A discussion of geospatial character of roadway vegetation roughness

Winter travel in the northern portions of the United States can be hazardous during times of blizzards, winter storms, and blowing snow events. For surface transportation, precipitation does not have to be falling in order for travel to become hazardous. Wind can transport snow from previous snow events onto the roadway, reducing visibility and accumulating in significant amounts to result in reduced traction and ice build-up on the roadway. The spatial pattern of roadway snow accumulation at a given site depends on the orientation of the roadway with respect to the prevailing winds during the event, the amount of snow mass present, and vegetative surface roughness factors along the roadway. Identifying the surface roughness and/or vertical extent of the vegetation is a geospatial problem that can be accomplished with ground-based observations.

The University of North Dakota Surface Transportation Weather Research Center has been a national leader in the development of traveler information systems in combination with North Dakota Department of Transportation, South Dakota Department of Transportation, and the Federal Highway Administration; its location within the upper Midwest offers an excellent opportunity for RGIS-Great Plains to assist rural America with traveler safety. Blowing snow models are currently being developed that would benefit greatly if detailed information on surface roughness and/or obstructions could be incorporated into the model.

This presentation will illustrate the work that has been done to improve the geospatial variability of roadway vegetation roughness (defined as the roughness associated with vegetation cover within a distance that affects the roadway conditions) used within a blowing snow model. It will highlight the need for an updated roughness categorization as well as examples of the updated categories within surface transportation weather research. The use of video mapping along a roadway will be discussed, as well as the process involved with building a GIS dataset from collected video.