Every single other piece, including all the concrete, wiring, etc. will be rebuilt several times during that period at an even higher cost than the original build since now it's in service.
NY has a $5B/year maintenance budget and continues to fall behind due to substantial under spending.
You cannot compare the two, that 5B maintenance budget is for a system that is:
A — Chronically Underfunded for decades
B — 10* the size of the proposed network additions
C — Close to or more than 100 years old (you can't expect construction standards to have been as good back then, nor can you compare maintenance costs of a 100-year-old line to a 30-50-year-old line)
D — Has to cope with far more density around said infrastructure
E — Has to cope with maintaining 13 hurricane-prone large tunnel crossings, 3 hurricane-prone large bridge crossings, as well as other river tunnels in the outer boroughs
F — Has a far worse rider etiquette, increasing the damage to the system
G — Has a far more complex network, requiring significantly more special trackwork
H — Is in the process of an insanely complicated signal modernization project (something these new lines likely won't have to cope with until they're 100 years old)
J — Has far more train usage per track segment
K — is largely made of steel structures in an aboveground setting (salt issues)
L — Has far more restrooms per capita
M — Is far less accessible and requires far more elevators.
N — Is located in a coastal city where salt-water is a real threat
Q — Was hit by a giant hurricane recently
R — Has far more vehicles per km of route track (16.3 for NYC compared to 11.4 for the TTC)
S — Has a more intensive vehicle maintenance schedule
S — Has a much older fleet
S — Has much older individual trains that are far less reliable than their modern counterparts
T — Has far larger costs associated with shutdowns
V — Runs overnight service
W — Has a far more complicated diversion system
Z — Has labor efficiency challenges
Compare line 4 to any of the NYC subway lines, or even Lines 1 and 2. They shut down line 4 for one, maybe 2 weekends every 3 years for special trackwork, and perform inspections far less frequently than on the 60-year old sections of the system. Line 4, as well as all of the proposed projects, have none of the issues associated with NYC (except for maybe underfunding). If our capital expenses for the system are 800 million dollars annually for the TTC (not including vehicles, 1 B if you include them), the cost per km of track annually for maintenance (including lines 1 and 2) would be 10.4 M. For the 38 km of the proposed new line, that would cost 400M dollars per year in maintenance (the highest assumption). We won't need additional second exits/third exits, elevators, additional signaling, etc with any of these projects. We might need some additional rolling stock at a cost of 1B for all lines combined, but that is a cost that can be paid off over 30 years. Other infrastructure renewal isn't as significant as the work required on Line 1, 2, 3, or the NYC subway.
