N.Y. Gen. Mun. Law § 125-A
It shall be the duty of every municipal corporation and person charged with the duty of maintaining any street or other roadway whenever such street or other roadway terminates in a dead end or at the embankment of a river, lake, canal, reservoir, stream or other body of water, to post and keep posted a sign readily visible by day and night. Such signs shall be installed in accordance with the state manual of uniform traffic control devices and shall be illuminated from one-half hour after sunset to one-half hour before sunrise. Where either the background or letters of the sign are of reflecting material so that such sign is readily visible at night when motor vehicle headlight rays fall upon the sign and it is placed in such position that the headlight rays of approaching vehicles will strike it, no additional illumination shall be necessary.
N.Y. Gen. Mun. Law § 125-A