Euro NCAP exposes fatal flaws in trailer underrun safety
Euro NCAP has revealed a shocking lack of protection from rear safety guards on masses of trailers and trucks operating across the EU and UK, contributing to hundreds of road deaths every year.
Rear impact guards, also known as Rear Underrun Protection Devices (RUPDs), are physical safety features that act as a low-slung barrier to prevent smaller vehicles from sliding underneath a truck’s frame during a rear-end crash.
With this type of crash leading to approximately 400 fatalities across the EU and UK every year, a comprehensive testing campaign carried out by Euro NCAP and collaborating organisations - Germany’s ADAC, the Swedish Transport Administration (Trafikverket) and the Insurance Institute for Highway Safety (IIHS) - has exposed the critical vulnerabilities relating to rear underrun protection.
“International research has revealed the devastating flaws of the rear safety guards fitted to the hundreds of thousands of trailers and trucks operating throughout Europe and the UK,” said Matthew Avery, Director of Strategic Development at Euro NCAP.
“This is grave cause for concern. We have spent decades improving the safety of passenger vehicles but those structures and restraint systems are rendered inadequate in the event of a trailer rear underrun, which is why we are seeing such a high fatality rate associated with this type of accident.
“That is unacceptable.”
What the testing exposed
Euro NCAP’s investigation was initiated and supported by the National Highways in the UK and based on collision data analysis.
Real-world track tests and crash testing was carried out at international research facilities across the UK, Germany and the US.
This testing exposed a double failure: the sensors of some older Advanced Driver Assistance Systems are failing to see trailers, while the physical safety guards fitted to the backs of trucks and trailers are, in some circumstances, failing to prevent cars from sliding beneath them. This is leading to significant injuries and fatalities.
To assess ADAS systems, Euro NCAP measured the performance of modern Autonomous Emergency Braking systems. Vehicle performance was compared against the standard Global Vehicle Target (GVT) and a fleet of real commercial trailers under varying real-world conditions. All passenger cars tested had ADAS systems fitted with both cameras and radar sensors.
When driven towards the GVT - a standard laboratory dummy target used in all manufacturer tests - the test vehicle successfully detected it at all times. However, when tested against real HGV rear-ends such as curtainside and skeletal trailers, the detection rate fell on multiple occasions.
Euro NCAP’s testing highlighted the flaws in the ability of older ADAS systems to identify stationary trucks and trailers, revealing that passing standard laboratory tests doesn't necessarily guarantee the same performance in real-world scenarios. As the average age of cars on the road continues to rise, it’s said to take more than 15 years before most cars are able to avoid stationary trailers, prompting an urgent call to action.
The mechanical failure
Should a driver and vehicle ADAS system fail to detect a trailer, then the trailer’s Rear Underrun Protection System (RUPS) should prevent the potentially fatal instance of a car sliding beneath its structure.
To evaluate physical guard strength, Euro NCAP and its partners took a five-star Euro NCAP-rated popular passenger car, deactivated its ADAS systems, and subjected it to crash testing into the rears of trailers with different RUPS solutions.
In the UK and Germany, the car was tested using trailers built to Europe's latest mandatory standard - the UN ECE R58.03 which has been enforced since 2022. In the US, it was tested using trailers that meet the voluntary IIHS Toughguard standard.
Two different commonly used trailers were selected which were both equipped with the regulated rear underrun protection system.
The outcomes were deeply concerning. In a 56 km/h (35 mph) passenger-side 30 per cent frontal offset crash performed at England’s HORIBA MIRA site, the guard fitted by trailer manufacturer Schmitz Cargobull offered little structural resistance. The trailer bed was found to slice directly through the passenger compartment, tearing the side out of the vehicle structure and inflicting fatal head and neck injuries to the crash test dummy.
In a separate test, a 75 per cent frontal-rear impact conducted at the same speed by Germany’s ADAC saw the Krone Trailer’s rear underrun bar fail. The test car’s occupant compartment was destroyed with no protection offered to the driver or passenger.
Both crash tests showed that, despite being in a high-performing car for its crash structure, the occupants were not protected due to the poor impact resistance of the rear underrun protection structure.
Euro NCAP therefore concludes that the current R58.03 European regulation requires significant improvement and is currently not fit for purpose.
Euro NCAP calls for legislation change
When the same Euro NCAP-rated five-star car was subjected to the same 56 km/h (35 mph) offset impact against a trailer built to the voluntary IIHS Toughguard standard in the US, the guard allowed the car’s safety structure to deform and protect the occupants as designed.
Since it entered the US market in 2017, an estimated 70 per cent of the latest trailers on the road are fitted with Toughguard-rated rear underrun devices.
Euro NCAP is now calling on EU and UK legislators to follow suit and mirror the IIHS Toughguard voluntary standard in the R58.03 legislation.
From the industry, the safety body is urging trailer manufacturers to introduce voluntary upgrades and retrofit solutions for existing fleets. Truck fleet operators are meanwhile called on to request that trailer manufacturers install retrofit solutions for their existing trailer structures to replace the thousands of inadequate guards currently in operation across EU and UK roads.
“The legislation behind Europe’s truck and trailer safety needs to be updated as a matter of urgency to help prevent this type of impact that can prove potentially fatal,” added Avery.
“The good news is that the template already exists in the US with the IIHS voluntary Toughguard standard; the sooner the rear impact guards on Europe’s and UK’s trucks and trailers are updated, the better so future lives can be saved.”
