For the purpose of section 2—

3. For the purpose of section 2— (a) the mileage of State roads in a State shall be taken to be that mileage as on the thirty-first day of December of the preceding financial year, and the average cost mentioned in paragraph (a) of that section shall be taken to be the average cost in that State calculated in the preceding financial year; and (b) the maintenance of State roads means the preservation, upkeep and restoration of State roads, roadside furniture, bridges, viaducts or culverts forming part thereof or connected therewith as nearly as possible in their original condition as constructed or as subsequently improved.