New York City Subway chaining
Current

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
BB
Broadway–Seventh Avenue Line
Van Cortlandt Park–242nd Street
96th Street
96th Street
New Lots Avenue
C
Flushing Line
Flushing–Main Street
Times Square
Times Square
Times Square
CC
Flushing Line
34th Street–Hudson Yards
Section opened after mileage system fell into disuse.
Times Square
-
D
Nostrand Avenue Line
Franklin Avenue (ties to IRT E)
Flatbush Avenue–Brooklyn College
Brooklyn Bridge–City Hall
New Lots Avenue
E
Eastern Parkway Line / New Lots Line
Borough Hall (ties to IRT M)
-
Brooklyn Bridge–City Hall
New Lots Avenue
F
Lenox Avenue Line / White Plains Road Line
180th Street–Bronx Park (demolished)
96th Street
96th Street
New Lots Avenue
J
Jerome Avenue Line
Woodlawn
125th Street/Lexington Avenue (ties to IRT L)
Park Avenue/38th Street
New Lots Avenue
K
Broadway–Seventh Avenue Line / Clark Street Tunnel
Chambers Street (ties to IRT V)
Borough Hall
Broadway/44th Street
New Lots Avenue
L
Lexington Avenue Line
125th Street/Lexington Avenue
Grand Central–42nd Street
Park Avenue/38th Street
New Lots Avenue
M
Lexington Avenue Line / Joralemon Street Tunnel
Brooklyn Bridge–City Hall
Borough Hall
Brooklyn Bridge–City Hall
New Lots Avenue
MM
42nd Street Shuttle / Lexington Avenue Line
Times Square
-
Brooklyn Bridge–City Hall
New Lots Avenue
MV
South Ferry loops
Bowling Green
Bowling Green
Bowling Green
New Lots Avenue
P
Pelham Line
Pelham Bay Park
125th Street/Lexington Avenue (ties to IRT L)
Park Avenue/38th Street
New Lots Avenue
V
Broadway–Seventh Avenue Line
Times Square–42nd Street
north of South Ferry loops
Broadway/44th Street
New Lots Avenue
VA
Broadway–Seventh Avenue Line
south of Rector Street (ties to IRT V)
South Ferry (new station)
Broadway/44th Street
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
Y
Dyre Avenue Line
Eastchester–Dyre Avenue
East 180th Street
132nd Street and Willis Avenue
New Lots Avenue

Question: At what intersection in New York' city's subway is the chaining where dual contracts a section of Lexington avenue line?
Answer: In New York City Subway chaining, Park Avenue/38th Street: The point where the Dual Contracts section of the Lexington Avenue Line (from Grand Central–42nd Street).