What type of air brake test is required when cars are picked up en route and are not a solid block?

The correct answer is the Class I, Initial Terminal Air Brake Test. This test is required when cars are picked up en route, especially when they are not part of a solid block because it ensures that the air brake system is functioning properly before the train continues its journey.

When cars are added to a train at an intermediate location, it is vital to verify that the air brakes on those cars have been checked for proper operation. The Class I test involves a thorough inspection of the air brake systems on all the cars to confirm they can adequately stop the train. This initial terminal test is crucial for safety, as it ensures that the integrated air brake mechanisms of all cars are working together efficiently.

The other types of tests serve different purposes. For instance, a Class II Test typically applies to cars being added to a train that has already been in operation and might be subject to check rather than a full initial test. A Class III test is more focused on application and release functionality checks rather than a comprehensive evaluation. The Transfer Train Air Brake Test pertains to specific operational scenarios and may not apply to just any train configuration. Therefore, the Class I test is the most appropriate choice for ensuring all necessary safety measures are in place when mixing cars into a train.