Gov. Olene Walker signed legislation that outlaws controllers in Utah that can change some traffic signals from red to green.

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 law, HB201, sponsored by state Rep. John Dougall, R-Highland, prohibits the possession or use of so-called mobile infrared transmitters, or MIRTs, by anyone except emergency personnel.

The devices, which sit on a vehicle’s dash, are not regulated by current federal standards because they rely on a beam of light instead of a radio wave to trigger the light-changing mechanisms that have been attached to some intersections.