It seems not a year can go by without some kind of additional EU limit for truck manufacturers to worry about, and 2026 will be no exception. Regulation (EU) 540/2014 is, as its name suggests, nothing new and was aimed at further reducing drive-by vehicle noise.
Replacing regulation 70/157/EEC, the original vehicle noise regulations introduced over half a century ago, implementation was broken down into three phases. Phases 1 and 2 came into force for new registrations on 1 July in 2016 and 2022 respectively, while the third and final phase limits are effective from the same date in 2026. New type approvals, however, needed to comply from two years earlier.
For heavy duty trucks over 12 tonnes (classified as N3), the Phase 1 limits were 79dBA for those with engines up to 150kW (201bhp), 81dBA for those between 150-250kW (201 to 335bhp), and 82dBA for trucks with power plants larger than that. Phase 2 limits were 2dBA lower, with Phase 3 limits another 2dBA lower again.
That may not, on first reading, sound like a huge change, but the decibel scale is logarithmic. In practice, where 0dBA is near silence, a rise to 10dBA equates to a 10-fold increase in the intensity of the sound being measured, while 20dBA is 100 times louder. To achieve a 3dBA reduction, noise intensity must be halved. These are not, therefore, by any means insignificant targets to meet.
While the UK is still consulting with the Society of Motor Manufacturers and Traders (SMMT) on whether and how it will mirror the EU legislation, early indications are only engine and vehicle generated noise will be included, not that of rolling road conditions. Tyre noise is already covered by a separate regulation within the EU, namely EC 6651/2009, which was taken into account when the 540/2014 limits were set.
COMPETITIVE MARKET
Curious, we attempted to find out how various manufacturers were going to – or, in some cases, already had – meet the Phase 3 requirements, but it turns out that most are tight-lipped, some citing competitive reasons for not wishing to get into any detail. Others, meanwhile, are happy to confirm they are already ahead of the game.
DAF Trucks, for example, launched a new version of its latest XB/XD/XF/XG range in September 2024. “I can confirm that with our latest trucks we meet the new drive-by noise requirements,” marketing manager Phil Moon tells us. “Over the years, DAF has paid a lot of attention to both drive-by and interior noise levels, with quieter drivelines and improved aerodynamics reducing wind noise.”
For Mercedes-Benz Trucks, a lot of what has been worked on for its most recent product, Actros L with ProCabin, has been about stopping what noise is made from getting out. Originally for the eActros 600 electric tractor unit, the ProCabin is highly aerodynamically sculpted to help conserve range, but means it is quieter, too.
“By closing up all the gaps on the cab and encasing open areas, we stop noise transmission,” David Simm, product manager for heavy duty trucks, tells us. “For example, we’ve made new seals for several areas and packaged and put protective covers over certain components.” Mercedes also offers an additional noise encapsulation package as an option for customers.
“Underneath our catwalk you’ll find some new plastic covers which create a noise barrier,” Simm continues. “Then if you tilt our cabs over, we’ve got specialist material which leads to sound deadening underneath.” Just as music played through a mobile phone can sound louder when placed into a glass or can, engine noise echoing off the shell of the cab itself can have the same effect. “By having soft materials there, we can deaden that sound instead.”
Then there is dealing with noise made by airflow itself. “With the product we’re marketing today, we have under body panelling, closing the gap between the road and the cab,” Simm says. “We have also closed the gap between tyre and wheel arch, as well as looking at other areas like how we have mounted the cab together and how it tilts over. For those gaps which have not been 100% closed, we have aerodynamic trim in place,” he adds, “which is why we have an almost seamless look to the ProCabin.”
In this country, however, the OEMs have an additional hurdle to overcome. “The elephant in the room is that the typical UK specification is a 6x2 mid lift,” Simm reminds us, “even if we’re not running fully freighted and therefore don’t actually run with it down.” Unfortunately, whichever position that extra axle is in, it creates noise. “Then there’s the question of whether a tag axle, where air flows past more instead of being trapped, is less noisy,” he says. “There are lots of areas like that where we could open a discussion.”
TRANSMISSIONS
Best known in our sector for its transmissions, German mobility technology specialist ZF says it definitely does have something new and 2026 noise limit-related coming very soon, which we may return to at a later date. For now, we can again only look to what is already out there.
“We have a centralised competency in this matter in our corporate R&D function,” press spokesperson Rashmi Parkhi says. “This includes acoustics experts who provide support to ZF‘s different divisions. At an R&D level, several sound sources contribute to the overall measured noise level.
“The most critical ones in a classic ICE driveline are engine, exhaust system, axle, drive shaft, tyres and transmission,” ZF tells us. “The admissible transmission noise contribution is defined based on our experience, regulations, and customer development targets.”
To predict the contribution its product will make to that over all noise in drive-by conditions, ZF’s engineers use a specialised simulation routine based on measurement using an acoustic test bench for truck and bus drivelines.
This has two e-dynos, each with a maximum power of 840kW, max torque of 6000Nm and a max speed of 5,000rpm and is powered by a 1MW DC supply. Tests are run with several international protocols, notably EN ISO 3744, covering the determination of sound levels in this arena.
Parkhi tells us its latest developments in the noise reduction area, at least as far as internal combustion engine transmissions are concerned, were included in its ZF Powerline portfolio.
Noise reduction is also considered in its latest e-drive designs. Powerline is ZF’s fully automatic 8-speed gearbox designed for medium-duty goods vehicles, buses and heavy duty pick-up trucks, which draws on previous advances made in the car arena. It can currently be found “in the wild” under the floor of DAF Trucks’ light, four-wheeled urban product, the XB.
Ultimately, regardless of what transpires in terms of legislation on this side of the channel, product sold here is usually simply a right-hand drive version of what has been designed and built for Europe. The UK and Ireland is a relatively small market and does not usually receive a great deal in specific R&D attention, so we will see – though hopefully not hear quite so much – the results of this latest change on our roads in the future.
