(1) If any notice or sign warning of the presence of a road barrier upon the highway is displayed to traffic approaching the road barrier, the notice or sign constitutes and is to be treated as an order addressed by the inspector operating the road barrier or causing the road barrier to be operated to the driver of any vehicle approaching the road barrier to stop the vehicle at or near and before reaching the road barrier and to keep the vehicle stationary until permitted by an inspector to proceed.
(2) If any notice or sign warning of the presence upon the highway of an inspector exercising powers of stopping and entering any vehicle is displayed to traffic approaching the inspector, the notice or sign constitutes and is to be treated as an order addressed by the inspector to the driver of any vehicle approaching the inspector to stop the vehicle near the inspector and before reaching the inspector and keep the vehicle stationary until permitted by the inspector to proceed.