As discussed in the Auran forum, the thick grid lines of the default wireframe texture can be thinned by replacing the entire texture.
My example how to do that can be downloaded here:
http://www.transdem.de/download/public/ ... idThin.cdp
Please note that the User ID part of the KUID has to be the same as in the original. Since this is an Auran KUID and not my own, I cannot upload the texture to the DLS.
Standard Surveyor view (ground texture from a 1:63,000 topo map, blurry by nature at close distance):
"Transparent" wireframe view with Trainz default texture:
Transparent wireframe view with replacement texture:
More images:
