Utah Gov. Olene Walker signed legislation that outlaws controllers in Utah that can change some traffic signals from red to green. A similar measure has passed the state House in Maryland and is awaiting approval in the state Senate.A traffic-light changer is designed to allow police, fire and other emergency officials to clear intersections before they approach. But some impatient drivers have managed to purchase them on the Internet for as low as $100, according to published reports. People can even buy kits and build the signal changers themselves.The new Utah law, HB201 prohibits the possession or use of so-called mobile infrared transmitters, or MIRTs, by anyone except emergency personnel. The Maryland bill, HB381, passed the House 136-1 and has been forwarded to the Senate for further consideration.