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Quantifying the Impact of Rockfall on the Mobility of Critical Transportation Corridors

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Quantifying the Impact of Rockfall on the Mobility of Critical Transportation Corridors QUANTIFYING THE IMPACT OF ROCKFALL ON THE MOBILITY OF CRITICAL TRANSPORTATION CORRIDORS FINAL PROJECT REPORT by Keith Cunningham University of Alaska, Fairbanks (UAF) Ben Leshchinsky, Michael Olsen, Katherine Holtan Oregon State University (OSU) Kristen Smith, Joseph Wartman University of Washington (UW) Sponsorship Pactrans and Oregon DOT for Pacific Northwest Transportation Consortium (PacTrans) USDOT University Transportation Center for Federal Region 10 University of Washington More Hall 112, Box 352700 Seattle, WA 98195-2700 In cooperation with the U.S. Department of Transportation, Office of the Assistant Secretary for Research and Technology i DISCLAIMER This report's contents reflect the views of the authors, who are responsible for the facts and the accuracy of the information presented herein. This document is disseminated under the sponsorship of the U.S. Department of Transportation’s University Transportation Centers Program, in the interest of information exchange. The Pacific Northwest Transportation Consortium, the U.S. Government and matching sponsor assume no liability for the contents or use thereof. ii TECHNICAL REPORT DOCUMENTATION PAGE 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. 4. Title and Subtitle 5. Report Date Quantifying the Impact of Rockfall on the Mobility 11/30/2020 of Critical Transportation Corridors 6. Performing Organization Code 7. Author(s) and Affiliations 8. Performing Organization Report No. Keith W. Cunningham – University of Alaska 0000-0002-6979- 2018-M-UAF-1 7893 Ben Leshchinsky – Oregon State University 0000-0003-3890-1368 Michael J. Olsen – Oregon State University 0000-0002-2989-5309 Joseph Wartman – University of Washington 0000-0001-7659- 7198 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) PacTrans Pacific Northwest Transportation Consortium 11. Contract or Grant No. University Transportation Center for Federal Region 10 69A3551747110 University of Washington More Hall 112 Seattle, WA 98195-2700 12. Sponsoring Organization Name and Address 13. Type of Report and Period Covered United States Department of Transportation Sept 1, 2018 - August 31, 2020 Research and Innovative Technology Administration 14. Sponsoring Agency Code 1200 New Jersey Avenue, SE Washington, DC 20590 15. Supplementary Notes Report uploaded to: www.pactrans.org 16. Abstract This work developed a framework to assist transportation planners and managers (and others) in making informed resource allocation decisions based on the risks that rockfalls pose to the mobility of critical highway corridors. Transportation agencies, already faced with difficult asset management decisions, will benefit from a data-driven framework that synthesizes objective, quantitative identification of unstable slopes, mitigation strategies, and historical data related to debris volumes and closure times. Such an analysis will enable identification of which slopes pose the greatest risk to highway closure from infrastructure damage, thus providing an objective approach for optimizing resource allocation and potential mitigation strategies. In particular, proactive slope remediation is typically beneficial, but the benefits are not well quantified. This framework will quantify the benefit of intervention for rockfall activity and, more importantly, the cost-efficacy (accounting for mobility loss) from a risk perspective. 17. Key Words 18. Distribution Statement Rockfall Impacts on Mobility (RIM), Rockfall Activity Index (RAI) No restrictions. 19. Security Classification (of this report) 20. Security Classification (of this page) 21. No. of Pages 22. Price Unclassified. Unclassified. 75 N/A Form DOT F 1700.7 (8-72) Reproduction of completed page authorized. iii SI* (MODERN METRIC) CONVERSION FACTORS iv TABLE OF CONTENTS List of Abbreviations .................................................................................................................... xi Acknowledgments........................................................................................................................ xiii Executive Summary ..................................................................................................................... xiv CHAPTER 1.Introduction............................................................................................................... 1 1.1. Project Background .................................................................................................... 2 1.1.1. Lidar Evaluation and Digital Surface Modeling ............................................ 2 1.1.2. The Rockfall Activity Index (RAI) ................................................................ 3 1.1.3. Photogrammetry from Unmanned Aircraft Systems (UAS) .......................... 4 1.1.4. Slope Morphology and Climate Change ........................................................ 5 1.2. Technology Transfer .................................................................................................. 6 CHAPTER 2.The Rockfall Impacts on Mobility (RIM) database .................................................. 7 2.1. Existing Rockfall Databases ...................................................................................... 7 2.2. Database Objectives and Specifications .................................................................... 9 2.2.1. ODOT Unstable Slopes Database .................................................................. 9 2.2.2. ODOT TripCheck ......................................................................................... 10 2.2.3. Alaska DOT GAM Program: Rockslopes .................................................... 12 2.2.4. AKDOT Geo-Event Tracker ........................................................................ 15 2.2.5. Washington Department of Natural Resources Database ............................ 18 2.2.6. NASA Landslide Viewer ............................................................................. 19 2.3. Database Management ............................................................................................. 21 2.4. The RIM Database ................................................................................................... 22 2.4.1. Database Structure........................................................................................ 24 2.4.2. Challenges .................................................................................................... 26 2.5. Analysis Results ....................................................................................................... 27 2.5.1. Closure Times .............................................................................................. 27 2.5.2. Costs ............................................................................................................. 31 2.5.3. Closure Times and Costs .............................................................................. 32 2.6. Conclusions .............................................................................................................. 35 CHAPTER 3.Study Site And Data ............................................................................................... 37 3.1. Data Collection ........................................................................................................ 38 v CHAPTER 4.Mitigation Assessment............................................................................................ 41 4.1. Introduction .............................................................................................................. 41 4.2. Background .............................................................................................................. 44 4.2.1. Regional Geology ......................................................................................... 44 4.2.2. Local Geology .............................................................................................. 44 4.2.3. Study Site ..................................................................................................... 46 4.2.4. Data Acquisition ........................................................................................... 49 4.2.5. Data Processing ............................................................................................ 49 4.3. Observations ............................................................................................................ 50 4.3.1. Site Characteristics ....................................................................................... 50 4.3.2. Data Acquisition and Preparation ................................................................ 52 4.4. Findings.................................................................................................................... 53 4.4.1. Hazard Data .................................................................................................. 53 4.4.2. Change Data ................................................................................................. 62 4.5. Discussion ................................................................................................................ 66 4.5.1. Excavation Damage...................................................................................... 70 4.5.2. Data Error ..................................................................................................... 70 4.5.3. RAI Hazard .................................................................................................. 70 CHAPTER 5.Summary
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