Subpart B—Motor Carrier Vehicle Safety Standards
§571.224 Standard No. 224; Rear impact protection.
S1. Scope. This standard establishes requirements for the
installation of rear impact guards on trailers and semitrailers
with a gross vehicle weight rating (GVWR) of 4,536 kg or more.
S2. Purpose. The purpose of this standard is to reduce
the number of deaths and serious injuries occurring when light duty
vehicles impact the rear of trailers and semitrailers with a GVWR
of 4,536 kg or more.
S3.Application. This standard applies to trailers and
semitrailers with a GVWR of 4,356 kg or more. The standard does not
apply to pole trailers, pulpwood trailers, road construction
controlled horizontal discharge trailers, special purpose vehicles,
wheels back vehicles, or temporary living quarters as defined in 49
CFR 529.2. If a cargo tank motor vehicle, as defined in 49 CFR
171.8, is certified to carry hazardous materials and has a rear
bumper or rear end protection device conforming with 49 CFR part
178 located in the area of the horizontal member of the rear
underride guard required by this standard, the guard need not
comply with the energy absorption requirement (S5.2.2) of 49 CFR
571.223.
S4. Definitions.
Chassis means the load supporting frame structure of a
motor vehicle.
Horizontal member means the structural member of the
guard that meets the configuration requirements of S5.1 of this
section when the guard is installed on the vehicle according to the
installation instructions or procedures required by S5.5 of §
571.223 , Rear Impact Guards.
Low chassis vehicle means a trailer or semitrailer having
a chassis that extends behind the rearmost point of the rearmost
tires and a lower rear surface that meets the configuration
requirements of S5.1.1 through 5.1.3 of this section.
Outer or Outboard means away from the trailer
centerline and toward the side extremities of the trailer.
Pulpwood trailer means a trailer that is designed
exclusively for harvesting logs or pulpwood and constructed with a
skeletal frame with no means for attachment of a solid bed, body,
or container.
Rear extremity means the rearmost point on a vehicle that
is above a horizontal plane located 560 mm above the ground and
below a horizontal plane located 1,900 mm above the ground when the
vehicle is configured as specified in S5.1 of this section and when
the vehicle’s cargo doors, tailgate, or other permanent structures
are positioned as they normally are when the vehicle is in motion.
Nonstructural protrusions such as taillights, rubber bumpers,
hinges and latches are excluded from the determination of the
rearmost point.
Road construction controlled horizontal discharge trailer means a trailer or semitrailer that is equipped with a mechanical
drive and a conveyor to deliver asphalt and other road building
materials, in a controlled horizontal manner, into a lay down
machine or paving equipment for road construction and paving
operations.
Rounded corner means a guard’s outermost end that curves
upward or forward toward the front of the vehicle, or both.
Side extremity means the outermost point on a vehicle’s
side that is located above a horizontal plane 560 mm above the
ground, below a horizontal plane located 190 cm above the ground,
and between a transverse vertical plane tangent to the rear
extremity of the vehicle and a transverse vertical plane located
305 mm forward of that plane when the vehicle is configured as
specified in S5.1 of this section. Non-structural protrusions such
as taillights, hinges, rubber bumpers, and latches are excluded
from the determination of the outermost point.
Special purpose vehicle means a trailer or semitrailer
that:
(1) Has work performing equipment that, while the vehicle is in
transit, resides in or moves through any portion of the space
bounded:
(i) Vertically from the ground to a horizontal plane 660 mm
above the ground;
(ii) Laterally the full width of the trailer, determined by the
trailer’s side extremities as defined in S4 of this section;
and
(iii) From the rear extremity of the trailer as defined in S4 of
this section to a transverse vertical plane 305 mm forward of the
rear extremity of the trailer; or
(2) Is equipped with a loading platform that, while the vehicle
is in transit, is completely stowed in the space bounded by a plane
tangent to the underside of the vehicle, the ground, the rear
extremity of the vehicle, and the rearmost axle, and that, when
operated, deploys from its stowed position to the rear of the
vehicle through any portion of the space described above.
Wheels back vehicle means a trailer or semitrailer whose
rearmost axle is permanently fixed and is located such that the
rearmost surface of tires of the size recommended by the vehicle
manufacturer for the vehicle on that axle is not more than 305 mm
forward of the transverse vertical plane tangent to the rear
extremity of the vehicle.
S5. Requirements.
S5.1 Installation; vehicle configuration. Each vehicle
shall be equipped with a rear impact guard certified as meeting
Federal Motor Vehicle Safety Standard No. 223, Rear Impact
Guards (§571.223). When the vehicle to which the guard is
attached is resting on level ground, unloaded, with its full
capacity of fuel, and with its tires inflated and air suspension,
if so equipped, pressurized in accordance with the manufacturer’s
recommendations, the guard shall comply with the requirements of
S5.1.1 through S5.1.3 of this section. See Figure 1 of this
section.
S5.1.1 Guard width. The outermost surfaces of the
horizontal member of the guard shall extend outboard to within 100
mm of the longitudinal vertical planes that are tangent to the side
extremities of the vehicle, but shall not extend outboard of those
planes. See Figure 1 of this section.
S5.1.2 Guard height. The vertical distance between the
bottom edge of the horizontal member of the guard and the ground
shall not exceed 560 mm at any point across the full width of the
member. Notwithstanding this requirement, guards with rounded
corners may curve upward within 255 mm of the longitudinal vertical
planes that are tangent to the side extremities of the vehicle. See
Figure 1 of this section.
S5.1.3 Guard rear surface. At any height 560 mm or more
above the ground, the rearmost surface of the horizontal member of
the guard shall be located as close as practical to a transverse
vertical plane tangent to the rear extremity of the vehicle, but no
more than 305 mm forward of that plane. Notwithstanding this
requirement, the horizontal member may extend rearward of the
plane, and guards with rounded corners may curve forward within 255
mm of the longitudinal vertical planes that are tangent to the side
extremities of the vehicle.
S5.2 Installation Requirements. Guards shall be attached
to the vehicle’s chassis by the vehicle manufacturer in accordance
with the installation instructions or procedures provided pursuant
to S5.5 of Standard No. 223, Rear Impact Guards (§571.223).
The vehicle must be of a type identified in the installation
instructions as appropriate for the guard.
[61 FR 2035, Jan. 24, 1996, as amended at 63 FR
3662, Jan. 26, 1998; 69 FR 64500, Nov. 5, 2004; 69 FR 67668, Nov.
19, 2004; 71 FR 9277, Feb. 23, 2006]