"reservoir" stations at 33rd/34th and 42nd Streets. The proposal entailed constructing a northbound-only tunnel under Lexington Avenue from 30th to 42nd Street, with stations at 34th and 42nd Streets, then converting the IRT tunnel under Park Avenue and the existing 33rd and 42nd Street stations to southbound-only use. The northbound and southbound stations at 33rd/34th and 42nd Streets would both have had two express tracks and one local track; the express tracks in either direction would have merged with each other north of 42nd Street and south of 30th Street. Although the "reservoir" plan was technically feasible, the $25 million projected cost was too high. The city government took over the IRT's operations on June 12, 1940. On April 13, 1948, the platform extensions to accommodate ten-car trains at this station, along with those at 23rd Street and 28th Street, were opened for use. On December 27, 1948, a new entrance to the station at 32nd Street opened for use. In 1979, the New York City Landmarks Preservation Commission designated the space within the boundaries of the original station, excluding expansions made after 1904, as a city landmark. The station was designated along with eleven others on the original IRT. The original interiors were listed on the National Register of Historic Places in 2004. Station layout Like other local stations, 33rd Street has four tracks and two side platforms. The 6 stops here at all times, rush-hour and midday <6> trains stop here in the peak direction; and the 4 stops here during late nights. The two express tracks are used by the 4 and 5 trains during daytime hours. The platforms were originally long, as at other local stations on the original IRT, but later became long. The platform extensions are at the southern ends of the original platforms. The express tracks stay level, while the local tracks slowly incline from south to north to allow for the easier deceleration of local trains. This results in a layout where the express tracks are at a lower elevation than the local tracks in the northern half of the station. North of the station, the two pairs of tracks in each direction separate into different tunnels because of the presence of the Murray Hill Tunnel, which runs under the center of this section of Park Avenue. As built, the tunnels were supposed to have been apart, but the northbound tunnel (to