From Texas Department of Transportation Standard Specifications for Construction and Maintenance of Highways, Streets, and Bridges:
“2.6.2. Flaggers. Designate in writing, a flagger instructor who will serve as a flagging supervisor and is responsible for training and assuring that all flaggers are qualified to perform flagging duties. Before beginning work, provide a list of flaggers certified to perform flagging duties.”
A list of approved training providers are available at Special Provision to to Item 7, 188.8.131.52.2. Flagger Training.