"Stand clear doors closing"

Over the past few months I've noticed that CityRail has installed orange flashing lights above each of the external doors on the older silver double-decker passenger carriages. These lights flash as the doors are closing. I'm a bit miffed on the purpose of these lights as they a fair way above the centre of the doors, so it's not like you would look up at a small flashing light when there are two big bright yellow doors siding shut at eye level. I could understand it if the lights started flashing before the doors started closing, sort of like an amber traffic light, it would act as a warning to hurry up a decide if you on or off the train. But they don't they start flashing as soon as the doors start closing.

The other possible use is that they are there for the guards to use, but I don't know how. Maybe they stay flashing if the door doesn't close properly?

Does anyone know what these new lights are for and why have they only been added now (when we are been told that there's going to be a heap of new trains to replace these trains over the next few years)?

Update: 29 May 2008

I was waiting for a train the other day in Strathfield and noticed that the lights tell the guard when the doors are stuck open.