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Feature Articles

Will Cell Phones Change How U.S. Thinks About Automated Traffic Enforcement?

by Winn Hardin, Contributing Editor - AIA

Machine vision cameras and image-based object tracking have become important tools for government agencies tasked with keeping roads safe. From the sands of the Middle East to congested Parisian streets, intelligent transportation systems (ITS) are widely used for enforcing speed, red light, tailgating, and toll violations.

In the U.S., however, while automated toll monitoring and associated license plate reading have taken off, privacy concerns still keep most automated imaging systems off highways and municipal streets. That means giving a green light to speed and red light violators. But drivers’ attitudes are starting to change, and in combination with technological developments that overcome traditional limitations like coverage area and reflectivity, traffic enforcement systems show promise to make the roads safer.

Accuracy and Safety
"We are discovering there is significant interest in a number of municipalities throughout many states which have enabling legislation,” says Bob Riebe, vice president of business development traffic systems at Vitronic Machine Vision Ltd. (Louisville, KY). “Police chiefs whose primary concern is public safety, in addition to city administration including city managers, council members, and mayors have also expressed specific interest in automated speed enforcement.”

Authorities note that traffic violations are getting worse as cell phones distract drivers. “Some municipalities have major speeding problems but don’t have enough funds to hire more law enforcement officers to address the problems,” Reibe says. “Our automated camera systems provide an extension of law enforcement. We still see a lot of pushback around red light enforcement. But the bottom line is [that] if you follow the laws, you’re not going to have a problem.”

Vitronic’s speed enforcement systems use light detection and ranging (LIDAR) technology. The newest traffic enforcement system from Vitronic, the FM1, sends out 15,000 infrared laser pulses in a fan shape per second, allowing it to monitor larger areas than radar systems, which can only measure a single point. The new smaller unit offers a color touchscreen and can be used in fixed or mobile installations. New software simplifies setup, and LIDAR’s speed and accuracy allows the system to simultaneously identify up to six different violations across six lanes of roadway. Video and still imagery of the violators is captured using a separate camera.

The Oregon Department of Transportation recently purchased the FM1 system to study traffic flow in construction areas based on ease of use, accuracy, and coverage area, says Riebe, who joined Vitronic’s U.S. operations in February and will spearhead business development for traffic applications in North America.

“The FM1 is much smaller than its predecessor and can be up and running in 10 minutes or less,” adds Riebe. “And if you move it from one location to another, you don’t have to recalibrate. Simply change the distance settings from the camera to the roadway and the road width, and you’re ready to go.”

New Sensors Adapt to Outdoor Lighting
Using lasers, LIDAR systems are extremely accurate and fast when it comes to creating 3D maps of moving vehicles, but a second camera must be used to capture video information for the legal enforcement process.

Those cameras face daunting challenges adapting to changing ambient lighting conditions as well as huge variations in the reflectivity of different license plate designs and the effects of hot spots caused by direct sunlight reflecting off glass and metal surfaces. These hot spots, whether on a windshield or a license plate, can cause the entire image to be unusable as automatic gain settings adjust to the bright pixels and lose image information in the rest of the image.

New sensors may overcome those challenges by giving cameras the ability to alter dynamic range settings on a pixel-by-pixel basis.

“We’re seeing a lot of interest from traffic applications for our cameras,” says Keith Wetzel, director of new product development at IMPERX (Boca Raton, FL). “These customers want simpler camera systems with fewer cables, in smaller footprints, requiring less maintenance with wider fields of view and and more sensitivity.”

For example, Wetzel says many traffic applications want both video and high-resolution still images from a single system. If it could be done by a single camera, then there’s a big reduction in the cabling, power, and maintenance requirements for the system.

IMPERX’s new Cheetah camera with the latest CMOS sensor “has the ability to take 12 megapixel (MP) still images while running high-definition video at 30 frames per second,” Wetzel says. “So when you go to enforcement, the authorities aren’t having to use low-resolution HD video stills. Instead, you have a high-resolution image that allows you to ID the license plate, vehicle model, and driver — everything you need to properly enforce a traffic violation.”

The other challenge traffic enforcement systems have to overcome is adapting to varying lighting conditions and acquiring high-quality images of highly reflective surfaces in uncontrolled environments. “The Cheetah has a wide dynamic range model that gives you three different exposure times for each frame,” Wetzel says. “Our newest camera, Puma, will have the same three different exposure times for a single frame but will also adjust gain on a pixel-by-pixel basis to deliver the highest dynamic range with the image quality of a CCD-based camera.” Wetzel adds that the Puma is so sensitive for low-light applications that the U.S. Department of Commerce is requiring a special export permit for overseas sales.

 

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