Most traffic lights here in the US use the led matrix and yes, they do fail. I think the ones in the UK are made differently. There are stull incandescent ones where i live, but LED has pretty much taken over (even streetlights).
Very interesting — thanks for sharing it, Lightbringer.
What’s very curious is how there’s no thermal compound between the MCPCB and the heat sink. I guess it’s machined to be very flush by the tightened screws? And perhaps also since there are 8 separate LED’s, it means they’re not driven very hard. The power supply module looks overbuilt… meant to last a very long time. I’m guessing that the switch controller is in the traffic light pole somewhere near the bottom for servicing.
If the rating was… 18W?, then that’s a little over 2W per LED, so there’s a good chance those are 3W “bead” type LEDs. Lots of surface area to spread the heat around, and with a 50% duty cycle on average (way less for arrows and yellow), it seems pretty conservative. And 12” across is pretty much a pie-plate, so ain’t too bad.
The PS is just on/off, 120V to whatever. Just like a dumb bulb, it gets wired in and that’s it, so yeah, the “smarts” are down in the box somewhere. Used to be the old mechanical “music box” spinners, later all electronical.
When Portland Oregon switched over they had a display. The new lights used 10mm emitters covering the entire size. LED’s do not produce enough heat to keep the lens from freezing up. This was a better design is since the heat was next to the lens. I went and got the old bulbs which were rated for 8000 hours.n