According to scientists at Spain's Universidad Carlos III de Madrid (UC3M), approximately five percent of vehicles on the road are responsible for about 90 percent of toxic vehicle emissions. Short of pulling each and every car over to analyze its tailpipe output, though, how does one go about identifying the offenders? Well, the UC3M researchers have helped design a system that images the emissions of individual vehicles in real time, on highways up to three lanes wide.

At the heart of the system is a modified infrared multispectral image camera, equipped with an internal wheel of lens filters. As the camera views the passing traffic, that wheel turns at high speed, allowing several different bands of light to be imaged independently for each vehicle. This is key to the technology, as different gases have "emissions signatures" that are visible in different bands.

As a result, users of the system are able to see how much each vehicle is spewing out, in the way of gases such as carbon dioxide, carbon monoxide, and hydrocarbons. Using that data, it is hoped that governments could introduce new policies limiting the use of the worst-polluting types of vehicles.

While other vehicle emissions-imaging systems do already exist, the UC3M team claim that its is the first one to be capable of analyzing more than two lanes of traffic at once. The technology is being developed in a collaboration with Spanish companies Technet and Tevaseñal, along with the CIEMAT research institute, as part of the INNPACTO project.

The prototype system, which is also capable of measuring traffic density, is reportedly now ready to enter commercial production. An unrelated system, which is already available, monitors traffic to identify the noisiest vehicles on the road.

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