With the Trans European road network expected to grow by 4,800km a year to 2020, there is a growing requirement for adequate and automated traffic solutions that remain efficient throughout service. Elements that are often required include a laser, radar or inductive loop sensors in order to detect vehicles and measure their speed before a high resolution camera can capture the infraction and provide documentation of the violation.

High-data-volume applications such as these require gigabit Ethernet (GigE) connections to process the large file sizes and quantities that pass through them, and it can be argued that few require GigE connection technology more so than road traffic enforcement cameras. As high-resolution images of the various road violations are captured, various images can quite often need to be processed simultaneously during peak traffic flow periods.

Traditional traffic enforcement systems can find themselves limited as to what infractions they can detect and police but, as Allied Vision Technologies product marketing manager Paul Kozik acknowledges, the advantages of GigE technology open up these systems to a wider range of detection capabilities.

A wider range of capabilities

Compared with analogue cameras, GigE cameras are higher resolution and operate at faster frame rates. This is because GigE offers much higher bandwidth than an analogue camera interface and GigE relies on standard, low-cost gigabit Ethernet networking hardware.

“Traditional traffic enforcement systems can find themselves limited as to what infractions they can detect and police.”

According to Kozik, “When GigE technology is employed in traffic applications; it is most often replacing analogue, cameralink or proprietary interface cameras. These installations are focused primarily on tolling, red light enforcement or speed enforcement.”

One such system which utilises GigE technology with growing popularity is the T-ExSpeed or T-ExSpeed 2 system, developed by Italian traffic control company Kria, which is capable of detecting excessive speed, red light and forbidden turn violations. The system uses three Allied Vision Technologies Prosilica GC or GB cameras to provide coverage, combining the high-resolution cameras with computational stereo software algorithms

The cameras are fitted with 15mm-35mm high quality OEM lenses in order to produce flawless images, while the GigE link remains a pivotal element of the system. The interface can output high resolution images at speeds up to 1GBp/s in real time whilst allowing a high-speed link between the camera and inspection system.

Cameras produced by Teledyne Dalsa, including the company’s Genie series of cameras, also boast gigabit Ethernet compliance based on the Automated Imaging Association (AIA), which directly links the cameras to a computer.

The gigabit Ethernet technology allows the transmission of image data over standard Cat 5e or Cat 6 cables travelling distances of up to 100m. This allows cameras, and inspection and processing units to be situated at greater distances from each other.

A break from tradition

More traditional forms of traffic enforcement cameras, such as analogue cameras or camera link technology, can offer increased bandwidth, but this comes at a price. As Kozik notes, “In contrast to GigE technology, analogue cameras require a frame grabber and the combination of a camera with a compatible frame grabber is essential and is often difficult to achieve for particular sensor and feature combinations.

“Compared with analogue cameras, gigabit Ethernet cameras are higher resolution and operate at faster frame rates.”

“Comparing GigE vision with camera link is a slightly different comparison. Camera link does offer higher bandwidth than GigE but comes at a much higher cost and limited cable lengths between cameras and the host computer.”

Traffic cameras that boast camera link technology can also suffer at the hands of frame grabber compatibility issues. As the frame grabber is central to how effective the camera performs, it could be argued that the camera’s effectiveness is linked to the compatibility of the frame grabber with the camera, which can produce several issues. “In comparison with compatibility issues affecting camera link technology, GigE has matured significantly in terms of third party compatibility with the adoption of GenIcam conventions and XML-based feature access,” argues Kozik.

Users benefit from competition

Another key benefit of GigE technology over propriety interface is the competitive manufacturer landscape, while vendors compete for custom based upon their products performance or pricing strategy. Propriety interface technologies used in traffic cameras are often subject to and suffer from single vendor offerings which can leave the customer feeling short changed.

Kozik believes this to be a key strength of GigE technology, stating, “This type of environment is only possible with a standard interface, whereas if a customer decides to use GigE Vision then they have many vendors to choose from and the ability to select first; second and third tier suppliers to manage lead time or pricing challenges.”

Not only this, but by basing the technology on a scalable and established platform such as Ethernet, replacement parts readily available allowing camera networks based using GigE to be easily maintained. Benefits such as these have led to the system being adopted across the globe, with Kozik adding, “GigE cameras are currently being used in Beijing, Dubai, France and major cities in the US and other countries.”