Mowing & Vegetation Management
INDOT maintains roadside vegetation along its limited-access, divided and rural state highways in an environmentally sensitive manner consistent with the special conditions presented by local climate, topography, vegetation and level of urbanization.
With more than 60,000 acres to maintain, INDOT is charged with balancing safety, costs and aesthetics when managing roadside vegetation.
The purpose of vegetation management is to:
- Enhance the safety of the motoring public
- Enhance environmental protection
- Mitigate erosion while providing adequate drainage
- Promote and preserve native wildlife habitats and native flora throughout the state
INDOT’s mowing practices are focused on maintaining vegetation at a safe height for driver visibility. In between mowing cycles, INDOT performs spot mowing to promote sight visibility at intersections or drainage. If grass or other vegetation is blocking intersection sight visibility, citizens are encouraged to report the area to the appropriate district.
Vegetation Management Plan
INDOT’s vegetation management practices aim to improve the overall look of rights-of-way, enhance environmental areas by preserving natural wildlife habitat, and control and remove invasive and noxious species.
It costs INDOT approximately $8 million each year to mow limited-access, divided and rural state highways. Herbicide application costs approximately $32 per acre. Improved vegetation management will reduce the need for future herbicide application, which will benefit the environment and reduce costs.
INDOT also utilizes its Hoosier Roadside Heritage Program to plant wildflower and native plants/grasses to landscape Indiana’s roadsides. This aids roadside beautification and enables INDOT to more effectively battle invasive and noxious vegetation.
INDOT’s vegetation management practices consist of the following elements:
Herbicide Treatments: As a member of the Indiana Invasive Species Council, INDOT’s goal is to eradicate invasive species and noxious weeds. By using a more stringent and uniform herbicide application process, our treatments will last two years as opposed to our previous one-year program. The first herbicide treatment addresses the typical weed growth, including broadleaf, clover, and dandelions. The second treatment targets invasive/noxious species, such as thistles, kudzu, and leafy spurge. With effective herbicide application, INDOT will improve roadside appearance and reduce costs.
Vegetation Management: When crews are clearing brush and trees from along the roadways, they will treat the ground and stumps to prevent re-growth.
Equipment: Crews will raise the mowing deck to allow plant roots to develop that control erosion and to shade out weed seeds from germinating.
Timing: Crews will closely monitor the growth of the vegetation and time mowing cycles based on geographic location and weather. The first mowing cycle will be scheduled to take place after the rapid spring growth ends, except in areas necessary for sight distance. Research has shown that altering spring mowing schedules will prevent the grass from springing back up and limit growth for the rest of the season. INDOT crews will address sight distance concerns between mowing cycles, including the treatment of noxious species through herbicide application, to limit the spread of invasive and noxious weeds that grow tall and unsightly.
Mowing Area: INDOT mows its limited-access, divided and rural state highways with a combination of full- and partial-width mowing focused on four zones:
- Zone 1, the roadway
- Zone 2, Clear Zone and Median (if applicable): This clear zone extends from the edge of the shoulder pavement to 30 feet out. It also includes the grassy median, if applicable. This area is mowed most frequently and will also be treated by a selective herbicide treatment every two years to target invasive and noxious weed species.
- Zone 3, Selective Zone: In areas where state right-of-way extends from 30 to 80 feet from the edge of pavement, INDOT will apply spot herbicide treatments to control invasive and noxious plants. These treatments will provide native plants more room to grow, and create more of a natural appearance. INDOT may mow this zone in urban areas if owners are maintaining adjacent properties.
- Zone 4, Natural Vegetation: Where state right-of-way extends more than 80 feet from the roadway, INDOT allows for native plants and forestation to take hold and serve as a defense against invasive species. This area shields neighboring properties from the roadway and connects fragmented wildlife habitat.
Customer Service Department
Indiana Department of Transportation
100 N. Senate Ave., IGCN 755
Indianapolis, IN 46204