In tests of SUVs and pickups by the IIHS (Insurance Institute for Highway Safety), the Volvo XC90 is one of few models to earn top ratings for whiplash protection systems. The independent research and safety institute used crash test dummies to register loads on the neck during a simulated impact from the rear.
This is the first time the IIHS has carried out a dynamic test with SUVs and pickup trucks. The test was carried out in two stages. First, the seats were measured to determine the head restraints' geometry and to determine the preconditions for protecting the head of a person of normal height. Only seats with good or acceptable head restraint geometry went on to the second stage, the dynamic crash test. Here, a moving platform was used to simulate a situation where a car standing still was hit from behind by a vehicle of the same weight driving at 20 mph.
The test method and the evaluation criteria have been developed within the framework of broad international cooperation between experts in preventive whiplash injuries (IIWPG – International Insurance Whiplash Prevention Group).
Only 6 of the 44 vehicles tested proved to offer effective protection against whiplash injuries. The Volvo XC90 was one of the best. The overall assessment includes both the seats' measured geometry and the results of the dynamic test.
The IIHS emphasizes that effective protection against whiplash injuries is an important factor for reducing both human suffering and the cost of rehabilitation. Collisions from behind are very common and neck injuries are the most common type of serious injury arising from car accidents.
The movement of the head and upper body must be synchronized
According to the IIHS, the key to effective protection is that the seat occupants' head and upper body should move in harmony during the collision sequence. The reason for whiplash injuries is usually that the head cannot keep up with the body as it jerks forward under the force of the impact. For this reason, the seat and head restraint must interact to support the head so that it accelerates together with the upper body. It is also important that the head restraint is sufficiently high and positioned close to the head.
"Volvo's head restraint is designed in precisely this say," explains Ingrid Skogsmo, Director of the Volvo Cars Safety Centre. "WHIPS, Volvo's Whiplash Protection System that is fitted as standard in all new Volvo cars, is designed in such a way that it ensures both that the head and torso move together, and also that acceleration forces are limited."
Volvo's advanced whiplash protection design is one of the reasons behind the excellent test results, and this is confirmed by the IIHS.
Volvo's Whiplash Protection System (WHIPS)
In Volvo's Whiplash Protection System, the front seats and their headrests are designed to provide uniform support for the entire back and head during the collision sequence. In addition, a bracket fitted between the seat backrest and the seat cushion helps the seat to absorb the incoming energy, thus reducing the acceleration forces in a rear-end impact. This is done by the weight of the occupant's body pressing the backrest rearward in a simultaneous horizontal and reclining position. This motion dampens the incoming forces rather like when a person catches a thrown ball, thus reducing the stress exerted on the occupant's body. It also reduces the subsequent forward motion.