(Note: This document has been converted from the original publication to 508-compliant HTML. The formatting has been adjusted for 508 compliance, but all the original text content is included, plus additional text descriptions for the images, photos and/or diagrams have been provided below.)
(Extended Text Description: Cover artwork for the publication "Methods and Practices for Setting Speed Limits: An Informational Report." The cover includes photos in the center of the design, depicting various speed limit signs in different environments. The first photo (on the left, center, and larger than the other photos) has a speed limit sign that reads "Speed Limit 30", next to a two-lane road running through a forest in the fall. The second photo shows a "Speed Limit 45" sign with a blue sky and a few clouds behind it. The third photo shows "Speed Limit 25" next to a road in a suburban area with green trees and grass. Under the photos is the text "FHWA Safety Program." At the bottom of the cover design are three logos, from left to right: The US Department of Transportation - Federal Highway Administration logo, the ITE - Institute of Transportation Engineers logo, and the Safe Roads for a Safer Future - Investment in roadway safety saves lives logo. In the bottom left corner is the text "FHWA-SA-12-004" and in the bottom right corer is the website link http://safety.fhwa.dot.gov.)
Disclaimer
The contents of this handbook reflect the views of the authors, who are responsible for the facts and the accuracy of the data published herein. The contents do not necessarily reflect the official view or policies of the Federal Highway Administration (FHWA). This handbook does not constitute a standard, specification, or regulation. It is not intended for construction, bidding, or permit purposes.
Notice
The United States Government does not endorse products or manufacturers. Trade or manufacturers' names appear herein solely because they are considered essential to the object of this handbook.
Acknowledgments
Gerald J. Forbes (F) served as the ITE Project Consultant and the overall technical editor for this report. He was responsible for the technical content and developing the case studies.
This report was based on a draft report, Best Practices for Setting Rational Speed Limits, prepared by Vanasse Hangen Brustlin, Inc. for the Federal Highway Administration, Office of Safety in May, 2009. Westat and Raghavan Srinivasan assisted in the development of the FHWA draft report.
ITE would like to acknowledge the following individuals who supplied information or provided comments in the development of this informational report:
Tony S. Abbo (M)
Richard F. Beaubien (F)
Leanna M. Belluz (M)
Robert Bucholc
Harry A. Campbell (F)
Tom Carmody
Christopher J. Dack (F)
Chris C. Day (M)
Andrew W. Edgar (M)
James W. Ellison (F)
John E. Fisher (F)
Kay Fitzpatrick (F)
Jenny L. Grote (F)
Abdullah J. Habibzai
Lawrence T. Hagen (F)
Wen Hu (M)
Kenton R. Jones
Arash Khoshghalb (M)
Chris King
Ryan C. Kump (M)
Greg M. Laragan (F)
Matthew P. Lawrie (M)
Mark A. Madden (M)
Sean P. Merrell (M)
Rock E. Miller (F)
Craig S. Neustaedter (F)
Michael D. Nichols (M)
Kwabena Ofosu (M)
Martin R. Parker Jr. (M)
Veronica Pelkey
Eduardo A. Petil (M)
William B. Raffensperger (M)
Lawrence E. Sefcik
Douglas A. Skowronek (M)
Harry W. Thompson (F)
Blair Turner
Elia Twigg
David C. Woodin (F)
Peter J. Yauch (F)
Erik H. Zandvliet (M)
ITE would like to acknowledge the ITE Traffic Engineering Council technical committee members who reviewed and provided comments on this report:
Gerald J. Forbes (F), Chair
Geni B. Bahar (M)
Marcus A. Brewer (M)
Wen Cheng (M)
John A. Davis (F)
Melisa D. Finley (M)
Paul Mackey (M)
Richard J. Porter (M)
Keith B. Rohling (M)
Kelly I. Schmid (M)
Rick J. Staigle (M)
James E. Tobaben (F)
John W. Van Winkle (M)
ITE would also like to acknowledge the Federal Highway Administration staff that reviewed and provided comments on this report:
Guan Xu (M), FHWA Project Manager
Craig Allred
James E. (Eric) Ferron (M)
Michael S. Griffith (M)
Note: Letters in parentheses indicate ITE member grade: M—Member, F—Fellow.
Technical Report Documentation Page
1. Report No. FHWA-SA-12-004 |
2. Government Accession No. |
3. Recipient's Catalog No. |
|
4. Title and Subtitle Methods and Practices for Setting Speed Limits: An Informational Report |
5. Report Date April 2012 6. Performing Organization Code |
||
7. Authors Gerald J. Forbes, P.Eng. |
8. Performing Organization Report No. |
||
9. Performing Organization Name and Address Institute of Transportation Engineers |
10. Work Unit No. (TRAIS) 11. Contract or Grant No. |
||
12. Sponsoring Agency Name and Address Federal Highway Administration |
13. Type of Report and Period Covered April 2011-April 2012 14. Sponsoring Agency Code |
||
15. Supplementary Notes FHWA Project Manager: Guan Xu |
|||
16. Abstract This informational report describes four primary practices and methodologies that are used in establishing speed limits (engineering approach, expert systems, optimization, and injury minimization). It also reviews the basic legalities of speed limits and presents several case studies for setting speed limits on a variety of roads. Despite the general acceptance and wide-spread use of speed limits throughout the world, there has been no consensus among practitioners concerning the methods and techniques that should be used to select the most appropriate speed limit for a particular facility. At the current time, it appears unlikely that any consensus will be achieved in the near future. This leaves practitioners without definitive guidance on this important issue, and in search of information to assist them. This report provides the information necessary for practitioners to make informed decisions in selecting a method for setting speed limits in their jurisdiction. This report presents the procedures that highway agencies can and do use to set speed limits. As an informational report it provides a broad overview of the different speed limit setting methods that are available for use, but it makes no specific policy recommendations or suggestions. Special situations, such as advisory, school zone, and work zone speeds are discussed. Speed limit enforcement and reevaluation of speed limits are discussed briefly. The design speed for the roadway will not be discussed, except as it may relate to the setting of speed limits. This is because design speed is a characteristic of the roadway that is essentially "built-in" to the road, and is not easily modified. |
|||
17. Key Words Speed Limits, Traffic Control Devices, Speed Signs, Speed Measurement, Speed Study Data Collection, Speed Limit Enforcement, Statutory Speed |
18. Distribution Statement No restrictions. |
||
19. Security Classif. (of this report) Unclassified |
20. Security Classif. (of this page) Unclassified |
21. No of Pages 22. Price 107 N/A |
Form DOT F 1700.7 (8-72) Reproduction of completed page authorized.
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 |
pound force |
4.45 |
Newtons |
N |
lbf/in2 |
pound force per square inch |
6.89 |
kilopascals |
kPa |
*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)
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 |
pound force |
lbf |
kPa |
kilopascals |
0.145 |
pound force 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)