A few notes for simulating actual reflective tape/paint:
- The Tex shader stays the same brightness no matter what the external lighting is.
- You can have seperate models for day and night
- Each LOD of the model can be totally different
- The AddATex shader provides a glow effect
So, doing the reflective bits as a seperate part of the model, in order of difficulty, you could; use the Tex shader and have them permanently lit to some extent, use the AddATex shader and have them permanently lit and glowing like there's a light shining on them, use LoDs to make the reflective bits glow more as the train gets nearer, or only make them light up at night.
If you just want to paint the things, they look ok as it is - you can just make the white a bit brighter if you want it newer, it'll wash out like it's reflecting strong daylight I'd imagine.

done with AddATex LoDs.