When is it necessary to stop at a railroad crossing?

Stopping at a railroad crossing is particularly necessary when the lights are flashing or the bells are ringing because these signals indicate an oncoming train. The flashing lights and ringing bells are designed as safety measures to warn drivers of an imminent train, and it's critical to obey these warnings to prevent accidents. The purpose of these signals is to ensure that drivers are alerted in a timely manner, providing them with the necessary information to stop safely before the tracks, ensuring the safety of both the driver and passengers.

While there are situations where other considerations apply — such as the absence of warning signals or the visibility of a train — the primary and definitive rule is adherence to active warning signals. When these signals are activated, stopping is not just encouraged; it's legally required to prevent potential collisions with trains, which often cannot stop in time to avoid an accident.