Interpretation ID: aiam4347
Safety Engineering
Mercedes-Benz of North America
Inc.
P.O. Box 350
Montvale
NJ 07645;
Dear Mr. Baloga: Thank you for your letter of May 28, 1987, to Stephen Oesch of my staf concerning the requirements of Standard No. 301 *Fuel System Integrity*. You noted that there is a conflict in the standard about the correct ground clearance of the contoured impact surface used in the school bus impact test of the standard. You noted that S7.5.1 of the standard refers to the dimension between the ground to the lower edge of the impact surface as 5.25 + 0.5 inches, while figure 2 of the standard shows the ground clearance to be 12.25. As discussed below, the correct dimension is 5.25 + 0.5 inches.; The agency adopted the use of the contoured barrier in a final rul issued on April 16, 1975. The preamble to the final rule stated that 'The contoured barrier would incorporated the moving barrier specification of SAE Recommended Practice J972a (March 1973). However, the impact surface of the barrier would be at a height 30 inches above the ground level, rather than 37 inches as specified in the SAE provision. Studies have shown that a 30- inch test height is more representative of actual collisions. This would be a typical engine height of vehicles that might impact a school bus.' Thus, in S7.5.1 of the standard, the agency adopted the ground clearance as 5.25 inches + 0.5 inches to ensure that the top of the barrier would be 30 inches from the ground. In Figure 2, the agency apparently incorporated the barrier dimensions directly from the SAE Recommended Practice J972a, without changing the ground clearance dimension; We will publish an amendment to the standard that will correct th ground clearance dimension set out in Figure 2 of Standard No. 301.; If you have any further questions, please let me know. Sincerely, Erika Z. Jones, Chief Counsel