An Overview of FMVSS 216a - Roof Crush Resistance Testing 2010-01-1020
This paper provides a detailed review of the testing procedures utilized for FMVSS 216a - Roof Crush Resistance and by the Insurance Institute for Highway Safety (IIHS). This new FMVSS 216a standard, announced by the National Highway Traffic Safety Administration (NHTSA) on April 30, 2009, will result in significantly stronger roof structures. The standard specified four major changes: 1) The maximum applied force must equal three times the unloaded vehicle weight for vehicles with a gross vehicle weight rating of 6,000 pounds or less, 2) The standard is expanded to include vehicles with a gross vehicle weight rating between 6,000 and 10,000 pounds, 3) Head room maintenance is monitored through the use of a head form representing a 50th percentile male seated in the front occupant positions, and 4) The platen force, displacement, and head form contact requirements must be met on both sides of the vehicle's roof structure. Since this upgrade requires much higher loading levels, those conducting this test will encounter significant challenges. The standard also adds a number of peripheral specifications in how the test is conducted which will result in additional test hardware, data, and vehicle set-up/fixturing.
The phase-in for FMVSS 216a is scheduled to be implemented over the next six years with 100% compliance of manufactured vehicles by September 1, 2015. Earlier, in February 2009, the IIHS announced a new rating system based around roof crush testing. Although their procedure is similar to that of FMVSS 216/216a, the requirement to earn the highest rating is 4.0 times the vehicle's curb weight. Furthermore, the vehicle set-up protocol varies in several areas such as vehicle attitude and tie-down, not utilizing a head form fixture, and test process. When announced, the load requirement not only exceeded the NRPM for FMVSS 216 released in 2005 (2.5 times), but it was also greater than the final rule of FMVSS 216a which was announced several months later. This paper will overview the new regulation, review background information leading to the new rule, detail the testing procedure, overview the IIHS test procedure, and present data from both the FMVSS 216a and IIHS test protocols. Readers of this paper will gain a much broader understanding of roof crush testing, details of the new procedure which are critical to performing the test correctly, and the impact that these new requirements will have on future vehicle designs.