In contrast to a frontal crash, there is little space in a side impact to absorb the impact energy. In order to evaluate the vehicle structure and the precise deployment of the airbags, the NCAP testers allow a deformable object to collide with the vehicle side. In another test, the pole impact, the vehicle is thrown sideways against a solid, narrow pole. Among other things, the testers determine the protection for the driver’s head – in the event that the pole penetrates into the interior.
USA: different set of rules
To prevent the crash barrier from hitting the energy-absorbing steel beam during a frontal collision, the American Insurance Institute for Highway Safety (IIHS) also carries out a so-called “small overlap test.” The impact takes place at 25 percent of the front, separately at the height of the driver and front passenger. Compared to the 40 percent overlap, controlled energy absorption takes place via the wheel and sill, i.e. no longer necessarily via longitudinal beams. This can cause the passenger cell to deform.
In the US NCAP test, the NHTSA carries out a rollover resistance assessment in addition to the frontal and side crashes. It is based on the so-called Static Stability Factor (SSF). This determines how top-heavy the vehicle is and whether it could tip over in a sharp bend, for example. The background: Almost ten percent of American road users do not use a safety belt. By way of comparison, the figure in Germany is around two percent. Stronger roofs can prevent these occupants from being thrown out of windows or doors damaged by deformed roofs. According to IIHS criteria, the roof must withstand a force four times the vehicle’s weight.