If the legislative body of the political subdivision determines that special benefits will accrue from the separation of grades to one or more districts within the political subdivision, and has made a finding to that effect and that the cost thereof, other than the portion to be paid by the railroad, interurban railroad, or street railroad involved, should be paid by such district or partly by the district and partly by the political subdivision, the commission may provide that such proportion of the total cost of the separation of grades, including the acquisition of property and the damage to property or an interest therein, as is not payable by the owners of the railroad, interurban railroad, or street railroad involved, may be assessed upon the district or that a part thereof may be paid by the district and a part by the political subdivision in accordance with the finding of the legislative body of the latter. The commission may provide that the physical work of making the grade separation as well as the proceedings for letting contracts therefor, collecting and enforcing the assessments, and making payment for damages and for the acquisition of property shall be done through the agency of the political subdivision in accordance with law. The order of the commission shall authorize the officers of the political subdivision to enter upon so much of the right of way of the railroad, interurban railroad, or street railroad as is necessary to effect the physical grade separation.