Pedestrian Risk from Cars and Sport Utility Vehicles - A Comparative Analytical Study

Abstract

Analysis of real-world crash data from the USA shows that 11.5 per cent of pedestrians struck by large sport utility vehicles (SUVs) are killed, compared with 4.5 per cent of pedestrians struck by passenger cars. The design of the vehicle front-end structure has a substantial influence on injury outcome when pedestrians are struck by vehicles. In the context of the rising population of SUVs, it is important to determine the causes of their increased hazard to pedestrians. In this paper, validated multi-body models are used to show that the shape of SUVs results in higher pedestrian injuries to the mid-body regions compared to passenger cars. Analysis shows that the mass difference between cars and SUVs is not significant for pedestrian injury causation and it is shown that an important effect of the higher front profile of SUVs is that the pedestrian is struck more centrally with respect to the body's centre of gravity, increasing the momentum transfer in the primary impact. A further important effect of the higher bonnet leading edge is that there is a direct impact to the mid-body region, which explains the significant abdomen and other internal injuries reported from real-world SUV/pedestrian impacts. By comparison, head injuries sustained from primary vehicle contact are shown to be similar or slightly lower for SUV/pedestrian impacts compared to car/ pedestrian impacts. However, real-world evidence and the current models suggest that the secondary impact with the ground is more severe in SUV/pedestrian impacts compared to car/ pedestrian impacts. Overall, these results show that the empirical finding that SUVs are more hazardous for pedestrians than passenger cars is primarily a function of the high bumper and bonnet for such vehicles.

Precrash Dipping Nose (PCDN) Needs Pedestrian Recognition

“…They concluded that the head injuries were similar or slightly lower from contact with SUVs compared to cars, but injuries to the mid-body regions were substantially higher. They analyzed that the primary reason for the increased hazard to pedestrians from SUVs is the high front shape of the bumper and bonnet, and the mass difference between cars and SUVs is not very significant for pedestrian injury causation [23]. The point where their results meet ours is their prediction or suggestion that lowering the bumper and bonnet and reducing the bonnet stiffness for SUVs would help reduce injuries to these mid-body regions.…”

“…It is calculated from the resultant head acceleration (measured in g) like (4), where time is measured in seconds, and the maximum time interval is 36 ms. In (4), a head denotes the resultant head acceleration in g unit, and t 1 and t 2 denote the impact starting and ending times, respectively [23]. The HIC has many shortcomings, but an HIC of 1000 has been associated with a 50% risk of skull fracture [24].…”

Pedestrian Model for Injury Prediction for Lateral Impact

“…The model is validated using both literature sources (Ishikawa et al 1993;Kerrigan et al 2005;Simms & Wood, 2006;Stammen & Barsan-Anelli, 2001) involving experiments with PMHS (Post Mortem Human Subject) and dummies, and also, in several cases, using computer simulations of performed tests. As a key source the work of Kerrigan et al (2005), presenting the detailed description of the experiment with a full-scale pedestrian impact, is chosen.…”

“…Despite the precise description of the test itself, the publication lacks detailed information about the car material characteristics. Hence additional literature sources (Simms & Wood, 2006;Stammen & Barsan-Anelli, 2001) are used to complete the model parameters. The car is modeled as rigid with parameters defined according to a real small car, as reported in Table 1.…”

“…It enables the simulation of a more realistic impact behavior of rigid bodies. The used bonnet and windscreen characteristics displayed in Figure 2 are adapted from (Simms & Wood, 2006). …”