N.Y. VAT Law § 1652-B

§ 1652-b. Supervision and installation of traffic devices in Suffolk\ncounty. The county superintendent of highways of Suffolk county may,\nwhen authorized by the Suffolk county governing board, erect and\nmaintain traffic signs, signals and markings on, and provide traffic\nengineering services in relation to any highway, road or street within a\ntown or village within such county, except state highways maintained by\nthe state, providing the governing body of the town or village having\njurisdiction over such highway, road or street determines on the basis\nof an engineering and traffic investigation that such traffic signs,\nsignals and markings are necessary, issues any necessary ordinance,\norder, rule or regulation with respect thereto, consents to the erection\nand maintenance of such traffic signs, signals and markings by the\ncounty and consents thereto by written agreement with the Suffolk county\ngoverning board as to the extent of the authority and responsibility of\nthe county superintendent of highways of Suffolk county and any\napportionment of costs for the erection and maintenance of signs,\nsignals and markings and traffic engineering services. The power granted\nto the Suffolk county superintendent of highways by this section shall\nin no way diminish any power over roads granted to him by law but shall\nbe in addition to any such powers.\n