17 Jul 2023
Electric trucks from MAN are kind to the climate – and the ears too. Independent noise metering has shown that logistics in the future could be quiet as a whisper.
It was still early morning when a dozen people and two MAN trucks gathered at the MAN test track in Munich. A pioneering comparison test was on the agenda. How much quieter is an eTruck than a traditional diesel truck? That’s exactly what the team from Peutz Consult GmbH, commissioned by the Fraunhofer IML, wanted to find out as they set up their metering equipment at daybreak. Calibrated hand-held sound meters were positioned 7.5 metres either side of the track. They also wanted to use a SoundCam to record noise levels from the two fully-laden trucks, each weighing 40 tonnes, producing a coloured image to show the sound sources from the passing trucks.
The measuring process began. The new MAN eTruck and the MAN TGX 18.510 passed the microphones again and again, enabling the team to investigate a range of scenarios. On some runs, the truck passed at 20 km/h with the AVAS acoustic warning system switched on. This is an artificial vehicle noise, which is used because the sound from the rolling tyres is only clearly audible above speeds of around 20 km/h. More measurements were taken at 30 km/h and when reversing, with the reversing warning sound switched on and off. Data was also collected when the trucks accelerated past. Each measurement was repeated at least ten times.
Groundbreaking: For the first time, the noise emissions of eTruck and diesel truck are compared with each other.
After a few hours, the results were clear: “The measurements showed that the noise levels from the eTruck were around 6 dB lower for the same drive past at 20 km/h,” reported Michael Wirtz, Metering Project Manager at Peutz Consult. “To illustrate this, the measurements mean that a MAN diesel truck is perceived to be as loud as four MAN eTrucks. We must also take into account the fact that the diesel truck used for these measurements is around 5 dB quieter at 20 km/h than the typical basis from the literature, which increases the difference between the eTruck and the literature basis to 11 dB. As a result, the eTruck sounds around half as loud as a traditional diesel truck. There was an even clearer 12-dB difference between the two trucks when it came to the accelerating drive past.” To classify the noise levels of the MAN eTruck even better, he compared them to a car: “With a noise level of around 49 dB(A)/m at 20 km/h, the eTruck is only 1 dB ‘louder’ than a car at 48 dB(A)/m.”
This was good news for MAN. “The measurements showed that our new MAN eTrucks could also be used at either end of the day, late at night or early in the morning,” commented Dr Christoph Jeßberger, Product Strategy Manager at MAN. “This opens up a broad spectrum of uses and high levels of flexibility for our customers. It means they can be used up to 24 hours a day, 7 days a week – provided the legal framework is in place for that.”
The experts gathered at the test track that day to show their support for this. New permits for deliveries at night or during off-peak hours are often difficult to obtain – there is simply a lack of any values to guide the authorities. “By creating a handbook for noise emissions from trucks using alternative drivetrains for deliveries in urban areas, we want to make the job of community and permit authorities easier,” said Daniela Kirsch, project leader at the Fraunhofer Institute for Material Flow and Logistics (IML). “We have determined that they lack data and measurements if, for example, they need to make a decision on nighttime deliveries in urban areas.”
Study to develop noise emission standards
The “Quiet Logistics Mobility Study” by the Fraunhofer IML plans to change that, for which today’s measurements of the eTruck and the diesel truck were taken. MAN Truck & Bus is involved in the study, which is backed by the Ministry of the Environment, Nature and Transport of the State of North Rhine-Westphalia. The study aims to develop standards for the measurement of noise emissions during delivery processes and is set to be published early in 2024.
The Netherlands is one step ahead in this area and has developed the PIEK noise protection standard. In order to obtain certification, such as for nighttime deliveries, trucks and transport equipment must undergo acoustic testing. They must not exceed a specified decibel limit at a distance of 7.5 metres. “We need a solution like the PIEK certificate that companies can use as their guide,” said Kirsch.
Its electric drivetrain means that the electric truck from MAN is kind not only to the climate, but also to the ears of those living close to supermarkets and mixed industrial areas, and ultimately to all road users. “With the MAN eTruck, we want to make a positive contribution for humankind and nature,” says Jeßberger, getting straight to the point. “We are doing this primarily by making it emission-free, but also through the clearly noticeable reduction in noise levels.”
Text: Anke Kotte / Christian Buck