What is a typical feature of runway threshold lights?

Runway threshold lights are specifically designed to provide visual guidance to pilots as they approach a runway for landing. The correct answer highlights that these lights show the direction of approach to the runway. They are typically placed alongside the runway's threshold and illuminate in a manner that helps pilots accurately identify the runway alignment, especially during low visibility conditions or at night.

This feature is crucial for ensuring safe landings, as it allows pilots to visually confirm the orientation of the runway as they descend. The lights also contribute to maintaining proper approach paths, facilitating smoother transitions from the air to the ground.

In contrast, the other choices do not accurately define the function of runway threshold lights. For example, threshold lights do not indicate the rotation speed of an aircraft, nor are they positioned at the edge of taxiways. Additionally, they do not serve to convey runway maintenance schedules. Their primary role is focused on visual guidance for control during the final approach and landing phases of flight.