Neb. Rev. Stat. §§ 23-368
When the real property is located outside the corporate limits of a city or village the county is authorized to pave, repave, surface, resurface, and relay paving; to widen, to improve the horizontal and vertical alignment, to insert traffic medians, channels, overpasses, and underpasses; to apply temporary surfacing; and to curb; but the county may not be required to make any such street improvement if for good reason it deems the same should not be made; Provided, that none of the powers herein granted shall be exercised within the boundaries of any existing sanitary and improvement district, or road improvement district; and provided further, that the powers delegated in this section shall never be exercised in the area within three miles of the corporate limits of a metropolitan city in such county or a primary city; within one mile of the corporate limits of a city of the first class; or within one-half mile of the corporate limits of a city of the second class or village.
Neb. Rev. Stat. §§ 23-368