N.Y. Gen. Mun. Law § 125-a

§ 125-a. Posting signs on dead-end roads. It shall be the duty of\nevery municipal corporation and person charged with the duty of\nmaintaining any street or other roadway whenever such street or other\nroadway terminates in a dead end or at the embankment of a river, lake,\ncanal, reservoir, stream or other body of water, to post and keep posted\na sign readily visible by day and night. Such signs shall be installed\nin accordance with the state manual of uniform traffic control devices\nand shall be illuminated from one-half hour after sunset to one-half\nhour before sunrise. Where either the background or letters of the sign\nare of reflecting material so that such sign is readily visible at night\nwhen motor vehicle headlight rays fall upon the sign and it is placed in\nsuch position that the headlight rays of approaching vehicles will\nstrike it, no additional illumination shall be necessary.\n