A Comparison of the NHTSA Research Offset Oblique and Small Overlap Impact Tests and the IIHS Moderate and Small Overlap Tests

The National Highway Traffic Safety Administration (NHTSA) and the Insurance Institute for Highway Safety (IIHS) have both developed crash test methodologies to address frontal collisions in which the vehicle's primary front structure is either partially engaged or not engaged at all. IIHS addresses Small Overlap crashes, cases in which the vehicle's primary front energy absorbing structure is not engaged, using a rigid static barrier with an overlap of 25% of the vehicle's width at an impact angle of 0°. The Institute's Moderate Overlap partially engages the vehicle's primary front energy absorbing structure using a deformable static barrier with 40% overlap at a 0° impact angle. The NHTSA has developed two research test methods which use a common moving deformable barrier impacting the vehicle with 20% overlap at a 7° impact angle and 35% overlap at a 15° impact angle respectively. In this paper, the authors present a case study in which an exemplar mid-size sedan was subjected to all four impact conditions. Following the NHTSA research procedures and IIHS protocols, the anthropomorphic test devices used in this study were THOR-NT (with LX instrumented lower legs) for the NHTSA research tests, and the Hybrid III AM50 for the IIHS tests. Differences with regards to resulting vehicle deformation, vehicle kinematics, and occupant kinematics were noted between the IIHS and NHTSA test methods and are discussed in this paper.