Long-term analysis of real-driving emissions using remote sensing
AWEL, a governmental agency of the Canton of Zürich, Switzerland, has been using Opus Remote Sensing Devices for 18 years, to study the real-world emissions from motor vehicles in Zurich.
Their constant work represents the best continuous evaluation of road traffic emissions in Europe.
AWEL began using RSD systems with close support from Opus, but soon had complete autonomy to use them independently. In this way, AWEL rents the equipment when needed with greater flexibility.
This collaborative format is used by other European partners.
Measuring every year in the same place
The methodology employed by AWEL is unique. Every year they place the Opus RSD in the same place, for a period of about 4 to 6 months. Only 2 locations have been used. As the emissions from motor vehicles driving in one location are different from those in another, this methodology allows the geographic variability to be eliminated. This way of assessing emissions over time allows for the identification of market trends, checking whether the emissions from vehicles are reducing year by year as they should.
RESULTS
The results are periodically published every year. The last report, issued on december 2019, is accesible in the following link:
The results of all the measurements since the year 2002 show that the decrease in real NOx emissions from gasoline-powered vehicles corresponds to the general trend in the tightening of emission standards. By contrast, the following findings were obtained for diesel-powered passenger cars and vans:
- Diesel vehicles between Euro 2 and Euro 6b emit around 5 to 20 times more NOx than petrol vehicles; for Euro 6c and newer (Euro 6dTEMP, Euro 6d) the differences between petrol and diesel vehicles are much less pronounced.
- Until around 2015, the trend in real NOx emissions was in the opposite direction to the trend in the tightening of exhaust standards. Emissions have risen sharply between the early 1990s (Euro 1) and 2000 (Euro 3). Thereafter they stagnated at a high level until 2015 (Euro 5 emissions standard). This means that newer Euro 4 and 5 vehicles (i.e. more than half of the current fleet of diesel cars) emit more NOx than old Euro 1 vehicles.
- Diesel vehicles complying with the Euro 6b emission standard are on average cleaner than Euro 5 vehicles. Although they emit half as much NOx as Euro 5 vehicles, they still emit five times as much as would be expected on the basis of the emissions standard and therefore have on average only slightly lower NOx emissions than diesel passenger cars at the beginning of the 1990s.
- For Euro 6b vehicles the range between the real NOx emissions of individual diesel vehicle groups is widening. Around half of the vehicles emit similar amounts of NOx as specified for type approval, even under real driving conditions. However, "high emitters" increasingly dominate the average emissions of all Euro 6b diesel vehicles, which are thus on average factors higher than targeted.
- Measurements of diesel passenger cars complying with Euro 6c and newer emission standards (Euro 6dTEMP and Euro 6d) show a more substantial reduction in real NOx emissions. For the first time, the NOx emissions in real driving operation for these exhaust standards are within the range of the specified limit value of the type test, taking into account the RDE uncertainty factor.
