How is a train not designated by an operating schedule referred to?

A train that is not designated by an operating schedule is referred to as an extra train. This term is used to describe trains that run outside of the typical, pre-established schedules and are often called into service as needed to accommodate additional freight or passenger demands. Extra trains can be utilized for various reasons, including increased demand, special events, or to handle unexpected cargo loads.

In rail operations, an extra train may not follow the regular timetable and can vary in frequency and timing based on operational needs. This flexibility allows railroads to respond effectively to changes in transportation requirements.

The other options represent different concepts within train operations. Controlled blocks are specific segments of a railway that are managed to maintain safety and efficiency. Deadhead trains refer to movements where crew members are traveling without cargo or passengers, typically to position themselves for their next scheduled duty. Freight trains are specifically designed to carry goods as part of regular operations, typically under a set timetable. Each of these terms highlights distinct aspects of railway operations that differ from the concept of an extra train.