Living snow fence utilization is one of the most sustainable engineering actions DOTs can do along highway corridors. Living snow fences are designed plantings of trees and/or shrubs and native grasses along highways, roads and ditches that create a vegetative buffer that traps and controls blowing and drifting snow. These strategically placed fences have been shown to be cost effective in reducing highway maintenance associated with blowing and drifting snow conditions.
This is not a new concept. As early as 1905 railroad companies planted trees as barriers to control blowing snow along rights of way. By 1915, the Great Northern Railway Company had planted over a million trees. In North Dakota over 96,000 trees and shrubs were established. This action reduced snow drifting, line closure and helped maintain an expected level of service along the rail line.
Many Highway road system designs do not take into account the potential of using living snow fences. It is possible that DOT and/or consulting designers do not understand the long term cost benefits of these snow fences and are not taking a big picture look at the long term highway maintenance operations and costs, when planning for wintertime conditions.
Many DOTs use wooden slat fencing in areas with large open areas and fetches that are expensive to purchase, install and maintain. The maintenance of snow fences was estimated to be $3 per mile per year, compared to $185 per mile per year for a 4 foot slat fence (USDA, 1994). In Minnesota, benefit/cost ratios range from 9:1 to 46:1 in favor of living snow fences (University of Minnesota, 2002).
Why is the implementation of living snow fences such a great sustainable transportation action for highway DOTs? The living snow fence concept really incorporates all the components associated with sustainable actions such as environmental condition improvements, consideration of financial resources and cooperation with the local landowners/community. The following summarizes the main advantages of living snow fencing and why DOTs should consider increasing their use along highway corridors:
- The service life of living snow fences is 50-75 years in comparison to the 20-25 year life of a slat fence.
- Living mature trees can capture up to 12 times more snow than slat fences.
- Living snow fences can be installed to address tree mitigation from highway construction projects
- Trees and shrubs sequester carbon that can reduce a DOTs overall carbon footprint
- Wildlife habitat is enhanced
- Maintenance plowing activities and the potential of road closures are reduced
- Reduced soil erosion along the right of way
- Reduced amount of snow plowing thus minimizing fuel consumption and costs, and green house gas emissions
- Increased vegetation provides enhanced aesthetic features along the highway corridor
- Maintenance free when trees are established
The challenges to living snow fences are that they require more space than the wooden slat fencing, plantings need to be protected from livestock and wildlife and it takes 5-7 years to provide effective snow control and up to 20 years for trees to reach full maturity. There may be site conditions such as shallow soils, arid climate and soil pH issues that may challenge plant establishment.
The design and implementation of living snow fences requires acceptance and cooperation of stakeholders. Generally for large open areas living snow fences need to be 150-200 feet away from the road surface which many times requires planting off the DOT right of way. Coordination with the following stakeholders may make the planning process more complex: 1) the local landowner, 2) county commissioners, 3) resource conservation districts, 4) state and federal forest services, 5) land management agencies and 6) local environmental organizations. Cooperation among stakeholder is critical to the success of the living snow fencing in regards to the following:
- site access
- tree plantings
- irrigation water
- fencing from livestock or wildlife
- weed maintenance
- erosion control
The Minnesota Department of Transportation initiated a Living Snow Fence Partnership Program with the US Department of Agriculture, Minnesota Association of Soil and Water Conservation Districts and the Natural Resource Conservation Service. The intent of the Program is to efficiently manage blowing and drifting snow on Minnesota roadways to reduce accidents and save lives. The Living Snow Fence Partnership Program is very proactive in establishing work groups, raising public awareness, cost sharing among stakeholders and defining specific program roles and responsibilities for all stakeholders.
Living snow fences can be a win/win for both the DOT and landowner by increasing the number of planted trees to sequester carbon, improving soil stability, improve aesthetics, and wildlife habitat improvements.
There needs to be more emphasis on using living snow fences along highway systems. It makes economic and environmental management sense for many DOTs to implement living snow fence programs. DOT’s environmental, maintenance and engineering professionals need to work together and review potential construction sites for implementing living snow fencing especially during the design-NEPA phase of the project. It is possible to directly specify the use of living snow fences in the NEPA document that must be incorporated into the final design. A landscaping plan that incorporates the NEPA requirements should be developed and provided to the selected construction contractor. DOTs should consider increased education, training and awareness about snow fencing design opportunities. Finally, DOTs could perform a state-wide, landscape GIS study to identify existing road corridors where cost effective living snow fences could be implemented along and near the existing highway right of ways.
The reader is directed to the following websites for living fence design criteria:
www.ext.colostate.edu/sam/windbreaks.html (Colorado State University Extension)
www.unl.edu/nac/aug94/snowfences/snowfence.html (USDA National Agroforestry Center)
www.extension.umn.edu/distribution/naturalresources/DD7277.html (University of Minnesota Extension)
http://climate.umn.edu/snow_fence/intro/html (Minnesota DOT)