How does proximity to the highway effect home value?

[Noah Carrico]

I am trying to figure out the ARV for a potential wholesale deal and need to know how proximity to the highway would affect the home value. Obviously it would decrease the value, but how much? The home is in a rural town, so comps also by the highway are limited. The home would probably sell for 165k - 170k if it weren't next to the highway. The highway isn't very loud, because of the angle of a hill but you know it is there. Any specific advice or thoughts on the general subject would be appreciated