At a railroad crossing, flashing red lights, lowered crossing gates, or ringing bells mean that

At a railroad crossing, flashing red lights, lowered crossing gates, or ringing bells mean that a train is about to pass or is passing. You must stop at least 15 feet from the nearest rail of the tracks. (Trains are at least six feet wider than the tracks they run on, so you don't want to be too close.) Remain stopped until the lights or bells have stopped and the crossing gates are fully raised.