Shading Problem

[MrScott2006]

I'm working on a fairly big layout in TRS2006. I've painted all the boards with a grass texture. I notice that when I start the map there are shading issues were the trainz boards meet. some are lighter lines, some darker lines. When I use the adjust height tool on the same areas the shading issue fixes itself but will come back as soon as I load the map again. One other note, I'm also using trainz tuner.
Is there any reasons for these shading marks?

 

[markbin]

When you merge boards that are fully textured , you can get those black lines on the merging borders.
So , do the texturing on those boards after the merge.

 

[MrScott2006]

Thanks for the reply. There was no merging on the map, It just one big map. I deleted the boards I didn't want. Then I textured each board until the all of the boards were textured.
I'm not sure but I think it's the texture color itself. I tested on small area by painting it with a different texture...the shading lines didn't show.
The bummer about this all is that it's about a 600 board layout. To re-texture everything I would have to start over with a new map.