To pay for the construction, reconstruction or repair of sidewalks and the reconstruction of curbs, gutters, curb cuts, curb cutbacks and driveways, special assessments shall be levied on all lots and pieces of land abutting on the improvement according to the front foot thereof. The cost of the construction, reconstruction or repair of such sidewalk, sidewalks, and the reconstruction of curbs, gutters, curb cuts, curb cutbacks and driveways shall be paid by the issuance of sidewalk scrip to the contractor, payable in not more than two years from the date of the issuance of such scrip, and said scrip shall bear interest at a rate not to exceed six percent. The cost of constructing, reconstructing or repairing all sidewalks and the reconstruction of curbs, gutters, curb cuts, curb cutbacks and driveways abutting on lots or pieces of land belonging to the city, the state or the United States shall be paid by the city at large. (C.O. 17 § 9, 1-30-71.)