After the September 11 attacks , ' '' 1 ' '' trains had to be rerouted since the IRT Broadway – Seventh Avenue Line ran directly under the World Trade Center site and was heavily damaged in the collapse of the Twin Towers . It initially ran as a shuttle alongside the ' '' 2 ' '' and ' '' 3 ' '' trains to Times Square , due to debris that fell on the tracks south of Pennsylvania Station . When that was cleared by September 17 , it ran only between 242nd Street and 14th Street , making local stops north of and express stops south of 96th Street . Local service was replaced by the ' '' 2 ' '' and ' '' 3 ' '' trains , running express from Canal Street to Fulton Street due to debris covering the stops between them . The skip-stop service with the ' '' 9 ' '' train was suspended for the duration of the 9/11 emergency service plan . On September 19 , after a few switching delays at 96th Street , service was changed . ' '' 1 ' '' trains made all stops from 242nd Street to New Lots Avenue via the Clark Street Tunnel and IRT Eastern Parkway Line , to replace '' '' '' trains ( which terminated at 14th Street ) at all times . All ' '' 1 ' '' trains continued running express with the ' '' 2 ' '' between the aforementioned streets until October 1 , when it terminated at Chambers Street in Manhattan overnight
September 11 attacks
September 11 attacks
1 (New York City Subway service)