While school buses have had reinforced roofs to better secure occupants in the event of rollover crashes since the mid-1970s, other passenger vehicles such as vans and Suburbans utilized in some school activity trips do not. They will soon be required to meet similar federal requirements after the National Highway Traffic Safety Administration published a final rule last month [PDF].
The NHTSA final rule upgrades Federal Motor Vehicle Safety Standard 216, Roof Crush Resistance applies to passenger cars and multipurpose passenger vehicles, trucks and buses weighing 6,000 pounds and extends a provision for similar vehicles weighing at least 6,000 pounds but not exceeding 10,000 pounds. It is part of a comprehensive plan to limit rollover occurrences and resulting deaths and serious injuries.
Published April 30, the rule doubles the amount of force the vehicle’s roof structure must withstand in specified tests, from one and a half times the vehicle’s unloaded weight to three times the vehicle’s unloaded weight. It also establishes a force requirement of one and a half times the vehicle’s unloaded weight for the heavier vehicles. Phase-in begins on Sept. 1, 2012, and by Sept. 1, 2015, all vehicles must meet the upgraded requirements by Sept. 1, 2016, except under certain circumstances. Vehicles produced in more than one stage and altered vehicles need not meet the requirements until Sept. 1, 2017.
The rule requires these passenger vehicles to meet the specified force requirements for two-sided test, or first on one side of the vehicle and then the other, instead of single-sided tests. The rule also establishes a new requirement for maintenance of headroom, or a passenger’s “survival space,” during testing and the existing limit on the amount of roof crush. Special provisions are included to address the needs of multi-stage manufacturers, alterers and small-volume manufacturers.
NHTSA developed its proposal after conducting research to examine potential methods for improving the roof crush resistance requirements including full vehicle dynamic rollover testing, inverted vehicle drop testing and comparing inverted vehicle drop testing to a modified FMVSS No. 216 test and reviewing public comments submitted going back to 2001. The rule on school bus roof strength is FMVSS 220.