It was every subway rider’s nightmare, times two. Who has ridden along New York’s 656 miles of subway lines and not wondered: “What if I fell to the tracks as a train came in? What would I do?” And who has not thought: “What if someone else fell? Would I jump to the rescue?” Wesley Autrey, a 50-year-old construction worker and Navy veteran, faced both those questions in a flashing instant yesterday, and got his answers almost as quickly. Mr. Autrey was waiting for the downtown local at 137th Street and Broadway in Manhattan around 12:45 p.m. He was taking...