Neb. Rev. Stat. § 18-824

(1) The board shall, as promptly as possible, rehabilitate, reconstruct, and modernize all portions of any transportation system acquired by the regional metropolitan transit authority, maintain at all times an adequate and modern public transit system suitable and adapted to the needs of the municipality or municipalities that form such authority, and provide for safe, comfortable, convenient, and expeditious transit service. (2) To ensure a modern, attractive public transit system, the board may establish a depreciation policy which makes provision for the continuous and prompt replacement of worn out and obsolete property. The board may make provision for such depreciation of property as is not offset by current expenditures for maintenance, repairs, and replacements under such rules and regulations as may be prescribed by the board.