runway guard lights

A light system intended to caution pilots or vehicle drivers that they are about to enter an active runway (ICAO). These are in two different configurations. In the first case, there is a pair of unidirectional flashing lights on either side of the taxi track. The lights in each unit of the configuration are lighted alternately. In the second case, there are unidirectional flashing yellow lights spaced at 10-ft (3 m) intervals. The lights are illuminated alternately, and alternative lights are illuminated in unison. The lights are illuminated between 30 and 60 cycles per minute.