Kernel Density for AADT Traffic Values of Roads

Discussion created by fedakd on Jun 5, 2012
I am trying to create a traffic density raster (AADT) for wildlife habitat modeling with a kernel distribution. I'm starting with road layers for different states with traffic volumes in the attribute table as AADT. For higher trafficked roads (interstates, etc), I'd like them to be weighted more heavily and have a larger search radius for the kernel density curve away from the road. For instance, I'd like highways to have a 2km search radius but also retain their initial value at the actual road, so it seems multiplying the output raster by 2 gives a value close to the original value. For more local roads, I'd like to use a search radius of 1km, which then does not need to be multiplied. I have several questions pertaining to this method:

Does anyone have the exact formula that ArcGIS uses for the kernel line density function in Spatial Analyst? Is there a way to manipulate the search radius and weighting of the kernel based on a separate attribute of the line (for instance, different road classes)? Or is the best solution to just run separate kernel density functions on each class of a line shapefile using a different search radius, multiply them by a factor, and then add them together?

I've included an example output that used a 3km search radius across the state of NC to give an idea of what I'd like for an output.