Are there any standards for these or is it just a general rule? I'm talking about platforms between tracks, specifically ones that need access by stairway or elevator. In this case I'd like to know the width of the center platform (or track center to center spacing) of the underground Amtrak station in Providence. There it's a wide center platform between pairs of tracks and I assume platforms along the outer tracks.
Platforms like the ones at Chicago Union Station would seem to be narrower since access is at the end of the platforms, but the ones at the Springfield, MA station along the old B&A tracks would have to be wider to accommodate the stairways leading into the station, I would think.
