COLORADO SPRINGS, Colo. - Four traffic-signal poles in Colorado Springs soon will take on a more ominous purpose: measuring radiation such as that found in "dirty bombs."

Detection devices made by Mobile Detect, Inc. of Toronto will transmit radiation levels to the city's central traffic control center.

High levels will trigger cameras to start filming in an effort to capture clues as to the deadly substance's source.

This is likely the first city in the nation to test a radiation detection system that reports data through a traffic signal system, said John Merrick, the city's principal traffic engineer.

"I think this could change the way we do homeland security," Merrick said.

If the $48,000, city-funded trial works, Merrick would propose expanding the concept citywide by placing sensors at 100 intersections. Cost: $2.5 million.

Merrick doesn't expect the city to cough up the cash. Instead, he would pursue funding from the Department of Homeland Security.

"I would say, 'Hey, I have a rational system. Why don't you make a demo of Colorado Springs and put in a system citywide?"'

Merrick isn't dreaming.

The federal government allocated roughly $7 billion this year for high-tech efforts to defend against potential terrorist attacks with biological, chemical or nuclear weapons.

The Department of Homeland Security got $1 billion for research, and one of its longterm visions is a national sensor system that could continuously monitor the air for pathogens, dangerous chemicals and other hazards. The sensors would be linked to central control centers, resembling the military's worldwide surveillance for a missile attack.

Although that concept is a long way off, Merrick thought the city should determine whether his idea could work locally. Although locations identified as likely terrorist targets are secret, Merrick said Colorado Springs' five military bases may be in the cross hairs, notably Northern Command, the nation's homeland defense command, at Peterson Air Force Base.

"I have a system of 520 signals that are connected by a communication system," he said. "That's a network that has a wide range of potential uses." After realizing that potential, Merrick went on the Internet to find what was available. He's convinced Mobile Detect is the only firm that can tie in to the city's traffic signal equipment, at least for now.

Although some may question whether terrorists would choose Colorado Springs, Merrick isn't deterred.

"As far as I know, there's never been a radiological attack," he said. "But there had never been a 9-11 either, and it wouldn't be that difficult to do."

Merrick is mostly worried about terrorists planting a deadly package that would silently expose large numbers of people.

"They could take this small amount and put it in a place where lots of people are standing," he said, noting radiological material can be bought on the Internet. "In five or six weeks, they (those exposed) will have flu symptoms, and in the sixth week, they die."

Here's Merrick's concept: A sensor that can detect radiation up to a radius of 200 yards is installed on a traffic signal pole and tied into the city's traffic signal system. When a dangerous level of radiation is detected, data is beamed to the city's traffic operations center where traffic cameras, which normally sense for traffic and don't record, start filming in four directions.

Although the equipment can detect small amounts of substances used for medical purposes, such low levels won't trigger filming.

The idea is to identify suspicious activity related to a dangerous exposure. If the city were equipped with enough detection devices and several alerted a danger, authorities might be able to target a suspect vehicle common in all the films, Merrick said.

One unknown is whether the black and white digital film will be sharp enough to identify a person or vehicle, Merrick said. Sites haven't been chosen for the four trial devices, which will be moved from place to place during the months-long trial.

Also, Mobile Detect is so new - the company formed less than a year ago - it has no track record. Its detection devices are being installed at Ottawa International Airport and also in vehicles used by the Canadian National Police Force, said company president Chris Clarke.

If the concept proves out, the city could apply for federal funds to install the system permanently, which would require new training for how to integrate the sensors into local response plans, Merrick said.