Summary

Vegetative assets and roadside safety features impact the longevity of structural assets. When vegetation fails, it can lead to pavement or bridge failure as the ground supporting the overall structure erodes. Many state departments of transportation (DOTs) staff members interviewed for this project stated they spend a large portion of their time working on vegetative assets and roadside safety features, as they are numerous. During the research project, researchers found that departments spent more money on labor than on equipment to assist with planning and completing asset maintenance tasks. Staff often work on the right-of-way (ROW) throughout the year to maintain vegetation and roadside safety features by mowing grasses and other vegetation, trimming or removing trees that are hazardous or obstruct drivers’ sight distance, applying herbicide to noxious plant species, and repairing structural assets damaged by errant vehicles. The vegetation and safety feature asset class includes guardrails, cable rails, sound walls, jersey walls, culverts, pollinator habitats, native restoration sites, wetlands, formally landscaped areas, turfgrass, and other vegetation. These assets are affected by both construction and snow and ice removal activities. In 2018, the Federal Highway Administration (FHWA) defined a Transportation Asset Management Plan (TAMP) as “an essential management tool which brings together all related business processes and stakeholders, internal and external, to achieve a common understanding and commitment to improve performance.” While the two legacy assets—bridges and pavements—are required to be included in state TAMPs, it is recommended that all vegetation and roadside safety features be included in a state TAMP to fully implement the FHWA goals.

Some state DOTs have begun developing asset management plans encompassing vegetative assets and roadside safety features. Agencies are benefiting from planning and managing these features with the tools and technology already in place for managing related assets that have a vegetation component, for example, culverts. Since culvert systems are used for stormwater management, more regulations and funding have historically been made available for them. States such as California are modifying software systems, namely their culvert condition rating and mapping systems to track and manage vegetation and roadside safety features. Other state DOTs have noted success in utilizing the software, hardware, and terminology used for managing structural assets in developing and maintaining asset plans for vegetation and roadside safety features.

Chapter one defines and describes Roadside Vegetation Asset Management (RVAM) and details the study’s objectives and scope. This chapter contains an overview of RVAM, and discusses research conducted on RVAM funding issues, funding sources, and associated budgetary constraints; the use of structural and vegetative assets; and barriers to implementing new technology. Finally, chapter one touches on the benefits of RVAM that will be explained in the report.

Chapter two reviews the research approach for the literature review, nationwide surveys, case studies, guidebook work plan, Interim Report, Technical Memorandum, and final deliverables. The literature review synthesized information on tools and technology that can assist state DOTs with tracking work progress, equipment, and asset condition, and remote and manual mapping of roadside vegetation assets. Using information collected during the literature review, two nationwide surveys were developed to determine current RVAM practices. Based on the nationwide survey responses, five state DOTs were selected to participate in case studies. Chapter two provides details on the state DOTs selected for case studies and their current RVAM practices. Findings from the literature review, nationwide surveys, and case studies were synthesized in an Interim Report, which is presented along with an overview of the project deliverables.

Chapter three provides an overview of the results and subsequent recommendations from the literature review, nationwide surveys, and case studies. The literature review identified both commonly available and new and evolving technology for state DOT use. This chapter covers funding sources and opportunities available at the time of the writing of this report. Finally, chapter three lists results from the nationwide surveys and a short comparison of the five case studies showcasing similarities and differences between state DOTs that were identified during the project.

Chapter four outlines suggestions for state DOTs to improve their RVAM practices based on the findings of the project including tools and technology implementation, terminology usage and consistency, asset condition rating systems, staffing and funding opportunities, and public outreach. This chapter also provides research recommendations to the Transportation Research Board (TRB) for possible future research projects, the formation of a subcommittee, and an RVAM transportation pooled fund research study. More information on each of these items is available within the guidebook.