Probably it won't be that easy...
Car activates trigger, trigger activates light on moving car. Sounds simple, but if it comes to more cars/trains (2 or many more) then the game has to know which car's lights have to get activated (might there exist any difference if the light is copied to all cars/trains or attached separately?).
Maybe something like if a light (or animation) itself hits a trigger (checkbox "activate if hitting any trigger" instead of connecting to a specific trigger), it will get activated...
Or if a light (or animation) is connected to more than one triggers, then it will do an action which you can set up in this light's options (e.g. trigger 1= on, trigger 2 = off, trigger 3= on color: red, trigger 4 = on color: blue dimming: 50%).