Interpretation ID: aiam2267
Staff Engineer
Blue Bird Body Company
P.O. Box 937
Fort Valley
GA 31030;
Dear Mr. Milby: This responds to Blue Bird Body Company's March 22, 1976, request fo interpretation of the provision of Standard No. 217, *Emergency Exits*, that requires unobstructed passage of a described parallelepiped through the opening provided by an open rear emergency door in the case of a school bus with a gross vehicle weight rating of more than 10,000 pounds (S5.4.2(a)). The dimensions of the parallelepiped are 45 inches by 24 inches by 12 inches, and it is oriented so that the 45-inch dimension is vertical, the 24-inch dimension is parallel to the opening, and the lower surface is in contact with the bus floor.; You point out that unobstructed passage' through the opening could b considered to occur when the rearmost surface of the parallelepiped coincides with a vertical transverse plane that intersects the outer surface of the bus body at either the top or the bottom of the opening, or intersects the inner surface of the bus body at either the top or the bottom of the opening.; The NHTSA considers unobstructed passage of the parallelepiped to occu when its rearmost surface coincides with the vertical transverse plane that intersects the outer surface of the bus body at the bottom of the opening in question. Thus, your intention to assure compliance by measuring unobstructed passage at the point when the rearmost surface is flush with the bus body outer surface appears justified. The agency does not consider the bus body outer surface to include rub rails or trim materials for purposes of this measurement.; Yours truly, Frank Berndt, Acting Chief Counsel