New York City Subway chaining
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New York City Subway chaining is a method to precisely specify locations along the New York City Subway lines. It measures distances from a fixed point, called chaining zero, following the twists and turns of the railroad line, so that the distance described is understood to be the "railroad distance," not the distance by the most direct route ("as the crow flies").
The
Terminology
Chaining zero
Chaining zero is a fixed point from which the chaining is measured on a particular chaining line. A chaining number of, for example, 243 at a specific line location (called a chaining station) identifies that the location is the length of 243 100-foot chains (24,300 feet or 4.60 miles or 7.41 kilometres) from chaining zero, usually measured along the center line of the railroad.[1]: 1
Once chaining is established, it is rare but not unheard of to change the location of chaining zero or the route along which it is measured on a given line. There are several examples of chaining numbers that refer to a chaining zero location that no longer exists or along a physical line that no longer exists, because of abandonment or demolition. Notable among these are several existing chaining lines that originated near New York City Hall via the Brooklyn Bridge, discontinued since 1944. It is occasionally possible for a reroute to alter the accuracy of chaining numbers slightly.
Exceptions exist to the principle that chaining numbers represent a railroad distance to the zero point. On the original IND chaining zero for the original system is a political rather than physical location, and there is no railroad at or near the zero point.[1]: 1 Sometimes trackage (usually but not always short distances) is chained backwards from a tie point with another line.
The three divisions each had a separate mileage zero before the 1958 opening of the
Chaining lines
Chaining lines are routes on physical railroad lines that are usually described by one or two letters for the purpose of identifying locations on those lines.
Chaining lines are not necessarily the same as the physical lines they run on. One physical line may have several chaining letters, and one chaining line may cover several physical lines.
The letters assigned to a chaining line have nothing to do with the letters displayed on trains, public maps and timetables. These letters are subway service letters. See: New York City Subway nomenclature and List of New York City Subway services.
For example, the BMT A chaining line begins at BMT South chaining zero north of
In a few cases, the chaining lines and service letters are coincident, such as the IND A chaining line following the A service from 207th Street to Euclid Avenue, while the IND C was the IND Concourse Line, which was originally served by the C service. However, that service was later moved off of the Concourse line, while the chaining code remains.
Chaining stations
Each specific location along a line is known as a chaining station, and is identified by a number unique to that chaining line. The
Signals are identified by the chaining line and track number, and by the nearest 100-foot chaining station. In this usage only the number of 100-foot chains from chaining zero are displayed. Thus, a signal on the BMT with a designation of A2 / 102 would be on the BMT chaining line A, track 2, within 50 feet of the chaining station at 10,200 feet from chaining zero.[1]: 1
Track numbers on chaining lines
Each track on a chaining line is given a number, letter or (rarely) a combination of both to identify a particular track on a particular line.
BMT/IND practice
On the
These track numbers provide a definitive way of determining whether a particular direction on a particular line is going "railroad" north or south. Especially it shows that "south" on several lines (including the BMT Jamaica Line, the IND Fulton Street Line and the BMT Myrtle Avenue Line) that run in an easterly to northerly compass direction for their entire route are nevertheless running railroad south.
The local (usually outside) tracks on a given
A1–A3–A4–A2
On the three track BMT West End Line, they are:
D1–D3/4–D2
On the two track BMT Canarsie Line, they are:
Q1–Q2
Some stations may have the same number of tracks, but a slightly different chaining. On most stations on the three-track IND Concourse Line, the chaining (from west to east) is:
C1–C3/4–C2
At
C1–C6–C2
IRT practice
On the IRT the signals are numbered differently. The track number for chaining purposes is added to the end of the survey number, so that the southbound signal numbers end in 4 (local) and 2 (express) and the northbounds are 1 (express) and 3 (local). On a four track line, the signal numbers end:[1]: 1
4–2–1–3
On a three track line, 1/2 are used signals on the middle track (1 is for signals governing northward moves, and 2 southward). 4 and 3 are still the local tracks:
4–1/2–3
And on a two-track line, there are no express tracks, so the two tracks are:
4–3
Strangely, IRT track designations differ from the signal chaining track numbers they are numbered from left to right (facing north), tracks number 1 through 4:
1–2–3–4
And on a three-track line:
1–M–4 or 2–M–3
Thus, a line will have signal numbers ending in "4–2–1–3" and tracks designated as "1–2–3–4".
Signals on the IRT governing in the opposite of the normal direction of travel will have a signal number ending N+4 from the signal numbers governing in the normal direction.
Examples of all four tracks at a particular survey location (on the signal plate, the "-" is a line break):
BMT:
B1-243 | B3-243 | B4-243 | B2-243
IRT:
2434-B | 2432-B | 2431-B | 2433-B
Handling chaining junctions
When one line splits from or joins another, a decision must be made on how to measure the chaining distances on the individual lines. One way is to establish a new zero point for one or more lines, but this is inefficient. Typically a major end-point terminal will be chosen as chaining zero, and all lines that are tributary to that terminal will measure their chaining from that point. This process is called tying. For example, if one line ties to another at a certain point, and the chaining station number at that point is 135+10 (13,510 feet from chaining zero), then a location on either branch that is 1,000 feet from that will have a chaining station number of 145+10.
Tying
When a new line or branch separates from another line, and the new line "picks up" the chaining numbers of the original line, the new line is said to be "tied" at that point. For example, where the BMT
Reverse tying
Sometimes when a line leaves another line, the chaining on the branch line should be tied to the original line, but sometimes the chaining distances go down instead of up. This is almost always because the branch joins the main line coming from the same direction as the main line, and we want the chaining numbers of the branch to be derived from the main line, so as not to have to establish a separate chaining zero location for the branch. An example of this was the Fulton Ferry branch of the Fulton Street Elevated (BMT K) which split from the Brooklyn Bridge branch at a location called Kings County (KC) Junction. Chaining zero for both branches was at
No tying
Sometimes two or more lines merge or abut but the chaining shouldn't be tied. For example, the Montague Street Tunnel Line BMT B is tied to Broadway Line BMT A at Canal Street, but BMT B returns to BMT A railroad south of the
Chaining codes
Following are tables describing the chaining lines of all three divisions, including defunct lines.
BMT
Current
Many of these lines originally had individual chaining zero points as a result of the different companies that built and operated them. The
All Mileage zeroes are at Coney Island–Stillwell Avenue.[1]
Chaining line | Physical line | North | South | Chaining zero | Mileage zero |
---|---|---|---|---|---|
A | Broadway Line / Brighton Line | 57th Street–Seventh Avenue
|
Canal Street lower level
|
57th Street–Seventh Avenue
|
Coney Island–Stillwell Avenue[1]
|
midpoint of Manhattan Bridge north tracks | Coney Island–Stillwell Avenue
| ||||
B | Broadway Line / Montague Street Tunnel | Canal Street upper level (ties to BMT A)
|
junction with Brighton Line south of DeKalb Avenue
| ||
C | BMT Culver Line (no longer in revenue service)[a] | Ninth Avenue lower level (ties to BMT D)
|
Fort Hamilton Parkway | ||
D | West End Line | 36th Street (ties to BMT F)
|
Coney Island–Stillwell Avenue
| ||
E | Sea Beach Line | 59th Street (ties to BMT F)
| |||
F | Fourth Avenue Line | Gold Street Interlocking north of DeKalb Avenue (ties to BMT A)
|
Bay Ridge–95th Street
| ||
G (tracks 1 and 2) | Astoria Line / 60th Street Tunnel | Astoria–Ditmars Boulevard
|
57th Street–Seventh Avenue
| ||
G (tracks 3 and 4) | 63rd Street Line
|
Lexington Avenue–63rd Street
|
57th Street–Seventh Avenue
|
Section opened after mileage system fell into disuse. | |
GD | 60th Street Tunnel Connection
|
Queens Plaza
|
junction with BMT G (Tracks 1/2) west of Queensboro Plaza (ties to BMT G)
|
Coney Island–Stillwell Avenue[1]
| |
H | Manhattan Bridge south tracks | Canal Street lower level (ties to BMT A)
|
interlocking north of DeKalb Avenue
| ||
J | Archer Avenue Line
|
Chambers Street
|
168th Street (demolished)
|
Chambers Street
| |
Jamaica Center–Parsons/Archer
|
Section opened after mileage system fell into disuse. | ||||
M | Myrtle Avenue Line | Sands Street (demolished) (tied to BMT K)
|
Broadway (abandoned)
|
Park Row (demolished)
|
Coney Island–Stillwell Avenue[1]
|
Myrtle Avenue
|
Middle Village–Metropolitan Avenue
| ||||
O | Franklin Avenue Line | Franklin Avenue/Fulton Street (ties to BMT K)
|
Prospect Park
| ||
P | Linden Shops
|
Livonia Avenue
|
Linden Shops
|
between Sutter Avenue
| |
Q | Canarsie Line | Eighth Avenue
|
Canarsie–Rockaway Parkway
|
Eighth Avenue
| |
R | Nassau Street Line | Chambers Street
|
Montague Street Tunnel (reverse-ties to BMT B) | 57th Street–Seventh Avenue
|
Former
Chaining line | Physical line | North | South | Chaining zero |
---|---|---|---|---|
K | Fulton Street Line (remaining portion transferred to IND) |
Fulton Ferry (demolished) (reverse-tied to main BMT K) | Kings County Junction | Park Row (demolished)
|
Park Row (demolished)
|
Ozone Park–Lefferts Boulevard
| |||
L | Lexington Avenue Line (demolished) | Grand Street/Myrtle Avenue (demolished) (tied to BMT M) | Broadway | |
N | Fifth Avenue Line (demolished)
|
Myrtle Avenue/Hudson Street (tied to BMT M) | 65th Street/Third Avenue (demolished) |
- BMT C: Original BMT C ran along the entire length of the Culver Line, from the lower level of 57th Street/Sixth Avenue to West Eighth Street). The surviving portion of the northern Culver Line, which today runs from Ninth Avenue lower level to about Fort Hamilton Parkway and 37th Street, is still chained BMT C.
- BMT G: Tracks 3 and 4, which constitute the BMT 63rd Street Line, are not to be confused with track G3-4, the single express track on the Astoria Line. Positions on the 63rd Street Line have approximately 100+00 added to the actual distance from the zero point.
- BMT K: The Fulton Ferry spur was chained from Park Rowto Kings County Junction (located east of former Sands Street station), then backwards from the junction to Fulton Ferry.
- BMT L: Gates Avenuestations).
- BMT P: Until recently, BMT P consisted of the Linden Shops.
- BMT Q: Originally, chaining for BMT Q began at Eighth Avenue, the new trackage was chained as BMT QW, with chaining starting at Sixth and increasing to Eighth. The Canarsie Line has since been entirely rechained as Q, running from the zero at Eighth Avenue south to Rockaway Parkway.
- BMT Y: This is used on yard leads.
IND
Current
All Mileage zeroes are at Far Rockaway–Mott Avenue.[1]
Chaining line | Physical line | North | South | Chaining zero | Mileage zero |
---|---|---|---|---|---|
A | Eighth Avenue Line / Fulton Street Line | West Fourth Street–Washington Square )
|
stub tracks past Euclid Avenue
|
IND zero | Far Rockaway–Mott Avenue[1]
|
B | Sixth Avenue Lines / Culver Line | 57th Street
|
midpoint of Manhattan Bridge north tracks | 57th Street and Chrystie Street sections opened after mileage system fell into disuse. | |
South of Columbus Circle
| |||||
West of Fifth Avenue/53rd Street
|
Jay Street–MetroTech)[2]
|
Far Rockaway–Mott Avenue[1]
| |||
BJ | Chrystie Street Cut | Broadway–Lafayette Street (reverse ties to IND B)
|
Essex Street
|
Section opened after mileage system fell into disuse. | |
C | Concourse Line | Norwood–205th Street
|
135th Street (ties to IND A)
|
Far Rockaway–Mott Avenue[1]
| |
D | Queens Boulevard Line | Jamaica–179th Street
|
interlocking between 42nd Street–Port Authority Bus Terminal (ties to IND A)
| ||
DA | Archer Avenue Line
|
Jamaica Center–Parsons/Archer
|
Briarwood (ties to IND D)
|
Section opened after mileage system fell into disuse. | |
E | Brooklyn–Queens Crosstown Line | Queens Plaza (reverse-ties to IND D)
|
Fulton Street
|
Far Rockaway–Mott Avenue[1]
| |
Fulton Street
|
Bergen Street (ties and reverse-ties to IND A at Hoyt Street.)
| ||||
F | Rockaway Line / Rockaway Park Branch | Rockaway Boulevard
|
Rockaway Park–Beach 116th Street
|
Long Island City (LIRR station)
| |
FA | Far Rockaway Branch (Rockaway Line) | Hammels Wye (ties to IND F) | Far Rockaway–Mott Avenue
| ||
K | Liberty Avenue El | east of Euclid Avenue
|
Ozone Park–Lefferts Boulevard
|
Park Row (demolished)
| |
S | Second Avenue Line | 96th Street
|
east of Lexington Avenue–63rd Street (ties to IND T)
|
IND zero | Sections opened after mileage system fell into disuse. |
T | 63rd Street Line
|
junction south of 36th Street
|
57th Street (ties to IND B)
|
Former
Chaining line | Physical line | North | South | Chaining zero |
---|---|---|---|---|
D (tracks 5 and 6) | World's Fair Line (demolished) | World's Fair station | Forest Hills–71st Avenue (tied to IND D)
|
Jamaica Yard
|
- IND zero: The zero point of the railroad northof West Fourth and decrease railroad south. As a result, the principle that chaining stations along any line reflect the accurate distance to a chaining zero point via the physical railroad is not true on the original IND.
- IND D (tracks 5 and 6): While the yard leads from the Forest Hills–71 Avenue station are tied to IND D, the chaining of Jamaica Yard and the World's Fair Line are not.[3][4]
- IND E: From Hoyt–Schermerhorn Streetsstation. North of Fulton Street, the line is reverse-tied to IND D.
- IND F/FA: The Long Island City, Queens, via the old Montauk Line. When the IND acquired the Rockaway Line south of Liberty Avenuein 1956, it preserved the LIRR chaining distances. The single-track connection between the east and west legs of Hammels Wye has its own chaining, which starts at the point it branches from the east leg.
- IND K: The Liberty Avenue Elevated, currently part of the Euclid Avenue.
- IND S: Ties to IND T near 2nd Avenue and 63rd Street, where the two lines intersect.
IRT
Current
All Mileage zeroes are at New Lots Avenue, except for the IRT Flushing Line, whose zero is Times Square.[1]
Chaining line | Physical line | North | South | Chaining zero | Mileage zero |
---|---|---|---|---|---|
B | Broadway–Seventh Avenue Line | 96th Street
|
Times Square–42nd Street (ties to IRT MM)
|
Brooklyn Bridge–City Hall
|
New Lots Avenue[1]
|
BB | Van Cortlandt Park–242nd Street
|
96th Street
| |||
C | Flushing Line[5] | Flushing–Main Street[5]
|
Times Square[5]
|
Times Square[5]
|
|
CC | Times Square[5]
|
34th Street–Hudson Yards[5]
|
Section opened after mileage system fell into disuse. | ||
D | Nostrand Avenue Line | Franklin Avenue (ties to IRT E)
|
Flatbush Avenue–Brooklyn College
|
Brooklyn Bridge–City Hall
|
New Lots Avenue[1]
|
E | Eastern Parkway Line / New Lots Line | Borough Hall (ties to IRT M)
|
New Lots Avenue
| ||
F | Lenox Avenue Line / White Plains Road Line | 180th Street–Bronx Park (demolished)
|
96th Street
| ||
J | Jerome Avenue Line | Woodlawn
|
125th Street/Lexington Avenue (ties to IRT L)
|
Park Avenue /38th Street
| |
K | Clark Street Tunnel
|
Chambers Street (ties to IRT V)
|
Borough Hall
|
Broadway/44th Street | |
L | Lexington Avenue Line | 125th Street/Lexington Avenue
|
Grand Central–42nd Street
|
Park Avenue /38th Street
| |
M | Lexington Avenue Line / Joralemon Street Tunnel | Brooklyn Bridge–City Hall
|
Borough Hall
|
Brooklyn Bridge–City Hall
| |
MM | 42nd Street Shuttle / Lexington Avenue Line | Times Square
|
Brooklyn Bridge–City Hall
| ||
MV | South Ferry loops
|
Bowling Green
| |||
P | Pelham Line | Pelham Bay Park
|
125th Street/Lexington Avenue (ties to IRT L)
|
Park Avenue /38th Street
| |
V | Broadway–Seventh Avenue Line | Times Square–42nd Street
|
north of South Ferry loops
|
Broadway/44th Street | |
VA | south of Rector Street (ties to IRT V)
|
South Ferry (new station)
|
Section opened after mileage system fell into disuse. | ||
W | White Plains Road Line | Wakefield–241st Street
|
West Farms Square–East Tremont Avenue (ties to IRT F)
|
96th Street
|
New Lots Avenue[1]
|
Y | Dyre Avenue Line | Eastchester–Dyre Avenue
|
East 180th Street (ties to IRT W)
|
Former
Chaining line | Physical line | North | South | Chaining zero |
---|---|---|---|---|
G | Bergen Cutoff (demolished) (from White Plains Road Line to Third Avenue Line) |
Jackson Avenue
|
143rd Street/Third Avenue upper level (demolished) (tied to IRT T)
|
South Ferry elevated station (demolished)
|
H | Third Avenue Line over Webster Avenue (before 1955 resignalling project) | Gun Hill Road lower level (demolished)
|
Fordham Road (tied to IRT T)
| |
N | Ninth Avenue Line (demolished) | 155th Street
|
South Ferry elevated station (demolished)
| |
Q | Queensboro Bridge (tracks removed) | 57th Street/Second Avenue (tied to IRT S)
|
Queensboro Plaza
| |
R | 162nd Street Connection (from Jerome Avenue Line to Ninth Avenue Line, demolished) | River Avenue/162nd Street | Putnam Bridge | U.S. Bulk Head Line on east shore of the Harlem River |
S | Second Avenue Line (demolished) | 129th Street
|
South Ferry elevated station (demolished)
|
South Ferry elevated station (demolished)
|
T | Third Avenue Line (demolished) | Bronx Park Terminal
| ||
T | Third Avenue Line over Webster Avenue (after 1955 resignalling project) | Gun Hill Road lower level
|
Fordham Road
| |
Z | Sixth Avenue Line (demolished) | 53rd Street/Ninth Avenue | Rector Street (tied to IRT N)
| |
ZA | 59th Street/ Sixth Avenue
|
53rd Street/ Sixth Avenue
|
- IRT A: This was the original IRT designation of the Astoria Line until it was completely transferred to BMT operations.
- IRT Y: This chaining letter was formerly assigned to the portion of the East 180th Street. The Dyre Avenue Line had originally been part of the New York, Westchester and Boston Railway, which had had its chaining zero at its southern terminus at Oak Point Yard in the South Bronx.[6]IRT Y has since been tied to IRT W under a new signal contract.
- Broadway/44th Street: The point where the Times Square–42nd Streetsouth) meets the Contract I section (north of 42nd Street).
- Park Avenue/38th Street: The point where the Grand Central–42nd Streetnorth) meets the Contract I section (south of 42nd Street).
Notes
- ^ The BMT Culver line segment that has BMT chaining was never part of the IND Culver line
References
- ^ a b c d e f g h i j k l m n o p q r s t u v "The ERA Bulletin 2017-01". Issuu. Electric Railroaders' Association. January 18, 2017. Retrieved January 18, 2017.
- ^ NYCTA General Signal Arrangement Drawing MW7B-778-SL-A
- ^ NYCTA General Signal Arrangement Drawing MW7D-1602-SL
- ^ IND World's Fair Railroad, contract drawings 7-2, 7-3, and 7-4.
- ^ a b c d e f g "Flushing Line 2016 Town Hall April 5, 2016 Sunnyside, Queens" (PDF). Access Queens. Metropolitan Transportation Authority. April 5, 2016. Retrieved October 22, 2017.
- ^ New York, Westchester and Boston Railway#Stations and route