Vehicle roof crush standards have not been significantly revised since 1971. The current requirements say one side of a vehicle's roof must support at least 1.5 times the total vehicle weight. However, the strength requirements reach a maximum at 5,000 lbs, whether or not the calculated
standard is greater. The regulations also do not
apply to convertibles or vehicles weighing more than 6,000 lbs. In 2005, a proposal was created to revise the requirement to 2.5 times the total vehicle weight on one side of the vehicle. Now that proposal has been altered, since NHTSA
says it is feasible to distribute the test to press on both sides of a vehicle's roof. It has also been proposed to increase the standards to cover vehicles up to 10,000 lbs. An active rollover test is ruled out though, due to repeatability issues and lack of variable control. To appease Congress, NHTSA must put a revised standard in place by April 2009.
While updating safety standards is always a good thing, the issued statements relating to the proposal leave some questions. It is not stated whether the testing weight cap of 5,000 lbs will be increased along with the maximum tested vehicle weight. These days, many automobiles weigh in at upwards of 4,000 lbs. 2.5 times a 4,000-lb vehicle falls well above the 5,000-pound limit. There is also still no mention of convertible safety. Hopefully the full proposal is more detailed than the points touched upon in this piece.
[Source: Auto News, Sub. Req'd]