N.Y. Comp. Codes R. & Regs. tit. 21 § 1220.55
Except when standing a bus in space, the use of which has been licensed specifically to the operator of such bus by written agreement with the Port Authority, drivers shall stand vehicles in the terminal only at space designated for such vehicles by the superintendent or by the Port Authority dispatcher or other Port Authority representative. Where space is used in common by the buses of more than one carrier, the drivers will cause their buses to stand in the most forward portion of such space available upon arrival, will, except when passengers are actually boarding or leaving the bus, continually move their buses forward, toward, and to the most forward vacant portion of the space, and will, except when passengers are actually boarding or leaving the bus, move or remove the bus to avoid blocking egress of a bus ready for departure.
N.Y. Comp. Codes R. & Regs. Tit. 21 § 1220.55