Do non-complying bull-bars increase the injury risk to occupants of other vehicles
Keywords: Vehicle Safety
Submission Date: 2012
In Australia, bull bars are commonly fitted to four wheel drive vehicles (4WDs). For vehicles under 3.5T gross vehicle mass, NSW requires bull bars to comply with the Australian Standard 4876.1-2002 Motor vehicle frontal protection systems-Road user protection (except clause 3.2) and is currently the only Australian jurisdiction to call up this standard.4WDs are generally higher than standard passenger vehicles. Some 4WDs are raised by their owners to enable them to operate under extreme off-road conditions. This study assessed the injury risks to occupants of vehicles side-impacted by 4WDs fitted with geometrically complying and non-complying (forward facing) bull bars, as well as varied suspension heights. The side impact poses sever challenges for occupant protection, mainly due to the minimal distance between impact point and occupant. A series of side impact tests were conducted using a popular large passenger car as the target vehicle and two similar models of 4WDs as bullet vehicles. One 4WD retained its original height and the other was raised by 65mm. The speeds of the bullet vehicles were adjusted to match the impact energy of an ADR 72 regulation test. Preliminary results indicate bull bars fitted to raised 4WDs increase the injury risks to occupants of the impacted vehicle and shift the injury profile to the upper part of the occupant’s body. The study also showed that target vehicle struck by a raised 4WD fitted with forward facing bull bar failed to comply with ADR 72 requirements and contra-intuitively increased the injuries to the occupant’s lower thorax due to rotation of the bar during the impact. While there was no increase in the risk of serious head injury encountered in these tests, it was noted that the intrusion could pose an increased risk to occupants of smaller vehicles who sit lower to the ground. Further tests will be conducted, including one at normal ANCAP test speed.