Actual Speeds on the Roads Compared to the Posted Limits FINAL REPORT 551 Prepared by: Sherry L. Skszek 505 N. Tanque Verde Loop Rd. Tucson, AZ 85748 OCTOBER 2004 Prepared for: Arizona Department of Transportation 206 South 17th Avenue Phoenix, Arizona 85007 in cooperation with U.S. Department of Transportation Federal Highway Administration The contents of the report reflect the views of the authors who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Arizona Department of Transportation or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. Trade or manufacturers’ names which may appear herein are cited only because they are considered essential to the objectives of the report. The U.S. Government and The State of Arizona do not endorse products or manufacturers. Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. FHWA-AZ-04-551 4. Title and Subtitle 5. Report Date October 2004 Actual Speeds on the Roads Compared to the Posted Limits 6. Performing Organization Code 7. Authors 8. Performing Organization Report No. Sherry L. Skszek 9. Performing Organization Name and Address 10. Work Unit No. Sherry L. Skszek 505 N. Tanque Verde Loop Rd. 11. Contract or Grant No. Tucson, AZ 85748 SPR-PL-1-(61) 551 12. Sponsoring Agency Name and Address 13.Type of Report & Period Covered ARIZONA DEPARTMENT OF TRANSPORTATION 206 S. 17TH AVENUE PHOENIX, ARIZONA 85007 14. Sponsoring Agency Code Project Manager: John Semmens 15. Supplementary Notes Prepared in cooperation with the U.S. Department of Transportation, Federal Highway Administration 16. Abstract The purpose of this report is to explore actual vehicle speeds on Arizona highways exceeding posted speed limits. This is done through a three-fold approach that includes a survey of state practices in setting and enforcing speed limits, a literature review, and an analysis of data from automatic traffic recording devices, which assesses whether speeding is a problem, where it is most prevalent, and if the incidence of speeding is on the rise. The survey of state practices showed no significant increase in speed-related fatalities in states that have adjusted speed limits upward. No state has data that addresses the effectiveness of speeding sanctions and no speed reduction practice is seen as the “most effective.” Fewer speed-related fatalities were seen in those states with commercial vehicle speed and/or lane restrictions. No factor used to establish speed limits was found to be predominant. Review of the literature shows choice of speed is determined by factors based on unconscious actions with unrecognized repercussions. The impact of travel time, speed-related crashes, vehicle operating costs, and pollution on society warrant speed management for economic reasons. The connection between speed and incidence of crashes is unclear. Speed and severity is governed by the laws of physics, warranting speed management for safety purposes. Data analysis shows the incidence of speeding on Arizona highways is widespread. The problem is worse on high volume roadways, primarily urban interstates. Reducing speeding on high-speed interstate highways, where the relationship between speed and severity of injury is clear, should be the target of enforcement efforts. Speed data from ATR sites should be used to identifying areas for targeted enforcement efforts. The findings of this report support the premise that speed limits should be raised to the 85th percentile where roadway design, accident history, road type and surface, and traffic volume warrant an increase. Enforcement efforts should be targeted at urban interstate highways using traffic data for optimal use of limited resources. 17. Key Words 18. Distribution statement 23. Registrant's Seal Speed limits, speed enforcement, traffic data, traffic safety, Document is available to the speed reduction practices, 85th percentile speed, annual U.S. public through the National average daily traffic, STEP, traffic fatalities, roadway design, Technical Information Service, traffic safety hazards, speed management, mobile patrol Springfield, Virginia, 22161 units, highway patrol, automated enforcement, aggressive driving, traffic citation. 19. Security Classification 20. Security Classification 21. No. of Pages 22. Price Unclassified Unclassified 108 SI* (MODERN METRIC) CONVERSION FACTORS APPROXIMATE CONVERSIONS TO SI UNITS APPROXIMATE CONVERSIONS FROM SI UNITS Symbol When You Know Multiply By To Find Symbol Symbol When You Know Multiply By To Find Symbol LENGTH LENGTH in inches 25.4 millimeters mm mm millimeters 0.039 inches in ft feet 0.305 meters m m meters 3.28 feet ft yd yards 0.914 meters m m meters 1.09 yards yd mi miles 1.61 kilometers km km kilometers 0.621 miles mi AREA AREA 2 2 2 2 in square inches 645.2 square millimeters mm mm Square millimeters 0.0016 square inches in 2 2 2 2 ft square feet 0.093 square meters m m Square meters 10.764 square feet ft 2 2 2 2 yd square yards 0.836 square meters m m Square meters 1.195 square yards yd ac acres 0.405 hectares ha ha hectares 2.47 acres ac 2 2 2 2 mi square miles 2.59 square kilometers km km Square kilometers 0.386 square miles mi VOLUME VOLUME fl oz fluid ounces 29.57 milliliters mL mL milliliters 0.034 fluid ounces fl oz gal gallons 3.785 liters L L liters 0.264 gallons gal 3 3 3 3 ft cubic feet 0.028 cubic meters m m Cubic meters 35.315 cubic feet ft 3 3 3 3 yd cubic yards 0.765 cubic meters m m Cubic meters 1.308 cubic yards yd NOTE: Volumes greater than 1000L shall be shown in m3. MASS MASS oz ounces 28.35 grams g g grams 0.035 ounces oz lb pounds 0.454 kilograms kg kg kilograms 2.205 pounds lb T short tons (2000lb) 0.907 megagrams mg Mg megagrams 1.102 short tons (2000lb) T (or “metric ton”) (or “t”) (or “metric ton”) TEMPERATURE (exact) TEMPERATURE (exact) ºF Fahrenheit 5(F-32)/9 Celsius temperature ºC ºC Celsius temperature 1.8C + 32 Fahrenheit ºF temperature or (F-32)/1.8 temperature ILLUMINATION ILLUMINATION fc foot candles 10.76 lux lx lx lux 0.0929 foot-candles fc fl foot-Lamberts 3.426 candela/m2 cd/m2 cd/m2 candela/m2 0.2919 foot-Lamberts fl FORCE AND PRESSURE OR STRESS FORCE AND PRESSURE OR STRESS lbf poundforce 4.45 newtons N N newtons 0.225 poundforce lbf lbf/in2 poundforce per 6.89 kilopascals kPa kPa kilopascals 0.145 poundforce per lbf/in2 square inch square inch TABLE OF CONTENTS EXECUTIVE SUMMARY ................................................................................................ 1 1.0 INTRODUCTION .................................................................................................. 3 1.1 PURPOSE........................................................................................................... 3 1.2 BACKGROUND ................................................................................................ 3 1.3 PROJECT OVERVIEW..................................................................................... 4 2.0 SURVEY OF SPEED LIMITS AND SPEED ENFORCEMENT PRACTICES... 5 2.1 PURPOSE........................................................................................................... 5 2.2 METHODOLOGY ............................................................................................. 5 2.3 SURVEY INSTRUMENT.................................................................................. 7 2.4 SURVEY RESULT............................................................................................ 7 2.4.1 Question 1................................................................................................... 8 2.4.2 Question 2................................................................................................. 12 2.4.3 Question 3................................................................................................. 15 2.4.4 Question 4................................................................................................. 15 2.4.5 Question 5................................................................................................. 17 2.4.6 Question 6................................................................................................. 20 2.4.7 Question 7................................................................................................. 21 2.4.8 Question 8................................................................................................. 23 2.4.9 Question 9................................................................................................. 25 2.4.10 Question 10............................................................................................... 26 2.4.11 Question 11............................................................................................... 27 2.4.12 Question 12............................................................................................... 27 2.5 CONCLUSIONS............................................................................................... 31 3.0 LITERATURE REVIEW..................................................................................... 33 3.1 PURPOSE......................................................................................................... 33 3.2 METHODS ....................................................................................................... 33 3.3 STATE DEPARTMENTS OF TRANSPORTATION ....................................