Re: How to build: Traffic Light Changer
Oh, I'm cringing at the thought the reaction to this, but... since you're talking about CHANGING the light... what about... Cosmetic Transform...? Just changing the color, after all...
A couple of dice of that, with limitations like "Only vs. properly-equipped traffic lights" and such and it'll be pretty darn cheap...
And if you want the ability to not just turn them green, but to turn them (for example) red to hinder pursuit, just go with the slightly expanded effect adder...