WSDOT has historically maintained a bare ground strip (formerly referred to as Zone 1) along most state highway pavement edges with the use of non-selective herbicides. However, many other state DOTs and county road maintenance organizations do not maintain a bare-ground strip on all road shoulders. WSDOT solicited the assistance of the University of Washington in conducting a preliminary study on what other state and county departments of transportation were doing and experiencing in managing vegetation at the edge of pavement. Initial study concluded that there were a variety of methods being applied in management of vegetation at the pavement edge, but very little documented data on costs and results.
This report is a follow-up to the 2005 UW study, documenting the costs, outcomes and recommendations resulting from 43 individual case studies on Washington State highways between the years of 2006 and 2009. Alternative approaches are grouped into five categories: Managed Vegetation up to the Edge of Pavement, Pavement Edge Design, Cultivation, Weed Barriers, and Non-Selective Herbicides. The first two categories are focused on a vegetated treatment at pavement edge, while the last three describe various methods of providing a nonvegetated pavement edge. Both of these conditions are now referred to as a Zone 1 treatment.