Does FMVSS 217 preempt state law safety requirements?

QUESTIONS PRESENTED FOR REVIEW Does Federal Motor Vehicle Safety Standard No. 217 (“FMVSS 217”) prohibit a greater level of safety by statutorily making it physically impossible for Texas common law to require an automatic in-motion lock to prevent an occupant from opening the rear emergency exit door when a school bus is traveling at highway speed? Does the statutory language of FMVSS 217, along with its legislative history, evidence congressional intent that a “locking mechanism” functions and moves distinctly from a “release mechanism”?