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Citation
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Thomson R, Fredriksson R, Mróz K, Kruse D, Törnvall FV. 27th International Technical Conference on the Enhanced Safety of Vehicles (ESV); April 3-6, 2023; Abstract #: 23-0321, pp. 16p. Washington, DC USA: US National Highway Traffic Safety Administration, 2023 open access. |
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Abstract
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27th International Technical Conference on the Enhanced Safety of Vehicles (ESV): Enhanced and Equitable Vehicle Safety for All: Toward the Next 50 Years
https://www-esv.nhtsa.dot.gov/Proceedings/27/27ESV-000321.pdf
In 1997 the Swedish parliament adopted Vision Zero, which reduced fatalities almost by 2/3 down to 1.9 road fatalities per 100,000 inhabitants for 2020. One guiding principle is to only allow maximum speed limits of 80 km/h without physically separating opposing lanes. Fatal frontal crashes between passenger cars and Heavy Goods Vehicles (HGVs) are a problem for the rural road network with speed limits between 50 and 80 km/h. A road network following the Safe System principles should not lead to fatalities if safe vehicles, safe infrastructure, and safe road users are present. In the scenario described above, a rural road posted at 80 km/h without median separation would need to be operated with safe vehicles, that is, vehicles that are capable of protecting occupants in frontal crashes. While it may be possible for late model cars with good safety performance to protect occupants in crashes with similar cars at relative crash velocities above 120 km/h, the case of a car-to-HGV impact is less obvious.
A study of real-world crash data and current vehicle technology suggested that a frontal crash between an HGV and passenger car with relative velocity of 100 km/h (50 km/h per vehicle) and 50% overlap would be a reference to assess infrastructure and vehicle safety levels. The test was based on both vehicles having active safety systems that reduce the original travel speeds to the proposed test speed before an impact. State-of-the-art vehicles, a Euro NCAP 5 star rated mid-sized sedan and HGV with energy absorbing Front Underride Protection Device (FUPD), were chosen. The test is also comparable with the Moving Progressive Deformable Barrier (MPDB) test currently used in Euro NCAP.
The test results showed that both vehicles need structural protection system improvements to provide consistent protection for road users in these types of high-severity crashes. The car sustained extensive deformations to the outboard area of the vehicle front resulting in significant deformation to the left wheel and A-Pillar area. This focused damage was due to the fracture of the FUPD on the HGV early in the crash event. The FUPD did not engage the energy absorbing structures in the car (longitudinal crash beams), which were essentially undamaged. The 50%ile male Hybrid III (HIII) dummy's head slid off the driver's airbag and struck the left A-Pillar due to a gap that developed between the side curtain and front airbag, this was related to the excessive A-Pillar deformation. High head accelerations exceeded the upper limit for recommended Head Injury Criteria (HIC).
Compatibility between HGVs and cars must be improved for frontal impacts when less than 50% of the car width engages the truck structures. The existing FUPD legal requirements should be reviewed to ensure that geometric and structural requirements for these structures reflect the real-world demands in a crash. Opportunities for improved passenger car restraint systems need vehicle structure interactions that can maintain a stable passenger car compartment and efficiently use energy absorption systems designed into both HGVs and passenger cars. The new EC regulation (2019/1892) for extended fronts is an opportunity that can be exploited to achieve better car-HGV compatibility by providing more design space in the HGV front-end. |