“The most amazing thing was the first time I saw it snowing underground”

New York subway-train operator Dennis H. Boyd is answering New York Times readers’ questions this week on the newspaper’s City Room blog. Today, in round two , Boyd fields complaints from riders upset by how slow the trains run and by the failure of the air-conditioning system (“What is a hot, quasi-suffocating, neurotic, claustrophobic rider to do?”). He also supplies the length and weight of a No. 4 train (500 feet, and 400 tons empty), shares the radio code for when a person gets hit by a train ("12-9”), and, as above, describes the weather inside a train tunnel.