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.