New sensor technology could improve air quality in cities

An international research consortium is working on new contactless exhaust measurement methods that will enable municipalities to take measures to reduce emissions.

The European Union-funded CARES (City Air Remote Emission Sensing) project aims to develop sensors that can be attached to roadsides, crash barriers or traffic signs which detect the exhaust emissions of passing vehicles in a matter of seconds.

We want to monitor vehicle emissions in cities and environmental zones under real conditions, without having to interfere with free-flowing traffic,” explained Alexander Bergmann, head of the Institute of Electronic Sensor Systems at Austria’s Graz University of Technology (TU Graz).

The researchers are looking at how cities could use these measurements to detect the exhaust class of each individual vehicle. They could then introduce an emissions-based city toll: the higher the emissions of the vehicle, the higher the charge would be.

The technology could also enable authorities to monitor entry into low-emission zones so that automatic barriers only open if the emissions of the approaching car are within the allowed range.

It could even be used to identify vehicles in which manipulated particle filters or chip tuning have been used to increase engine performance (and thus emissions).

In tests at TU Graz using conventional tuning forks, particles between the fork are excited through laser pulses, which in turn produce an acoustic signal. Each individual particle emits acoustic signals which are recorded and played back by the tuning fork. The more particles there are, the louder the sound becomes. The volume can then be used to determine how many particles are in the environment.

The technology has already been used successfully for gas measurements.

Low-cost remote sensors for emission measurement are expected to be ready for production by the end of the 2022 project at the latest.

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