430 ILCS 105/2
At all times during which men are working where one-way traffic is utilized, the contractor or his authorized agent in charge of such construction will be required to furnish no fewer than two flagmen, one at each end of the portion of highway or bridge on which only one-way traffic is permitted, and at least 100 feet away from the nearest point of the highway or bridge on which only one-way traffic is safe and permitted. The flagmen shall be equipped with safe, suitable, and proper signal devices as prescribed in the Manual on Uniform Traffic Control Devices for Streets and Highways published by the Department of Transportation, and shall so use such devices as to inform approaching motorists to stop or proceed. In addition, safe, suitable, and proper signals and signs as prescribed in the Manual shall be so placed as to warn approaching persons of the existence of any portion of highway or bridge upon which only one-way traffic is safe and permitted. At bridge construction or bridge repair sites, where one-way traffic is utilized, traffic control signals conforming to the Manual may be installed and operated in lieu of, or in addition to, flagmen. Whenever the Department of Transportation or local authorities determine that a bridge or highway construction site requires the closing of a road to through traffic, the contract documents relating to such construction may specify alternate procedures for flagging and controlling traffic, when such procedures have been approved by the Department. When alternate procedures are not included, traffic control and flagging will be as prescribed in the first paragraph of this Section.
430 ILCS 105/2