A reminder for those of you with plans to attend tonight’s big Elton John and Billy Joel double bill at Nationals Park (or anyone traveling on the Green Line, for that matter): Metro will be providing extended rail service to reduce congestion after the show, but there will not be any Circulator buses or shuttle service from RFK Stadium, as there normally is for Nationals games. Thinking about driving to the first concert at the new ballpark? As Post reporter Robert Thomson says, “Don’t think about parking on the street near the stadium unless you really know where you are and what you’re doing.” It seems like this one’s going to be quite the transportation nightmare, so pack your patience if you’re heading down.