Real World Emission Testing

The recent debacle involving diesel engines in Volkswagen cars has introduced an element of doubt in the general public about the validity of some emission levels claims. Scania, incidentally owned by Volkswagen, seeks to make it clear their vehicles do meet the limits and are tested in the real world, not just in labs.


Emissions from Scania trucks are measured by three mobile test labs for making sure all of its vehicles meet Euro 6 standards. The Euro 6 regulations, which came into effect in Europe in December 2013, require tests to be carried out under normal traffic/driving conditions.


From the outside the mobile emissions testing lab looks like an ordinary trailer hitched to a Scania P 360 prime mover, but the 30 foot container is crammed with equipment for measuring emissions.


“With these labs we can check the emissions from at least 50 vehicles per year,” said Sven Andersson, an emission test engineer at Scania. “Most of the tests are conducted on prime movers to which we can attach the trailer with the mobile test lab. But we can also use these labs for rigid trucks as well as buses and coaches.”


Previously, heavy vehicle manufacturers used stationary test rigs to check emissions. But the Euro 6 regulations require tests to be carried out under normal traffic conditions. The trucks are also loaded to 50-60 per cent of their rated payload.


“We perform on-road analyses on at least one customer vehicle per month,” said Andersson. “We test vehicles during the development and production phases as well. We also test trucks in our own transport operations.”


Each test run takes between three to four hours and is designed to be as realistic as possible.


“This means we drive on city, rural and highway roads,” said Andersson. “The idea is to measure emissions in normal traffic under normal conditions.”


Once a test lab has been attached to a prime mover it is connected to the vehicle’s on-board diagnostics system and an exhaust gas analyser is mounted on the tailpipe.


“Using a laptop we then get readings on different emissions: carbon monoxide, carbon dioxide, hydrocarbons and nitrogen oxides,” said Andersson. “We can also see the exhaust flow, exhaust temperature and exhaust pressure, as well as GPS data and weather data, such as temperature and humidity.”


The test engineers can also access any other relevant data: engine speed, vehicle speed, engine temperature, torque, and fuel consumption.


“Thanks to our mobile test labs, we can be sure that Scania vehicles meet Euro 6 standards for on-road emissions,” said Andersson.