I can verify that I think I still have a defective green light... about 25% of the lights either flicker or are dead which would point to a series - parallel configuration.
It's a big bugger... about 12 - 14 inches across and has a 14 X 14 grid of 5 mm green LED's arranged in a circle. I saw a traffic maintenance guy replacing one so I waited until he dropped the cherry picker down and I asked him for the defective one. It has 2 PCB's one for the display and one for a direct ac mains powered (No Transformer)
single output CC driver. In series each "String" will see a constant current and the current multiplies as you add more "Strings" in parallel.
This device is marked as having been Mf'd in 2005. AC power is 117VAC @ 12.6 W. This would point to Very high efficiency LED's operating at ~5 - 10 mA. I didn't want to connect it up and work on it... when I first got it because I then didn't own a 110V 1 - 1 isolation transformer and now it's a conversation piece...
Bob