The Maine Department of Transportation (MaineDOT) is set to begin a vegetation control program in several regions of the state in order to control unwanted vegetation behind roadside guardrails and to improve safety.
“We have seen increasing explosions of plant growth behind guardrails in recent years, which have obscured visibility and reduced safety for the travelling public,” explained statewide vegetation manager Bob Moosmann who oversees the integrated roadside vegetation management program for MaineDOT.
Removing plants around guardrails helps keep Maine highways safe by maintaining proper sight distances at curves, intersections, driveways, hills, and road entrances. Guardrails provide a safety barrier in areas along the road that otherwise could lead to serious lane departure accidents due to steep slopes or water hazards.
“Guardrails should be visible to the public and in many cases we are seeing vegetation growing around and over the guardrails, obscuring them from view,” said Moosmann. “We are also seeing an increasing incidence of invasive plants growing in guardrail locations such as black locust, sweet clover, and oriental bittersweet”.
Invasive plants can obscure the guardrail, encroach to the edge of pavement, and decrease the life expectancy of the infrastructure. Invasive plants also reduce biodiversity of native plants by outcompeting them. Another problem the department encounters is the risk to workers repairing guardrail or working in the area from plants that may pose a health risk such as poison ivy or wild parsnip. Deer ticks which harbor Lyme disease also may be present on vegetation growing in guardrail areas.
MaineDOT anticipates using its own crews to accomplish this work. The materials used for spraying will be Accord Concentrate (glyphosate) and Oust XP (sulfometuron methyl).The department also has vegetation management contractors working in each of its five regions and may hire them as well to treat guardrails. Each region reviews its roads to determine which roads have guardrails that need to be sprayed. “We are using mapping programs and GPS to track the locations of work”, Moosmann said. “In order to reduce our use of herbicides, our strategy is to spray in half the region one year and the other half of the region in the second year.”
“We will also be brush mowing behind guardrails in advance of applying herbicides”, Moosmann stated. “The public may see mowing machines working to cut down brush and other growth in guardrail areas this year throughout the state. This treatment is used when the vegetation has gotten beyond the point where spraying is effective. Afterwards, when the vegetation becomes manageable, we follow up with an herbicide spray program.”
In addition to guardrail spraying, the department will be experimenting with selective treatments to control weeds in roadside areas this year.
“We are exploring alternatives to mowing in order to reduce roadside growth,” Moosmann said. The use of selective herbicides can be very helpful to reduce the incidence of weeds in roadside areas while maintaining grasses to prevent soil erosion. “We have seen that weeds and trees are more of a problem obscuring visibility than are the grasses we commonly have growing in roadside areas in Maine,” Moosmann explained. Treatments with herbicide are less expensive and can reduce the use of fossil fuels used to run mowing equipment.
# # #