CDL School Bus Endorsement Practice Exam 2025 - Free School Bus Practice Questions and Study Guide

The indication that you must stop at a railroad crossing is signaled by the flashing red lights of a crossbuck sign. When these lights are activated, they serve as a direct warning that a train is approaching, and it is imperative for drivers to stop their vehicles. This is a critical safety measure to prevent accidents between vehicles and trains, which can have devastating consequences.

Flashing red lights are a standard traffic control device used to ensure that drivers are alerted to the presence of an oncoming train long before they reach the tracks. This system allows drivers to make informed decisions about whether it is safe to proceed or if they need to come to a complete stop.

It’s important to note that while the sound of a bell indicates that a train is nearby, it is not the sole requirement for stopping. The presence of a gate does indicate that you must stop as well, but the question specifically highlights the indication mechanism at the crossing—flashing red lights are an unequivocal signal to halt. The location of the crossing itself does not dictate the need to stop unless accompanied by these visual warnings.