An article on Thursday about the death of a New York City subway motorman who collapsed in his cab as the train pulled out of a station in Queens referred incorrectly to the train’s so-called dead-man feature, in which emergency brakes are applied if the operator lets go of the controller arm for any reason. While several transit officials and subway experts said this was the first time they had heard of the feature being activated, it has happened at least twice before. (A reader pointed out that, according to The Times’s archives, the paper had written about such instances in 1927 and in 1940.)− Secuencia de pedal no pisado: • A los 2,5 s de estar libre el pedal se enciende una luz azul de aviso en el pupitre. • Si no se hace nada 2,5 s después suena un aviso acústico. • Si no se hace nada 2,5 s después se abre el lazo de freno provocando el frenado de emergencia.