Stop Bar Lights are another type of lighting used at runways to lower the risk of hazardous collisions. They are usually used at the busiest airports in the world (e.g. 16 American airports had been equipped with such bar lights by 2016). They are installed along the stopping line; they give out a red light. While a yellow color indicates enhanced caution, a red color says clearly: STOP.
When the bar lights are on, it means that there are taking-off or landing operations going on (or are about to happen) on the runway. An aircraft that is to move along a taxiway can set off only when the red bar lights are turned off. The lights used at runways and taxiways can be of differing intensity across different airports. It is usually a result of using different types of lamps. Currently, the majority of airports choose LED lights.