Under what conditions would a train NOT have a Trip ID?

A Trip ID is a unique identifier assigned to each train's journey to facilitate operational management and safety monitoring. In the context of the PATH Train system, there are specific conditions under which a train may not possess a Trip ID.

When a train is in ATC (Automatic Train Control) Bypass mode, it is effectively not operating under the standard automated systems that use a Trip ID for tracking. During this mode, the train is bypassing automatic controls, which can include speed restrictions and tracking mechanisms that are typically tied to a Trip ID. As a result, the operational framework that assigns and utilizes Trip IDs is not applicable while the train is in this mode.

In contrast, the other conditions may not necessarily preclude a train from having a Trip ID. For example, trains can still be assigned a Trip ID while stationary, moving slowly due to regulation, or even during maintenance if they are in service under supervision or moving rail operators. Thus, ATC Bypass is the specific circumstance that would effectively result in the absence of a Trip ID, ensuring clarity on the operational status of the train.