Neb. Rev. Stat. § 39-899

The department shall have the power and authority to enter into agreements with an adjoining state to accomplish such design and preliminary engineering studies as may be deemed necessary prior to the construction of, or any construction upon, an interstate bridge. Such agreements may provide that such design and preliminary engineering studies may be accomplished by consulting engineers contracted for such purpose, or by any other means deemed suitable by the department and the adjoining state after joint consultation.