Nothing in sections 18-2001 to 18-2004 shall be construed to repeal or amend any statutes except those specifically repealed, and sections 18-2001 to 18-2004 shall be supplemental to and in addition to any other laws of the State of Nebraska related to street improvements. Other statutes may be relied upon, if need be, to supplement and effectuate the purposes of sections 18-2001 to 18-2004.