IND Concourse Line

IND Concourse Line
The B train serves the IND Concourse Line south of Bedford Park Boulevard during weekday rush hours only while the D train serves the entire line at all times.
Overview
Type	Rapid transit
System	New York City Subway
Locale	Manhattan and The Bronx
Termini	Norwood – 205th Street 145th Street
Stations	12
Daily ridership	223,492
Operation
Opened	1933
Owner	City of New York
Operator(s)	New York City Transit Authority
Character	Underground
Technical
Line length	6.5 miles (10.5 km)
Number of tracks	2-3
Track gauge	4 ft 8 1⁄2 in (1,435 mm)
Electrification	600V DC third rail

The Concourse Line is an IND rapid transit line of the New York City Subway system. It runs from 205th Street in Norwood, Bronx to 145th Street in Harlem, Manhattan. It is the only B Division line in the Bronx, as well as the only fully underground line in the Bronx.

The Concourse Line runs north to south through the Bronx and portions of Harlem, parallel to the mostly-elevated IRT Jerome Avenue Line which lies between two and four blocks to the west for its entire length in the Bronx. It begins as a two-track line at Norwood – 205th Street, running east-to-west underneath East 205th Street, then under private property, then for a short portion under Van Cortland Avenue. As it travels west, a center track forms which leads to the Concourse Yard. The line then curves south at Mosholu Parkway to the Grand Concourse, from which it derives its name, at 206th Street. Two tracks from the Concourse Yard arrive between the two revenue tracks with switches and diamond crossovers between all four of them before the yard tracks merge to form the center track at Bedford Park Boulevard.

South of this station, the two outer tracks depress into a lower level and merge into a single center express track, while the center track splits to become the local tracks. The line then runs south with diamond crossovers at Tremont Avenue. Due to the terrain, the vicinity of 174th–175th Street station is uniquely built both underground and over 175th Street. Between 170th Street and 167th Street are more switches and crossovers, with a lay-up track adjacent to the Manhattan-bound local track.