If the commissioner of transportation finds in an investigation instituted by the commissioner or upon complaint and after opportunity for hearing, that a crossing guard is necessary to protect life and property at a grade crossing, it shall order the railway company operating the railroad at the crossing to provide a crossing guard and shall specify in the order the hours when the presence of the guard is required. The railway company shall then provide a crossing guard during that time. The crossing guard shall have full control over the traffic at this crossing.