The station's decline commenced in the late 1940s when platforms on the IRT Broadway–Seventh Avenue Line from 103rd Street to 238th Street were lengthened to to allow trains of ten cars to stop at these stations; previously, platforms could only accommodate six-car local trains. The platform extensions were opened in stages through 1948. The IRT routes were given numbered designations with the introduction of "R-type" rolling stock. These fleet contained rollsigns with numbered designations for each service. The first such fleet, the R12, was put into service in 1948. The Broadway route to 242nd Street became known as the 1 and the Lenox Avenue route as the 3.