Purpose-built

These connections can be used by trains in revenue service:

• 60th Street Tunnel Connection, also known as the 11th Street Cut (Queens) (BMT/IND) (R train)
• 63rd Street Lines (Manhattan) (BMT/IND)
• Coney Island–Stillwell Avenue station (BMT/IND) (originally all BMT) (D​, F, <F>​​, N​, and Q trains)
• Chrystie Street Connection (Manhattan) (BMT/IND) via the Manhattan Bridge (B and ​D trains) and via the Williamsburg Bridge (M train)

This connection is not for revenue service due to the differing widths of the trains:

• Astoria Line / Flushing Line (Queens) (BMT/IRT)

Yards

These connections are located within the subway's rail yards and are not intended for revenue service.

• 207th Street Yard (Manhattan) (IND/IRT); trains from the IND Eighth Avenue Line and IRT Broadway–Seventh Avenue Line
• Coney Island Complex (Brooklyn) (BMT/IND); trains from the IND Culver Line, BMT Sea Beach Line and BMT West End Line
• Concourse Yard (Bronx) (IND/IRT); trains from the IND Concourse Line and IRT Jerome Avenue Line
• Linden Yard (Brooklyn) (BMT/IRT/LIRR); trains from the BMT Canarsie Line and IRT New Lots Line

Other

• BMT West End Line / South Brooklyn Railway (Brooklyn) (BMT/Mainline RR)

Unused connections in the same division

In some places, there are track connections within the same division that are unused in regular service.^[15]

The Bronx

• IRT Jerome Avenue Line: Single center track between 149th Street–Grand Concourse and Woodlawn. Some northbound 4 trains in the morning and afternoon rush hours operate express from 167th Street until Burnside Avenue, where they short-turn.
• IRT White Plains Road Line: Single center track between East 180th Street and Wakefield–241st Street.
• IRT Dyre Avenue Line: Combinations of track and right of way between the flyover and Dyre Avenue.
• IRT Pelham Line: Single center track between Parkchester and Pelham Bay Park.
• IRT Broadway–Seventh Avenue Line: Single center track between Dyckman Street and 242nd Street.

Brooklyn

• BMT Sea Beach Line: One center track between 86th Street and Eighth Avenue. These were originally a pair of tracks which were briefly used by the NX service in 1967–1968; in 1999, one of the tracks was rehabilitated and the other was disconnected from the line leaving it unusable. The track is used occasionally for reroutes in either direction and possibly equipment testing. In the past, these tracks have been used to store rolling stock that are about to be scrapped.
• BMT West End Line: Single center track between Ninth Avenue and Bay 50th Street. Occasionally used for reroutes in either direction.
• BMT Brighton Line: Two center tracks between Brighton Beach and Ocean Parkway. These are used for layups and for terminating/turning B trains but are listed here since they are a continuation of the express tracks from the Brighton line, and exist through Ocean Parkway station.
• IND Culver Line: Single center track between Church Avenue and Avenue X.
• BMT Jamaica Line: Single center track between Myrtle Avenue and Broadway Junction.

Manhattan

• IRT Broadway–Seventh Avenue Line: Single center track between 96th Street and 145th Street.
• IRT Lenox Avenue Line: Single center track at 135th Street.

Queens

• BMT Astoria Line: Single center track between 39th Avenue and Astoria –Ditmars Boulevard. This track was last used for W trains in the peak direction, and being unpopular with residents, was discontinued on January 15, 2002.
• IND Fulton Street Line and IND Rockaway Line: On the Fulton Street Line, a single center track between Rockaway Boulevard and west of 88th Street (the track continues through 80th Street but leads only to the Pitkin Yard), and two center tracks from north of Aqueduct to south of Howard Beach–JFK Airport on the IND Rockaway Line.

The Bronx

• IRT Broadway–Seventh Avenue Line from south of 231st Street to Van Cortlandt Park–242nd Street
• IRT Jerome Avenue Line from 149th Street–Grand Concourse to Woodlawn
• IRT White Plains Road Line from Third Avenue–149th Street to Wakefield–241st Street
• Entire IRT Dyre Avenue Line, except for Pelham Parkway
• IRT Pelham Line from Hunts Point Avenue to Pelham Bay Park

Brooklyn

• BMT Jamaica Line from west of Marcy Avenue (on the Williamsburg Bridge) to 75th Street–Elderts Lane
• BMT Myrtle Avenue Line from west of Central Avenue to Myrtle–Wyckoff Avenues
• Entire IRT New Lots Line
• Entire BMT Sea Beach Line
• Entire BMT West End Line
• BMT Canarsie Line at Wilson Avenue (southbound platform elevated, northbound platform is actually on street level but in tunnel below elevated southbound platform), and from Broadway Junction to Canarsie–Rockaway Parkway ^[f]
• IND Culver Line from south of Carroll Street to Fourth Avenue/Ninth Street, and south of Church Avenue to Coney Island–Stillwell Avenue
• BMT Brighton Line from Prospect Park to Coney Island–Stillwell Avenue
• Entire BMT Franklin Avenue Line
• Both Manhattan Bridge lines

Manhattan

• IRT Broadway–Seventh Avenue Line at 125th Street and from Dyckman Street to north of 225th Street.
• IRT Lenox Avenue Line is at street level at Harlem–148th Street.
• BMT Jamaica Line on the Williamsburg Bridge
• Both Manhattan Bridge lines

Queens

• BMT Jamaica Line from 75th Street–Elderts Lane to east of 121st Street
• BMT Myrtle Avenue Line from Myrtle–Wyckoff Avenues to Middle Village–Metropolitan Avenue
• Entire BMT Astoria Line
• IRT Flushing Line from Hunters Point Avenue to west of Flushing–Main Street
• IND Fulton Street Line east of Grant Avenue
• Entire IND Rockaway Line

Three-tracked portions

The New York City Subway has fewer triple track sections than it has quadruple track sections^{[original research?]}. These sections are listed below. The third track, when in use, is generally for peak-direction express service or reroutes, with exceptions noted below.

1. IRT Broadway–Seventh Avenue Line (1 train) from south of Van Cortlandt Park–242nd Street to north of Dyckman Street and from north of 145th Street to north of 96th Street
2. IRT White Plains Road Line (2 and ​5 trains) from south of Wakefield–241st Street to east of Third Avenue–149th Street
3. IRT Lenox Avenue Line (2 and ​3 trains) at 135th Street – center track is not usable in revenue service
4. IRT Jerome Avenue Line (4 train) – entire line, except for Woodlawn
5. IRT Dyre Avenue Line (5 train) – entire line
6. IRT Pelham Line (6 and <6>​ trains) – entire line
7. IRT Flushing Line (7 and <7>​ trains) – from 33rd Street–Rawson Street to Flushing–Main Street
8. IRT New Lots Line (2, ​3, ​4, and ​5 trains) at Junius Street – center track is not usable in revenue service
9. IND Fulton Street Line (A train) – from west of 80th Street to west of Ozone Park–Lefferts Boulevard; the westernmost portion of this track goes to Pitkin Yard
10. BMT West End Line (D train) – from Ninth Avenue to Bay 50th Street
11. IND Concourse Line (B and ​D trains) – from 145th Street to Bedford Park Boulevard
12. IND Culver Line (F and <F>​ trains) – from south of Church Avenue to Avenue X
13. BMT Jamaica Line (J, M, and Z​ trains) – from Marcy Avenue to Broadway Junction. Also, at 111th Street, the center track is not usable in revenue service
14. BMT Canarsie Line (L train) at East 105th Street – easternmost track is not usable in revenue service
15. BMT Astoria Line (N and ​W trains) – from east of Queensboro Plaza to south of Astoria–Ditmars Boulevard
16. IND Crosstown Line (G train) at Bedford–Nostrand Avenues – middle track can be used to turn trains coming from either direction
17. BMT Broadway Line at Whitehall Street – middle track used to turn southbound (W) and northbound (R) trains
18. BMT Sea Beach Line (Eighth Avenue to 86th Street)

Additionally, there are several pocket tracks in the subway where the line temporarily widens from two to three tracks, such as east of Eighth Avenue on the BMT Canarsie Line, and south of Court Square on the IND Crosstown Line.

Four-tracked portions

Quadruple-tracked portions of track are fairly common in the subway system. This makes it unique among most metro systems in the world, as most others only have two tracks per line. Generally, these portions are a pair of express and a pair of local tracks unless otherwise noted.

1. Trunk lines:
   1. IND Sixth Avenue Line between Broadway– Lafayette Street and 47th–50th Streets
   2. IND Eighth Avenue Line between Chambers Street–World Trade Center and 168th Street, and again at Dyckman Street (two local tracks and two tracks leading to the 207th Street Yard)
   3. IRT Lexington Avenue Line between Brooklyn Bridge–City Hall and 125th Street
   4. IRT Broadway–Seventh Avenue Line between Chambers and 96th Streets
   5. BMT Broadway Line between Canal Street and 57th Street–Seventh Avenue
   6. BMT Nassau Street Line at Chambers Street (originally a four platform station)
2. Branch lines:

   Manhattan branches:

   1. 63rd Street Lines at Lexington Avenue (two levels of one-direction tracks, with both levels containing one track each of IND and BMT, with connections between lines on both levels)
   2. Chrystie Street Connection (one pair IND and one pair BMT)
   3. Manhattan Bridge (one pair of tracks on each of the north and south sides of the bridge)

   Queens branches:

   1. IND Queens Boulevard Line east of Queens Plaza
   2. IND Rockaway Line north of Jamaica Bay
   3. Archer Avenue Lines from Sutphin Boulevard and east (two levels of paired tracks: all IND on one, all BMT on the other, without connections between lines)
   4. IRT Flushing Line and BMT Astoria Line at Queensboro Plaza (two levels of one-direction tracks, with both levels containing one track each of IRT and BMT, with a non-revenue connection between lines on upper level)

   Brooklyn branches:

   1. IRT Eastern Parkway Line (entire line)
   2. IND Culver Line north of Church Avenue
   3. IND Fulton Street Line between Hoyt–Schermerhorn Streets and Euclid Avenue
   4. BMT Brighton Line between Ocean Parkway and Prospect Park
   5. BMT Fourth Avenue Line north of 59th Street
   6. Manhattan Bridge (one pair of tracks on each of the north and south sides of the bridge)

The Bronx has no four-tracked lines. Pocket tracks are not included.

Vestiges of former lines

• IRT White Plains Road Line: Just north of the Third Avenue–149th Street station, exiting the tunnel portal, one can see the initial framework of the IRT Third Avenue Line. There used to be a connection from the White Plains Road line to the Third Avenue El, which ran south across the Harlem River to Manhattan.
• IRT White Plains Road Line: The other end of the Third Avenue El connected to the White Plains Road line at the lower level of the Gun Hill Road station (closed 1973). Also on the White Plains Road line is the remnant of the short section of track to the original Bronx Park terminal.
• IRT Jerome Avenue Line: North of the 161st Street–Yankee Stadium station is the framework for the connection from the IRT Ninth Avenue Line.
• IRT Dyre Avenue Line: The Dyre Avenue Line was part of the New York, Westchester, and Boston Railway; it continued north beyond Eastchester–Dyre Avenue to White Plains and Port Chester; and south of the present connection to the White Plains Road line at East 180th Street, to 133rd Street where it ran alongside the New Haven Railroad. The platforms of the NYW&B station are still visible at East 180th Street station and are sometimes used to store trains. The structure south of East 180th Street ends abruptly at the Lebanon Street.
• IRT Flushing Line: Part of the trackway from the Queensboro Bridge and the IRT Second Avenue Line is still visible at the east end of Queensboro Plaza.
• BMT Nassau Street Line/BMT Broadway Line: The BMT Nassau Street Line used to connect to the south side of the Manhattan Bridge north of Chambers Street. The trackways were disconnected from the Manhattan Bridge after the Chrystie Street Connection opened. Also, heading northbound over the Manhattan Bridge north side, an abandoned tunnel is visible before entering Grand Street. Heading northbound on the south side, the remains of the tunnel to the BMT Nassau Street Line loop is briefly visible. This area was reconfigured as part of the Chrystie Street Connection.
• BMT Fulton Street Line: Trackways are still visible at BMT Canarsie Line stations at Broadway Junction and Atlantic Avenue. Framework for the el was up until early 1998, visible at the Franklin Avenue Shuttle station at Franklin Avenue–Fulton Street. The structure served as a pedestrian walkway and was demolished in 1998 when the station and the Franklin Avenue Line was rebuilt as a single-tracked line.
• BMT Fulton Street Line: On the IND Fulton Street Line heading westbound from 80th Street, one can see the stub end of the old BMT Fulton Street Line continuing straight ahead while the IND Fulton Street Line curves into Grant Avenue, an underground station.
• BMT Culver Line (now IND Culver Line): At Ninth Avenue and at Ditmas Avenue, the original Culver line connected. The trackway is visible at Ditmas Avenue and the ramps are visible at Ninth Avenue.
• BMT Jamaica Line: West of Gates Avenue, one can see where the structure turned onto Lexington Avenue to head toward the Brooklyn Bridge. The structure is only visible from street level.
• BMT Jamaica Line: West of Marcy Avenue, the BMT Jamaica Line veers right onto the Williamsburg Bridge while the original structure continues straight ahead.
• BMT Jamaica Line: East of 121st Street, the 144th Street BMT powerhouse and 168th Street station house still exist along Jamaica Avenue.
• The LIRR's Rockaway Beach Branch runs from the White Pot Junction to just east of Rockaway Boulevard, where the IND Rockaway Line begins.