Tenn. Code Ann. § 54-4-402: Powers and duties of commissioner

(a) The commissioner has full power, and it is made the duty of the commissioner, after consultation with local officials, to designate those highways and roads that are considered of sufficient importance to be included in the state-aid highway system. In the selection and designation of highways and roads as part of the state-aid highway system, the commissioner shall consider any highways and roads that are not a part of the state highway system, the number of miles of highways and roads in each county, and the area and population of each county, traffic volume, type of traffic, land use, and function that each route serves in the county road network.

(b) After consulting with local officials, the commissioner may make adjustments in the system that appear to be necessary as a result of any change in local conditions and traffic patterns as shown by studies and data of the planning division of the department.

(c) The commissioner is authorized to lease to local officials any equipment of the department.