N.Y. R.R. Law § 201
For the purpose of providing for the more speedy transportation of persons across public parks in the cities within the state of New York having a population of one million five hundred thousand or upwards it shall be lawful for the municipal authorities, officers, departments, or boards having control of such parks to construct railroads in and upon tunnels or roads or ways depressed below the surface of said parks in such cities in this state, and to extend the same east or west to connect with any surface railroads in such cities, now in existence, and with railroads which hereafter may be built by companies now chartered and existing, and to contract in the name of such cities, with any person or corporations for the construction thereof, and for the equipment and running of the same either with or without public advertisement upon such terms and conditions, including the rates of fare to be charged to persons using such railroads, for such compensation to be paid to such cities, and subject to such rules, regulations and requirements as may be determined upon in said contract, and as the department or board, or officer having charge of said parks may, from time to time, thereafter establish or impose.
N.Y. R.R. Law § 201