What does this electronic sign indicate when flashing?

• It informs drivers about upcoming road closures due to construction work.
• It indicates the presence of a nearby train station where passengers can board or alight trains.
• It indicates the rail malfunctioning near the intersection.
• It warns drivers and pedestrians about an approaching train and advise them to be prepared to stop.
  Explanation:

  "These electronic signs are posted at all metro light rail intersections and flash when a train is approaching. Drivers and pedestrians must come to a halt when they see the lights flashing."