What does track gauge refer to?

Track gauge specifically refers to the distance between the inner sides of the rails on a railway track. This measurement is critical as it determines the stability and safety of the trains that operate on that track. An appropriate gauge ensures that the train wheels fit properly onto the rails, which is essential for the train's smooth operation and the safety of its movement.

Different rail systems may employ various gauges, such as standard gauge, which is commonly used globally, and narrow or broad gauges, which may be utilized for specific regional purposes. The correct gauge size is vital not just for the functionality of the trains but also for interoperability between different rail systems.

Other options do not accurately define track gauge. The weight a rail can hold pertains to its structural integrity rather than the distance between the rails, the speed limit relates to operational safety and efficiency rather than physical measurements, and the length of a track segment deals with track construction, not its gauge.