Grand Central was the terminal for some trains of the IRT Third Avenue Line

IRT Third Avenue Line

The IRT Third Avenue Line, commonly known as the Third Avenue El, was an elevated railway in Manhattan and the Bronx, New York City. Originally operated by an independent railway company, it was acquired by the Interborough Rapid Transit Company and eventually became part of the New York subway...

. It was part of the original Third Avenue El, which opened on Tuesday, August 27, 1878. When the El north of 42nd Street opened, this segment was reduced to a shuttle, which connected to the mainline at 42nd Street

42nd Street (IRT Third Avenue Line)

42nd Street was an elevated station on the IRT Third Avenue Line in New York City. It had two levels with the lower level having three tracks. The main line tracks were served by two side platforms. A side platform connected to the southbound platform for shuttle service to Grand Central...

. This station had two tracks and one island platform

Island platform

An island platform is a station layout arrangement where a single platform is positioned between two tracks within a railway station, tram stop or transitway interchange...

 and two side platform

Side platform

A Side platform is a platform positioned to the side of a pair of tracks at a railway station, a tram stop or a transitway. A pair of side platforms are often provided on a dual track line with a single side platform being sufficient for a single track line...

s, all connected at the west end. It was closed on December 6, 1923.