Were they not operating correctly, or did the driver ignore them is one of the questions the investigation will answer.
The system is called Runway Status Lights. And in case there is a disagreement between the ATC clearance and the lights the drivers are supposed to not enter the runway.
> When activated, these red lights indicate that ... there is an aircraft on final approach within the activation area
This pdf talks more about how it is implemented: https://www.oig.dot.gov/sites/default/files/WEB_Final_RWSL.p...
“RWSL is driven by fused multi-sensor surveillance system information. Using Airport Surface Detection Equipment-Model X (ASDE-X), external surveillance information is taken from three sources that provide position and other information for aircraft and vehicles on or near the airport surface. RWSL safety logic processes the surveillance information and commands the field lighting system to turn the runway status lights on and off in accordance with the motion of the detected traffic.”