Which locomotive test is required after adding locomotives to a consist?

The required test after adding locomotives to a consist is the Locomotive Air Brake Test. This test is crucial because, when additional locomotives are coupled to an existing train, it is essential to ensure that the air brake systems on all units function correctly and synchronously.

This test verifies that the air brake system is operating properly, which includes checking that the brakes can hold the train and release efficiently, thereby ensuring the train's overall safety during operation. Proper brake function is vital since any malfunction could lead to safety hazards or operational issues.

In contrast, while other tests like the Locomotive Brake System Test may assess the mechanics of the braking system or the Emergency Brake Test may check the immediate response of brakes under emergency situations, the Locomotive Air Brake Test specifically ensures that all parts of the air brake system are working harmoniously after modifications to the train's configuration. Routine Brake Inspections typically address the general condition of the brakes but do not specifically cater to new additions in the train consist.