If the board of supervisors is unable, by agreement with the owner, to acquire the necessary right-of-way to effect such change, a compensation commission shall be selected pursuant to section 6B.4 , to appraise the damages consequent on the taking of the right-of-way. [SS15, §1527-r1, -r2; C24, 27, 31, 35, 39, § 4610; C46, 50, §306.51; C54, 58, 62, 66, §306.22; C71, 73, 75, 77, 79, 81, §306.28 ] 99 Acts, ch 171, §29, 42 ; 2023 Acts, ch 66, §57 Referred to in §306.19 , 306.27 , 331.304