Scale and Scope of Safety Assessment Methods in the Project Development Process

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Federal Highway Administration
Office of Safety
1200 New Jersey Avenue, SE
Washington, DC 20590
www.safety.fhwa.dot.gov

FHWA-SA-16-106

United States Department of Transportation Logo

November 2016

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This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document. The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document.

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1. Report No. FHWA-SA-16-106	2. Government Accession No.	3. Recipient's Catalog No.
4. Title and Subtitle Scale and Scope of Safety Assessment Methods in the Project Development Process	5. Report Date November 2016
6. Performing Organization Code
7. Author(s) Jennifer Atkinson, Karen Dixon, Joseph Jones, Kelly Donoughe-Palframan, Mike Colety, Michael Pratt	8. Performing Organization Report No.
9. Performing Organization Name and Address Leidos 11251 Roger Bacon Dr. Reston, VA 20190 Subconsultants: Texas Transportation Institute Kimley-Horn Associates	10. Work Unit No. (TRAIS)
11. Contract or Grant No. DTFH61-10-D-00024
12. Sponsoring Agency Name and Address United States Department of Transportation Federal Highway Administration Office of Safety 1200 New Jersey Avenue, SE Washington, DC 20590	13. Type of Report and Period Covered
14. Sponsoring Agency Code HSA
15. Supplementary Notes Ray Krammes (Ray.Krammes@dot.gov), Office of Safety, served as the Task Manager for the Federal Highway Administration (FHWA). Jerry Roche (Jerry.Roche@dot.gov), Office of Safety, served as a technical advisor for FHWA. The Highway Safety Manual Implementation Pooled Fund Study funded this project. Pooled-fund State representatives served as reviewers
16. Abstract This document is intended to help users identify and apply suitable methods to assess quantitatively the safety performance impacts of project development decisions in terms of crash frequency and severity. This Guide suggests safety assessment methods that may be suitable for answering safety performance related questions that typically arise during each phase of the development process and for projects of various types. It also provides examples that illustrate the thought process for selecting a safety assessment method. This information on safety performance can then be considered in concert with other project criteria to make more informed highway investment decisions.
17. Key Words Highway Safety Manual, project development, safety assessment method, safety performance	18. Distribution Statement No restrictions.
19. Security Classification (of this report) Unclassified	20. Security Classification (of this page) Unclassified	21. No of Pages 152	22. Price N/A

1. Report No.

FHWA-SA-16-106

2. Government Accession No.

3. Recipient's Catalog No.

4. Title and Subtitle

Scale and Scope of Safety Assessment Methods in the Project Development Process

5. Report Date

November 2016

6. Performing Organization Code

7. Author(s)

Jennifer Atkinson, Karen Dixon, Joseph Jones, Kelly Donoughe-Palframan, Mike Colety, Michael Pratt

8. Performing Organization Report No.

9. Performing Organization Name and Address

Leidos
11251 Roger Bacon Dr.
Reston, VA 20190

Subconsultants:
Texas Transportation Institute
Kimley-Horn Associates

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

DTFH61-10-D-00024

12. Sponsoring Agency Name and Address

United States Department of Transportation
Federal Highway Administration
Office of Safety
1200 New Jersey Avenue, SE
Washington, DC 20590

13. Type of Report and Period Covered

14. Sponsoring Agency Code

HSA

15. Supplementary Notes

Ray Krammes (Ray.Krammes@dot.gov), Office of Safety, served as the Task Manager for the Federal Highway Administration (FHWA). Jerry Roche (Jerry.Roche@dot.gov), Office of Safety, served as a technical advisor for FHWA. The Highway Safety Manual Implementation Pooled Fund Study funded this project. Pooled-fund State representatives served as reviewers

16. Abstract

This document is intended to help users identify and apply suitable methods to assess quantitatively the safety performance impacts of project development decisions in terms of crash frequency and severity. This Guide suggests safety assessment methods that may be suitable for answering safety performance related questions that typically arise during each phase of the development process and for projects of various types. It also provides examples that illustrate the thought process for selecting a safety assessment method. This information on safety performance can then be considered in concert with other project criteria to make more informed highway investment decisions.

17. Key Words

Highway Safety Manual, project development, safety assessment method, safety performance

18. Distribution Statement

No restrictions.

19. Security Classification (of this report)

Unclassified

20. Security Classification (of this page)

Unclassified

21. No of Pages

152

22. Price

N/A

SI* (Modern Metric) Conversion Factors

APPROXIMATE CONVERSIONS TO SI UNITS
SYMBOL	WHEN YOU KNOW	MULTIPLY BY	TO FIND	SYMBOL
LENGTH
in	inches	25.4	millimeters	mm
ft	feet	0.305	meters	m
yd	yards	0.914	meters	m
mi	miles	1.61	kilometers	km
AREA
in²	square inches	645.2	square millimeters	mm²
ft²	square feet	0.093	square meters	m²
yd²	square yard	0.836	square meters	m²
ac	acres	0.405	hectares	ha
mi²	square miles	2.59	square kilometers	km²
VOLUME
fl oz	fluid ounces	29.57	milliliters	mL
gal	gallons	3.785	liters	L
ft³	cubic feet	0.028	cubic meters	m³
yd³	cubic yards	0.765	cubic meters	m³
NOTE: volumes greater than 1000 L shall be shown in m³
MASS
oz	ounces	28.35	grams	g
lb	pounds	0.454	kilograms	kg
T	short tons (2000 lb)	0.907	megagrams (or "metric ton")	Mg (or "t")
TEMPERATURE (exact degrees)
^oF	Fahrenheit	5 (F-32)/9 or (F-32)/1.8	Celsius	^oC
ILLUMINATION
fc	foot-candles	10.76	lux	lx
fl	foot-Lamberts	3.426	candela/m²	cd/m²
FORCE and PRESSURE or STRESS
lbf	poundforce	4.45	newtons	N
lbf/in²	poundforce per square inch	6.89	kilopascals	kPa

APPROXIMATE CONVERSIONS FROM SI UNITS
SYMBOL	WHEN YOU KNOW	MULTIPLY BY	TO FIND	SYMBOL
LENGTH
mm	millimeters	0.039	inches	in
m	meters	3.28	feet	ft
m	meters	1.09	yards	yd
km	kilometers	0.621	miles	mi
AREA
mm²	square millimeters	0.0016	square inches	in²
m²	square meters	10.764	square feet	ft²
m²	square meters	1.195	square yards	yd²
ha	hectares	2.47	acres	ac
km²	square kilometers	0.386	square miles	mi²
VOLUME
mL	milliliters	0.034	fluid ounces	fl oz
L	liters	0.264	gallons	gal
m³	cubic meters	35.314	cubic feet	ft³
m³	cubic meters	1.307	cubic yards	yd³
MASS
g	grams	0.035	ounces	oz
kg	kilograms	2.202	pounds	lb
Mg (or "t")	megagrams (or "metric ton")	1.103	short tons (2000 lb)	T
TEMPERATURE (exact degrees)
^oC	Celsius	1.8C+32	Fahrenheit	^oF
ILLUMINATION
lx	lux	0.0929	foot-candles	fc
cd/m²	candela/m²	0.2919	foot-Lamberts	fl
FORCE and PRESSURE or STRESS
N	newtons	0.225	poundforce	lbf
kPa	kilopascals	0.145	poundforce per square inch	lbf/in²

*SI is the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380.
(Revised March 2003)

Chapter 1. Introduction
	1.1 Overview of the Project Development Process
	1.2 Safety Assessment Methods for Varying Project Applications
	1.3 Selecting Suitable Safety Assessment Methods
	1.4 How to Navigate This Guide
	1.5 Chapter References
Chapter 2. Planning and Scoping Applications
	2.1 Priority Ranking Urban Signalized Intersections based onPedestrian Crashes
	2.2 Conducting Site Evaluations Supplemented by Collision Diagrams for an Urban Arterial Intersection
	2.3 Justifying the Need for Potential Cost-effective Safety Countermeasures for a Rural Two-lane Highway
	2.4 Predicting Crashes to Evaluate Level of Service of Safety for a Rural Two-lane Highway
	2.5 Predicting Incremental Benefits Associated with Increased Lane Width for a Rural Two-lane Highway
Chapter 3. Alternatives Analysis Applications
	3.1 Comparing Design Alternatives for Seven-Lane Urban Arterial
	3.2 Predicting Crash Frequency for Alternative Intersection Turn Lane Options at Four-lane Rural Undivided Highways
	3.3 Calculating Expected Crashes for Rural Two-Lane Highways
	3.4 Calculating Expected Crashes for Urban Freeway Ramps
Chapter 4. Preliminary and Final Design Applications
	4.1 Predicting Crashes for a New Urban Multilane Arterial
	4.2 Calculating Predicted Crash Frequency for Proposed Two-Lane Roundabout
	4.3 Documenting a Design Decision for a Sharp Horizontal Curve on a Rural Two-Lane Highway
Chapter 5. Urban Street Continuous Case Study
	5.1 Urban Street Continuous Case Study – Planning and Scoping
	5.2 Urban Street Continuous Case Study – Alternatives Analysis
	5.3 Urban Street Continuous Case Study – Preliminary Final Design
Appendix – Alternative Calculations for Select Example Problems
	A-3.2 Hand Calculated Example – Predicting Crash Frequency for Alternative Intersection Turn-lane Options at Four-Lane, Rural, Undivided Highways
	A-3.4 Hand Calculated Example – Calculating Expected Crashes for Urban Freeway Ramps
	A-4.1 Hand Calculated Example – Predicting Crashes for a New Urban Multilane Arterial
	A-4.3 Hand Calculated Example – Documenting a Design Decision for a Sharp Horizontal Curve on a Rural Two-Lane Highway.

Figures

Figure 1. Project Development Phases and Corresponding Chapter Organization

Figure 2. Example Problem Sample Header

Figure 3. The Project Development Cycle and Corresponding Planning and Scoping Chapter

Figure 4. The Approach for Selecting a Safety Assessment Method for Planning and Scoping

Figure 5. The Project Development Cycle and Corresponding Alternatives Analysis Chapter

Figure 6. The Project Development Cycle and Corresponding Design Chapters

Tables

Table 1. Primary Analysis Application for Safety Assessment Methods

Table 2. Safety Assessment Methods for Project Phase, Task, and Type

Table 3. Example Project Type Descriptions for Safety Assessment Method Identification

Table 4. Data Needs for Safety Assessment Methods

Table 5. Planning and Scoping Safety Assessment Objective

Table 6. Safety Assessment Performance Measures and Data Needs

Table 7. Example Summary of Available Data

Table 8. Alternatives Evaluation and Identification Safety Assessment Objective

Table 9. Preliminary and Final Design Safety Assessment Objective

List of Acronyms

AADT	Annual Average Daily Traffic
AASHTO	American Association of State Highway and Transportation Officials
ADT	average daily traffic
B/C	benefit/cost
CMF	Crash Modification Factor
DOT	department of transportation
EB	Empirical Bayes
EPDO	equivalent property damage only
FAQ	frequently asked questions
FHWA	Federal Highway Administration
FI	fatal and injury
HSM	Highway Safety Manual
IHSDM	Interactive Highway Safety Design Model
ISATe	Enhanced Interchange Safety Analysis Tool
ITE	Institute of Transportation Engineers
LOSS	level of service of safety
MP	mile post
NCHRP	National Cooperative Highway Research Program
NEPA	National Environmental Policy Act
PDO	property damage only
S.E.	standard error
SPF	Safety Performance Function
vpd	vehicles per day

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Page last modified on May 4, 2021