Whenever the commission finds it necessary to acquire land, rights-of-way or easements in order to carry out the purposes of this article, and the commission is unable to purchase the same from the owners at an agreed price, or is unable to obtain a good and sufficient title therefor by purchase from the owners, then the commission may exercise the right of eminent domain and acquire any such lands, rights-of-way or easements necessary for the aforesaid purpose by condemnation in the manner prescribed in chapter fifty-four of this code.