New York Consolidated Laws, Vehicle and Traffic Law - VAT § 1685. All vehicles must stop or yield at certain railroad grade crossings where a stop or yield sign is erected

The state transportation commissioner, with respect to state highways, and local authorities with respect to local streets within their jurisdiction, with the approval of the state transportation commissioner are hereby authorized to install a stop or yield sign at any highway-railroad crossings within their respective jurisdictions.

The design and place and manner of installation of such signs shall conform to the manual and specifications for a uniform system of traffic control devices adopted by the state transportation commissioner.

Whenever any such crossing is so designated and a stop or yield sign is installed, it shall be unlawful for the driver of any vehicle to fail to stop or yield within fifty feet but not less than fifteen feet from such railroad tracks before traversing such crossing.  The failure to erect, or the erection of, or failure to replace or maintain such signs shall not be a basis for any action of negligence against a municipality or the state nor a basis of a defense by a railroad in an action based on negligence against a railroad.