To varying degrees nationwide, the conventional method of roadside vegetation management beyond the safety clear zone (30 feet from the edge of pavement) has been based on routine mowing to maintain vegetation in a set condition. In contrast, managed succession is a technique that allows vegetation to grow in as natural a state as possible. A number of state DOTs have reduced or eliminated mowing outside of the safety clear zone along wider transportation corridors to encourage managed succession. Managed succession is based on a strategic approach of selective control measures that utilize a combination of zero maintenance, targeted mowing, mechanical trimming and removal, and chemical and/or biological treatments. This approach is often part of a long-term plan to further minimize ROW maintenance requirements over time. Roadside maintenance managers from at least two-thirds of the state DOTs are interested in determining whether managed succession beyond the safety clear zone offers the potential for driver safety, environmental and reduced cost benefits, and the possible extent of those benefits. Therefore, research is needed to evaluate potential cost, environmental, and driver safety benefits of managed succession to roadside vegetation management compared to routine mowing.
The objectives of this research are to identify and quantify the cost, safety, and environmental impacts of routine mowing compared with managed succession of vegetation for areas outside the clear zone and develop guidelines for recommended roadside vegetation management practices. The guidelines should include an interactive tool that effectively evaluates potential costs and benefits of a managed succession approach to roadside vegetation management compared with routine mowing. This comparison, without compromising safety, will provide recommendations on how to assign and weight values (including non-monetary values) of direct labor, equipment, materials, and management/planning costs, within the context of individual agencies and regional ecosystems.
The NCHRP is seeking the insights of proposers on how best to achieve the research objective. Proposals are expected to describe a research plan that can realistically be accomplished within the constraints of available funds and contract time. Proposals must present the proposers' current thinking described in sufficient detail to demonstrate their understanding of the issues and the soundness of their approach to meeting the research objective.
The work proposed must be divided into tasks and proposers must describe the work proposed in each task in detail. The tasks must be divided into two phases. Phase I will consist of information gathering and planning tasks, culminating in the submittal of an interim report. The interim report will describe the work completed in the Phase I tasks, provide an updated work plan for the Phase II tasks, and include an annotated outline of the guidelines report. The updated Phase II work plan should address the manner in which the proposer intends to use the information obtained in Phase I to satisfy the project objective. A face-to-face interim meeting with NCHRP will be scheduled to discuss the interim report. Work on Phase II tasks shall not begin until the updated Phase II work plan is approved by NCHRP. The project schedule should include 2 months for NCHRP review and approval of the interim report and conduct of the interim meeting
The research plan shall include, but not be limited to:
- Development of an amplified work plan
- A kick-off teleconference between the research team and NCHRP to be scheduled within 1 month of the contract’s execution to discuss the amplified work plan
- A literature review to include domestic best practices
The final deliverables shall provide:
- Stand-alone guidelines, including an interactive tool
- A final report documenting the conduct of the research
STATUS: Research underway.