Now that we have an allow_underground parameter that means that certain things can only be built underground, is it worth considering a revised lighting standard for rendering such objects? Normal objects, which appear above ground, have a simulated sun in their lighting setup in Blender, which makes one direction much lighter than another.
In principle, this should not apply to underground objects, such as underground signals and even depots. Should we adopt a flat lighting setup for these objects, perhaps allowing for bespoke local lighting to simulate light sources in the object itself? Or is the difficulty that the vehicles will remain lit in daylight making the whole thing look odd?