PBR and traffic

That material is still relevant, I would not have linked to that else
There's many implications with switching to PBR now (I've explained this also in another thread not long ago)_

One of that is fixing/adjusting the gamma conversion, which is at the very base of a graphics engine ( in the PBR era this is important, before that not so much )
Here you can find a nice article that explains that: http://filmicworlds.com/blog/linear-space-lighting-i-e-gamma/

Fixing that is very possible, although all the assets that was made so far will look wrong, and needs to be adjusted.
This is quite some work, but most important it will break pretty much all mods that has meshes/textures (break as in, they will look very wrong).

So yeah, PBR is surely fantastic and I'd be eager to have that, but it stays research material for now. Perhaps in the future

The reason for that is that our engine started as a fork of T3D to then change further from what the stock T3D is. There are a lot of custom changes and improvements made to fit our changes.