Unsuck DC Metro points us to this solid effort at capturing the need to have a visual representation of just how often D.C.’s Metro system breaks down. Flickr user brhefele has offered up the “Fail Rail,” a play on the ubiquitous Fail Whale familiar to Twitter users everywhere. Nicely done. Writes brhefele: ‘When the train stops working, they should just put this sucker up instead of incessantly repeating “Due to mechanical difficulties…” “There is a…