The Effectiveness of the National Advanced Driving Simulator (NADS) in Evaluating the Effect of Tire Tread Belt Detachments 2013-01-0467

Tire failures, including tread belt detachments, have been associated with loss of control crashes including rollovers. Numerous reasons exist for control loss including forces created by the failed or failing tire, cornering capacity diminishment for the detreaded tire combined with control demands beyond the remaining capacity of the vehicle and inappropriate driver demands including excessive steering. Extensive studies have been completed to define the various causes of control loss and to identify risk-reducing countermeasures. These studies have included reconstructions of crashes and tests of real vehicles in test track environments with tires purposely caused to fail. In order to gain insight into driver factors and their relationship to vehicle design, the National Highway Traffic Safety Administration (“NHTSA”) commissioned a 2002 study by the University of Iowa that used its National Advanced Driving Simulator (NADS) to evaluate lay driver responses to a simulated rear tire tread belt detachment. The study, authored by Ranney, et. al., observed the capability of those subjects to maintain control of the simulated vehicle. It then used those observations to test the hypothesis that the magnitude of a vehicle's linear range understeer gradient was related to the likelihood that a driver would lose control when the simulated tire tread detachment occurred.

The purpose of this paper is to compare the results of the Ranney NADS study with available information from real-world case studies and test-track evaluations of real vehicles that experienced rear tire tread belt detachments. The comparison revealed that the Ranney NADS study produced results that are not consistent with the real vehicle evaluations. The likely causes of the discrepancy in results include a lack of fidelity in simulating the forces, moments and noise of a detaching tire tread that may have caused anomalous and unexpected responses by drivers in the Ranney NADS study. Furthermore, a lack of fidelity in simulating the remaining lateral force capacity of the detreaded rear tire may have compromised the ability of the Ranney NADS study to allow evaluation of its hypothesis regarding a correlation of vehicle understeer gradient to likelihood of control loss with a rear tread belt detachment.