When should a train not exceed the speed shown on a Speed Limit Sign?

The correct answer is based on the principle of maintaining safety and compliance with operational protocols in train management. A train should not exceed the speed specified on a Speed Limit Sign until the entire train has passed the Resume Speed Sign. This ensures that all cars of the train are moving through the area of restricted speed in a controlled manner, thereby preventing potential accidents or unsafe conditions that could arise if the speed limit were disregarded.

When a train approaches a Speed Limit Sign, the speed restriction applies not only to the front of the train but also to the trailing cars. If the front of the train accelerates too quickly after passing the sign before the last car has cleared the speed limit zone, it could lead to derailments or other safety incidents. Thus, adherence to this regulation ensures that all sections of the train are in a safe speed boundary for the entirety of the designated area.

This practice is critical not only for the safety of the train and its crew but also for passengers and surrounding infrastructure. It establishes a clear and consistent procedure to be followed, reducing the chances of human error and enhancing the overall reliability of train operations.