Radar detectors warn drivers of highway hazards.

Technology already widely used by American motorists is the basis for a low-cost safety warning system that will inform drivers of highway hazards such as traffic accidents, approaching emergency vehicles, construction delays or visibility problems. With support from a consortium of consumer electronics companies, researchers at the Georgia Tech Research Institute (GTRI), Atlanta, have developed a transmitter and messaging system capable of sending a wide range of emergency warnings to motorists using advanced radar detectors.

The Safety Warning System will also provide a general warning to the estimated 20 million drivers using older radar detectors not capable of displaying text messages.

“Intelligent transportation systems planned for the future will improve highway safety by providing drivers with information about the hazards ahead of them, but it’s going to be years before such systems are implemented,” says Gene Greneker, a principal research associate at GTRI.

“The system will provide a sophisticated warning capability today and serve as a stepping stone to the systems of the future,” he says.

The key to development of the system was an agreement by four leading radar detector manufacturers to use a common technique for sending emergency information and a standard set of warning messages compatible with National Highway Traffic Safety Administration guidelines.

The new generation of “smart,” radar detectors includes a built-in liquid crystal display capable of displaying up to 64 characters. When such a detector receives a safety message, it first sounds a special tone to alert the driver before displaying the message.

A second message can also be sent and displayed along with the first. This allows the system to warn of a hazard while also alerting the driver of a reduced speed limit, for instance.

Because the transmitter also sends out microwave signals on the K band, drivers using older radar detectors would still be alerted to a traffic hazard, though they could not be told the specific nature of it.

The consortium of electronics companies, known as RADAR, has recently filed a patent application to protect the technology.

Transmitters would be located on police and other emergency vehicles and on construction equipment, bridges, existing overhead sign warning systems and other fixed sites. Portable transmitters could also be moved to locations wherever needed.

GTRI has built and tested one transmitter system and will be building others as part of larger-scale testing. RADAR is pursuing efforts to commercialize the transmitter system.

Since 1991 the Federal Communications Commission (FCC) has allowed use of unattended radar transmitters to trigger radar detectors and thereby warn drivers of hazards ranging from highway construction zones to road maintenance. Though these “drone” systems cannot broadcast specific warnings, they have been considered useful for helping to improve highway safety.

“At least two studies have shown that drone transmitters capable of setting off the current generation of radar detectors are effective at slowing traffic in construction zones,” says Janice Lee, president of RADAR. “We believe this technology has much untapped potential. Enhanced transmitters, when they are coupled with `smart’ radar detectors, will let the driver differentiate between various types of road hazards.”

The transmitter system, which was developed by Greneker and with help from the engineering staffs of each of the participating industry members, broadcasts the safety warning message using a binary encoded modulation technique that is received and displayed by the new K-band detectors.

Because the 64 standard warning messages are pre-programmed and stored in the detector’s memory, the simple code is all the receiver needs to determine which message to display.

The seven-bit code can be repeated as often as 10 times a second, which helps boost reliability.

“You don’t have to transmit every letter of the message, so there is plenty of opportunity to receive the warning,” Greneker says.

Customized warning messages can also be sent using a keyboard and a simple computer-based menu system.

Messages on unattended systems could be changed remotely through a dial-up system.

Additionally, programming functions allow the system to broadcast during certain times of the day, to operate only when vehicles are approaching, or to turn themselves on only after sensing a hazard such as a bridge failure or low visibility.

RADAR has petitioned the FCC to allow higher transmitting power that would increase the range of the system and enhance the ability of moving emergency vehicles to broadcast warnings. With present power levels, the system is designed to provide a warning at least one mile ahead of the highway hazard.