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

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


Notice

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

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.


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)

Table of Contents

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 November 18, 2016
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