How much should the brake pipe reduction be increased during the air test after adding helpers?

When performing an air test after adding helpers, it's essential to increase the brake pipe reduction to ensure that the entire train, including the newly added locomotives, is adequately tested for brake responsiveness. A common practice in rail operations dictates that the brake pipe reduction should be increased by 8 psi during an air test under these circumstances. This increase accounts for the additional weight and braking power of the helpers, ensuring that the entire train's braking system is functioning as intended and that all cars are properly receiving brake pressure.

The increase in brake pipe reduction allows for a more thorough test that validates the effectiveness of the brake system across the entire train formation. This is crucial for safety, especially when managing longer trains that may require more sophisticated braking power due to increased mass and momentum. By adhering to the standard of an 8 psi increase, crews can confidently confirm the integrity of the air brake setup, ensuring that it meets operational standards and is safe for movement.