Today is already one of the busiest travel days of the year, and thanks to a problem with Amtrak train signals below the East River, all service out of Penn Station — including Amtrak, New Jersey Transit, and the Long Island Rail Road — was shut down at about 5:30 p.m. The crowding in Penn got so bad that it was difficult to move, and at one point thousands of people flooded onto the streets outside the station. The situation was resolved at 7:00 p.m., but delays will continue throughout the evening. If we didn’t fear the wrath of relatives still trapped in the station, we’d say the timing is so bad it’s impressive.