When people stand waiting for the train to stop at busy stations like L'Enfant, they often stand between the people existing the train and the escalator many of those people will need to take to get to the next platform: change the color of the tile at the top and bottom of escalators leading to the train and post signs saying "do not stand on pink tiles - keep pink tiles clear" or add arrows to the floor pointing in the direction of the train route ("Green Line Branch Ave")
I have actually been pushed back onto the Green Line train trying to exit at L'Enfant. People line up right at the bottom of the 'up' escalator and no one can get past them to board the escalator. At Fort Totten, the line is blocking the egress to the escalators and passengers must turn right, away from the escalators to the middle of the platform, then U-turn back toward he escalators. If there were signs on the floor that showed where the trains were (arrows that say "Toward Branch Ave" or "Toward Greenbelt" so people could be herded in the right direction rather than stopping at the bottom of the escalator to survey the situation). Vibrantly colored tiles surrounding stairs and escalators would remind people to stand clear.