not been designed for express service. The track south of 145th Street is not long enough to allow an express train to pass a local, resulting in merging delays at 103rd Street which would eliminate any time saved. In addition, the busiest stops on the route north of 96th Street would be bypassed without any time savings. Extending all-local service to 242nd Street or adding additional trains were dismissed since they would require additional subway cars, which were not available at the time. On July 28, 1989, the MTA Board approved a revised 1/9 skip-stop plan unanimously, with the plan scheduled to take effect on August 21, 1989. Unlike the original plan, 1 trains would skip 145th Street, 191st Street, 207th Street and 225th Street, while 9 trains would skip 157th Street, Dyckman Street, 215th Street and 238th Street. Beginning at 6:30 a.m. on Monday, August 21, 1989, the services were coordinated as the 1/9 and both ran between Van Cortlandt Park–242nd Street and South Ferry. The plan was to have skip-stop service begin north of 116th Street–Columbia University, but due to objections, most notably that riders did not want 125th Street to be a skip-stop station, skip-stop service was only implemented north of 137th Street–City College between the hours of 6:30 am and 7:00 pm weekdays. All 1 trains skipped Marble Hill–225th, 207th, 191st and 145th Streets, while all 9 trains skipped 238th, 215th, Dyckman and 157th Streets. On September 4, 1994, midday skip-stop service was discontinued, and 191st Street became a common station for skip-stop service. 9/11 and recovery After the September 11 attacks in 2001, 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 the debris was cleared by September 17, the 1 ran only between 242nd Street and 14th Street, making local stops north of 96th Street and express stops south of that point. 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