I know a way, but it seems a little Jetson-esque or something that is out of science fiction.
If only we could put invisible force fields at the edges of the platforms, and then the force field deactivates when the doors open and the red lights illuminate. Once the doors close and the lights go green, then the force field reactivates. For construction workers, they will wear vests that can penetrate the fields. If an ordinary person hits the force fields they will just look like they hit a wall created by a mime.
This is the train to (NYC). Stopping at: Babylon, Lindenhurst, Copiague, Amityville, Massapequa Park, Massapequa, Seaford, Wantagh, Bellmore, Merrick, Freeport, Baldwin, Rockville Centre, Lynbrook, Valley Stream, Jamaica, Kew Gardens, Forest Hills, Woodside, Penn Station OR Grand Central.