This will have to be looked into but I remember at specific times of the night, the train's lights from carriages illuminate the ground or nearby walls of tunnels or ground. I don't know too much about this, there's got to be some specific things for this to happen however. Cabin lights also can illuminate the ground under specific circumstances. I know passenger DMU's and EMU's with certainty would have the ability to illuminate the ground after the sun goes down because the windows are quite wide and and lights inside if they are set to bright.
