Reduced fuel consumption, fewer carbon emissions, better weed control, cost savings and improved habitat for pollinators are among the many benefits of the Washington State Department of Transportation’s (WSDOT) new policy to reduce mowing on the state’s roadsides.
WSDOT’s revised mowing policy, adopted in 2015, changes the focus of roadside maintenance from aesthetics in favor of a more natural approach.
Under the revised mowing policy, WSDOT has eliminated almost all mowing that had been conducted for aesthetic reasons in areas with wide rights of way extending beyond 30 feet from the pavement edge. The change will result in a one-third reduction in mowing for non-safety-related reasons annually, according to an agency summary.
The policy specifies that routine mowing “will generally be limited to one pass adjacent to the paved shoulder except in rare cases where a wider annual mowing swath is necessary for safety or for specifically indicated vegetation control.”
Most areas beyond the 30-foot limit that had previously been managed with routine mowing will now be designated as “naturally managed areas” and left to grow mostly naturally, unless hazard trees or designated noxious weeds need to be controlled. Certain higher profile areas will be selectively managed as meadows where all weeds are controlled and natural succession of desirable native plants is encouraged.
In a related effort, the agency is conducting a pilot study during the summer of 2015 that will be the first published research in the country to provide a cost/benefit analysis of grazing (using goats) as a mowing tool in state highway rights of way.
All of these actions are part of a multi-year strategy by the agency to create more self-sustaining and lower-maintenance roadsides that are complimentary to the surrounding native ecosystems, according to Ray Willard, Roadside Maintenance Program Manager at WSDOT.
Benefits of Reduced Mowing
Benefits of reduced mowing include lower fuel consumption—the department expects to save approximately 2,500 gallons per year of diesel fuel for mowing equipment—and an associated reduction of 23 metric tons in CO2 emissions.
WSDOT also expects to save money in labor and equipment costs. The department will be able to divert its maintenance crews to higher priority work and also switch from using large tractors with wide mowing decks to smaller, more efficient and versatile mowers. Overall, WSDOT expects to save approximately $550,000 each year in mowing costs.
The revised policy will also provide more effective nuisance weed control in designated high profile areas. In freeway interchanges and designated scenic corridors, WSDOT will carefully coordinate mowing patterns and timing with other vegetation management treatments with the goal of removing unwanted nuisance weeds and trees and encouraging more desirable native roadside plant communities over a series of years.
Looking out for Pollinators
Another benefit of reduced mowing is improved habitat for pollinators such as honey bees and butterflies, a topic that has recently taken on national significance. In June 2014, President Barack Obama issued a memorandum directing federal agencies to take actions to protect pollinator species, including calling on the Department of Transportation to work with state DOTs to increase pollinator habitat along roadways.
Roadsides can offer pollinators improved forage for food, breeding, or nesting, and help link fragmented habitat, according to a literature review released by the Federal Highway Administration in May 2015. The report supports the development of best management practices for pollinator habitat protection and enhancement in highway rights of way.
The Transportation Research Board is also planning a webinar on promoting the practice of integrated vegetation management and managed succession over routine mowing, according to Willard, who also serves as research coordinator for TRB’s Roadside Maintenance Operations Committee (AHD50).
Federal leadership together with the agency’s executive leadership on the pollinator issue were contributing factors leading to WSDOT’s revised mowing policy, according to Willard. “What we have now is really good motivation from the top down that we should be taking a more natural approach to managing roadsides,” Willard said.
He also pointed to an FHWA publication, Vegetation Management: An Ecoregional Approach, which he said laid the groundwork nationwide for this new approach.
System Tracks Acres Mowed
To monitor progress in implementing the new policy, WSDOT maintenance staff will be deploying the department’s new Highway Activity Tracking System (HATS). The system allows field staff to document their vegetation management activities in greater detail using tablet computers and geographic information system mapping.
In the past, documenting the number of acres mowed was “kind of a wild guess,” according to James Morin, Maintenance Operations Manager at WSDOT. “You knew how wide the mower was and roughly how far you travelled.” But under the new system “as long as [maintenance crews] turn on their iPADs, they’ll know exactly how many acres they mowed.”
HATS will be integral to implementing the revised mowing policy because it will allow the department to document savings in terms of fuel consumption, carbon emissions and other lifecycle costs, according to Willard.
Public and Agency Outreach
As roadsides begin to take on a more natural and less manicured appearance, people will continue to question and debate the merits of visual quality vs. environmental sustainability, Willard said. “It is important that we collect and maintain clear scientific evidence of the overall environmental benefits from mowing less,” he added
The popular desire to see neatly mowed roadsides carries over into the culture and historic practice of highway maintenance, where agencies receive positive feedback when the roadsides are mowed, Willard said.
There’s also the potential for political pressure on state DOTs to mow for aesthetics in the name of tourism, quality of life, or for the benefit of neighboring businesses, according to Willard.
To help educate the public, WSDOT is developing a four-page color print folio on the revised mowing policy and is developing similar language to feature on its website.
To help convince the agency’s staff, managers have focused on the benefits to the natural environment. “The maintenance employees take a lot of pride in a neatly cared-for roadside, so it’s really [about] shifting from seeing the roadside as a pretty thing to seeing it as a beneficial thing to the natural environment,” Willard said.
Where environmental considerations alone might not convince staff, the economic savings are also compelling, according to Morin. “If we can have a native roadside that’s high functioning, we don’t typically have as many weed issues and it doesn’t cost us as much in terms of effort or money to maintain,” Morin said.
An important factor in WSDOT’s success in implementing the new policy has been having planning guidelines and objectives that are consistent statewide, yet still offer flexibility to the local maintenance areas, according to Willard. For WSDOT this has involved updating the integrated roadside vegetation management plans for each of the state’s 24 maintenance areas to incorporate reduced mowing on a case by case basis.
Another key strategy within the new policy is encouraging local governments to “adopt” freeway roadsides through their cities if they desire a more park-like appearance. WSDOT has developed permits to allow this type of local participation where appropriate.
Testing Goats as ‘Biological Mowers’
In a related effort to evaluate a more natural approach to vegetation management, WSDOT is conducting a pilot project using grazing goats as a mowing tool on state highway rights of way.
“Goats are basically biological mowers,” Willard said, and can perform a similar function as mechanical mowing but without burning fossil fuels and generating carbon emissions. Another advantage is that some weed seeds are sterilized as they pass through a goat’s digestive system, allowing for more effective weed control than mechanical mowing. Goats can also easily access steep and uneven terrain.
However, concerns over the use of grazing in highway applications include higher costs associated with fencing, watering and supervising the animals; liability; and potential distractions to drivers, according to an agency summary of the research.
While there has been extensive research on grazing for vegetation management and weed control over the years, the feasibility and cost/benefit of grazing in the highway right of way has not been well documented. To help do this, WSDOT is conducting field trials using goats in three different vegetation management situations and terrains around the state.
The study is testing goats for routine mowing of unwanted weeds and brush around fenced stormwater ponds at several sites near Vancouver, using goats donated by a WSDOT maintenance employee. The trials also will study water quality impacts in areas with standing water and potential outflow.
A second site in Spokane is studying the use of goats to prevent or delay seed production in a noxious weed infestation along US 395.
Finally, the department is using goats to clear unwanted vegetation from a former homeless camp along Interstate 5 in Olympia.
As part of the study, WSDOT will document all costs associated with labor, feed, transportation, and fencing of the goats and will issue its findings in a research report, expected in fall of 2015.
The initial finding of the research is that in general, goats have a very limited application for roadsides, according to Willard. One type of situation that may prove effective is in controlling vegetation within fenced stormwater ponds, where the animals don’t require constant supervision and don’t present a potential distraction to drivers.
This compendium provides models of many successful approaches. Of particular use are the following Chapters: Chapter 3: Designing for Environmental Stewardship in Construction & Maintenance, Chapter 4: Construction Practices for Environmental Stewardship, Chapter 9: Roadside Vegetation Management.