The 14th Street–Union Square station is an express station on the IRT Lexington Avenue Line. The 4 and 6 trains stop here at all times; the 5 train stops here at all times except late nights; and the <6> train stops here during weekdays in the peak direction. When the subway opened, the next local stop to the north was ;
The station has four tracks and two island platforms. The uptown and downtown platforms are offset from each other, having been extended at their rear ends, and are curved. This is because the portions of the platforms under the mezzanine are too narrow for elevators. According to a separate report by engineering firm STV, it would be prohibitively expensive to relocate the southbound platform northward to eliminate the gap fillers.
The station has two abandoned local side platforms; the northbound platform is visible through windows, bordered with wide, bright red frames.<!-- These side platforms were built to accommodate extra passenger volume and were built to the five-car length of the original IRT local trains. When trains were lengthened, the side platforms were deemed obsolete, and they were closed and walled off.-->
Design
As with other stations built as part of the original IRT, the station was constructed using a cut-and-cover method. The tunnel is covered by a U-shaped trough that contains utility pipes and wires. The bottom of this trough has a foundation of concrete no less than thick.