The Arizona Department of Transportation (ADOT) manages vegetation along approximately 1,390 miles of highways across Arizona. The primary goals of roadside vegetation management are maintaining traffic safety, preserving highway infrastructure, and maintaining a resilient native roadside plant community. State laws and regulations require ADOT to control weeds that occur in the right-of-way; it is also important for maintaining good relationships with adjacent landowners. ADOT has agreements with the US Forest Service and the Bureau of Land Management under the Four Agency Partnership in Arizona regarding maintenance of transportation easements on their land. ADOT is a signatory to the Candidate Conservation Agreement for the Sonoran desert tortoise, which identifies spread of invasive species into desert habitat and a related change in fire regime as a primary threat to the species. Also recognizing that widespread pollinator species are declining, ADOT is considering how vegetation management practices may impact insect pollinators and ways to promote conservation of pollinators as part of regular vegetation management.
In order to manage roadsides with these objectives in mind, ADOT undertook an update to their roadside vegetation management guidelines. ADOT's goal is to use a system of Integrated Roadside Vegetation Management (IRVM) to establish plant communities that are self-sustaining, resist weeds, require low maintenance effort and provide necessary soil stabilization and erosion control. To this end, guidelines for vegetation management were developed based on input from the maintenance, construction, landscape architecture, design and environmental groups within ADOT. Achieving the envisioned goal will require a process of removing undesirable species, such as noxious and invasive weeds, and replacing them with desirable native species using seasonally-timed control measures.
The vegetation management guidelines are tied to existing activity codes used by the maintenance divisions to plan and record activities in the Performance Controlled System (PeCoS). The intent is for the guidelines to be used by supervisors in planning activities and to guide standard work for staff in the field. A series of graphics and maps were developed to reach a mutual understanding of concepts across the design, construction and maintenance groups within ADOT, including land ownership and biotic communities where maintenance practices will vary across the state.
Following rollout of the guidelines, we are working with each of the Districts to develop Vegetation Guides which will identify vegetation management approaches and goals for each highway section and then prioritize the timing and priorities for vegetation management activities each year. The goal is for these Guides to be continually adapted over time to adjust to changes in roadside conditions and allow for continuous improvement of work practices and conservation outcomes.