This article contains a few of the findings from our recent study of automobile safety in frontal crashes. Parts of the data analyses are presented but details such as the relationship of a particular design feature to the measured injury indicators are highly dependent on specific cases and are available only for individual discussions.
As is known, major changes have been instituted by the National Highway Traffic Safety Administration in the measurement procedure and publications of the safety ratings system for automobiles of model years 2011 and later (http://www.safercar.gov/staticfiles/safetytech/st_landing_ca.htm). These ratings are published by the NHTSA as part of their 'New Car Assessment Program' (NCAP) with the stated intent of helping customers select vehicles that are 'safer' which NHTSA states as 'more stars'. There are no legal requirements that vehicles have to achieve any particular level of performance in these NCAP tests. However, with the wide publicity given to this and other comparative safety ratings and with the intense marketplace competition among automakers, such ratings have become a de-facto 'standard' (in addition to the Federal Motor Vehicle Safety Standards) for designing automobiles and all vehicle manufacturers try to achieve the highest possible ratings for their new product.
One of the interesting aspects of the new NCAP is that NHTSA will now publish an 'overall score' for the vehicle's crashworthiness by combining the scores from frontal crash, side impacts and rollovers. Other significant changes in the NCAP are the addition of a test dummy representing small occupants, the inclusion of new injury-related parameters and significantly raised thresholds for achieving the highest (five stars) rating. These changes in the NCAP will lead to changes in many aspects of automobile design. This note analyzes frontal crash test data from recent NCAP tests. Similar evaluation of side impacts, rollovers and crash avoidance performance has also been completed and will follow in future notes.
NCAP Tests for Frontal Crashes : Frontal crashes have been assigned the largest weight in the new overall NCAP rating for the vehicle. The test configuration for this mode remains unchanged - 35 miles per hour impact of the vehicle into a fixed rigid barrier - but the measurements and calculations have changed significantly. This front impact of an automobile into a rigid barrier simulates crashes with fixed and rigid objects on the roads and also represents full frontal crash of the car with another identical car. It (the front NCAP rating) cannot be used to directly compare vehicles of different sizes and masses.
Measurements are now made on two different representations of occupants - the driver is represented by an anthropomorphic test device (ATD) simulating a fiftieth percentile male in the US population whereas the front passenger ATD simulates a fifth percentile female. The measured ATD parameters in this impact include responses of head, chest, femurs and the newly added criteria of neck forces and moments. These measured values are used to calculate 'relative risk' scores which are then translated into separate 'stars' for the driver and the passenger. According to NHTSA, the following relationship exists between the ratings ('stars') and the risk of injury in frontal crashes.
Dr. Mukul Verma, is a well-known expert in Automobile Safety and Crashworthiness, Vehicle Structures, Product Design, and Statistical Analyses of Traffic Trends and Regulations . He has worked in many engineering and management positions at a major automobile manufacturer including assignments in R&D, vehicle design, analysis and testing and engineering program management.
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