STEERING COLUMN MOVEMENT IN SEVERE FRONTAL CRASHES AND ITS POTENTIAL EFFECT ON AIRBAG PERFORMANCE

Excessive movement of steering columns in crashes can significantly degrade the performance of restraints, especially airbags. Although steering column movement does not appear to be a major problem in full-width rigid barrier crashes, it can be an issue in other frontal crash types. Results from 106 frontal offset crash tests at 64 km/h (40 mi/h) were used to characterize different patterns of steering column intrusion for different vehicle types. Large movements of the steering column often were associated with the dummy’s head striking the steering wheel through the airbag. Some of the tested models were redesigned over the course of this testing, and comparisons with older designs showed that improving the structural integrity of the occupant compartment could lead to less longitudinal movement of the steering column, but this was not necessarily the case for vertical column movements for some models in the data set. Multipurpose passenger vehicles—pickups, utility vehicles and passenger vans—tended to have more vertical steering column movement than cars. Examples of fatal frontal crashes from the National Automotive Sampling System/Crashworthiness Data System and serious frontal crashes from the Insurance Institute for Highway Safety’s Seven-County Crash Investigation Study were examined to better understand the real-world consequences of steering column movement. Both crash samples included cases in which serious and fatal injuries were attributed to driver contact with the steering wheel despite the presence of a deployed airbag. Some examples of these injuries occurred in crashes without catastrophic collapse of the occupant compartment, and some of the drivers were belted. As crash test results suggest, movement of the steering column in frontal crashes can degrade real-world airbag effectiveness, and this phenomenon deserves more attention than it has received in the past.