How many brake modules are used for each stage when configured for uni-directional?

When the system is configured for uni-directional operation, it requires a specific number of brake modules to ensure that the braking system functions efficiently and safely. In a uni-directional configuration, only one direction of travel is considered, which can influence the number of brake modules needed.

The correct choice indicates that 9 brake modules are required for each stage in this specific configuration. The design of the braking system is such that having 9 modules provides the necessary support and control for the operation under uni-directional movement, ensuring adequate stopping power and reliability. Each module contributes to the overall performance of the braking system, and reaching a total of 9 is based on the system's engineering requirements and safety standards.

It's essential to understand that any discrepancy in the number of modules, either too few or too many, could lead to inadequate braking performance or unnecessary complexity in the system. This selection reflects a well-balanced approach to ensure the system is equipped to handle the expected loads and operational conditions.