I like this sign down by the Boston College T stop, aimed directly at the trains leaving the yard:
I’m not a railroad engineer, but I image that simply refraining from building any curbs across the tracks in the first place would alleviate the need for such signage.
The Boston College station was renovated last year. While the shiny new platform and shelter are a welcome change from the aging infrastructure they replaced, the logistics of the whole affair are just embarrassing.
Outbound trains stop just short of the sidewalk (or crosswalk, more properly) cutting across the mouth of the rail yard, affording easy access to passengers running west to catch their trains.
The new design erected a short railing ostensibly blocking direct access to trains, and forcing passengers to overshoot the station and backtrack down steps (or a ramp) to the platform. This is almost certainly meant to be a safety measure keeping harried commuters from running in front of trains that are about to move, but realistically a small segment of railing will do little to prevent that.