Archival Superseded by HEC-25 3rd edition - January 2020 Publication No. FHWA-NHI-07-096 June 2008 U.S. Department Hydraulic Engineering Circular No. 25 of Transportation Federal Highway Administration Archival Superseded by HEC-25 3rd edition - January 2020 Highways in the Coastal Environment Second Edition Archival Superseded by HEC-25 3rd edition - January 2020 Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. FHWA NHI-07-096 4. Title and Subtitle 5. Report Date HIGHWAYS IN THE COASTAL ENVIRONMENT June 2008 Hydraulic Engineering Circular 25 Second Edition 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Scott .L. Douglass and Joe Krolak 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Department of Civil Engineering University of South Alabama 11. Contract or Grant No. 307 University Boulevard Mobile, Alabama 36688 DTFH61-03-C-00015 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Office of Bridge Technology 14. Sponsoring Agency Code Federal Highway Administration 400 Seventh Street, S.W. Washington, D.C. 20590 15. Supplementary Notes Project Manager: Joe Krolak, FHWA OfficeArchival of Bridge Technology Technical Reviewers: Richard Weggel, Billy Edge, Kevin Bodge, Rick Renna, Dave Henderson, Larry Arneson 16. Abstract This report provides guidance for the analysis, planning, design and operation of highways in the coastal environment. The focus is on roads near the coast that are always, or occasionally during storms, influenced by coastal tides and waves. A primary goal of this report is the integration of coastal engineering principles and practices in the planning and design of coastal highways. It is estimated that there are over 60,000 road miles in the United States that can be called “coastal highways.” Some of the physical coastal science concepts and modeling tools that have been developed by the coastal engineering community, and are applicable to highways, are briefly summarized.Superseded This includes engineering by tools HEC-25for waves, water levels, and sand movement. Applications to several of the highway and bridge planning and design issues that are unique to the coastal environment are also summarized. This includes coastal revetment design, planning and alternatives for highways that are threatened by coastal erosion, roads that overwash in storms, and coastal bridge issues including wave loads on bridge3rd decks. edition - January 2020 17. Key Words 18. Distribution Statement 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 246 Form DOT F 1700.7 (8-72) Reproduction of completed page authorized Page Intentionally Left Blank Archival Superseded by HEC-25 3rd edition - January 2020 Table of Contents Table of Contents Table of Contents........................................................................................................................... i List of Figures .............................................................................................................................. vi List of Tables............................................................................................................................... xii List of Symbols............................................................................................................................xiii Acknowledgements.................................................................................................................... xvi Glossary...............................................................................................................Glossary: 1 of 18 Part 1 – Background & Context .................................................................................................... 1 Chapter 1 - Introduction ................................................................................................................ 3 1.1 Purpose.......................................................................................................................3 1.2 Target Audience..........................................................................................................3 1.3 Organization ................................................................................................................4 1.4 Units in this Document ................................................................................................5 Chapter 2 - Coastal Highways ...................................................................................................... 7 2.1 What are Coastal Highways?Archival ......................................................................................7 2.2 Estimating the Extent of Coastal Roads and Bridges..................................................8 2.3 Societal Demand for Coastal Highways ......................................................................8 2.4 Natural Coastal Processes Impacting Highways.........................................................9 2.4.1 Water Level Change......................................................................................10 2.4.2 Storm Surge ..................................................................................................10 2.4.3 Major Weather Events ...................................................................................10 2.4.4 Waves............................................................................................................13Superseded by HEC-25 2.4.5 Shoreline Erosion ..........................................................................................13 2.4.6 Littoral Drift3rd ....................................................................................................13 edition - January 2020 2.4.7 Shoreline Recession......................................................................................14 2.4.8 Tsunamis .......................................................................................................14 2.4.9 Upland Runoff................................................................................................15 2.4.10 High-Velocity Flows .......................................................................................15 2.4.11 Other Processes............................................................................................15 2.5 Coastal Highway Planning and Design .....................................................................15 i Table of Contents 2.6 Coastal Engineering as a Specialty Area ..................................................................16 2.6.1 Education.......................................................................................................16 2.6.2 State-of-Practice............................................................................................16 2.6.3 Resources .....................................................................................................17 2.7 Coastal Engineering in the Highway Community ......................................................17 Part 2 – Principles of Coastal Science & Engineering ................................................................19 Chapter 3 - Tides, Storm Surge and Water Levels .....................................................................21 3.1 Astronomical Tides....................................................................................................21 3.1.1 Characteristics of Astronomical Tides ...........................................................21 3.1.2 Tidal and Survey Datums ..............................................................................23 3.2 Storm Surge ..............................................................................................................24 3.2.1 Modeling Approaches....................................................................................25 3.2.2 Design Water Levels .....................................................................................28 3.3 Sea Level Rise ..........................................................................................................29 3.4 Lake Water Level Fluctuations ..................................................................................32 Chapter 4 - Waves ...................................................................................................................... 33 4.1 Definitions, Theories, and Properties of Waves ........................................................33 4.2 Wave Transformation andArchival Breaking..........................................................................41 4.3 Irregular Waves .........................................................................................................47 4.3.1 Numerical Models..........................................................................................50 4.4 Wave Generation ......................................................................................................51 4.5 Tsunamis...................................................................................................................53 4.6 Ship Wakes ...............................................................................................................54 Chapter 5 - Coastal SedimentSuperseded Processes...................................................................................55 by HEC-25 5.1 Overview of Coastal Geomorphology........................................................................55