Final answer:
A controlled railroad crossing is identified by the presence of automatic gates, flashing red lights, and sometimes a ringing bell, which are safety measures designed to halt traffic and prevent accidents when a train is approaching.
Step-by-step explanation:
To know if it's a controlled railroad crossing, you should look for specific signals and safety devices installed at the crossing. A controlled railroad crossing typically will have automatic gates, flashing red lights, and often a ringing bell, indicating a train is approaching. These safety measures are in place to stop road traffic and ensure vehicles and pedestrians do not cross the tracks when a train is imminent, thereby greatly reducing the risk of accidents and promoting safety.
The referenced text does not directly explain how to determine if a railroad crossing is controlled. However, it provides insights into traffic control and safety measures in various contexts. For instance, it mentions tollbooths having wires to detect vehicles, traffic signals to control vehicle speed and ensure pedestrian safety, and the strategic placement of sentinels for bridge security in historical contexts.