Application of Three-Dimensional Laser Scanning for the Identification, Evaluation, and Management of Unstable Highway Slopes Pooled Fund Study Final Report TPF-5(166) March 2015 Prepared by: John M. Kemeny, Ph.D. Dept. of Mining and Geological Engineering University of Arizona 1235 E. James E. Rogers Way, Room 229 Tucson, AZ 85721-0012 Published by: Arizona Department of Transportation 206 S. 17th Avenue Phoenix, AZ 85007 in cooperation with U.S. Department of Transportation Federal Highway Administration This report was funded in part through grants from the Federal Highway Administration, U.S. Department of Transportation. The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data, and for the use or adaptation of previously published material, presented herein. The contents do not necessarily reflect the official views or policies of the Arizona Department of Transportation or the Federal Highway Administration, U.S. Department of Transportation. This report does not constitute a standard, specification, or regulation. Trade or manufacturers’ names that 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. 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. FHWA-TPF-5(166) 4. Title and Subtitle 5. Report Date March 2015 Application of Three-Dimensional Laser Scanning for the Identification, 6. Performing Organization Code Evaluation, and Management of Unstable Highway Slopes 7. Author 8. Performing Organization Re port No. John M. Kemeny, Ph.D 9. Performing Organization Name and Address 10. Work Unit No. University of Arizona 1235 E. James E. Rogers Way, Room 229 11. Contract or Grant No. Tucson, AZ 85721-0012 TPF-5(166) 12. Sponsoring Agency Name and Address 13.Type of Report & Period Covered Arizona Department of Transportation FINAL (12/08 – 12/11) 206 S. 17th Avenue Phoenix, Arizona 85007 14. Sponsoring Agency Code 15. Supplementary Notes Project performed in cooperation with the Federal Highway Administration. 16. Abstract Ground-based LIDAR (Light Detection and Ranging) is a new technology for capturing and visualizing three-dimensional (3D) data. The output of a LIDAR scan is a “point cloud” consisting of millions of points that represent the 3D surface that was scanned. Measurements and calculations can be made from the point cloud itself, or from a triangulated surface produced from the point cloud. This report describes the results of a Transportation Pooled Fund project to investigate the use of ground-based LIDAR for highway geotechnical applications. The eight states in the project are Arizona, California, Colorado, New Hampshire, New York, Pennsylvania, Tennessee, and Texas. As part of the pooled fund project, LIDAR scanning was conducted in each of these states, and the point clouds were analyzed for rock mass characterization, rockfall, rockfall hazard ratings, slope stability, and change detection. This report describes the scanning and point cloud processing that was conducted, and the final results of the analysis, for each of the eight states. This report also discusses best practices that were developed for ground-based LIDAR scanning and point cloud processing, and some new techniques that were developed to analyze overhangs, joint persistence, and joint friction angle. Some specific guidelines are given for estimating the time required for scanning and point cloud processing, as well as some issues to be aware of when using ground-based LIDAR for highway geotechnical applications. Overall, it is shown that ground-based LIDAR is an efficient and accurate way to collect field information for highway geotechnical analysis. 17. Key Words 18. Distribution Statement 23. Registrant's Seal Ground-based LIDAR, point cloud processing, rock Document is available to the U.S. mass characterization slope stability, rockfall, Public through the National overhangs, rockfall hazard ratings, change detection Technical Information Service, Springfield, Virginia, 22161 19. Security Classification 20. Security Classification 21. No. of Pages 22. Price Unclassified Unclassified 137 SI* (MODERN METRIC) CONVERSION FACTORS APPROXI MATE CONV ERSIONS T O SI UNITS Sy mbol When You Know Multiply By To Find Symbol LENGT H in inches 25.4 millimeters mm ft feet 0.305 meters m yd yards 0.914 meters m mi miles 1.61 kilometer s km ARE A in 2 square inches 645.2 square millimeters mm 2 ft 2 square feet 0.093 square meters m2 yd 2 square yard 0.836 square meters m2 ac acres 0.405 hectares ha mi 2 square miles 2.59 square kilometers km 2 VOLUME fl oz fluid ounces 29.57 milliliters mL gal gallons 3.785 liters L ft 3 cubic feet 0.028 cubic meters m3 yd 3 cubic y ards 0.765 cubic meters m3 NOTE: volumes greater than 1000 L shall be shown in m 3 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") TEMPERAT URE (exa ct degrees) oF Fahrenheit 5 (F- 32)/9 Celsius oC or (F -32)/1.8 ILLUMINATI ON fc foot-candles 10.76 lux lx fl foot-Lamberts 3.426 candela/m 2 cd/m 2 FORCE and PRESSURE or STRESS lbf poundforce 4.45 newtons N lbf/in 2 poundforce per square inch 6.89 kilopascals kPa APPROXI MATE CONV ERSIONS F ROM SI UNITS Sy mbol When You Know Multiply By To Find Symbol LENGT H mm millimeter s 0.039 inches in m meters 3.28 feet ft m meters 1.09 yards yd km kilometer s 0.621 miles mi ARE A mm 2 square millimeters 0.0016 square inches in 2 m2 square meters 10.764 square feet ft 2 m2 square mete rs 1.195 square yards yd 2 ha hectares 2.47 acres ac km 2 square kilometers 0.386 square miles mi 2 VOLUME mL milli liter s 0.034 fluid ounces fl oz L liter s 0.264 gallons gal m3 cubic meters 35.314 cubic feet ft 3 m3 cubic meters 1.307 cubic yards yd 3 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 TEMPERAT URE (exa ct degrees) oC Celsius 1.8C+32 Fahrenheit oF ILLUMINATI ON lx lux 0.0929 foot-candles fc cd/m 2 candela/m2 0.2919 foot-Lambe rts fl FORCE and PRESSURE or STRESS N ne wtons 0.225 poundforce lbf kPa kilopasca ls 0.145 poundforce per square inch lbf/in 2 *SI i s the sy mbol fo r the Interna tional System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. (Revised March 2003 ) CONTENTS LIST OF FIGURES ................................................................................................................... vii LIST OF TABLES .................................................................................................................... xii ACRONYM LIST ................................................................................................................... xiii ACKNOWLEDGMENTS ......................................................................................................... xiv EXECUTIVE SUMMARY ........................................................................................................... 1 1. INTRODUCTION ......................................................................................................... 3 2. GROUND-BASED LIDAR AND POINT CLOUD PROCESSING ............................................ 5 GROUND-BASED LIDAR .............................................................................................................. 5 POINT CLOUD PROCESSING ........................................................................................................ 7 3. FIELD SITE SELECTION AND TYPES OF ANALYSIS CONDUCTED .................................... 13 FIELD SITE SELECTION ............................................................................................................... 13 TYPES OF ANALYSIS CONDUCTED ............................................................................................. 15 4. ARIZONA ................................................................................................................. 17 OVERVIEW OF THE ARIZONA SITE ............................................................................................ 17 LIDAR SCANNING AT THE ARIZONA SITE ................................................................................... 18 POINT CLOUD PROCESSING OF THE SCANS FROM THE ARIZONA SITE ...................................... 20 5. CALIFORNIA ............................................................................................................. 29 OVERVIEW OF THE CALIFORNIA SITE ........................................................................................ 29 LIDAR SCANNING AT THE CALIFORNIA SITE .............................................................................. 30 POINT CLOUD PROCESSING OF SCANS FROM THE CALIFORNIA SITE ......................................... 32 6. COLORADO .............................................................................................................. 43 OVERVIEW OF LIDAR SCANNING IN COLORADO ....................................................................... 43 RESULTS OF POINT CLOUD PROCESSING OF THE COLORADO SCANS ........................................ 46 7. NEW HAMPSHIRE ..................................................................................................... 53 OVERVIEW OF THE NEW HAMPSHIRE SITE ............................................................................... 53 LIDAR SCANNING AT THE NEW HAMPSHIRE SITE ....................................................................