I created a roadway using the landscape spline editor. It came out looking fine, but for reasons I can’t explain the collision boxes for the roadway spline are about 10 units above the actual mesh making the player walking on the spline road appear to be floating in air. I double checked the collision box of the static mesh used to create the road surface and the collision box is aligned with the top surface as it should be. What’s going on here?
Normally I make roads with no collision and let them just collide with the terrain. Why do you need the road to collide specially? But that said, I would try the crappy work around and just move the collision mesh lower and re-import to see if that solves it. I know, not a clean fix 
but its a quick and dirty simple thing to try.
I found the problem. It seems that if you use a plane for your road surface, the engine creates its own collision box which is taller than the plane surface. It seems to do this even if you specify your own collision bounds. The work around is to not use planes. Instead, give the surface a 3d structure. In my case, I just drooped the edges of the road surface.
BTW, the reason for not just using the landscape collision is that is very tedious trying to get the landscape surface to match the height of a road without ending up with lots of hidden pot holes or portions of the landscape poking through.