N.Y.C. Admin. Code § 19-141: § 19-141 Property owners may voluntarily lay sidewalks.

Any owner of property, upon obtaining a permit from the commissioner, may lay a sidewalk in front of such owner's premises, of such material and in such a manner as may be prescribed by such commissioner. Heating pipes or electric cables for the purpose of melting snow and ice may be incorporated in the construction of sidewalks with the approval of the commissioner.