How many percent of the cars in a train must have operative brakes under all circumstances?

The requirement that at least 95 percent of the cars in a train must have operative brakes ensures that the train maintains a high level of safety during operations. This percentage is critical because it plays a significant role in controlling and stopping the train effectively. Having most of the train's cars equipped with working brakes allows for better distribution of braking forces across the entire length of the train, reducing the risk of excessive pulling or pushing forces that could lead to derailments.

In practice, when a train has at least 95 percent of its cars with operative brakes, it significantly enhances the overall braking capability and responsiveness of the train in various conditions, such as when responding to signals, navigating downgrades, or making emergency stops. This requirement also complies with regulatory standards in the industry, providing a benchmark for safety and operational integrity.

The other percentages listed do not meet the stringent safety criteria set forth for train operations, which underscores the importance of maintaining a high standard of braking functionality in the rail transport sector.