49 C.F.R. § 571.222 Standard No. 222; School bus passenger seating and crash protection.
Title 49 - Transportation
S1. Scope. This standard establishes occupant protection requirements for school bus passenger seating and restraining barriers. S2. Purpose. The purpose of this standard is to reduce the number of deaths and the severity of injuries that result from the impact of school bus occupants against structures within the vehicle during crashes and sudden driving maneuvers. S3. Application. This standard applies to school buses. S4. Definitions. Contactable surface means any surface within the zone specified in S5.3.1.1 that is contactable from any direction by the test device described in S6.6, except any surface on the front of a seat back or restraining barrier 76 mm or more below the top of the seat back or restraining barrier. School bus passenger seat means a seat in a school bus, other than the driver's seat. Wheelchair means a wheeled seat frame for the support and conveyance of a physically disabled person, comprised of at least a frame, seat, and wheels. Wheelchair occupant restraint anchorage means the provision for transferring wheelchair occupant restraint system loads to the vehicle structure. Wheelchair securement anchorage means the provision for transferring wheelchair securement device loads to the vehicle structure. Wheelchair securement device means a strap, webbing or other device used for securing a wheelchair to the school bus, including all necessary buckles and other fasteners. S4.1 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 millimeters divided by 381 and rounded to the nearest whole number. S5. Requirements. (a) Each vehicle with a gross vehicle weight rating of more than 4,536 kg shall be capable of meeting any of the requirements set forth under this heading when tested under the conditions of S6. However, a particular school bus passenger seat (i.e., test specimen) in that weight class need not meet further requirements after having met S5.1.2 and S5.1.5, or having been subjected to either S5.1.3, S5.1.4, or S5.3. (b) Each vehicle with a gross vehicle weight rating of 4,536 kg or less shall be capable of meeting the following requirements at all seating positions other than the driver's seat: (1)(A) In the case of vehicles manufactured before September 1, 1991, the requirements of §§571.208, 571.209, and 571.210 as they apply to multipurpose passenger vehicles; or (B) In the case of vehicles manufactured on or after September 1, 1991, the requirements of S4.4.3.3 of §571.208 and the requirements of §§571.209 and 571.210 as they apply to school buses with a gross vehicle weight rating of 4,536 kg or less; and (2) The requirements of S5.1.2, S5.1.3, S5.1.4, S5.1.5, S5.3, and S5.4 of this standard. However, the requirements of §§571.208 and 571.210 shall be met at W seating positions in a bench seat using a body block as specified in Figure 2 of this standard, and a particular school bus passenger seat (i.e., a test specimen) in that weight class need not meet further requirements after having met S5.1.2 and S5.1.5, or after having been subjected to either S5.1.3, S5.1.4, or S5.3 of this standard or §571.210. S5.1 Seating requirements. School bus passenger seats shall be forward facing. S5.1.1 [Reserved] S5.1.2 Seat back height and surface area. 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 above the seating reference point, of not less than 90 percent of the seat bench width in millimeters multiplied by 508. S5.1.3 Seat performance forward. When a school bus passenger seat that has another seat behind it is subjected to the application of force as specified in S5.1.3.1 and S5.1.3.2, and subsequently, the application of additional force to the seat back as specified in S5.1.3.3 and S5.1.3.4: (a) The seat back force/deflection curve shall fall within the zone specified in Figure 1; (b) Seat back deflection shall not exceed 356 mm; (for determination of (a) and (b) the force/deflection curve describes only the force applied through the upper loading bar, and only the forward travel of the pivot attachment point of the upper loading bar, measured from the point at which the initial application of 44 N of force is attained.) (c) The seat shall not deflect by an amount such that any part of the seat moves to within 102 mm of any part of another school bus passenger seat or restraining barrier in its originally installed position; (d) The seat shall not separate from the vehicle at any attachment point; and (e) Seat components shall not separate at any attachment point. S5.1.3.1 Position the loading bar specified in S6.5 so that it is laterally centered behind the seat back with the bar's longitudinal axis in a transverse plane of the vehicle and in any horizontal plane between 102 mm above and 102 mm below the seating reference point of the school bus passenger seat behind the test specimen. S5.1.3.2 Apply a force of 3,114W newtons horizontally in the forward direction through the loading bar at the pivot attachment point. Reach the specified load in not less than 5 nor more than 30 seconds. S5.1.3.3 No sooner than 1.0 second after attaining the required force, reduce that force to 1,557W newtons and, while maintaining the pivot point position of the first loading bar at the position where the 1,557W newtons is attained, position a second loading bar described in S6.5 so that it is laterally centered behind the seat back with the bar's longitudinal axis in a transverse plane of the vehicle and in the horizontal plane 406 mm above the seating reference point of the school bus passenger seat behind the test specimen, and move the bar forward against the seat back until a force of 44 N has been applied. S5.1.3.4 Apply additional force horizontally in the forward direction through the upper bar until 452W joules of energy have been absorbed in deflecting the seat back (or restraining barrier). Apply the additional load in not less than 5 seconds nor more than 30 seconds. Maintain the pivot attachment point in the maximum forward travel position for not less than 5 seconds nor more than 10 seconds and release the load in not less than 5 nor more than 30 seconds. (For the determination of S5.1.3.4 the force/deflection curve describes only the force applied through the upper loading bar, and the forward and rearward travel distance of the upper loading bar pivot attachment point measured from the position at which the initial application of 44 N of force is attained.) S5.1.4 Seat performance rearward. When a school bus passenger seat that has another seat behind it is subjected to the application of force as specified in S5.1.4.1 and S5.1.4.2: (a) Seat back force shall not exceed 9,786 N; (b) Seat back deflection shall not exceed 254 mm; (for determination of (a) and (b) the force/deflection curve describes only the force applied through the loading bar, and only the rearward travel of the pivot attachment point of the loading bar, measured from the point at which the initial application of 222 N is attained. (c) The seat shall not deflect by an amount such that any part of the seat moves to within 102 mm of any part of another passenger seat in its originally installed position; (d) The seat shall not separate from the vehicle at any attachment point; and (e) Seat components shall not separate at any attachment point. S5.1.4.1 Position the loading bar described in S6.5 so that it is laterally centered forward of the seat back with the bar's longitudinal axis in a transverse plane of the vehicle and in the horizontal plane 343 mm above the seating reference point of the test specimen, and move the loading bar rearward against the seat back until a force of 222 N has been applied. S5.1.4.2 Apply additional force horizontally rearward through the loading bar until 316W joules (J) of energy has been absorbed in deflecting the seat back. Apply the additional load in not less than 5 seconds nor more than 30 seconds. Maintain the pivot attachment point in the maximum rearward travel position for not less than 5 seconds nor more than 10 seconds and release the load in not less than 5 seconds nor more than 30 seconds. (For determination of S5.1.4.2 the force deflection curve describes the force applied through the loading bar and the rearward and forward travel distance of the loading bar pivot attachment point measured from the position at which the initial application of 222 N of force is attained.) S5.1.5 Seat cushion retention. In the case of school bus passenger seats equipped with seat cushions, with all manual attachment devices between the seat and the seat cushion in the manufacturer's designated position for attachment, the seat cushion shall not separate from the seat at any attachment point when subjected to an upward force in newtons of 5 times the mass of the seat cushion in kilograms and multiplied by 9.8 m/s2 , applied in any period of not less than 1 nor more than 5 seconds, and maintained for 5 seconds. S5.2 Restraining barrier requirements. Each vehicle shall 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 of its seating reference point, measured along a horizontal longitudinal line through the seating reference point in the forward direction. S5.2.1 Barrier-seat separation. The horizontal distance between the restraining barrier's rear surface and the seating reference point of the seat in front of which the barrier is required shall not be more than 610 mm measured along a horizontal longitudinal line through the seating reference point in the forward direction. S5.2.2 Barrier position and rear surface area. 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. S5.2.3 Barrier performance forward. When force is applied to the restraining barrier in the same manner as specified in S5.1.3.1 through S5.1.3.4 for seating performance tests: (a) The restraining barrier force/deflection curve shall fall within the zone specified in Figure 1; (b) Restraining barrier deflection shall not exceed 356 mm; (for computation of (a) and (b) the force/deflection curve describes only the force applied through the upper loading bar, and only the forward travel of the pivot attachment point of the loading bar, measured from the point at which the initial application of 44 N of force is attained.) (c) Restraining barrier deflection shall not interfere with normal door operation; (d) The restraining barrier shall not separate from the vehicle at any attachment point; and (e) Restraining barrier components shall not separate at any attachment point. S5.3 Impact zone requirements. S5.3.1 Head protection zone. Any contactable surface of the vehicle within any zone specified in S5.3.1.1 shall meet the requirements of S5.3.1.2 and S5.3.1.3. However, a surface area that has been contacted pursuant to an impact test need not meet further requirements contained in S5.3. S5.3.1.1 The head protection zones in each vehicle are the spaces in front of each school bus passenger seat which are not occupied by bus sidewall, window, or door structure and which, in relation to that seat and its seating reference point, are enclosed by the following planes; (a) Horizontal planes 305 mm and 1016 mm above the seating reference point; (b) A vertical longitudinal plane tangent to the inboard (aisle side) edge of the seat; and (c) A vertical longitudinal plane 83 mm inboard of the outboard edge of the seat; (d) Vertical transverse planes through and 762 mm forward of the reference point. S5.3.1.2 Head form impact requirement. When any contactable surface of the vehicle within the zones specified in S5.3.1.1 is impacted from any direction at 6.7 m/s by the head form described in S6.6, the axial acceleration at the center of gravity of the head form shall be such that the expression shall not exceed 1,000 where “a” is the axial acceleration expressed as a multiple of “g” (the acceleration due to gravity), and “t1” and “t2” are any two points in time during the impact. S5.3.1.3 Head form force distribution. When any contactable surface of the vehicle within the zones specified in S5.3.1.1 is impacted from any direction at 6.7 m/s by the head form described in S6.6, the energy necessary to deflect the impacted material shall be not less than 4.5 joules before the force level on the head form exceeds 667 N. When any contactable surface within such zones is impacted by the head form from any direction at 1.5 m/s the contact area on the head form surface shall be not less than 1,935 mm2 . S5.3.2 Leg protection zone. Any part of the seat backs or restraining barriers in the vehicle within any zone specified in S5.3.2.1 shall meet the requirements of S5.3.2.2. S5.3.2.1 The leg protection zones of each vehicle are those parts of the school bus passenger seat backs and restraining barriers bounded by horizontal planes 305 mm above and 102 mm below the seating reference point of the school bus passenger seat immediately behind the seat back or restraining barrier. S5.3.2.2 When any point on the rear surface of that part of a seat back or restraining barrier within any zone specified in S5.3.2.1 is impacted from any direction at 4.9 m/s by the knee form specified in S6.7, the resisting force of the impacted material shall not exceed 2,669 N and the contact area on the knee form surface shall not be less than 1,935 mm2 . S5.4 Each school bus having one or more locations designed for carrying a person seated in a wheelchair shall comply with S5.4.1 through S5.4.4 at each such wheelchair location. S5.4.1 Wheelchair securement anchorages. Each wheelchair location shall have not less than four wheelchair securement anchorages complying with S5.4.1.1 through S5.4.1.3. S5.4.1.1 Each wheelchair securement anchorage shall have a wheelchair securement device complying with S5.4.2 attached to it. S5.4.1.2 The wheelchair securement anchorages at each wheelchair location shall be situated so that— (a) A wheelchair can be secured in a forward-facing position. (b) The wheelchair can be secured by wheelchair securement devices at two locations in the front and two locations in the rear. (c) The front wheel of a three-wheeled wheelchair can be secured. S5.4.1.3 Each wheelchair securement anchorage shall be capable of withstanding a force of 13,344 Newtons applied as specified in paragraphs (a) through (d) of this section. When more than one securement device share a common anchorage, the anchorage shall be capable of withstanding a force of 13,344 Newtons multiplied by the number of securement devices sharing that anchorage. (a) The initial application force shall be applied at an angle of not less than 30 degrees, but not more than 60 degrees, measured from the horizontal. (See Figure 4.) (b) The horizontal projection of the force direction shall be within a horizontal arc of ±45 degrees relative to a longitudinal line which has its origin at the anchorage location and projects rearward for an anchorage whose wheelchair securement device is intended to secure the front of the wheelchair and forward for an anchorage whose wheelchair securement device is intended to secure the rear of the wheelchair. (See Figure 4.) (c) The force shall be applied at the onset rate of not more than 133,440 Newtons per second. (d) The 13,344 Newton force shall be attained in not more than 30 seconds, and shall be maintained for 10 seconds. S5.4.2 Wheelchair securement devices. Each wheelchair securement device shall— (a) If incorporating webbing or a strap— (1) Comply with the requirements for Type 1 safety belt systems in S4.2, S4.3, and S4.4(a) of FMVSS No. 209, Seat Belt Assemblies; and (2) Provide a means of adjustment to remove slack from the device. (b) If not incorporating webbing or a strap, limit movement of the wheelchair through either the equipment design or a means of adjustment. S5.4.3 Wheelchair occupant restraint anchorages. S5.4.3.1 Each wheelchair location shall have: (a) Not less than one anchorage for the upper end of the upper torso restraint; and (b) Not less than two floor anchorages for wheelchair occupant pelvic and upper torso restraint. S5.4.3.2 Each wheelchair occupant restraint floor anchorage shall be capable of withstanding a force of 13,344 Newtons applied as specified in paragraphs (a) through (d). When more than one wheelchair occupant restraint share a common anchorage, the anchorage shall be capable of withstanding a force of 13,344 Newtons multiplied by the number of occupant restraints sharing that anchorage. (a) The initial application force shall be applied at an angle of not less than 45 degrees, but not more than 80 degrees, measured from the horizontal. (See Figure 5.) (b) The horizontal projection of the force direction shall be within a horizontal arc of ±45 degrees relative to a longitudinal line which has its origin at the anchorage and projects forward. (See Figure 5.) (c) The force shall be applied at an onset rate of not more than 133,440 Newtons per second. (d) The 13,344 Newton force shall be attained in not more than 30 seconds, and shall be maintained for 10 seconds. (e) When a wheelchair securement device and an occupant restraint share a common anchorage, including occupant restraint designs that attach the occupant restraint to the securement device or the wheelchair, the loads specified by S5.4.1.3 and S5.4.3.2 shall be applied simultaneously, under the conditions specified in S5.4.3.2 (a) and (b). (See Figure 6.) S5.4.3.3 Each anchorage for a wheelchair occupant upper torso restraint shall be capable of withstanding a force of 6,672 Newtons applied as specified in paragraphs (a) through (d). (a) The initial application force shall be applied at a vertical angle of not less than zero degrees, but not more than 40 degrees, below a horizontal plane which passes through the anchorage. (See Figure 7.) (b) The projection of the force direction onto the horizontal plane shall be within zero degrees and 45 degrees as measured from a longitudinal line with its origin at the anchorage and projecting forward. (See Figure 7.) (c) The force shall be applied at the onset rate of not more than 66,720 Newtons per second. (d) The 6,672 Newton force shall be attained in not more than 30 seconds, and shall be maintained for 10 seconds. S5.4.4 Wheelchair occupant restraints. (a) Each wheelchair location shall have wheelchair occupant pelvic and upper torso restraints attached to the anchorages required by S5.4.3. (b) Each wheelchair occupant restraint shall comply with the requirements for Type 2 safety belt systems in S4.2, S4.3, and S4.4(b) of FMVSS No. 209, Seat Belt Assemblies. S6. Test conditions. The following conditions apply to the requirements specified in S5. S6.1 Test surface. The bus is at rest on a level surface. S6.2 Tires. Tires are inflated to the pressure specified by the manufacturer for the gross vehicle weight rating. S6.3 Temperature. The ambient temperature is any level between 0 degrees C and 32 degrees C. S6.4 Seat back position. If adjustable, a seat back is adjusted to its most upright position. S6.5 Loading bar. The loading bar is a rigid cylinder with an outside diameter of 152 mm that has hemispherical ends with radii of 76 mm and with a surface roughness that does not exceed 1.6 µm, root mean square. The length of the loading bar is 102 mm less than the width of the seat back in each test. The stroking mechanism applies force through a pivot attachment at the center point of the loading bar which allows the loading bar to rotate in a horizontal plane 30 degrees in either direction from the transverse position. S6.5.1 A vertical or lateral force of 17,792 N applied externally through the pivot attachment point of the loading bar at any position reached during a test specified in this standard shall not deflect that point more than 25 mm. S6.6 Head form. The head form for the measurement of acceleration is a rigid surface comprised of two hemispherical shapes, with total equivalent mass of 5.2 kg. The first of the two hemispherical shapes has a diameter of 166 mm. The second of the two hemispherical shapes has a 50 mm diameter and is centered as shown in Figure 3 to protrude from the outer surface of the first hemispherical shape. The surface roughness of the hemispherical shapes does not exceed 1.6 µm, root mean square. S6.6.1 The direction of travel of the head form is coincidental with the straight line connecting the centerpoints of the two spherical outer surfaces which constitute the head form shape. S6.6.2 The head form is instrumented with an acceleration sensing device whose output is recorded in a data channel that conforms to the requirements for a 1,000 Hz channel class as specified in SAE Recommended Practice J211a, December 1971. The head form exhibits no resonant frequency below three times the frequency of the channel class. The axis of the acceleration sensing device coincides with the straight line connecting the centerpoints of the two hemispherical outer surfaces which constitute the head form shape. S6.6.3 The head form is guided by a stroking device so that the direction of travel of the head form is not affected by impact with the surface being tested at the levels called for in the standard. S6.7 Knee form. The knee form for measurement of force is a rigid 76 millimeter-diameter cylinder, with an equivalent weight of 44 N that has one hemispherical end with a 38 mm radius forming a contact surface of the knee form. The hemispherical surface roughness does not exceed 1.6 µm, root mean square. S6.7.1 The direction of travel of the knee form is coincidental with the centerline of the rigid cylinder. S6.7.2 The knee form is instrumented with an acceleration sensing device whose output is recorded in a data channel that conforms to the requirements of a 600 Hz channel class as specified in the SAE Recommended Practice J211a, December 1971. The knee form exhibits no resonant frequency below three times the frequency of the channel class. The axis of the acceleration sensing device is aligned to measure acceleration along the centerline of the cylindrical knee form. S6.7.3 The knee form is guided by a stroking device so that the direction of travel of the knee form is not affected by impact with the surface being tested at the levels called for in the standard. S6.8 The head form, knee form, and contactable surfaces are clean and dry during impact testing. [41 FR 4018, Jan. 28, 1976, as amended at 41 FR 28528, July 12, 1976; 41 FR 36027, Aug. 26, 1976; 41 FR 54945, Dec. 16, 1976; 42 FR 64120, Dec. 22, 1977; 43 FR 9150, Mar. 6, 1978; 44 FR 18675, Mar. 29, 1979; 48 FR 12386, Mar. 24, 1983; 54 FR 46268, Nov. 2, 1989; 58 FR 4593, Jan. 15, 1993; 58 FR 46876, Sept. 3, 1993; 63 FR 28948, 28950, May 27, 1998]
Title 49: Transportation
PART 571—FEDERAL MOTOR VEHICLE SAFETY STANDARDS
Subpart B—Federal Motor Vehicle Safety Standards
§ 571.222 Standard No. 222; School bus passenger seating and crash protection.
