Whenever, in the opinion of the board of county commissioners, it is for the best interests, security, and convenience of the public in carrying out any contract for the construction, use, and maintenance of a joint bridge, such board may establish new highways and widen, change the location of, alter, straighten, narrow, change the grade of, or vacate a part or all of any public highway established or to be established under previous contract.
R.C. §5591.05