The provisions of this act shall apply to canals, ditches, conduits and other openings through the public highways of the state, which are already built over and across the same, whether built and maintained by the public authorities or the owner and proprietors of such ditches, canals, conduits and other openings. And when it shall become necessary to build, rebuild, repair or maintain bridges and viaducts already existing over canals, ditches, conduits and other openings through a public highway as set out in Kan. Stat. Ann. § 42-350, such duty shall devolve upon the owner and proprietor thereof without regard to who has performed such duty heretofore: Provided, That in case said bridges or viaducts become in a dangerous condition for travel and the owner or proprietor of said canal, ditch or conduit shall fail or refuse to repair or reconstruct said bridge or viaduct the highway officials having jurisdiction over said bridge or viaduct may repair or reconstruct the same and certify the cost to the county clerk who shall enter the same against the property of said owner or proprietor on the tax rolls for collection the same as other taxes.