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.