What type of air brake test is required for blocked cars that have not received air supplies for 5 hours?

A Class 1 air brake test is required for blocked cars that have not received air supplies for 5 hours due to the potential for air brake systems to lose air pressure or components to become unserviceable when left inactive. This type of test involves a thorough inspection of the entire train's air brake systems to ensure they are functioning properly. It includes verifying that the air pressure is adequate and that all brake components are operational.

This requirement is in place to ensure safety; any car that has not been in use for an extended period could potentially have issues that need to be addressed before it can be safely operated. Performing a Class 1 air brake test helps verify that the brakes will perform effectively when needed, thus reducing the risk of accidents related to brake failure.