranking 

results; and

• Summary of EPDO network screening 

method and site ranking results.

Site Selection for Detailed Investigation

• Documentation of sites selected for 

detailed investigation.

Diagnose Results and 

Selection of Countermeasures

• Summary of existing site conditions, crash, 

and roadway characteristics; and

• Summary of analysis and countermeasures 

selected for possible implementation.

Countermeasure Prioritization

• Summary of prioritization process and results 

based on the benefit-cost ratio method.

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

At this stage of the process, diagnosis, countermeasure selection, and prioritization would be complete 

for all intersections selected for additional analysis in Step 3. Next, the agency works on implementing the 

countermeasures. 

Obtaining the necessary human and financial resources is a major consideration in implementing any safety 

project or program. 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. The Toolkit also provides more information about funding opportunities.

This Scenario

The FHWA’s Vegetation Control for Safety Guide2 provides guidance on checking and improving intersection 

sight distance. Drivers approaching an intersection need a clear line of sight to the intersection and along the 

intersection to react to potential conflicting vehicles, bicyclists and pedestrians to avoid a collision. Figure 9 from 

the FHWA’s guide shows the sight triangles formed by the sightlines of two vehicles approaching an intersection.

Figure 9. FHWA’s Vegetation Control for Safety Guide – Sight Triangle Diagram 

Satisfactory

Hazardous

Source: Vegetation Control for Safety, A Guide for Local Highway and Street Maintenance Personnel, FHWA Office of Safety.

2 http://safety.fhwa.dot.gov/local_rural/training/fhwasa07018/.
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Improving Safety on Rural Local and Tribal Roads

Step 6

In this scenario, vehicles stopped at the intersection on First Street need sight distance to see vehicles 

approaching from either direction of Main Street, so that the stopped driver can safely turn left, turn right, or 

proceed across the intersection. Of the three options, the sight distance needed for a left turn is the longest and 

can be used to establish the corner sight triangle for both legs of the minor road.

Vegetation at the northwest corner of the intersection is cleared and maintained for 20 years. No shrubs or 

plants within the corner sight triangle should be allowed to grow more than three feet high. Trees over three feet 

high are removed. In cases where sight distance is limited by vegetation on private property, staff can work with 

the private property owner to identify opportunities for controlling and managing vegetation.

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

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

Introduction

• Description of concerns; and

• Description of approach to 

analyzing conditions.

Data Collection and Evaluation

• Description of the data collected and 

summary of the data:

– Crash data tables;

– Traffic volume data;

– Roadway characteristics summary or 

sketches; and

– Other agency-specific or 

statewide documents.

Network Screening Results

• Summary of crash frequency network 

screening method and site ranking 

results; and

• Summary of EPDO network screening 

method and site ranking results.

Site Selection for Detailed Investigation

• Documentation of sites selected for 

detailed investigation.

Diagnose Results and 

Selection of Countermeasures

• Summary of existing site conditions, crash, 

and roadway characteristics; and

• Summary of analysis and countermeasures 

selected for possible implementation.

Countermeasure Prioritization

• Summary of prioritization process and results 

based on the benefit-cost ratio method.

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 of 

identifying sites for detailed investigation.
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Improving Safety on Rural Local and Tribal Roads

Step 7

Step 7. Evaluate Effectiveness

Background

Three to five years after implementing and maintaining the 

treatment, agency staff should measure the effectiveness of 

the treatment. This can be completed by tabulating the number 

and type of crashes at the site since implementing the improvement – essentially repeating Step 1 and recreating Table 3 in 

this scenario and/or conducting more rigorous before-and-after 

study evaluations. Step 7 of the Toolkit provides more information about optional methods for evaluation.

This Scenario

In this scenario, assuming traffic volume does not change 

dramatically, crash records for the three-year period after implementing the treatment are collected and compared to the three-year period before treatment implementation.

Table 13 shows how the before-and-after crash data can be tabulated. In this scenario, three years after clearing 

and maintaining the sight distance triangles, angle crashes at the intersection decreased from eight in the threeyear period before the treatment to two in the three-year period after, or a 75 percent reduction in angle crashes. 

Because of statistical issues associated with crash data (explained in the Toolkit) – it should not be concluded 

that there was a 75 percent reduction in angle crashes. It can be concluded that angle crashes have decreased, 

but this analysis is not statistically rigorous enough to quantify the change in crash frequency. 

Table 13 also shows that there has been a slight increase in rear-end crashes from the before to the after 

period. This could be due to the natural variation in crash frequency or it could reflect a new crash pattern 

emerging. It would be valuable to continue monitoring the intersection to ensure there are no additional modifications necessary.

Table 13. Example of Comparison of Before-and-After Period Crash Data

Crash Type

Before 

(2010-2012)

After 

(2014-2016)

Angle 8 2

Run-Off 2 1

Single Vehicle 0 0

Head-On 1 0

Rear-End 5 7

Sideswipe 2 2

Other 1 1

Total 19 12

Use Caution with 

Simple Before-and-After 

Analysis Results

A simple before-and-after analysis 

does not provide a quantitative result. 

Because of statistical limitations of 

crash data, a simple analysis is not 

sufficient to make an accurate quantitative assessment.
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Improving Safety on Rural Local and Tribal Roads

Step 7

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. 

Documenting the results of the effectiveness analysis in a memo to file 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 being considered in the future. 
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Improving Safety on Rural Local and Tribal Roads

4.0 Options for 

Additional Activities

Completing the analysis in this scenario results in an identified list of sites with potential for safety improvement 

and countermeasures selected for each location. If possible, the improvements can be implemented immediately, or the agency can develop a longer-term plan for implementing the countermeasures over time as funding 

and/or other resources become available.

Looking forward from implementing the treatments identified at each of the sites investigated in this safety 

analysis, there are other activities the agency could undertake to complement the work done this far and continue to build community interest in road safety. The agency manager could:

• Contact the stakeholders that were concerned about intersection safety in the community and gauge 

their interest in developing and participating in a community traffic safety committee. This committee 

could study traffic safety on other facilities in the community, or study and develop action plans for 

behavioral safety issues, if appropriate.

• If there is sufficient interest, this committee also could include staff members from the sheriff’s department and the community hospital or clinic.

• Collaborate with police enforcement in the community to enhance enforcement throughout the community.

• Conduct a network screening analysis on another type of intersection or roadway in the community.

Resources about these activities can be found in the Toolkit.
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Improving Safety on Rural Local and Tribal Roads

5.0 Conclusions

User Guide #2 focuses on studying safety conditions at many sites. The need for the network screening analysis was derived from community concern for enhanced roadway safety at intersections. The agency manager 

chose to study all of the community’s two-way stop-controlled intersections first because most of the community 

intersections operate this way. After conducting the network screening analysis, the agency manager identified 

a number of sites with potential for safety improvement. This list of potential study sites was whittled down to 

a smaller number of sites for detailed investigation based on staff and funding resources available to conduct 

the analysis. The detailed study at each site includes evaluating crash conditions (diagnosis) and identifying 

countermeasures, prioritizing and selecting countermeasures, implementing the countermeasure, and over 

time evaluating the effectiveness of the countermeasures that have been implemented.

At the conclusion of these activities, the practitioner also should evaluate whether there are other safety-related 

activities that could be undertaken as part of ongoing work in the agency. This can be especially successful 

while the community is interested and focused on road safety.

The information herein has been presented as a “go-by” to help a practitioner get through the process. The 

Toolkit associated with this User Guide provides many resources for conducting each of the steps.