Runway Status Lights (RWSL) have been installed as a visual means of checking for aircraft and vehicles to prevent runway intrusion and ensure that aircraft and passengers can use Osaka International Airport in safety and with confidence.
This is an automatic control system that aids safe aircraft operations by using lit and unlit visual navigation aids. This, to indicate "runway intrusion" to aircraft attempting to cross a runway and "hold, takeoff not cleared" to aircraft attempting to take off when aircraft or vehicles are on the runway.
<Osaka International Airport Overview Runway Status Lights>