Signal lights on passenger cars

I have seen a set of signal lights mounted on the side of Amtrak and Commuter cars. The light unit consists of three lights, however I have only seen the orange one lit, which I guess indicates that the passenger doors are locked.

What are the other colors and what do they indicate ?

Thanks
Ian Clasper

Green= brakes are released, yellow/orange whatever your seeing =brakes set

Thanks, that makes sense

Howabout the third light ?

Dont nkow about the third…only 2 i have seen is the yellow/green on amtrash