Light Trucks And Vans Research Articles

A finite element approach in estimating driver fatality ratio of a fleet of LTVs striking a passenger car based on vehicle’s intrusion, acceleration and stiffness ratios in side-impact accidents

The driver fatality ratio (DFR) proposed by the National Highway Traffic Safety Administration (NHTSA) demonstrates the relative fatality risks of occupants in various vehicle-to-vehicle (VtV) crashes. The readily available DFR is based on statistical crash data; hence, estimating the DFR of occupants for newer fleet of vehicles can be quite difficult. Three systematic methods such as the intrusion, deceleration and stiffness ratios of two colliding vehicles in side-impact accidents are proposed to estimate the DFR. A fleet of light trucks and vans (LTVs) striking a sedan car is reconstructed using the non-linear explicit code, LS-DYNA. The simulation results have shown that the intrusion and acceleration ratios-based approaches are in good agreement with the statistical DFR, whereas the DFR estimated using the stiffness-ratio based approach yielded poor agreement. The intrusion and acceleration ratios-based approaches are then utilized to formulate a combined DFR estimation model. In the second part of the study, the proposed methodology is carried further to estimate the DFR of occupants for a fleet of LTVs impacting a newer passenger car. The proposed methodology can be a viable tool for estimating the DFR for newer road vehicles and to improve its crash compatibility with collision partners.

Evaluation of NASS-CDS Side Crash Delta-V Estimates Using Event Data Recorders

Objective: Planar crash severity is most commonly defined by delta-V (ΔV), which is the change in a vehicle's velocity vector during a crash. All ΔV estimates contained in the NASS-CDS are generated using a damage-based program called WinSMASH. WinSMASH ΔV accuracy in side crashes has not previously been validated against real-world crash data. This study will investigate the accuracy of WinSMASH ΔV estimates in real-world side crashes.Methods: This study uses biaxial ΔV data from event data recorders (EDRs) to assess the accuracy of side crash ΔV estimates in NASS-CDS crash cases. Single-event side crashes were identified in the NASS-CDS for which (a) WinSMASH ΔV had been coded and (b) biaxial EDR data were available. For these crashes, the WinSMASH-estimated resultant ΔV was compared with the EDR-recorded resultant ΔV to assess the accuracy of the former. EDR ΔV values were adjusted for an assumed average restitution value of 10 percent, based on values reported in the literature. Principal direction of force (PDOF) is the orientation of the net crash impulse relative to the vehicle and is a key parameter in WinSMASH reconstructions. NASS-CDS PDOF estimates were compared to the PDOF computed from the EDR data to assess their accuracy as well.Results: WinSMASH systematically overestimates EDR ΔV by about 12.9 percent for cars struck by cars and by about 2.4 percent for cars struck by light trucks and vans (LTVs). ΔV error was significantly different (at 95% confidence) for crashes to different areas of the vehicle side. The mean discrepancy in NASS-CDS PDOF was −0.9° with a standard deviation of 12.6°.Discussion: WinSMASH systematically overestimates ΔV at common velocity by about 13 percent for cars struck by cars and about 2 percent for cars struck by LTVs. Since WinSMASH's assumption of zero restitution is accounted for in this analysis, this suggests that WinSMASH stiffness parameters represent LTV impacts better than car impacts in side crashes. ΔV error differs by impacted area, suggesting that side impact stiffness parameters used in damage-based ΔV reconstruction must closely represent the crash mode being reconstructed for best results. NASS-CDS estimates of PDOF do not appear to exhibit any systematic discrepancy. The amount of random PDOF discrepancy observed here is consistent with prior studies.

Indexing crash worthiness and crash aggressivity by vehicle type

Crash aggressivity (CA), along with conventional crash worthiness (CW), has been recently studied to deal with the crash incompatibility between vehicles on roads. Clearly, injury severity depends on the attacking ability of striking vehicle as well as the protective ability of struck vehicle. This study proposes a systematic crash-based approach to index CA and CW of various vehicles. The approach deviates from existing methods in three aspects: (a) an explicit definition and specification in the model for CW and CA; (b) Bayesian hierarchical analysis to account for the crash-vehicle two-level data structure; (c) a five-level ordinal model to explicitly consider all levels of crash severity. The case study on major vehicle types illustrated the method and confirmed the consistency of results with previous studies. Both crash worthiness and crash aggressivity significantly vary by vehicle types, in which we identified the dominating effect of vehicle mass, and also highlighted the extraordinary aggressivity of Light Trucks and Vans (LTVs). While it was not surprising to identify least CA and CW of motorcycles, buses were unconventionally found to be less aggressive than other motor vehicles. The method proposed in this research is applicable to detailed crash-based vehicle inspection and evaluation.

The fatality and injury risk of light truck impacts with pedestrians in the United States

In the United States, passenger vehicles are shifting from a fleet populated primarily by cars to a fleet dominated by light trucks and vans (LTVs). Because light trucks are heavier, stiffer, and geometrically more blunt than passenger cars, they pose a dramatically different type of threat to pedestrians. This paper investigates the effect of striking vehicle type on pedestrian fatalities and injuries. The analysis incorporates three major sources of data, the Fatality Analysis Reporting System (FARS), the General Estimates System (GES), and the Pedestrian Crash Data Study (PCDS). The paper presents and compares pedestrian impact risk factors for sport utility vehicles, pickup trucks, vans, and cars as developed from analyses of US accident statistics. Pedestrians are found to have a two to three times greater likelihood of dying when struck by an LTV than when struck by a car. Examination of pedestrian injury distributions reveals that, given an impact speed, the probability of serious head and thoracic injury is substantially greater when the striking vehicle is an LTV rather than a car.

The Crash Compatibility of Cars and Light Trucks

This paper investigates the compatibility of cars, light trucks, and vans (LTVs) involved in traffic crashes. An analysis of U.S. crash statistics shows that, although LTVs currently account for approximately one–third of registered U.S. passenger vehicles, collisions between cars and LTVs account for over one–half of all fatalities in light vehicle–to–vehicle crashes. In these crashes, 81 percent of the fatally injured are found to be occupants of the car. These statistics suggest that LTVs and passenger cars are incompatible in traffic crashes, and that LTVs are the more aggressive of the two vehicle classes. The fundamental incompatibility between cars and LTVs is observed even when the analysis is restricted to collisions between vehicles of model year 1990 or later - indicating that, despite the availability of newer safety countermeasures, e.g., airbags, the incompatibility between cars and LTVs will persist in future fleets. Through examination of crash test results, field crash statistics, and vehicle measurements, the paper explores the design imbalances between cars and LTVs, e.g., mass, stiffness, and geometry, which lead to these severe crash incompatibilities.

Safety implications of extending some Canadian Motor Vehicle Safety Standards to light trucks and vans

The primary objective of this research was to evaluate the implications of extending specific Canadian Motor Vehicle Safety Standards (CMVSS) to light trucks and vans (LTVs). This was accomplished through the examination of the potential safety-related benefits of these standards comparing the injury frequencies and severities of the light trucks and vans and the passenger cars (PCs). The standards considered, which currently apply to passenger cars but not to LTVs, are the head restraint (CMVSS 202), side door strength (CMVSS 214), and roof crush strength (CMVSS 216) standards. The comparison was effected by means of logit models developed from multidimensional tables with injury frequency and severity as dependent variables. There are indications that installing head restraints in light trucks and vans could reduce or prevent minor neck injuries and that modest benefits could be achieved by extending the roof crush standard to the LTVs. It was also determined that the side door strength standard may not necessarily be as beneficial to LTVs in conditions in which the vehicle is struck on the side by another LTV. It is suggested that the general public be made aware of the differences in safety standards between LTVs and PCs.