The Insurance Institute for Highway Safety (IIHS) began publishing side impact crashworthiness evaluations for consumer information in 2003. The test on which the evaluations are based uses a barrier representing the ride height and front-end geometry of a pickup truck or sport utility vehicle. In this test a stationary vehicle is struck laterally by a 1,500 kg moving deformable barrier traveling at 50 km/h. In determining the impact severity for the test, the goal was to select an impact velocity that would both drive improvements in side impact protection and discriminate between vehicles in the current fleet offering varying levels of protection.

In the present study the Simulating Motor Vehicle Accident Speeds on the Highway (SMASH) computer program was used to obtain delta Vs for vehicles tested in the IIHS side impacts. These were compared with delta V estimates calculated using the principle of conservation of momentum. The delta Vs calculated from the IIHS tests were compared with those from injuryproducing side crashes in the National Automotive Sampling System (NASS) to see how the severity of the IIHS test compares with real-world side crashes.

Analysis of 49 side crashes conducted by IIHS indicates that, overall, SMASH calculations produced delta Vs within 5 km/h of the delta V determined using the conservation of momentum principle. The SMASH delta Vs ranged from 18 to 31 km/h, and the average delta V was 24 km/h. The maximum occupant compartment crush in these tests ranged from 27 to 46 cm. Comparison of delta Vs and maximum crush measures from the 1998-2003 NASS data files indicates that 30- 55 percent of real-world front-to-side crashes with seriously injured nearside occupants and 10-25 percent of the crashes with fatal injuries to nearside occupants are less severe than the IIHS side impact test.