How traffic signal changes work
The tag lines on various Web sites make them seem too good to be true.
"CHANGE STOPLIGHTS FROM RED TO GREEN IN SECONDS!"
"NOW YOU CONTROL THE INTERSECTIONS!"
The devices, mobile infrared transmitters, allow a person to change an upcoming traffic light from red to green from as far as 1,500 feet.
They are intended for emergency personnel, but sales of the devices to civilians on the Internet is making authorities nervous.
"We can't have that type of technology in the wrong hands," said Brandon Aghamalian, director of governmental relations for Fort Worth.
Four bills before the state Legislature this session propose to make it illegal for anyone but emergency personnel to possess a signal changer.
State Sen. Kim Brimer, R-Fort Worth, offered one of the bills at the urging of city officials, Aghamalian said.
While the devices can cost more than $1,000 each from official dealers such as 3M, various Web sites sell knockoffs for less than $200.
Due mostly to the availability of the cheaper versions online, local police and fire officials have been hearing accounts of signal changers being used by civilians in other states, Aghamalian said.
Using such a device is already against the law because it is illegal to tamper with a traffic control device, said Tela Mange, spokeswoman for the Department of Public Safety.
Brimer's bill would make possessing a signal changer a Class B misdemeanor. A bill proposed by Sen. Bob Deuell, R-Greenville, would make possession a third-degree felony.
There have been no reported problems with unauthorized use of the devices locally, said Harry Jones, supervisor of the Fort Worth Police Department's traffic division.
Most of the Internet sites selling the devices advertise them for emergency personnel, but some broaden the definition to include private investigators and funeral homes.
Some sites also claim to target groups that have a right to the technology but could afford only the cheaper versions, like volunteer fire departments.
Illicit use of the devices is not likely to be a problem for Fort Worth, said Ronnie Varnell, traffic signal engineer for the city.
The city installed traffic signal changers in some fire trucks five years ago, Varnell said.
Each device is specially coded so that only they can change the city's traffic signals, he said.
While Fort Worth is probably safe, some other Texas cities use older signal changers and are more vulnerable to devices being used by civilians, Varnell said.
"I think the legislation is probably appropriate," he said.
For emergency vehicles racing toward a crisis, signal changers can mean the difference between life and death. They allow emergency crews to respond to an emergency more quickly and reduce the chance of an accident when they are passing through intersections.
When a signal changer on a traffic light detects a properly equipped emergency vehicle approaching, the light responds accordingly. If the light is red, the signal changer will immediately give vehicles in other directions a yellow light, followed by a red light. Then the emergency vehicle will be given a green light.
If the light is already green, it will remain green until the vehicle has passed.
