Okay, this is off topic, but you seem like you would know.

Around here, there have been a number of new traffic signals put up, or maybe just had their bulbs replaced, and they, especially the green ones, are super-bright. They're also of a significantly different shade of green than the old ones.

It's my guess that these are lit by an array of large LEDs instead of a more traditional bulb, but I don't have any proof of that. Do you have any idea?