LED (light emitting diode) technology for mass transit could be around the corner. This technology makes it possible for information and advertisements to be placed anywhere on the subway platform and inside the train.
See-through LED can replace the conventional doors and windows to convey messages to the passengers or to display digital decorations while the doors and windows retain their primary functions. LED tech could be useful in NYC's subways where often times, in cases of emergency and/or changes in train schedule, passengers are unable to make sense of what is being said over the loudspeaker. It might work.