running on rails
Train derailments like those at Potters Bar, UK in 2002, which killed seven, or the Hatfield rail crash in 2000, which killed four, are rare but can be catastrophic. Maintenance on trains typically takes place in a workshop, but this is sometimes impractical, especially in large countries where rail networks stretch over long distances.
A system for in-situ inspection of cargo train
wheels has been developed in China, allowing maintenance checks to be carried out without stopping the train. The system uses three area scan cameras from Basler Vision Technologies situated on the rail bed and two cameras beside the rail. Images of the under carriages and wheels are captured as trains travel past at speeds of 50-60km/h.
The sensitivity of the camera allowed sharp
images to be captured of the moving train, while the high frame rate allowed a number of images
image processing is carried out at the camera level onboard the DSP, including ANPR at 50fps. These systems are used mainly on roads
with tunnels – Survision has equipped the Limfjord tunnel in Denmark and the Toulon tunnel in France. ‘Vehicles carrying dangerous goods are not forbidden in the Limfjord tunnel, but if there is an accident, it is useful for the emergency services to know if there is a truck transporting hazardous substances inside,’ says Jouannais of Survision. ‘The emergency services will handle the accident differently depending on any potential hazardous material involved. In the case of Toulon, dangerous goods vehicles are forbidden and the technology helps enforce that.’
Networking Being able to connect a number of cameras together into a network is one of the factors that Yvon Bouchard, technology director at vision company Dalsa, identifies for expanding the range of traffic enforcement applications. ‘By connecting to a central server, for instance, a bank of cameras can have access to high-performance image processing for pattern recognition and data extraction, such as recognising licence plate numbers,’ he says, adding that network connectivity also extends the reach of the vision system, with connections such as Ethernet supporting coordinated operation over virtually unlimited distances via the Internet. This means that traffic flow monitoring, for instance, can operate on a city-wide basis.
Trains travelling between 50 and 60km/h can be captured for maintenance checks. Image courtesy of Basler Vision Technologies
The built-in intelligence of ITS cameras is also
extending their range of applications according to Bouchard, with cameras able to calculate the speed of a vehicle in speed enforcement systems through reference points between timed image captures. The camera can then alert a central server and provide a number plate and image of the vehicle as proof of the speeding violation. Cadd at NDI-RS believes that the ANPR and
ITS markets are moving towards high-definition digital imagery. In addition, Cadd says that ANPR systems are now being installed with wider fields of view, with one camera covering more than one lane of traffic. ‘There is a general progression in this technology,’ he says. ‘The accuracy levels are expected to increase, the ability of the cameras to read more plates at faster speeds over more lanes of traffic is developing, along with faster processing times.’
Further inFormation
l Allied Vision Technologies:
www.alliedvisiontec.com
l Survision:
www.survision.fr l Sony Europe’s Image Sensing Solutions:
www.pro.sony.eu
l Pleora Technologies:
www.pleora.com l NDI Recognition Systems:
www.ndi-rs.com l ProPhotonix:
www.prophotonix.com l Gardasoft Vision:
www.gardasoft.com l Dalsa:
www.dalsa.com/mv l Basler Vision Technologies:
www.baslerweb.com
to be captured as the train moves past. The images are transmitted to a control room for further analysis. The system has been developed for cargo trains, although according to Tang Tay Joo, sales manager at Basler Asia, the Chinese railway ministry has also increased efforts to inspect passenger trains and high-speed trains.
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