Interpretation ID: 18805.drn
Ms. Barbara Goodman
Associate Director, Pupil Transportation
Commonwealth of Virginia
Department of Education
P.O. Box 2120
Richmond, VA 23218-2120
Dear Ms. Goodman:
This responds to your request for an interpretation of school bus seat back height requirements in Federal Motor Vehicle Safety Standard No. 222, School bus passenger seating and crash protection. I regret the delay in this response.
I understand that you explained to Mr. Charles Hott of our agency that the C. E. White Company manufactures school bus seats that are integrated with child restraints, and which have 711 millimeter (28 inch) high seat backs. While you are interested in having some of these seats installed in school buses along with standard school bus seats with 508 millimeters (20 inch) high seat backs, you ask about Standard 222's requirements that apply to a 711 millimeter (28 inch) high seat back. You pose five questions, which we answer below.
1. "If a C. E. White or similar type seat, with a 39 inch seat cushion width and a 28 inch seat back height is installed in a school bus, what is the federal requirement for the seat back/barrier immediately in front of the [tall] C. E. White seat?"
We believe you are asking whether the height of the seat back or barrier in front of the tall seat has to be at least 508 millimeters (20 inches) or at least 711 millimeters (28 inches). As explained below, assuming the width of the seat bench in front of the C.E. White type seat is 990 millimeters (39 inches), the seat back or restraining barrier in front of the C.E. White type seat has to be at least 508 millimeters (20 inches), not 711 millimeters (28 inches).
Seat back height. The minimum height required of seat backs is specified in S5.1.2 of Standard 222. S5.1.2 states: "Each school bus passenger seat shall be equipped with a seat back that, in the front projected view, has a front surface area above the horizontal plane that passes through the seating reference point, and below the horizontal plane 508 mm [20 inches] above the seating reference point, of not less than 90 percent of the seat bench width in millimeters multiplied by 508." Simply stated, this section requires seat back heights of at least 508 millimeters (20 inches) above the seating reference point.(1) Standard 222 does not require the seat back to be taller if it is in front of a school bus seat that has a 711 millimeter (28 inch) high seat back.
Restraining barrier height. Paragraph S5.2 of Standard 222 requires each vehicle to be equipped with a restraining barrier forward of any designated seating position that does not have the rear surface of another school bus passenger seat within 610 mm (24 inches) of its seating reference point.
The minimum height for restraining barriers is specified in S5.2.2 of Standard 222. That section states: "The position and rear surface area of the restraining barrier shall be such that, in a front projected view of the bus, each point of the barrier's perimeter coincides with or lies outside of the perimeter of the seat back of the seat for which it is required."
In an interpretation letter of April 8, 1977, to Wayne Corporation (copy provided), this agency interpreted the restraining barrier requirement to mean that a restraining barrier must only coincide with or lie outside of the seat back surface required by S5.1.2. Thus, in a front projected view of the bus, each point of the barrier's perimeter would have to coincide with or lie outside of the perimeter of a seat back with a height of 508 millimeters (20 inches) (assuming the width of the bench seat for which the seat back is required is 990 millimeters (39 inches)).
2. "If a C. E. White or similar seat, with a 28 inch seat back height, is installed as the rear seat of a sixty four passenger school bus, will each of the seat backs in front of each seat require a 'New York-type' seat back (28 inch height)."
As answered above, the seat backs in front of the tall C.E. White type seat do not have to be 711 millimeters (28 inches) in height simply because they are positioned in front of a seat that has a 711 millimeter (28 inch) seat back. The size of a seat back depends on the width of the seat for which it provides a back.
3. "Can a school bus body be configured with different heights of seat backs installed in a single unit."
By "in a single unit," I will assume you mean "in one school bus." Alternatively, you might mean "in one row of seats." Our answer is that nothing in Standard 222 specifies that in a school bus or row of seats, each seat back must be of the same height. However, each passenger seating position must have a seat back that meets S5.1.2 and have in front of it a seat back that meets S5.1.2, or a restraining barrier that meets S5.2.2.
4. "Can seat back heights exceed the federal requirement, and if so, how does this impact other seats within the same unit?"
As previously stated, the area and height of any seat back depends on the width of the seat bench for which it provides a back, not on the height of other seat backs. Each passenger seating position must have a seat back that meets S5.1.2, and must be faced with a seat back or a restraining barrier.(2)
5. "If the first seat has a short (30 inch width) seat cushion, what is the federal requirement for both the barrier height and width and the seat back height and width."
You explained to Dorothy Nakama of my staff that this question asks about the situation where the first row of seats has a 762 millimeter (30 inch) width and the second row directly behind the first row has a 990 millimeter (39 inch) width. There is a restraining barrier in front of the first row. You are concerned about how a child sitting in the second row in the 228 millimeter (9 inch) section not faced by a seat back is to be protected.
The child sitting in the 228 millimeter (9 inch) section in the second row must be protected in part by a restraining barrier. Referring again to the letter of April 8, 1977 to Wayne Corporation, the combination of the restraining barrier and the seat back of the first row seat must coincide with or lie outside of the perimeter of the second row's required seat back surface.
I hope this information is helpful. If you have any further questions, please feel free to contact Dorothy Nakama of my staff at this address or by telephone at (202) 366-2992.
Sincerely,
Frank Seales, Jr.
Chief Counsel
Enclosures
ref:222
d.4/26/99
1. For a 990 millimeter (39 inch) bench seat, the seat back must have a front surface area at least .9(990) multiplied by 508, or 452,628 square millimeters (702 square inches).
2. An issue that may be implicit in your question is whether States may require a seat back height greater than 508 millimeters (20 inches). Our position is that any State requirement relating to seat back height, other than one identical to the Federal formula that establishes a minimum height of 508 millimeters (20 inches), is preempted under 49 USC 30103(b) of our statute. However, our statute does not prevent governmental entities from specifying additional safety features in vehicles purchased for their own use. Thus, for public school buses, a State may specify a seat back higher than 508 millimeters (20 inches). See March 23, 1976 to Mr. Martin V. Chauvin, copy enclosed.