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Serving as a windbreak, properly sited and designed snow fences have been proven effective in mitigating the negative impacts of blowing snow. To achieve the best snow-control effects, the ideal locations for snow fences are usually outside the roadway right-of-way. Few efforts have been made to examine the economic efficiency of snow fences and explore ways to reward private landowners. The objective of this project was to develop methodologies for evaluation of the costs and benefits of snow fences in Illinois and identify ways to encourage private landowners’ participation in the snow fence program while keeping it cost-effective. The researchers conducted a literature review as well as agency and landowner surveys. They also acquired crash data, snow fence and blowing snow segment inventory data, and blowing snow removal expenditure data as well as performed benefit-cost analyses of three types of snow fences following Federal Highway Administration guides. The survey results suggested that standing corn rows (SCRs) and structural snow fences (SSFs) were the least intrusive options for landowners and living snow fences (LSFs) with trees were the most intrusive. Some concerns related to LSFs could be reduced by allowing landowners to play a role in the design and plant-selection process. The crash data indicated that no fatal and severe crashes occurred at snow fence segments, while several fatal and severe crashes occurred at blowing snow segments during 2012–2016. The results of the benefit-cost analyses showed that the benefit-cost ratios for LSFs and SSFs are comparable. However, LSFs are favorable over SSFs because little maintenance is needed after the plants are mature. Although SCRs have the highest benefit-cost ratio, the need to renew the agency-landowner agreement annually and the alternating of crops planted may limit their snow-control effectiveness and large-scale implementation. A tool was developed using MS Excel to facilitate the benefit-cost analysis of snow fences.

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No abstract

Blowing snow accounts for a large part of Illinois Department of Transportation’s total winter maintenance expenditures. This project aims to develop recommendations on the design and placement of living snow fences (LSFs) to minimize snowdrift on Illinois highways. The research team examined historical IDOT data for resource expenditures, conducted a literature review and survey of northern agencies, developed and validated a numerical model, field tested selected LSFs, and used a model to assist LSF design. Field testing revealed that the proper snow fence setback distance should consider the local prevailing winter weather conditions, and snow fences within the right-of-way could still be beneficial to agencies. A series of numerical simulations of flow around porous fences were performed using Flow-3D, a computational fluid dynamics software. The results of the simulations of the validated model were employed to develop design guidelines for siting LSFs on flat terrain and for those with mild slopes (< 15° from horizontal). Guidance is provided for determining fence setback, wind characteristics, fence orientation, as well as fence height and porosity. Fences comprised of multiple rows are also addressed. For sites with embankments with steeper slopes, guidelines are provided that include a fence at the base and one or more fence on the embankment. The design procedure can use the available right-of-way at a site to determine the appropriate fence characteristics (e.g., height and porosity) to prevent snow deposition on the road. The procedure developed in this work provides an alternative that uses available setback to design the fence. 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. Recommendations were made to facilitate the implementation of research results by IDOT. The recommendations include a proposed process flow for establishing LSFs for Illinois highways, LSF siting and design guidelines (along with a list of suitable plant species for LSFs), as well as other implementation considerations and identified research needs.