Final Research Report Agreement T2695, Task 67 ”Roadside Vegetation” Assessment of Alternatives in Roadside Vegetation Management by Kristina Hill, Ph.D. Richard Horner, Ph.D. Associate Professor Research Associate Professor Department of Landscape Architecture University of Washington, Box 355734 Seattle, Washington 98195 Washington State Transportation Center (TRAC) University of Washington, Box 354802 1107 NE 45th Street, Suite 535 Seattle, Washington 98105-4631 Washington State Department of Transportation Technical Monitor Ray Willard, Roadside Maintenance Program Manager WSDOT Headquarters Maintenance Office Olympia, Washington Prepared for Washington State Transportation Commission Department of Transportation and in cooperation with U.S. Department of Transportation Federal Highway Administration December 2005 TECHNICAL REPORT STANDARD TITLE PAGE 1. REPORT NO. 2. GOVERNMENT ACCESSION NO. 3. RECIPIENT'S CATALOG NO. WA-RD 621.1 4. TITLE AND SUBTITLE 5. REPORT DATE ASSESSMENT OF ALTERNATIVES IN ROADSIDE December 2005 VEGETATION MANAGMENT 6. PERFORMING ORGANIZATION CODE 7. AUTHOR(S) 8. PERFORMING ORGANIZATION REPORT NO. Kristina Hill and Richard Horner 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. WORK UNIT NO. Washington State Transportation Center (TRAC) University of Washington, Box 354802 11. CONTRACT OR GRANT NO. University District Building; 1107 NE 45th Street, Suite 535 Agreement T2695, Task 67 Seattle, Washington 98105-4631 12. SPONSORING AGENCY NAME AND ADDRESS 13. TYPE OF REPORT AND PERIOD COVERED Research Office Final Research Report Washington State Department of Transportation Transportation Building, MS 47372 Olympia, Washington 98504-7372 14. SPONSORING AGENCY CODE Kim Willoughby, Project Manager, 360-705-7978 15. SUPPLEMENTARY NOTES This study was conducted in cooperation with the U.S. Department of Transportation, Federal Highway Administration. 16. ABSTRACT This study was conducted for the Washington State Department of Transportation (WSDOT) to explore both the need for and the variety of alternatives to the use of an annual application of herbicides for removing vegetation in the area immediately adjacent to the pavement edge. Our study approached these questions in two different ways, developing both a literature review and a set of interviews with people who have specific knowledge or views of these issues. We conducted interviews with three groups of people to identify issues, maintenance alternatives, and significant literature references: (1) staff at other federal, state, and county transportation agencies, (2) staff and volunteers who work with advocacy groups, and (3) researchers at academic institutions who specialize in related areas. Our literature review contains a set of citations that present related management issues and alternative practices. The abstracts for these references were included when available. To summarize what we learned from the interviews and literature sources, we developed a decision framework that could be used to guide WSDOT district maintenance staff in formulating management plans for vegetation. The decision framework differs from current practice primarily in that it begins with the assumption that maintenance of the area immediately adjacent to the pavement is not necessary unless some particular, observable condition triggers the need for such maintenance. 17. KEY WORDS 18. DISTRIBUTION STATEMENT Vegetation management, herbicides, pavement No restrictions. This document is available to the edge, Zone 1, environmental management, weeds, public through the National Technical Information roadside maintenance, road ecology, best practices, Service, Springfield, VA 22616 integrated vegetation management (IVM) 19. SECURITY CLASSIF. (of this report) 20. SECURITY CLASSIF. (of this page) 21. NO. OF PAGES 22. PRICE None None DISCLAIMER The contents of this 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 Washington State Transportation Commmission, Department of Transportation, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. iii iv CONTENTS Section Page Executive Summary................................................................................................. ix Chapter 1. Introduction........................................................................................... 1 Chapter 2. Literature Review ................................................................................. 5 Summary of Literature on Decision Factors.............................................................. 6 Drainage and Roadside Vegetation................................................................ 6 Literature on the Associated Effects of Relatively Low-Risk Herbicides..... 7 Dynamics of Fire-Starts Adjacent to Roadway Paved Areas ........................ 10 Interactions between Roadside Vegetation Patterns and Wildlife Habitat Use 10 Relative Safety of Alternative Practices ........................................................ 11 Summary of Literature on Alternative Practices ....................................................... 12 Chapter 3. Interview Summary ............................................................................. 15 Interviews of Transportation Agency Staff................................................................ 16 Stormwater Ponding....................................................................................... 16 Native Plant Mixes......................................................................................... 18 Best Alternative Practices.............................................................................. 19 Interviews with Other Government Agency Staff ..................................................... 19 Interviews with Consultants....................................................................................... 20 Interviews with University Researchers .................................................................... 21 Chapter 4. Decision Framework ............................................................................ 23 Background and Scope .............................................................................................. 23 Decision Framework Context ........................................................................ 23 Definitions...................................................................................................... 25 Use of the Framework in Integrated Vegetation Management Planning....... 26 Modules...................................................................................................................... 31 Decision Factors Module ............................................................................... 31 General Procedure.............................................................................. 31 Surface Drainage-Related Decision Factor........................................ 31 Subsurface Drainage-Related Decision Factor .................................. 32 Stormwater Management Decision Factor......................................... 32 Pavement Breakup Decision Factor................................................... 33 Visibility for Safety Decision Factor ................................................. 33 Maintenance Worker Safety Decision Factor.................................... 34 Fire Starts Decision Factor................................................................. 34 v Landscape Design Decision Factor.................................................... 35 Wildlife Road Kill Decision Factor ................................................... 36 Structural Deterioration Decision Factor........................................... 36 Noxious Weed Presence ................................................................... 36 Alternatives Assessment Module................................................................... 37 A. Alternatives for Maintenance of Zone 1 ....................................... 37 B. Alternatives for Vegetation Control.............................................. 46 Environmental Sensitivity Analysis Module ................................................. 52 Chapter 5. Further Work ....................................................................................... 54 Vegetation Management Plans .................................................................................. 54 Observing Problem Areas.......................................................................................... 54 Experimental Field Trials .......................................................................................... 55 Next Steps .................................................................................................................. 56 References ................................................................................................. 59 Appendix A – Literature References...................................................................... A-1 I. Articles in Peer-Reviewed Journals, and Peer-Reviewed Books ........................... A-1 II. Government Agency “Toolkit” Resources for Selecting Alternative Practices.... A-12 III. Government Reports ............................................................................................ A-12 IV. Conference Presentations....................................................................................