What is the significance of the '30-60-90 second rule' in air brake timing?

The '30-60-90 second rule' is crucial in the operation of air brakes as it establishes guidelines for the timing of brake applications and releases to maintain safety and efficiency. By following this rule, engineers can ensure that the air brake system functions correctly, providing a smooth and controlled response when braking. The timings specified in this rule—30 seconds for the application of brakes, 60 seconds for holding, and 90 seconds for release—help in preventing abrupt changes that could lead to instability or accidents.

This sequence allows both the train and passengers to experience manageable deceleration without causing undue stress on the braking system or the train structure. Ensuring proper timing enhances braking performance and aids in maintaining control over the train’s speed and stopping distance, which is essential in various operational scenarios, including stopping at stations or navigating curves safely.