Blowing snow accounts for a large part of the Illinois Department of Transportation’s (IDOT) total winter maintenance expenditures. This project developed recommendations for the design and placement of living snow fences to minimize snowdrift on Illinois highways. More effective and efficient snow and ice control operations could produce significant economic, environmental, and social benefits for the state.
In northern climates, snow drifting can create hazardous driving conditions or necessitate nearly continuous plowing, excessive use of chemicals, or road closures. Structural (wooden, plastic, or metal) snow fences have been used to disrupt wind patterns, decelerate wind-blown snow, and constrain it to an area other than the pavement. Alternatives to structural snow fences are living snow fences (LSFs), such as strategically planted trees, shrubs, and prairie grasses. LSFs can provide a longer-lasting and cost-effective solution to snow drifting. They also do not have to be installed and taken down annually, are almost maintenance-free once established, and are more visually appealing. However, research is lacking on the site-specific design of LSFs to reduce the impacts of snowdrifts.
For this project the research team conducted a review of the barrier treatments and policies of other northern states. Then they developed a computational fluid dynamics (CFD) model to numerically simulate snow drifting around LSFs. This was followed by field testing of selected LSFs along the Illinois highway system.
The researchers used CFD software to perform a series of numerical simulations of flow around porous fences. Following validation, the numerical approach was used to test a model for fence porosity and to investigate the effect of row spacing for fences composed of two rows of vegetation. The simulations focused on a range of average wind speeds and fence porosity over flat terrain.
The researchers also conducted field testing on seven LSFs in Illinois to provide data for calibrating the numerical model and to evaluate the effectiveness of LSFs. The test sites were monitored over two winter seasons, and several snow events were recorded each winter. The testing showed that snow deposition was generally higher immediately behind the snow fence barrier and decreased gradually with increasing distance from the snow fence and toward the roadway. Despite not having a long setback distance from the roadway, the LSFs tested in Illinois that were within a right-of-way (ROW) were found to be effective at trapping blowing snow during the milder winters that occurred during the study. No evidence showed that high-volume snow was deposited on the roadway at those sites. This finding indicated that the proper snow fence setback distance should be based on the local prevailing winter weather conditions and that snow fences within ROWs can be beneficial.
The resulting guidelines are for siting LSFs on terrain that is flat or mildly sloped. Guidance is provided for determining fence setback, wind characteristics, fence orientation, and fence height and porosity. Fences composed of multiple rows, such as standing rows of corn, are also addressed. For sites with steeper embankments, guidelines include a fence at the base and one or more fences on the embankment. The design procedure uses the available ROW and setback at a site to determine the appropriate fence characteristics (such as height and porosity) to prevent snow deposition on the road. This approach does not consider snow transport over an entire season and may be less effective in years with several large snowfall events, very large single events, or a sequence of small events with little snowmelt in between. However, this procedure is expected to be effective for more frequent snowfall events such as those that occurred over the field-monitoring period.
Authors:
John Petrie
Sen Du
Xianming Shi
WSU Department of Civil and Environmental Engineering
Yan Qi
Md Al Adib Sarker
Pranesh Biswas
Southern Illinois University Edwardsville
Mark Cornwell
Sustainable Salting Solutions, LLC
Sponsors:
Illinois Center for Transportation
Illinois Department of Transportation