Forgets to mention that Colorado is open range. So if the government wants to make its highways safe from animals it must fence them in.
"White-tailed deer can jump almost eight feet high, so effective upright fences against them should be this high. Deer may be able to jump high, but not both high and over a distance. So a fence may not be as high, perhaps six feet, but slanted outward."
Effective Deer Fences - University of Vermont