Q: I have a situation where a pickup struck the side of a semi trailer between the landing gear and the trailer's wheels. The trailer was at a 30 degree angle to the pickup and the pickup skidded straight into the collision. Any information on this type of damage?
A: NOTE: In an angled underride crashes, not all the energy goes into the vehicle crush. A significant amount of energy may be dissipated as the vehicle moves and slides and gouges subsequent to the initial impact. I would suggest brushing up on some of the concepts of Energy Correction Factor(ECF).
- Please see Energy Correction factor.
- There are many angled barrier crash tests whcih are included in the database. McHenry Software Users, from medit32, simply select Databases->NHTSA Databases w/Extended data
- Struble, Welsh & Struble "Crush Energy Assessment in Frontal Underride/Override Crashes”,SAE Paper 2009-01-0105
- Abstract: Compatibility or aggressivity between vehicles in frontal crashes can be manifested by differences in the ways that upper and lower structures deform, when compared to each other, or when compared to the deformation modes in full-width impacts into rigid barriers. Flat barrier tests are very useful for characterizing the structure and determining the crush energy, and are indeed the underpinning of existing reconstruction methods. However, conventional methods can be problematic when flat barrier test data are applied to underride/override crashes. Useful insights in grappling with such situations were obtained by analyzing a series of NHTSA-sponsored crash tests into full-width rigid barriers, in which advanced measurement protocols were employed. Dynamic force-deflection characteristics were developed, and absorbed energies were calculated, for the upper and lower structures of the tested vehicles. Distinct CRASH III-type models were developed for these structures. For all the other crash test data not employing advanced measurement protocols, a means was developed for approximating the crush energy contributions from the upper and lower structures, based on data from full-width rigid barrier impacts. To test its validity for under/override crashes, the method was applied to published crash test data for some repeated frontal impacts into an overhanging barrier. Good predictions of the crush energy were obtained. The paper contains recommendations for future measurement protocols, and how to use the developed procedures for vehicles not tested according to improved protocols.
- Limitations “The proposed underride/override model has been validated against a very narrow range of vehicles only. It should be tested against other staged underride/override crashes as they become available.”
- Another paper is by Trego, et al "A Scientific Approach to Tractor-Trailer Underride Analysis", SAE Paper 2003-01-0178
- Abstract: Crashes between passenger vehicles and large tractor trailer vehicles often result in serious injuries and death. There have been few studies of this class of crash involving the side of the large tractor trailers and the passenger vehicles. Studies have shown that side underrides are underreported in crash records. A literature search has shown that there are no generally accepted methodologies to document and scientifically reconstruct a side underride accident. Some of the problems existed because there was a general lack of information on the side underride crash. Rear underride crashes were being studied which yielded helpful information. This led the authors to study a series of trailer side underride crashes that were performed to determine if there were sufficient relationships between passenger vehicle body and roof styles and the side of large highway trailers to allow the development of a general formula for underride impact speed analysis of a vehicle where the roof and roof support structure of the vehicle was damaged. These tests provided valuable insight into the relationships between passenger vehicle roof structures and the sides of large box trailers.