Did some strange things to get the road decals to work better.
I render them from last to first. This seams to help with the blend issues caused by overlapping road decals.
I bind the gColor buffer to the decalNpassDef_shader and use only its alpha channel to help blend the normalMap with the existing gNormal. The blend between the gNormal and the decals normal map must be done in order to have the correct bump mapping on the terrain.
I am having serious lighting issues with ALL decals because screwed up normals being written.

Working on fixing Terra.

Terrain Work:
Shader Work: