Interpretation ID: aiam3452
Vice-President Engineering
Mid Bus Inc.
710 East Wayne Street
P.O. Box 1985
Lima
OH 45802;
Dear Mr. Barrington: This responds to your July 28, 1981, letter asking whether a portion o your school bus would be considered part of the sidewall or roof for purposes of complying with Standard No. 222, *School Bus Passenger Seating and Crash Protection*.; Paragraph S5.3.1.1 defines the head impact zone in which the hea protection requirements apply. The bus sidewall, windows and doors are exempted from complying with the requirements for head impact protection even if they fall within the head impact zone. The bus roof, on the other hand, must comply with the requirements if it falls within the zone. In the bus to which you refer in your letter, the bus wall and roof structure are not distinctly separated. You ask, therefore, where the roof stops and the sidewall begins.; The agency has stated by interpretation that the roof begins where th radius of curvature of the interior structure decreases sharply. From the sketch that you enclosed with your letter, it appears that the roof would begin at the point marked 'B'. Assuming that your diagram is correct, the side of the bus below point 'B' would be considered part of the bus sidewall and would not be required to comply with the head impact requirements.; Sincerely, Frank Berndt, Chief Counsel