Hold bar lights that are used to identify runway areas that require permission from the control tower prior to crossing are which color?

Hold bar lights are specifically designed to indicate areas on the runway where aircraft must receive clearance from the control tower before proceeding. The color amber is used for these lights because it serves as a caution signal. Amber lights visually alert pilots that they must wait for instructions or clearance before entering or crossing the runway.

This visual indication is crucial for safety purposes, as it helps prevent potential runway incursions and ensures that all aircraft are properly monitored as they approach critical points on the airfield. The use of amber in this context conveys a clear message that something needs to be verified, which is essential in the management of airport operations.