What term refers to the time interval between trains?

The term that accurately describes the time interval between trains is headway. Headway refers specifically to the time that elapses between the departures of successive trains on a given route. Understanding headway is crucial for train operators, as it affects the capacity of the rail system, allows for efficient scheduling, and ensures safety by maintaining adequate intervals between trains. The concept of headway is essential for both operational planning and for passengers to understand train schedules.

While terms like spacing, frequency, and separation are related to the operation of trains, they do not specifically denote the time interval between trains. Spacing generally refers to the distance between trains at a given point, frequency deals with how often trains arrive at a station, and separation indicates the required distance for safety between trains. Hence, headway is the correct term for defining the time gap between train operations.