It seems in order to add new 'road type' and or 'markings', the option value and name <option value="X">Example</option> need to be added to the desired user interface.
I did a text search for one of the texture names using Sublime Text, and that turned up nothing, so I searched 'road' and the results listed the files I was looking for.
We know the color and normal maps are in '.\textures\terrain\ground', the opacity maps are in '.\textures\roads' and use a cut-off value listed in profiles.pgm. This is a great way to handle it so it makes sense because the layers can re-used, which is done by the '.\www\mixer.html', so that the 'markings' can be ontop of some of the road types.
What I do not know yet is where/how <option value="X"> is defined, as well as how the layers are assigned per option.
The most obvious files to start with are:
'.\Anteworld\www\roads.html'
'.\Anteworld\www\mixer.html':
'.\Anteworld\www\builder.html':
'.\Anteworld\www\editor.html':
These contain everything involved in the road tools that I can find, and should be all is necessary to include new road types, markings and materials, reference new diffuse, normal and opacity maps, and mix the markings with the new road types.
I will put together a demo soon for the AeroKinetics mod which will include Space Launch Complex 37B launch pad with custom textures specifically designed for the crawlerway, launch pad, flame trench, parking lot and fuel pipe-lines running from the storage tanks to the launch pad. I think displacement mapping is also possible so that a road could have raised features such as curbs, sidewalks, storm drains and many other things. I have had this in mind for some time now and it is time to get it done.
Here is the key I just made for current road types, and markings, materials combinations.
Regards,
Uriah