Caught on Camera
The traffic control industry is an ever-growing market with new infrastructures being built worldwide, with, for example, the trans-European road network expected to grow by 4,800km per annum until 2020. This translates into a steady annual rise in passenger and freight traffic, resulting in an increasing need for more efficient and automated traffic enforcement solutions to make road safer for all users particularly in dense metropolitan areas.
The New Generation: Machine Vision Based Traffic Enforcement
Traditional traffic enforcement devices require laser, radar or inductive loop sensors to detect vehicles and measure their speed, as well as a camera, usually a high resolution consumer SLR camera, to provide documentation of the traffic violation. These systems are limited to vehicle speed measurement, one vehicle at a time.
Italian traffic control company Kria developed and patented T-EXSPEED, followed by the slimmer T-EXSPEED 2 in 2010, an innovative and fully automated system that entirely relies on digital machine vision cameras and computational stereo software algorithms to track and detect traffic violations. T-EXSPEED operates without the use of external sensors and is able to detect multiple traffic violations such as excessive speed, red light violations, forbidden left or right turns directly from images taken by high resolution digital industrial cameras that repeat the real-time stereo process 24/7. The system can measure vehicle speed up to 300 km/h and track many vehicles in parallel (up to a three-lane footprint), in both directions.
Stereo Camera Set-Up for 3D Real-Time Detection
T-EXSPEED is already implemented on highways and metropolitan areas in Italy and has been approved by the Italian Ministry of Transportation. The original T-EXSPEED system is based on three Prosilica GC cameras while the newer and slimmer version, T-EXSPEED 2, relies on three Prosilica GB cameras. The Prosilica GB cameras are board-level versions of the Prosilica GC and share the same sensors, features and attributes.
The T-EXSPEED system is composed of three parts: the acquisition unit, the processing unit and the central unit:
The acquisition unit consists of a 84cm long weatherproof IP66 housing that holds two monochrome Prosilica GB2450 cameras, one color Prosilica GB1380C camera, as well as an infrared lighting system for night time license plate detection. The supporting and housing structure is made out of over 200 carbon fiber, alloy and polycarbonate components and is designed to guarantee the internal rigidity of the system and provide external isolation in a wide range of temperatures and weather conditions for quality insurance and reliability purposes.
The 1.4 Megapixel GB1380C and 5 Megapixel GB2450 are board-level machine vision cameras with a Gigabit Ethernet interface (GigE Vision®). Both cameras feature top of the range Sony CCD sensors (ICX285 with ExView technology for the GB1380C and ICX625 for the GB2450) offering high sensitivity, low noise, fast frame rates and excellent image quality to insure optimum results, as well as consistency and reliability in demanding applications such as outdoor imaging. The cameras are fitted with rugged, high quality 15-35mm OEM lenses for a flawless stereovision process. Kria selected the board-level Prosilica GB cameras for the reliability of their Gigabit Ethernet interface that outputs high resolution images at speeds up to 1GB/s in real-time. Their small form factor (51x89mm) also allows them to be tightly integrated inside the compact IP66 enclosure without the need for additional protective casing.
The three Prosilica GB cameras are mounted in a 70cm tall stereo set-up inside the housing, with the two monochrome GB2450 cameras on either side of the color GB1380C camera. The device is placed on a vertical pole mount at a slight angle from traffic, 15-25 meters behind or ahead of the monitored area. The stereoscopic set-up allows the two GB2450 camera sensors to compute the speed and trajectory of each passing vehicle by simulating depth perception and analyzing the distance between the sensors and the vehicle. The two monochrome cameras are synchronized to run 15 frames per second in continuous shooting mode. The color camera is programmed to capture a shot of a vehicle when a defined traffic violation occurs. The color image is automatically associated with the traffic data to provide the necessary legal documentation for the traffic violation file requirements. Parameters such as shutter speed, gain and binning are dynamically controlled by the processing unit in closed-loop to adapt to any lighting and weather conditions. T-EXSPEED can also be mounted horizontally on top of police cars for static or dynamic speed enforcement.
The acquisition unit links to the processing unit via CAT6 cable or fiber optics depending on its location (either on-site or up to 20km away). It consists of an industrial PC running a Windows operating system that powers Kria’s proprietary T-EXSPEED software for traffic violation detection. In addition, the processing unit manages and stores video and image data that are transmitted to the central unit in real-time via a TCP/IP network.
The central unit, usually located at the Police Control Room, is a server with an encrypted database that receives selected compressed data from the processing unit and allows clients and authorized users to retrieve all traffic violation records and documentation.
System installation is non-intrusive and does not require any civil work or on-site reconfiguration and is achieved without any traffic interruption.
The system is calibrated during production to ensure micron-level mounting accuracy for overall system stability and reliability in the long run. In addition, the system performs a self-diagnostic procedure during each detected traffic violation. This fairly unique and distinctive feature allows the device to check if the internal structure is accurately calibrated and automatically detects any modifications that may affect its precision. The self-check output is automatically added to the violation documentation for legal purposes. The average certified error rate is less than 1% on speed in the 20-240km/h range.
T-EXSPEED incorporates a handful of additional features such as a License Plate Recognition engine (LPR) and 3D vehicle classification. Used in road surveillance, the real-time LPR engine reads domestic and international license plates and matches them to a user-defined black list to, for instance, detect vehicles carrying dangerous goods. The system can also provide the complete trajectory and a 3D reconstruction of the shape of a vehicle for violations related to vehicle spatial behaviors when vehicle classification is required.
Already approved by the Italian Ministry of Transportation, Kria is looking to expand the commercialization of its innovative system to international markets. In 2008, T-EXSPEED was nominated for the Italian “Compasso d’Oro” design award alongside other well-known names in the vehicle traffic sector such as the Fiat 500 and the Ducati Monster.