Interpretation ID: nht89-1.24

TYPE: INTERPRETATION-NHTSA

DATE: 02/23/89

FROM: DIANE K. STEED -- NHTSA

TO: HOWARD WOLPE -- U.S. HOUSE OF REPRESENTATIVES

TITLE: NONE

ATTACHMT: TRANSMITTAL LETTER DATED 12/21/88 FROM HOWARD WOLPE -- CONGRESS TO JAMES BURNLEY; LETTER DATED 12/12/88 FROM DENNIS D. FURR TO HOWARD WOLPE -- CONGRESS

TEXT: Dear Mr. Wolpe:

Thank you for your letter to former Secretary Burnley on behalf of your constituent, Mr. Dennis Furr of Lansing, Michigan. I've been asked to respond to your letter since the National Highway Traffic Safety Administration (NHTSA) is responsible for admi nistering Federal programs relating to school bus safety.

Mr. Furr is concerned about the potential safety problems that may result if school bus seats are being overloaded. In particular, Mr. Furr asks whether NHTSA's Highway Safety Program Guideline (HSPG) No. 17, Pupil Transportation Safety (23 CFR @ 1204.4 ), is consistent with Federal Motor Vehicle Safety Standard (FMVSS) No. 222, School Bus Passenger Seating and Crash Protection (49 CFR @ 571.222), with regard to seating specifications. Mr. Furr is particularly interested in how manufacturers are calcul ating the number of seating positions on a bench seat.

I am pleased to address your constituent's concerns. Before I begin, I want to note that we have answered a number of similar inquiries from Mr. Furr in past years.

We have two sets of "regulations" for school buses. The first, issued under the Vehicle Safety Act, includes our motor vehicle safety standards which apply to the manufacture and sale of new school buses. Compliance with these standards is mandatory fo r new vehicle manufacturers, and is enforced by this agency with civil penalties. FMVSS No. 222, with which your constituent is concerned, is one such safety standard. The second set of "regulations," or guidelines, for school buses was issued under th e Highway Safety Act. Guidelines issued under this Act are not mandatory for the states; rather, they are recommended practices. Highway Safety Program Guideline No. 17, to which Mr. Furr frequently refers in his letter, consists of recommendations to the States for operating their school buses and pertains to Federal funding of State highway safety programs.

Both FMVSS No. 222 and Guideline No. 17 contain specifications for school bus seating. Paragraph S4.1 of FMVSS No. 222 states: "The number of

seating positions considered to be in a bench seat is expressed by the symbol W, and calculated as the bench width in inches divided by 15 and rounded to the nearest whole number." The guideline for seating accommodations in HSPG 17 states:

Seating should be provided that will permit each occupant to sit in a seat in a plan view lateral location, intended by the manufacturers to provide seating accommodation for a person at least as large as a 5th percentile adult female, as defined in 4 9 CFR 571.3.

Mr. Furr appears to see a conflict between the formula used in calculating the forces to be applied to the seats of large school buses under FMVSS No. 222, on the one hand, and the use by States and manufacturers of 13-inch seating positions for rating t he capacity of a 39-inch seat, on the other hand. I believe that Mr. Furr's belief in the existence of a conflict rests on a misunderstanding.

We view Standard No. 222 and HSPG 17 as complementary, not inconsistent. HSPG 17 reflects NHTSA's belief that all school bus passengers should be seated in the interest of safety. To that end, the guideline provides that there should be a seating posit ion for each passenger and that the position should be at least large enough to accommodate a 5th percentile adult female. The hip width (sitting) of a 5th percentile adult female is 12.8 inches.

The figure "15" in FMVSS No. 222's compliance formula is not a minimum requirement for the width of a seating position. It is the number which is used to establish the number of designated seating positions and ensures that the forces applied to the sea t during compliance tests are reasonable reflections of the crash forces that would be involved in a real-world crash. It is also the number which ensures that the width of the smallest seat is approximately equal to the hip width of the 5th percentile female. That is consistent with HSPG 17 which provides that seating positions shall be at least large enough for a 5th percentile female. Use of the figure "15" in the FMVSS No. 222 formula results in a minimum seating position width of 12.67 inches (f or a 38-inch wide seat.) That is only slightly smaller than the 12.8 inch hip width of the 5th percentile female. For a 39-inch wide seat, the single position width is 13 inches, which is slightly larger than the hip width of a 5th percentile female.

It should be remembered, however, that the number of seating positions derived from the FMVSS No. 222 formula is not meant to be a measure of the absolute capacity of the bus for all size occupants. We recognize that, in practice, school buses transport a tremendously wide variety of student sizes. For example, a bus that may be capable of easily accommodating 65 preschool or elementary students may be capable of carrying only 43 high school students. When the bus is used to transport students of wide ly varying ages and sizes, reasonable accommodations may vary between those values. The decision on how many passengers may be

comfortably and safely accommodated, therefore, is a decision that must be reached by the bus operator, in light of the ages and sizes of passengers involved.

NHTSA does not have the authority under either the Highway Safety Act or Vehicle Safety Act to regulate how States use school buses. Therefore, NHTSA could not preclude a State from carrying more passengers on a bench seat than there are designated seat ing positions. However, this agency argues with Mr. Furr that a student should not sit on a seat unless the student can sit fully on the seat instead of sitting only partially on the seat and thus only being partially protected by the compartmentalizati on. We believe that Mr. Furr's concerns as they apply to public schools would be best addressed by his working with the local school board and state officials.

Mr. Furr is also concerned about a reference in our occupant crash protection standard (No. 208) to a 95th-percentile adult male occupant size. He asks why FMVSS No. 222 uses a 15-inch seat dimension, when FMVSS No. 208 references the 95th-percentile ad ult male occupant size in specifying occupant sizes which safety belts must adjust to fit.

Both FMVSS No. 208 and FMVSS No. 222 are directed at providing occupant crash protection. Both of these standards set forth comprehensive requirements that are directed at protecting occupants likely to be inside a vehicle in a crash. With regard to sch ool buses, the agency determined that the crash protection requirements should be developed taking into account the full size range of passengers typically riding on school buses. If we designed the force and deflection (energy-absorbing) characteristic s of the seats for the 95th percentile males, the seats may be too stiff for a small child.

Finally, Mr. Furr asks whether, when voluntarily installing safety belts on large school buses, States are violating Federal law by using S4.1 of FMVSS No. 222 in determining how many positions (and belts) there are on a bench seat. The answer is no. FM VSS No. 222 requires safety belts only for the passenger positions of small (10,000 pounds or less GVWR) school buses. Under S5 of the standard, belts on a small school bus bench seat are installed at "W" seating positions, as determined under S4.1. If a State wishes to order belts on its new large school bus and to use the same method for determining the number of belts to be installed, the State may do so.

I hope this information is helpful. If you have any further questions, please do not hesitate to contact me.

Sincerely,