Originally it was a combo pedestrian bridge that spanned from the Westbound temporary platform when it was under construction all the way to the low-level Eastbound platform that would be torn up shortly afterward. On October 25th, 1968 they closed the low-levels off and tore down the South half. I've got a FOIL that I requested from NYSDOT of the project, and the project was a tight squeeze to begin with according to blueprints. Unlike Copiague and Lindenhurst, there were two stair cases on the South end at the top (going up one set, then at the mid-level deck where you would go up perpendicular to the tracks there were two sets of stairs, then the WB platform part was just one single staircase). I'll be going back this month or next month to the AHS and use my Mom's iPhone to take clearer pictures since I keep having trouble distinguishing if that's the pedestrian bridge or the end of the platforms where the M1 is.
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.