Question:

I am not seeing any response of the vehicle to a modified friction factor of a section of the road in my terrain model. I am carefully watching the output variable for Mu (surf) and it isn't showing that the tire sees the changed friction factor.  Why might this be happening?

Answer:

One of the most common answers to this question is that your terrain model has the surface normal of that section of roadway pointing away from the tire.  In the 3D Editor workshop at the HVE Forum, one of the topics covered explains how the GetSurfaceInfo routine determines the current terrain model attributes below each tire to use in the calculations, and the  tire needs to see the surface normal of a polygon pointing directly back at the tire.  If the normal is pointing away from the tire, it will not see any attributes of that surface.