Global Technical Regulation No. 7
|Name:||Global Technical Regulation No. 7|
|Official Title:||Head Restraints.|
|Country:||ECE - United Nations|
|Date of Issue:||2008-03-13|
|Number of Pages:||79|
|Vehicle Types:||Bus, Car, Component, Heavy Truck, Light Truck|
|Subject Categories:||Occupant Protection|
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head, restraint, seat, position, test, restraints, back, height, backset, annex, vehicle, paragraph, torso, rear, requirements, regulation, angle, front, whiplash, procedure, h-point, dynamic, adjustment, dummy, machine, point, seating, measurement, positions, measured, line, adjustable, seats, vertical, centre, design, gtr, r-point, occupant, vehicles, injuries, outboard, top, injury, pan, rearward, manufacturer, reference, plane, load
All InterRegs documents are formatted as PDF files and contain the full text, tables, diagrams and illustrations of the original as issued by the national government authority. We do not re-word, summarise, cut or interpret the regulatory documents. They are consolidated, published in English, and updated on a regular basis. The following text extract indicates the scope of the document, but does not represent the actual PDF content.
June 4, 2008
Created on November 18, 2004, Pursuant to Article 6 of the
AGREEMENT CONCERNING THE ESTABLISHING OF GLOBAL TECHNICAL
REGULATIONS FOR WHEELED VEHICLES, EQUIPMENT AND PARTS WHICH
CAN BE FITTED AND/OR BE USED ON WHEELED VEHICLES
(ECE/TRANS/132 and Corr.1)
DONE AT GENEVA ON JUNE 25, 1998
GLOBAL TECHNICAL REGULATION NO. 07
(ESTABLISHED IN THE GLOBAL REGISTRY ON MARCH 13, 2008)
Minimum height measurement test procedure
Minimum width measurement test procedure
GAP measurement test procedure
Backset measurement test procedure using the HRMD method
Backset measurement test procedure using the R-Point method
Displacement, backset retention, and strength test procedure
Energy absorption test procedure
Height retention test procedure
Dynamic performance test procedure
Non-use position test procedure
Three-dimensional reference system
Procedure for validation of the H-Point and R-Point relationship for seating positions in
Description of the three-dimensional H-Point machine
2. UNDERSTANDING WHIPLASH
4. Although whiplash injuries can occur in any kind of crash, an occupant's chances of
sustaining this type of injury are greatest in rear-end collisions. When a vehicle is struck
from behind, typically several things occur in quick succession to an occupant of that
vehicle. First, from the occupant's frame of reference, the back of the seat moves forward
into his or her torso, straightening the spine and forcing the head to rise vertically. Second,
as the seat pushes the occupant’s body forward, the unrestrained head tends to lag behind.
This causes the neck to change shape, first taking on an S-shape and then bending
backward. Third, the forces on the neck accelerate the head, which catches up with − and,
depending on the seat back stiffness and if the occupant is using a shoulder belt, passes −
the restrained torso. This motion of the head and neck, which is like the lash of a whip,
gives the resulting neck injuries their popular name.
3. CURRENT KNOWLEDGE
5. There are many hypotheses as to the mechanisms of whiplash injuries. Despite a lack of
consensus with respect to whiplash injury biomechanics, there is research indicating that
reduced backset will result in reduced risk of whiplash injury. For example, one study of
Volvo vehicles reported that, when vehicle occupants involved in rear crashes had their
heads against the head restraint (an equivalent to 0 mm backset) during impact, no
whiplash injury occurred. By contrast, another study showed significant increase in injury
and duration of symptoms when occupant's head was more than 100 mm away from the
head restraint at the time of the rear impact.
6. In addition, the persistence of whiplash injuries in the current fleet of vehicles indicates that
the existing height is not sufficient to prevent excessive movement of the head and neck
relative to the torso for some people. Specifically, the head restraints do not effectively limit
rearward movement of the head of a person at least as tall as the average occupant.
Biomechanically, head restraints that reach at least up to the centre of gravity of the head
would better prevent whiplash injuries, because the head restraint can more effectively limit
the movement of the head and neck.
7. In a recent report from the Insurance Institute for Highway Safety (IIHS), Farmer, Wells, and
Lund examined automobile insurance claims to determine the rates of neck injuries in rear
end crashes for vehicles with the improved geometric fit of head restraints (reduced backset
and increased head restraint height). Their data indicate that these improved head
restraints are reducing the risk of whiplash injury. Specifically, there was an 18% reduction
in injury claims. Similarly, United States of America computer generated models have
shown that the reduction of the backset and an increase in the height of the head restraint
reduces the level of neck loading and relative head-to-torso motion that may be related to
the incidence of whiplash injuries.
13. It was proposed that the gtr, as it pertains to front outboard seats, should apply to vehicles
up to 4,536 kg. The United States of America presented justification (HR-4-4), developed in
1989, when the applicability of their Regulation was increased to 4,536 kg. By extending
the applicability from passenger cars to include trucks, buses, and multipurpose passenger
vehicles, there was an estimated reduction of 510 to 870 injuries at an average cost of
$29.45 per vehicle (1989 dollars). The United States of America presented further analysis
(HR-10-3) that showed an additional 348 injuries reduced when the requirements of the gtr
are applied to Category 2 vehicles (light trucks) between the range of 3,500 − 4,500 kg
GVM. Japan presented 2004 data (HR-4-10) showing the breakdown, by vehicle weight, of
crashes resulting in whiplash injuries. They show 7,173 (2.3%) rear impacts involving
vehicles with a GVM over 3,500 kg that resulted in bodily injury.
14. There is consensus to recommend a wide application in the gtr. Specifically, that head
restraints in all front outboard seating positions for Category 1-1 vehicles, for
Category 1-2 vehicles with a gross vehicle mass of up to 4,500 kg, and for Category 2
vehicles with a gross vehicle mass up to 4,500 kg.
15. Given the variability in target population in different jurisdictions, such as the differing data
from the United States of America and Japan, it was recommended that the gtr should be
drafted to have a wide application to vehicles, to maximize the ability of jurisdictions to
effectively address regional differences in whiplash crash characteristics. The gtr would
establish that if a jurisdiction determines that its domestic regulatory scheme is such that full
applicability is inappropriate, it may limit domestic regulation to certain vehicle categories or
mass limits. The jurisdiction could also decide to phase-in the requirements for certain
vehicles. A footnote was added to the gtr text to make it clear that jurisdictions can decide
to limit the applicability of the Regulation. This approach recognizes that niche vehicles that
are unique to a jurisdiction would best be addressed by that jurisdiction, without affecting the
ability or need for other jurisdictions to regulate the vehicles. When a Contracting Party
proposes to adopt the gtr into its domestic regulations, it is expected that the Contracting
Party will provide reasonable justification concerning the limitation of the application of the
16. The informal group was unable to define a purpose that correlated with injury since the
mechanisms are not well understood. Therefore, more general text was developed from the
definition of head restraints. The recommended text for the purpose is: "This gtr specifies
requirements for head restraints to reduce the frequency and severity of injuries caused by
rearward displacement of the head."
19. Ideally, the degree of whiplash injury should be evaluated based on dynamic testing that
represents "real world" crashes; that is, based on a vehicle acceleration that occurs in real
crashes and a dummy with high biofidelity that reflects the injury mechanism, and injury
indices. However, at present, there is still not a sufficient amount of medical data to
accurately define the injury mechanism; therefore appropriate injury indices have not been
developed. In the interim, AC.3 recommends a dynamic testing option, as an alternative to
the static performance requirements in this gtr. A dynamic test option was proposed
primarily for two reasons. First, a dynamic test better represents "real-world" injury-causing
events and thus is expected to produce greater assurance than the static measurement
option of effective real world performance.
Second, as explained below, it is believed that a dynamic test will help to encourage
continued development and use of "dynamic" head restraint systems because the test is
designed to allow a manufacturer the flexibility necessary to offer innovative dynamic head
20. Dynamic head restraint systems deploy in the event of a collision to minimize the potential
for whiplash. During the normal vehicle operation, the dynamic head restraint system is
"retracted." Because a dynamic head restraint system requires a certain range of motion to
work effectively, an "undeployed" dynamic head restraint system might not meet the static
performance requirements, in particular the backset measurement requirements.
21. Although the dynamic compliance option is intended to ensure that the gtr encourages
continuing development of dynamic head restraint systems, the option is left to the
manufacturer and is available to both dynamic and conventional, or "static," head restraint
systems. That is, both types of head restraints can be evaluated to either static
requirements or the dynamic test option.
22. The United States of America currently has the only regulation with a dynamic testing
option. Under the United States of America dynamic option, the entire vehicle is exposed to
a half-sine deceleration pulse with a target of 8.8 g peak and 88 ms duration. The
50th percentile male Hybrid III dummy in each seat must have a maximum head-to-torso
rotation of less than 12° and a HIC15 (Head Injury Criteria) of less than 500.
23. In this gtr under direction from AC.3, when the dynamic test procedure with Hybrid III is
allowed the maximum relative head-to-torso rotation value is limited to 12° with the
50th percentile male dummy in all seats, with the head restraint adjusted vertically midway
between the lowest and the highest position of adjustment. The head restraint is to be
positioned at the middle position of vertical adjustment because there are concerns with the
effects of this gtr on dynamic head restraint systems. As previously stated, there is a need
to ensure that the dynamic test option encourages continuing development of dynamic head
restraint systems. As discussed below, research indicates that current head restraint
systems can meet the head-to-torso rotation limit in this gtr when the head restraint is
adjusted midway between the lowest and the highest position of adjustment.
26. The United States of America performed sled testing as specified in the dynamic
compliance option on a specially designed seat to explore how various seat characteristics
affect relative head rotation and other dummy injury measures. An OEM seat with an
adjustable head restraint was modified by removing the original recliner mechanism and
replacing it with a pin joint free to rotate. The seat back was also reinforced with steel
channels that provided the attachment points for a spring and damper system on each side
of the seat. Seat back strength in the rearward direction was modified by changing the
springs and or their location of attachment relative to the hinge joint. In addition to seat
back strength, sensitivity analyses to head restraint attachment strength and seat back
upholstery compliance were also performed. Tests were performed with belted
5th percentile female, 50th percentile male and 95th percentile male Hybrid III dummies.
27. The head restraint height was either 750 mm or 800 mm and the backset was always
50 mm as measured by the HRMD. However, the majority of tests (20 tests) were
performed with the 50th percentile male dummy with a 750 mm high head restraint. For all
seat back parameters tested with this configuration of dummy and head restraint height, the
range of relative head-to-torso rotation was 6 to 16°. HIC15 was measured for half of these
tests and ranged from 40 to 75. Nearly half of the seat configurations (9 of 20) met the 12°
limit placed on the dynamic compliance option for a head restraint in the lowest adjustment
position (750 mm). In general, the smallest relative rotations were seen for the baseline
seat back strength and non-rotating seat backs irrespective of the other seat/head
restraint parameters. From these tests, it was concluded that the head rotation and HIC
limits selected can be met with typical seat back/head restraint designs when appropriate
consideration is given to design in terms of height, backset and strength of head restraint
28. In a separate set of tests, the United States of America subjected a MY 2000 Saab 9-3 seat
to the sled pulse of the dynamic test option. A 95th percentile male Hybrid III dummy
occupied the seat. The Saab 9-3 has a dynamic head restraint system, and the head
restraint was set to its highest position of adjustment. The maximum head-to-torso rotation
was 9°. Viano and Davidsson (Viano, D., Davidsson, J., "Neck Displacement of Volunteers,
BioRID P3 and Hybrid III in Rear Impacts: Implications to Whiplash Assessment by a Neck
Displacement Criterion (ND)," Traffic Injury Prevention, 3:1005-116, 2002) also sled tested a
9-3 head restraint at a slightly lower, 16 km/h ∆V, with the seat occupied by a
50th percentile male Hybrid III dummy. With the head restraint in the up position, the
relative head rotation was measured at 6.5°. With the head restraint midway between the
lowest and the highest position of adjustment, the relative head rotation was 10° at
23.5 km/h ∆V. It is assumed that this configuration would yield an even smaller head
rotation at the 17.2 km/h ∆V.
29. In summary, research indicates that the head-to-torso rotation limit of 12° will not discourage
the development of dynamic head restraint systems. Current systems, such as the one in
2000 Saab 9-3 and the Toyota Whiplash Injury Lessening (WIL) seat (measured 6° of
rotation), can meet the head-to-torso rotation limit in this gtr. The United States of America
testing has also shown that current static head restraints/seats need more extensive
modification to meet the head-to-torso rotation limits. These changes might include
increasing the strength of attachment to the seat for adjustable head restraints and
optimization of the seat back upholstery for compliance.
32. The specified sled pulse is representative of one experienced in a crash when the head
restraint is needed to provide protection. The appropriateness of the ∆V and average
acceleration of the pulse is supported by a 2002 Swedish study by Krafft and others
(Krafft, M., Kullgren, A., Ydenius, A., and Tingvall, C. (2002) Influence of Crash Pulse
Characteristics on Whiplash Associated Disorders in Rear Impacts − Crash Recording in
Real-Life Impacts, Traffic Injury Prevention, Vol. 3 (2), pp 141-149). This study examined
rear impact crashes with crash recorders where the crash pulse was known (66 such
crashes). It examined the relationship between whiplash injury risk and parameters such as
∆V, peak acceleration, average acceleration, and average windowed acceleration for 18 ms,
36 ms, and 80 ms. It found that the mean acceleration best correlated with whiplash injury
risk. For most occupants who had whiplash symptoms for longer than a month, the mean
acceleration of the crash pulse was greater than 4.5 g and above a ∆V of 15 km/h. For this
group, the mean acceleration was 5.3 g and the average ∆V was 20 km/h. The crash pulse
has a 5.6 g mean acceleration and 17.3 km/h ∆V. The EEVC have published a review of
the latest information available concerning rear impact pulses and their relationship to
whiplash and associated disorders (Recommendations for a Low Speed Rear Impact Sled
Test Pulse, EEVC, September 2007, http://www.eevc.org). The report was not able to
recommend a single specific pulse shape correlating to injury, instead proposing either a
bimodal or triangular, with a ΔV of 20 km/h and mean acceleration of 5-6 g to address
longer-term (symptoms greater than one month duration). Therefore, it is believed that
the sensors should be designed to activate the head restraint in such a situation. There is
concern that if a trigger point is specified, i.e., specified that the head restraint be activated
at a specific point in time as part of the test procedure, there would be no test of the sensors
and no assurance that the head restraint would activate during the type of crash simulated
by the sled pulse. At this time, GRSP does not recommend including a trigger point.
33. Research indicates that currently available dynamic head restraints can meet the
requirements of this option for the gtr. Given that the informal group strongly encourages
the development of a future fully developed alternative dynamic test procedure, including
dummy recommendations and criteria for evaluating whiplash injuries, that would further
encourage innovative dynamic head restraint designs, further discussion concerning
revision of the current dynamic option was suspended. Notwithstanding that an alternative
dynamic test, incorporating BioRID II, may be introduced into this gtr, it is expected that
research to develop a single dynamic test would supersede efforts to revise the Hybrid III
dynamic option. However, if future information led to different conclusions than those used
to develop the existing procedure and criteria (such as the trigger point or head-to-torso
angle rotation), amendments could be made to this option.
Seat Set Up and Measuring Procedure for Static Requirements
41. There were two proposals under discussions concerning the set-up of the seat for the
measurement of height and backset. One proposal is to use the manufacturer's
recommended seating position as detailed in UNECE Regulation No. 17. The other is to
use the procedure that is outlined in the recently adopted United States of America
FMVSS No. 202, which positions the seat in the highest position of adjustment and sets the
seat back angle at a fixed 25°. GRSP recommends that the seat be measured at the
manufacturer’s design position to allow additional flexibility to account for vehicles with very
upright seat back design angles.
42. It was argued that there are several vehicle concepts (e.g., light trucks, minivans, SUV’s and
full size vans) in which a seat back angle of 25° is not realistic nor feasible, thus leading to a
much larger backset using United States of America’s procedure as compared to the real
world situation. It was stated that SAE J-1100 July 2002 recommends a 22° nominal torso
43. Also, it was stated that 5th percentile female stature occupants do not sit at 25° torso
angles, but prefer about 18° and some as little as 14. It argued that this more upright back
angle greatly reduces the backset to the point it interferes with the head of some of these
occupants, not just the hair.
44. After considering the arguments, the informal group believes the flexibility of using the
design seat back angle is appropriate. Additional flexibility is needed to account for vehicles
with very upright design angles. As a practical matter, this approach provides some
additional backset flexibility for most seats, since the typical design seat back angle is 23.5°.
Specifying that such a seat be tested at the design seat back angle instead of 25° is roughly
equivalent to increasing the backset limit by 4.5 to 6 mm. Therefore, this helps address
possible concerns related to comfort.
45. It was also noted that while the Head Restraint Measurement Device (HRMD) was designed
to be used at 25°, the device has an articulation to allow for adjustment of the head for
varying torso angles. The device can therefore be used at different seat back angles. It is
relatively rare that a seat can be adjusted to have a seatback angle of exactly 25°. Thus,
even prior to the change to specify seat back angle, the standard specified testing in the
adjustment position closest to 25°. For these reasons, there should be no problem in testing
vehicles at the design seatback angle.
50. Both UNECE Regulation No. 17 and the FMVSS No. 202 Final Rule require front outboard
head restraints with a minimum height of 800 mm above the R-Point/H-Point,
respectively. A proposal was made to recommend a minimum height of 850 mm, to
accommodate the taller citizens of some countries. Using recent anthropometric research
(see HR-3-6 and HR-4-16) it was demonstrated that when considering erect sitting height a
95 percentile Netherlands male needs a head restraint height of 849 mm to give protection
equivalent to that of the average occupant. The UK submitted data (HR-4-14 and HR-6-11)
showing their population is tall enough to need taller head restraints. The UK also provided
an EEVC Cost Benefit Analysis (UK Cost Benefit Analysis: Enhanced Geometric
Requirements for Vehicle Head Restraints, European Enhanced Vehicle-safety Committee
(EEVC), September 2007, http://www.eevc.org) demonstrating benefits for increasing
head restraint height above 800 mm.
51. There are concerns with raising the height of the head restraint above 800 mm at this time.
It was noted that with an 800 mm head restraint, it is starting to become a challenge for
manufacturers to be able to install seats in the vehicle, and a larger head restraint can also
restrict occupant visibility (blocking vision rearward and to the side)
(see HR-3-5). Additional data was presented (see HR-3-4) that showed that in small cars,
850 mm head restraints could severely restrict rearward vision in the rearview mirror.
52. Additionally, there are concerns that the method in which the height is measured may not
reflect the effective height that would be needed to address the safety concerns of taller
occupants. There have been some proposals put forth to improve the measurement
method, but they were not yet fully developed for inclusion in the gtr. (See Section 5.6.4. for
further discussion of this measurement method.)
53. At this time, AC.3 has directed that the height requirement be limited to 800 mm, but
recommends that the discussion on increasing the height requirement and/or revising the
measurement method be continued in Phase 2 to this gtr.
Front Centre and Rear Head Restraints
a. Defining a Front Centre and Rear Head Restraint
54. This gtr provides an objective definition and a test procedure for determining the presence
of a head restraint. A vehicle seat will be considered to have a head restraint if the
seatback or any independently adjustable seat component attached to or adjacent to the
front centre or rear seat back, that has a height equal to or greater than 700 mm, in any
position of backset and height adjustment.
60. After considering the reduction in safety benefits and a review of the fleet, it was determined
that the clearance exemption is not needed for front or rear seats for folding positions and
therefore it is recommended that an exemption of 25 mm only be applied in cases of
interference with the interior roofline (headliner) or backlight. An exemption of 50 mm for
convertible roofs is also recommended to account for the articulation of the folding top
Adjustable Front Head Restraints − Front Contact Surface Area
61. It was initially proposed to include in the gtr the UNECE Regulation No. 17 requirement that
the height of the head restraint face be a minimum of 100 mm to ensure sufficient surface
for the occupant’s head to contact. The UNECE Regulation No. 17 requirement is
measured in the same manner as the overall height of the head restraint. There have been
concerns expressed that the measurement taken in this manner does not address the
effective height of the restraint. In the case of extremely contoured head restraints, the
height of the surface that the head would contact is less than the measured height. This is
demonstrated in Figure 2.
Ineffective Part of the Head Restraint
68. The consensus within the biomechanics community is that the backset dimension has an
important influence on forces applied to the neck and the length of time a person is disabled
by an injury. As early as 1967, Mertz and Patrick first showed that reducing the initial
separation between the head restraint and head minimizes loading on the head during a
rear impact. More recently, the Olsson study, which examined neck injuries in rear end
collisions and the correlation between the severity of injuries and vehicle parameters,
showed that the duration of neck symptoms was correlated to the head restraint backset.
Specifically, reduced backset, coupled with greater head restraint height, results in lower
injury severity and shorter duration of symptoms.
69. A different study examined sled tests to determine the influence of seat back and head
restraint properties on head-neck motion in rear impacts. The study concluded that the
head restraint backset had the largest influence on the head-neck motion among all the seat
properties examined. With a smaller backset, the rearward head motion was stopped
earlier by the head restraint, resulting in a smaller head to torso displacement. The findings
indicated that a reduction in backset from 100 mm to 40 mm would result in a significant
reduction in whiplash injury risk.
70. A study conducted by Eichberger examined real world rear crashes and sled tests with
human volunteers to determine whiplash injury risk and vehicle design parameters that
influence this risk. The study found a positive correlation between head restraint backset
and head to torso rotation of the volunteers and to the reported whiplash injury complaints.
The most important design parameters were a low horizontal distance between the head
and head restraint as well as the head restraint height.
71. A study conducted by Dr. Allan Tencer, PhD, used rigid occupant body models enhanced
with finite element models of the cervical spine for simulating rear impacts in order to
examine the effect of backset on neck kinematics and forces and moments in the neck. The
study concluded larger backset correlates to greater displacement between cervical
vertebrae and shearing at the facet capsules that are likely associated with whiplash injury.
With the head initially closer to the head restraint, the time difference between the
occurrences of the peak upper and lower neck shear forces are smaller. At 50 mm backset
and lower, the head moved more in phase with the torso and extension of the head was
reduced indicating a lower risk of whiplash injury. IIHS, in its studies of head restraints,
considers a backset of 70 mm or less to be "good".
77. GRSP recommends that it is necessary that the H-Point manikin and HRMD machine are
considered as a single tool and that they must therefore be calibrated together and remain
as a matched pair for use in regulatory assessments. However, GRSP has noted that at
this time there is no agreed calibration procedure or generally available calibration
equipment to ensure compliance with this recommendation. This poses significant risk with
respect to reproducibility. It therefore recommends that, a suitable calibration procedure
and equipment be incorporated into regulations that use type approval as a method for
78. Transport Canada conducted a study to verify whether the HRMD is an adequate tool to
measure backset. Among other things, the study sought to verify specifications and
dimensional tolerances of the HRMD headform and measuring probes. Transport Canada
reported that the headform is manufactured to have a mass of 3,150 ± 50 grams, and all
linear dimensions of the headform are within ± 0.25 mm of the drawing specifications for the
headform size "J" provided in ISO DIS 6220 − Headforms for use in the testing of protective
helmets. It also reported that both height and backset probes are within ± 2 mm of the
RONA Kinetics drawing specifications, and that conformity with the drawing specifications is
accomplished with the specially designed "jig". Dimensional drawings for this headform
have been provided in the Annex to this gtr.
79. The HRMD is a purely mechanical device. Also, unlike a crash dummy, it is not subjected to
crash test forces. The informal group notes that the International Insurance Whiplash
Prevention Group (IIWPG), of which ICBC is a member, has identified that variability
between three-dimensional manikins can be an issue when using the ICBC HRMD. To
address this issue, IIWPG has developed a "Gloria jig" to calibrate the combination together
as one single unit. The Working Group understands that the Gloria jig (or its specification)
will not be available commercially, but rather will be used by a commercial enterprise to offer
a calibration service. For this reason the Working Group cannot specify its use as part of
this gtr. Therefore, although no detailed calibration procedure is included in the gtr text, the
group recommends that such procedure is developed.
80. In a study conducted by the United States of America (HR-5-4), variation in backset
measurements when using multiple laboratories was examined. This study concluded,
among other things, that taking the average of three backset measurements at each of three
labs reduced the average measurement range between the labs by about half (from 8.5 mm
to 4.5 mm). Using an average of three measurements in each of backset position of
adjustment, at a 2 standard deviation (s.d.) (97.7%) level of certainty, the expected
variability was 5.64 mm; at a 3 s.d. (99.9%) level of certainty, the expected variability was
8.47 mm. Data were presented by Japan showing a variability of up to 29mm (HR-7-10).
Data was presented by International Organization of Motor Vehicle Manufacturers (OICA)
showing a variability of up to 11 mm. (GRSP-41-22)
81. The Transport Canada study, which used eight vehicles, sought to verify whether the HRMD
is an adequate tool to measure backset. It concluded that the HRMD provides repeatable
and reproducible results after calibration. It also found that increasing the number of
measurements always reduced the backset measurement variability. Using an arithmetic
mean of the three measurements in each backset position of adjustment, at a 2 s.d. (97.7%)
level of certainty, the expected variability was 2.6 mm; at a 3 s.d. (99.9%) level of certainty,
the expected variability was 3.9 mm.
Backset Limit and Comfort
86. When the United States of America benefit analysis for regulating height and backset was
examined, it was noted that all the benefits for the front seat passengers come from
regulating the backset. These benefits are achieved by improving the current situation. The
United States of America proposed a backset limit of 55 mm measured at manufacturer’s
design seat back angle and measured with the HRMD, using the H-Point as the initial
reference. Others proposed a less stringent backset of 70 mm.
87. The EEVC Cost Benefit Analysis (UK Cost Benefit Analysis: Enhanced Geometric
Requirements for Vehicle Head Restraints, EEVC, September 2007, http://www.eevc.org)
considered the potential costs and benefits of introducing a backset limit of between 40 and
100mm. Benefits were determined by the evaluation of potential casualty savings that might
occur as a result of a regulatory change with the cost to industry consistent based on the
US data. The study used UK data and proposed that significant savings could be achieved
through changes to existing head restraint geometry (including the introduction of a backset
requirement, Figure 3.
Potential Long-term Whiplash Injury Savings in the
UK through Increased Height and Backset Requirements
Head Restraint Height Adjustment Retention Devices (Locks)
93. GRSP recommends that performance requirements for adjustable head restraints be
included in the gtr which are intended to assure that the front head restraints remain locked
in specific positions. A 1982 United States of America NHTSA study (HR-3-13) found that
the effectiveness of integral head restraints was greater than adjustable head
restraints. The study concluded that this difference in effectiveness was due, in part, to
adjustable head restraints not being properly positioned. Although one reason for improper
positioning is a lack of understanding on the part of the occupant on where to place the
head restraint, it also could be due to the head restraint's moving out of position either
during normal vehicle use or in a crash. Adjustment locks can mitigate this problem by
helping to retain the adjusted position. IIHS has also been critical of adjustable head
restraints, especially when they do not provide locks, in their evaluation of head restraints.
This criticism has manifested itself in that IIHS, in its rating of head restraints, automatically
gave adjustable restraints a lower rating on the assumption that these restraints would not
be properly adjusted. In addition, it only evaluated adjustable head restraints without locks
in their lowest position. The United States of America has received comments during its
regulatory process to update its head restraint regulation from consumer groups and vehicle
manufacturers supporting adjustable head restraints that lock.
94. The proposed requirements of this gtr are expected to improve the performance of all
adjustable head restraints. The performance of adjustable head restraints may be further
improved if steps are taken to ensure that a restraint remains in position after it has been set
by the user.
95. Therefore, GRSP is recommending that adjustable head restraints for the front outboard
seating positions must maintain their height (i.e., lock) in several height positions under
application of a downward force. In addition to locking at a position of not less than
800 mm, they must also lock at the highest adjustment positions. It may be that, for some
designs, the highest position is at 800 mm. Adjustable head restraints for the front centre
and rear outboard seating positions must lock at the highest position of adjustment above
750 mm, if this position exists. In addition to locking at these specified positions of height
adjustment, both front centre and rear outboard head restraints must be capable of retaining
the minimum height of 750 mm under application of a downward force. Adjustable head
restraints for rear centre seating positions must lock at the highest position of adjustment
above 700 mm and be capable of retaining the minimum height of 700 mm under the
application of a downward force.
96. The proposed height adjustment retention lock test begins by applying a small initial load to
the head restraint. A headform is used to apply the load and a reference position is
recorded. The reference position is measured with this load applied to eliminate variability
associated with the soft upholstery of the head restraint. A 500 N load is then applied
through the headform to test the locking mechanism. Finally, the load is then reduced to the
initial value and the headform is checked against its initial position. In order to comply, the
locking and limiter mechanisms must not have allowed the headform to have moved more
than 25 mm from the initial reference position.
Front Outboard Seats
101. The informal group believed it was important to balance the need to ensure that the head
restraint is in the proper position while maintaining the functionality of the seat. In some
current designs the head restraint can be placed in a non-use position when the vehicle seat
is folded down to increase the cargo capacity of the vehicle. It has been proposed to allow
non-use positions in the front outboard seats, as long as they automatically return to the
proper position when the seat is occupied. GRSP is recommending a test procedure using
the 5th percentile female Hybrid III dummy or a human surrogate to evaluate these systems.
Front Centre and Rear Seats
a. Manually Adjusted Non-use Positions
102. It is recommended to regulate of non-use positions in the rear seats, as long as the position
is "clearly recognizable to the occupant". There is discussion on how to objectively evaluate
this requirement. One proposal is to define "clearly recognizable" as a head restraint that
rotates a minimum of 60° forward or aft. There was concern that this definition is too design
restrictive as the sole method and additional methods have been proposed (HR-4-13).
103. The United States of America developed a human factors study to determine if an occupant
would be likely to reposition their head restraint as a function of the torso angle change the
head restraint produced in the non-use position (HR-5-23). The baseline seat for this study
was the second row captain’s chair of a 2005 model year Dodge Grand Caravan. In its
original equipment manufacturer configuration, the seat created a nominal 5° torso angle
change between its non-use and in-use positions. The head restraint was then modified by
introducing two forward offsets that generated either a 10 or 15° torso angle change. One
other condition that was used was to attach a label to the head restraint in the 5° condition.
The label was modified from a label used by Volvo.
104. Of the participants who adjusted the head restraint, 88% adjusted it immediately after sitting
down. The 5° condition and label condition were unsuccessful in motivating participants to
adjust the head restraint. For the 5° condition, only 3 out of 20 participants (15%) adjusted
the head restraint. None of the participants (0 out of 20) adjusted the head restraint as a
result of the label. The 10° condition had a nearly 80% success rate, 19 out of 24. Only
four participants were run in the 15° condition since the percentage of participants who
adjusted the head restraint in the 10° condition was high. The 15° condition had a 100%
rate of adjustment. Based on the results of this study, GRSP agreed to recommend the 10°
torso angle change option as an alternative.
105. Some experts and participants support the use of labels since these head restraints are
optional, and a label in a non-use position is better than no label at all. Additionally, the
need for labels was suggested because the use of the torso angle change method or
discomfort metric may be incompatible with the installation of child restraints. Some experts
do not support the use of labels, because there are already too many labels in the vehicles
and, based on the United States of America study, the labels were ineffective in causing the
occupant to move the head restraint out of the non-use position, although 50% of those
questioned understood what the label meant, and an additional 30% understood that the
head restraint was adjustable. To accommodate all views in the gtr, labels will be
recommended as an optional method to be accepted by the Contracting Party. Based on
the available data, Contracting Parties can choose the level of risk they are comfortable
111. GRSP is recommending an energy absorption requirement specifying that when the front of
the head restraint is impacted by a headform the deceleration of the headform must not
exceed 80 g continuously for more than 3 milliseconds. This recommendation is different
from the current United States of America and UNECE Regulations in that it does not
specify a type of impactor, but rather a required energy. This would allow either the linear
impactor, the free motion impactor, or the pendulum impactor to be used for
testing. Studies showed that the results of the test were similar regardless of what type of
impactor was used (HR-4-8, HR-5-6).
Radius of Curvature
112. The informal group discussed incorporating the UNECE Regulation No. 17 requirement that
designated parts of the front of the head restraint shall not exhibit areas with a radius of
curvature less than 5 mm pre- and post-test. There was concern that a breakage could
occur during the test which would produce a sharp edge. This sharp edge could harm
occupants in a secondary impact. The informal group was unable to agree on a test
procedure and therefore the requirement was not included in the gtr at this time. Due to
these concerns, some Contracting Parties may wish to continue regulating for radius of
curvature under their current regulation scheme.
Displacement Test Procedures/Adjustable Backset Locking Test/Ultimate Strength
113. GRSP is recommending the incorporation of requirements to evaluate the head restraint's
ability to resist deflection and significant loading. The displacement test requires that a
head restraint cannot deflect more than 102 mm when a 373 Nm moment is applied to the
seat. Additionally, the seat system must not fail when an 890 N load is applied to the seat
and maintained for 5 seconds.
114. Additionally, GRSP is recommending, based on Contracting Party determination, that head
restraints with adjustable backset maintain their position while under load. Some strongly
believe that if an occupant adjusts his head restraint backset so that it is less than the
requirement, then he should have some assurance that it will maintain that position when
loaded. Some further believe, that this requirement should only apply to required head
restraints and not those optionally installed. Others strongly believed that the safety needs
are met at the requirement. Therefore the gtr was drafted so that a Contracting Party can
designate whether adjustable head restraints will be tested at all positions of backset and to
which head restraints this will apply. The test for adjustable head restraints incorporates
both the evaluation for total displacement of the head restraint and the evaluation of the
locking mechanism for the adjustable backset.
8. REVIEW OF EXISTING INTERNATIONAL REGULATIONS
120. The following existing Regulations, Directives, and Standards pertain to head restraints:
UNECE Regulation No. 17 − Uniform provisions concerning the approval of vehicles
with regard to the seats, their anchorages, and any head restraints.
UNECE Regulation No. 25 − Uniform provisions concerning the approval of head
restraints (Head Rests), whether or not incorporated in vehicle seats.
European Union Directive 74/408/EEC (consolidated), relating to motor vehicles with
regard to the seats, their anchorages and head restraints.
European Union Directive 78/932/EEC.
(e) European Union Directive 96/03/EC, adapting to technical progress
Council Directive 74/408/EEC relating to the interior fittings of motor vehicles
(strength of seats and of their anchorages).
United States of America Code of Federal Regulations Title 49: Transportation;
Part 571.202: Head Restraints.
Australian Design Rule 3/00, Seats and Seat Anchorages.
Australian Design Rule 22/00, Head Restraints.
Japan Safety Regulation for Road Vehicles Article 22 − Seat.
Japan Safety Regulation for Road Vehicles Article 22-4 − Head Restraints, etc.
Canada Motor Vehicle Safety Regulation No. 202 − Head Restraints.
International Voluntary Standards -SAE J211/1 revised March 1995 − Instrumentation
for Impact Test − Part 1 − Electronic.
Korea Safety Regulation for Road Vehicles Article 99 − Head Restraints.
121. Additionally, research and activities being conducted by European Enhanced Vehicle Safety
Committee (EEVC) Working Group 12, EEVC Working Group 20, EuroNCAP, and Korea
NCAP were also considered.
3.9. "H-Point" means the pivot centre of the torso and thigh of the H-Point machine when
installed in a vehicle seat in accordance with Annex 12. Once determined in accordance
with the procedure described in Annex 12, the "H" Point is considered fixed in relation to
the seat-cushion structure and is considered to move with it when the seat is adjusted.
3.10. "R-Point" means a design point defined by the vehicle manufacturer for each designated
seating position and established with respect to the three-dimensional reference system
as defined by Annex 11. The R-Point:
3.10.1. Establishes the rearmost normal design driving or riding position of each designated
seating position in a vehicle;
3.10.2. Has coordinates established relative to the designed vehicle structure;
3.10.3. Simulates the position of the centre pivot of the human torso and thigh;
3.10.4. Is defined in Annex 12 of this Regulation.
3.11. "Top of the head restraint" means the point on the head restraint centreline with the
3.12. "Torso line" means the centreline of the probe of the H-Point machine with the probe in
the fully rearward position.
3.13. "Actual torso angle" means the angle measured between a vertical line through the
H-Point and the torso line using the back angle quadrant on the H-Point machine. The
actual torso angle corresponds theoretically to the design torso angle.
3.14. "Design torso angle" means the angle measured between a vertical line through the
R-Point and the torso line in a position which corresponds to the design position of the
seat back established by the vehicle manufacturer.
4. GENERAL REQUIREMENTS
4.1. Whenever a range of measurements is specified, the head restraint shall meet the
requirement at any position of adjustment intended for occupant use.
4.2. In each vehicle subject to the requirements of this Regulation, a head restraint shall be
provided at each front outboard designated seating position, conforming to either
Paragraph 4.2.1. or Paragraph 4.2.2.
4.2.1. The head restraint shall conform to Paragraphs 5.1., 5.2., 5.4., and 5.5. of this Regulation.
4.2.2. The head restraint shall conform to Paragraphs 5.1.1. through 5.1.4., 5.3., 5.4., and 5.5. of
4.3. For vehicles equipped with rear outboard and/or front centre head restraints, the head
restraint shall conform to either Paragraph 4.3.1. or Paragraph 4.3.2.
4.3.1. The head restraint shall conform to Paragraphs 5.1.1. through 5.1.4., 5.2., 5.4., and 5.5. of
4.3.2. The head restraint shall conform to Paragraphs 5.1.1. through 5.1.4., 5.3., 5.4., and 5.5. of
22.214.171.124. Rear Outboard Designated Seating Positions Equipped with Head Restraints
The top of a head restraint located in a rear outboard designated seating position shall
have a height of not less than 750 mm in any position of adjustment, except as provided in
Paragraph 126.96.36.199. of this Regulation.
The requirements of Paragraph 188.8.131.52. of this Regulation do not apply if the interior
surface of the vehicle roofline, including the headliner, or backlight physically prevent a
head restraint, located in the rear outboard designated seating position, from attaining the
required height. In those instances, the maximum vertical distance between the top of the
head restraint and interior surface of the roofline, including the headliner, or the backlight
shall not exceed 50 mm for convertibles and 25 mm for all other vehicles, when the head
restraint is adjusted to its highest position intended for occupant use.
5.1.2. Minimum Width
When measured in accordance with Annex 2, the lateral width of a head restraint shall be
not less than 85 mm on either side of the torso line (distances L and L' measured as per
5.1.3. Gaps within Head Restraint
If a head restraint has any gap greater than 60 mm when measured in accordance with
Annex 3, the maximum rearward displacement of the head form shall be less than 102 mm
when the head restraint is tested at that gap in accordance with Annex 6.
5.1.4. Gaps between Head Restraint and the Top of the Seat Back
When measured in accordance with Annex 3, there shall not be a gap greater than 60 mm
between the bottom of the head restraint and the top of the seat back if the head restraint
can not be adjusted in height.
In the case of head restraints adjustable in height to more than one position intended for
occupant use, when measured in accordance with Annex 3, there shall not be a gap
greater than 25 mm between the bottom of the head restraint and the top of the seat back,
with the head restraint adjusted to its lowest height position.
5.1.5. Backset Requirements
184.108.40.206. General Specifications
220.127.116.11.1. Head restraints on the front outboard designated seating positions shall meet the backset
requirements of Paragraph 18.104.22.168.
22.214.171.124. Static Maximum Backset Requirements
126.96.36.199.1. For height adjustable head restraints, the requirements shall be met with the top of the
head restraint in all height positions of adjustment between 750 mm and 800 mm,
inclusive. If the top of the head restraint, in its lowest position of adjustment, is above
800 mm, the requirements of this Regulation shall be met at that position only.
188.8.131.52.1.3. Return to within 13 mm of its initial reference position after the following sequence occurs:
application of a 373 Nm moment about the R-Point; reduction of the moment to 0 Nm; and
by re-application of the initial reference load 37 Nm.
184.108.40.206.1. When the head restraint is tested in the rearmost (relative to the seat) position of
horizontal adjustment (if provided) in accordance with Annex 6, the head form shall not be
displaced more than 102 mm perpendicularly and rearward of the displaced extended
torso line during the application of a 373 Nm moment about the R-Point.
5.2.4. Head Restraint Strength
When the head restraint is tested in accordance with Annex 6, the load applied to the head
restraint shall reach 890 N and remain at 890 N for a period of 5 seconds.
5.3. Dynamic Performance Requirements
5.3.1. Based on a determination by each Contracting Party or regional economic integration
organization, either a Hybrid III 50th percentile male dummy or a BioRID II
50th percentile male dummy shall be used to determine compliance. If a Hybrid III dummy
is used, the head restraint shall meet the requirements of Paragraph 5.3.2. If a BioRID II
dummy is used, the head restraint shall meet the requirements of Paragraph 5.3.3.
5.3.2. Hybrid III Requirements
220.127.116.11. When tested during forward acceleration of the dynamic test platform, in accordance with
Annex 9, at each designated seating position equipped with a head restraint, the head
restraint shall conform to Paragraphs 18.104.22.168 and 22.214.171.124.
126.96.36.199. Angular Rotation
Limit the maximum rearward angular rotation between the head and torso of the
50th percentile male Hybrid III test dummy to 12° for the dummy in all outboard designated
188.8.131.52. Head Injury Criteria
Limit the maximum HIC15 value to 500. HIC15 is calculated as follows: For any two
points in time, t and t , during the event which are separated by not more than a
15 millisecond time interval and where t is less than t , the head injury criterion (HIC15) is
determined using the resultant head acceleration at the centre of gravity of the dummy
head, a , expressed as a multiple of g (the acceleration of gravity) and is calculated using
HIC = ⎢
( t − t )
( t − t )
184.108.40.206. In front centre and rear designated seating positions equipped with head restraints, the
head restraint shall, when tested in accordance with Annex 10, be capable of manually
rotating either forward or rearward by not less than 60° from any position of adjustment
intended for occupant use in which its minimum height is not less than that specified in
Paragraph 5.1.1. of this Regulation.
220.127.116.11. When measured in accordance with Annex 10, the lower edge of the head restraint (HLE)
shall be not more than 460 mm, but not less than 250 mm from the R-Point and the
thickness (S) shall not be less than 40 mm.
18.104.22.168. When tested in accordance with Annex 10, the head restraint shall cause the torso line
angle to be at least 10° closer to vertical than when the head restraint is in any position of
adjustment in which its height is not less than that specified in Paragraph 5.1.1. of this
22.214.171.124 The head restraint shall be marked with a label in the form of a pictogram which may
include explanatory text. The label shall either provide an indication when the head
restraint is in a non-use position or provide information to enable an occupant to determine
whether the head restraint is in a non-use position. The label shall be durably affixed and
located such that it is clearly visible by an occupant when entering the vehicle to the
designated seating position. Examples of possible designs of pictograms are shown in
5.5. Removability of Head Restraints
The head restraints shall not be removable without a deliberate action distinct from any
action necessary for upward head restraint adjustment.
MINIMUM HEIGHT MEASUREMENT TEST PROCEDURE
The purpose of this test procedure is to demonstrate compliance with the minimum height
requirements described in Paragraph 5.1.1. of this Regulation.
2. PROCEDURE FOR HEIGHT MEASUREMENT
Compliance with the requirements of Paragraph 5.1.1. of this Regulation is demonstrated by
using the height measurement apparatus defined in Paragraph 2.2. below.
The seat is adjusted such that its H-Point coincides with the R-Point; if the seat back is
adjustable, it is set at the design seat back angle; both of these adjustments are in
accordance with the requirements of Paragraph 2.1. below. The height of the head restraint
is the distance between Point A and the intersection of Lines AE and FG.
2.1. Relationship between the H-Point and the R-Point
When the seat is positioned in accordance to the manufacturer's specifications, the H-Point,
as defined by its coordinates, shall lie within a square of 50 mm side length with horizontal
and vertical sides whose diagonals intersect at the R-Point, and the actual torso angle is
within 5° of the design torso angle.
2.1.1. If these conditions are met, the R-Point and the design torso angle are used to determine the
height of the head restraints in accordance with this Annex.
2.1.2. If the H-Point or the actual torso angle does not satisfy the requirements of Paragraph 2.1.,
the H-Point and the actual torso angle are determined twice more (three times in all). If the
results of two of these three operations satisfy the requirements, the conditions of
Paragraph 2.1.1. shall apply.
2.1.3. If the results of at least two of the three operations described in Paragraph 2.1.2. do not
satisfy the requirements of Paragraph 2.1. the centroid of the three measured points or the
average of the three measured angles is used and be regarded as applicable in all cases
where the R-Point or the design torso angle is referred to in this Annex.
2.2. Height Measuring Apparatus
The height measurement apparatus consists of (see Figure 1-1):
2.2.1. A straight edge AE. The lower Point A is placed at the R Point location in accordance with
Paragraph 2.1. of this Annex. The Line AE is parallel to the design torso angle.
2.2.2. A straight edge FG, perpendicular to the Line AE and in contact with the top of the head
restraint. The height of the head restraint is the distance between Point A and the
intersection of the Lines AE and FG.
GAP MEASUREMENT TEST PROCEDURE
The purpose of this test procedure is to evaluate any gaps within head restraints as well as
gaps between the bottom of the head restraint and the top of the seat back, in accordance with
the requirements of Paragraphs 5.1.3. and 5.1.4. of this Regulation.
Any gaps within the head restraint are measured using the sphere procedure described in
Paragraph 2. of this Annex.
Gaps between the bottom of the head restraint and the top of the seat back are measured
using either the sphere procedure described in Paragraphs 2.1. through 2.5. of this Annex, or,
at the manufacturer option, using the linear procedure described in Paragraph 3. of this Annex.
2. GAP MEASUREMENT USING A SPHERE
2.1. The seat is adjusted such that its H-Point coincides with the R-Point; if the seat back is
adjustable, it is set at the design seat back angle; both these adjustments are in accordance
with the requirements of Paragraph 2.1. of Annex 1.
2.2. The head restraint is adjusted to its lowest height position and any backset position intended
for occupant use.
2.3. The area of measurement is anywhere between two vertical longitudinal planes passing at
85 mm on either side of the torso line and above the top of the seat back.
2.4. Applying a load of no more than 5 N against the area of measurement specified in
Paragraph 2.3. above, place a 165 ± 2 mm diameter spherical head form against any gap such
that at least two points of contact are made within the area.
2.5. Determine the gap dimension by measuring the straight line distance between the inner edges
of the two furthest contact points, as shown in Figures 3-1 and 3-2.
2.6. For gaps within the head restraint, if the measurement determined in Paragraph 2.5 of this
Annex exceeds 60 mm, then in order to demonstrate compliance with the requirements of
Paragraph 5.1.3. of this Regulation, the seat back displacement test procedure described in
Annex 6 is performed, by applying to each gap, using a sphere of 165 mm in diameter, a force
passing through the centre of gravity of the smallest of the sections of the gap, along
transversal planes parallel to the torso line, and reproducing a moment of 373 Nm about the
3. LINEAR MEASUREMENT OF GAP
3.1. The seat is adjusted such that its H-Point coincides with the R-Point; if the seat back is
adjustable, it is set at the design seat back angle; both these adjustments are in accordance
with the requirements of Paragraph 2.1. of Annex 1.
3.2. The head restraint is adjusted to its lowest height position and any backset position intended
for occupant use.
3.3. The gap between the bottom of the head restraint and the top of the seat is measured as the
perpendicular distance between two parallel planes, described as follows (see Figure 3-3).
3.3.1. Each plane is perpendicular to the design torso line.
3.3.2. One of the planes is tangent to the bottom of the head restraint.
3.3.3. The other plane is tangent to the top of the seat back.
2.11. Confirm the actual torso angle remained ± 1° of the design seat back angle by placing an
inclinometer on the lower brace of the torso weight hangers. If the actual torso angle is outside
this range, if possible carefully adjust the seat back angle to be ± 1° of the design seat back
angle. If the legs and seat pan of the three-dimensional H-Point machine move during this
procedure, remove the HRMD, the buttock and torso weights, and repeat the steps contained in
Paragraphs 3.9. through 3.11. of Annex 12, along with steps as described in Paragraphs 2.6.
through 2.10. of this Annex until the actual torso angle is ± 1° of the design seat back angle.
2.12. Level the HRMD and extend the sliding scale on the back of the head until it contacts the head
restraint. Confirm that the scale is positioned laterally within 15 mm of the torso line and take the
2.4. Adjust the front head restraint so that its top is at any height between and inclusive of 750 mm
and 800 mm. If the lowest position of adjustment is above 800 mm, adjust the head restraint to
that lowest position of adjustment.
2.5. In the case of head restraint with adjustable backset, adjust the head restraint at the most
rearward position, such that the backset is in the maximum position.
2.6. Establish Point D on the head restraint, Point D being the intersection of a line drawn from
Point C horizontally in the x-direction, with the front surface of the head restraint.
2.7. Measure the distance CD. The backset is the measured distance CD minus 71 mm.
2.5. When determining the rearward displacement for head restraints at a gap greater than 60 mm in
accordance with Paragraph 5.1.3. of this Regulation, the load of Paragraph 2.4. of this Annex is
applied through the centre of gravity of the smallest of the sections of the gap, along transversal
planes parallel to the torso line.
2.6. If the presence of gaps prevents the application of the force, as described in Paragraph 2.4. of
this Annex at 65 ± 3 mm from the top of the head restraint, the distance may be reduced so that
the axis of the force passes through the centre line of the frame element nearest to the gap.
3. PROCEDURES FOR BACKSET RETENTION AND DISPLACEMENT
3.1. If the seat back is adjustable, it is adjusted to a position specified by the vehicle manufacturer. If
there is more than one inclination position closest to the position specified by the manufacturer,
set the seat back inclination to the position closest to and rearward of the manufacturer specified
position. If the head restraint position is independent of the seat back inclination position,
compliance is determined at a seat back inclination position specified by the manufacturer.
Adjust the head restraint to the highest position of vertical adjustment intended for occupant use.
3.2. Adjust the head restraint to any backset position.
3.3. In the seat, place a test device having the back pan dimensions and torso line (vertical centre
line), when viewed laterally, with the head room probe in the full back position, of the
three-dimensional H-Point machine.
3.4. Establish the displaced torso line by creating a rearward moment of 373 ± 7.5 Nm about the
R-Point by applying a force to the seat back through the back pan at the rate between
2.5 Nm/second and 37.3 Nm/second. The initial location on the back pan of the moment
generating force vector has a height of 290 mm ± 13 mm. Apply the force vector normal to the
torso line and maintain it within 2° of a vertical plane parallel to the vehicle vertical longitudinal
zero plane. Constrain the back pan to rotate about the R-Point. Rotate the force vector direction
with the back pan.
3.5. Maintain the position of the back pan as established in Paragraph 3.4. of this Annex. Using a
165 ± 2 mm diameter spherical head form, establish the head form initial reference position by
applying, perpendicular to the displaced torso line, a rearward initial load at the seat centreline at
a height 65 ± 3 mm below the top of the head restraint that will produce a 37 Nm moment about
the R-Point. Measure the rearward displacement of the head form during the application of the
3.6. If the presence of gaps prevents the application of the forces, as described in Paragraph 3.5. of
this Annex at 65 ± 3 mm from the top of the head restraint, the distance may be reduced so that
the axis of the force passes through the centre line of the frame element nearest to the gap.
3.7. Increase the initial load at the rate of 2.5 Nm/second to 37.3 Nm/second until a 373 Nm moment
about the R-Point is produced. Maintain the load level producing that moment for not less than
5 seconds and then measure the rearward displacement of the head form relative to the
displaced torso line.
3.8. Reduce the load at the rate of 2.5 Nm/second to 37.3 Nm/second until 0 Nm. Wait 10 minutes.
Re-load to 37 Nm about the R-Point. While maintaining the load level producing that moment,
measure the rearward displacement of the head form position with respect to its initial reference
ENERGY ABSORPTION TEST PROCEDURE
Evaluate the energy absorption ability of the head restraint by demonstrating compliance with
Paragraph 5.2.1. of this Regulation in accordance with this Annex.
2. SEAT SET-UP
The seat is either mounted in the vehicle or firmly secured to the test bench, as mounted in the
vehicle with the attachment parts provided by the manufacturer, so as to remain stationary when
the impact is applied. The seat-back, if adjustable, is locked in the design position specified by
the vehicle manufacturer. If the seat is fitted with a head restraint, the head restraint is mounted
on the seat-back as in the vehicle. Where the head restraint is separate, it is secured to the part
of the vehicle structure to which it is normally attached.
3. PROCEDURES FOR ENERGY ABSORPTION
The adjustable head restraints are measured in any height and backset position of adjustment.
3.1. Test Equipment
3.1.1. Use an impactor with a semispherical head form of a 165 ± 2 mm diameter. The head form and
associated base have a combined mass such that at a speed of not more than 24.1 km/h at the
time of impact an energy of 152 Joule will be reached.
3.1.2. Instrument the impactor with an acceleration sensing device whose output is recorded in a data
channel that conforms to the requirements for a 600 Hz channel class filter as specified in
ISO Standard 6487 (2002). The axis of the acceleration-sensing device coincides with the
geometric center of the head form and the direction of impact. As an alternative the impactor
can be equipped with 2 accelerometers sensing in the direction of impact and placed
symmetrically in comparison to the geometric centre of the spherical head form. In this case the
deceleration rate is taken as the simultaneous average of the readings on the two
3.2. Accuracy of the Test Equipment
The recording instrument used is such that measurements can be made with the following
degrees of accuracy:
Accuracy = + 5% of the actual value;
Cross-axis sensitivity = < 5% of the lowest point on the scale.
Accuracy: + 2.5% of the actual value;
Sensitivity: 0.5 km/h.
HEIGHT RETENTION TEST PROCEDURE
Demonstrate compliance with the height retention requirements of Paragraph 5.2.2. of this
Regulation in accordance with this Annex.
2. PROCEDURES FOR HEIGHT RETENTION
2.1. Seat Set-up
Adjust the adjustable head restraint so that its top is at any of the following height positions at
any backset position:
2.1.1. For front outboard designated seating positions:
126.96.36.199. The highest position; and
188.8.131.52. Not less than, but closest to 800 mm
2.1.2. For rear outboard and front centre designated seating positions
184.108.40.206. The highest position; and
220.127.116.11. Not less than, but closest to 750 mm.
2.1.3. For rear centre designated seating position
18.104.22.168. The highest position; and
22.214.171.124. Not less than, but closest to 700 mm.
2.2. Orient a cylindrical test device having a 165 ± 2 mm diameter in plane view (perpendicular to
the axis of revolution), and a 152 mm length in profile (through the axis of revolution), such
that the axis of the revolution is horizontal and in the longitudinal vertical plane through the
vertical longitudinal zero plane of the head restraint. Position the midpoint of the bottom
surface of the cylinder in contact with the head restraint.
2.3. Establish initial reference position by applying a vertical downward load of 50 ± 1 N at a rate
of 250 ± 50 N/minute. Determine the reference position after 5 seconds at this load. Mark an
initial reference position for the head restraint.
2.4. Measure the vertical distance between the lowest point on the underside of the head restraint
and the top of the seat back. (see Paragraph 2.9. of this Annex)
2.5. Increase the load at the rate of 250 ± 50 N/minute to at least 500 N and maintain this load for
not less than 5 seconds.
DYNAMIC PERFORMANCE TEST PROCEDURE
Demonstrate compliance with Paragraph 5.3. in accordance with this Annex, using a
50th percentile male Hybrid III test dummy.
2. TEST EQUIPMENT
2.1. An acceleration or deceleration test sled
2.2. 50th percentile male test dummy
2.2.1. Hybrid III
126.96.36.199. Three accelerometers are in the head cavity to measure orthogonal accelerations at the
centre of gravity of the head assembly. The three accelerometers are mounted in an
orthogonal array, and the intersection of the planes containing the sensitivity axis of the
three sensors will be the origin of the array.
2.2.3. Equipment for measuring the head to torso angle.
2.2.4. Equipment for measuring and recording sled accelerations.
3. PROCEDURES FOR TEST SET-UP
3.1. Mount the vehicle on a dynamic test platform so that the vertical longitudinal zero plane of
the vehicle is parallel to the direction of the test platform travel and so that movement
between the base of the vehicle and the test platform is prevented. Instrument the platform
with an accelerometer and data processing system. Position the accelerometer sensitive
axis parallel to the direction of test platform travel.
3.2. Remove the tires, wheels, fluids, and all unsecured components. Rigidly secure the engine,
transmission, axles, exhaust system, vehicle frame and any other vehicle component
necessary to assure that all points on the acceleration vs. time plot measured by an
accelerometer on the dynamic test platform fall within the corridor described in Figure 9-1
and Table 9-1.
3.3. Place any moveable windows in the fully open position.
3.4. Seat Adjustment
3.4.1. At each designated seating position, if the seat back is adjustable, it is set at an initial
inclination position closest to 25° from the vertical, as measured by the three-dimensional
H-Point machine, as specified in Annex 13. If there is more than one inclination position
closest to 25° from the vertical, set the seat back inclination to the position closest to and
rearward of 25°.
3.7. Hybrid III Test Dummy Positioning Procedure
Place a test dummy at each designated seating position equipped with a head restraint.
The transverse instrumentation platform of the head is level within ½°. To level the head of
the test dummy, the following sequence is followed. First, adjust the position of the H-Point
to level the transverse instrumentation platform of the head of the test dummy. If the
transverse instrumentation platform of the head is still not level, then adjust the pelvic angle
of the test dummy. If the transverse instrumentation platform of the head is still not level,
then adjust the neck bracket of the dummy the minimum amount necessary from the
non-adjusted "0" setting to ensure that the transverse instrumentation platform of the head
is horizontal within ½°. The test dummy remains within the limits specified in after any
adjustment of the neck bracket.
3.7.2. Upper Arms and Hands
Position each test dummy as specified below:
188.8.131.52. The driver's upper arms shall be adjacent to the torso with the centre lines as close to a
vertical plane as possible.
184.108.40.206. The passenger's upper arms are in contact with the seat back and the sides of the torso.
220.127.116.11. The palms of the drivers test dummy are in contact with the outer part of the steering wheel
rim at the rim's horizontal centre line. The thumbs are over the steering wheel rim and are
lightly taped to the steering wheel rim so that if the hand of the test dummy is pushed
upward by a force of not less than 0.91 kg and not more than 2.27 kg, the tape shall release
the hand from the steering wheel rim.
18.104.22.168. The palms of the passenger test dummy are in contact with the outside of the thigh. The
little finger is in contact with the seat cushion.
3.7.3. Upper Torso
Position each test dummy such that the upper torso rests against the seat back. The
midsagittal plane of the dummy is aligned within 15 mm of the head restraint centreline. If
the midsagittal plane of the dummy cannot be aligned within 15 mm of the head restraint
centreline then align the midsagittal plane of the dummy as close as possible to the head
3.7.4. Lower Torso
The H-Points of the driver and passenger test dummies shall coincide within 12.5 mm in the
vertical dimension and 12.5 mm in the horizontal dimension of a point 6.25 mm below the
position of the H-Point determined by the manikin defined in Annexes 12 and 13.
22.214.171.124.2. Vehicles with wheelhouse projections in passenger compartment
Place the right and left feet in the well of the floor pan/toeboard and not on the wheelhouse
projection. If the feet cannot be placed flat on the toeboard, initially set them perpendicular
to the lower leg centrelines and then place them as far forward as possible with the heels
resting on the floor pan.
126.96.36.199. Rear Passenger's position
Position each test dummy as specified in Paragraph 188.8.131.52. of this Annex, except that feet
of the test dummy are placed flat on the floorpan and beneath the front seat as far forward
as possible without front seat interference. If necessary, the distance between the knees
can be changed in order to place the feet beneath the seat.
3.8. All tests specified by this Standard are conducted at an ambient temperature of 18 to 28° C.
3.9. All tests are performed with the ignition "on."
4. TEST PROCEDURE
4.1. Accelerate or decelerate the dynamic test platform to reach a delta V of 17.3 ± 0.6 km/h. All
of the points on the acceleration vs. time curve fall within the corridor described in
Figure 9-1 and Table 9-1 when filtered to channel Class 60, as specified in the
SAE Recommended Practice J211/1 (revision March 1995). Measure the maximum
rearward angular displacement.
4.2. Calculate the angular displacement from the output of instrumentation placed in the torso
and head of the test dummy and an algorithm capable of determining the relative angular
displacement to within one degree and conforming to the requirements of a 600 Hz channel
class, as specified in SAE Recommended Practice J211/1, (revision March 1995). No data
generated after 200 ms from the beginning of the forward acceleration are used in
determining angular displacement of the head with respect to the torso.
Sled Pulse Acceleration Corridor
The target acceleration with time expressed in milliseconds is a = 86 sin(πt/88) m/s , for
�V = 17.3 ± 0.6 km/h. The time zero for the test is defined by the point when the sled acceleration
achieves 2.5 m/s (0.25 g's).
2.2.3. Verify the transverse distance between the centres of the front of the knees is 160 to 170 mm.
Centre the knee separation with respect to the seat centreline.
2.2.4. If needed, extend the legs until the feet do not contact the floor pan. The thighs are resting on
the seat cushion.
2.2.5. If the human contacts the interior move the seat rearward until a maximum clearance of 5 mm
is achieved or the seat is in the closest detent position which does not cause human contact.
2.2.6. Passenger Foot Positioning
184.108.40.206. Place feet flat on the toe board, or
220.127.116.11. If the feet cannot be placed flat on the toe board, the feet are perpendicular to the lower leg,
and the heel is as far forward as possible and resting on the floor pan, or
18.104.22.168. If the heels do not touch the floor pan, the legs are vertical and the feet parallel to the floor
2.2.7. Passenger Arm/Hand Positioning
22.214.171.124. Place the human's upper arms adjacent to the torso with the arm centrelines as close to a
vertical longitudinal plane as possible.
126.96.36.199. Place the palms of the human in contact with the outer part of the thighs.
188.8.131.52. Place the little fingers in contact with the seat cushion.
2.3. Start the vehicle engine or place the ignition in the "on" position, whichever will turn on the
suppression system, and close all vehicle doors. Note the position of the head restraint.
Remove the human from the seat. If the head restraint returns to a retracted position upon
removal of the human, manually place it in the noted position. Determine compliance with the
height requirements of Paragraph 5.1.1. by using the test procedures of Annex 1.
2.4. Return the ignition switch to the "off" position
3. 60° ROTATION EVALUATION
Procedures for the rear and front centre designated seating positions to demonstrate
compliance with Paragraph 184.108.40.206.
3.1. Place the head restraint in any position meeting the requirements of Paragraph 220.127.116.11. or
Paragraph 18.104.22.168. of the Regulation;
3.1.1. Mark a line on the head restraint with one end at the point of rotation. Measure the angle or
range of angles of the head restraint reference line as projected onto a vertical longitudinal
3.1.2. Fold or retract the head restraint to a position in which its minimum height is less than that
specified in Paragraph 22.214.171.124. or Paragraph 126.96.36.199.;
3.1.3. Determine the minimum change in the head restraint reference line angle as projected onto a
vertical longitudinal vehicle plane from the angle or range of angles measured in
Paragraph 3.1.1. of this Annex.
5. 10° TORSO LINE CHANGE
Procedures for the rear and front centre designated seating positions to demonstrate
compliance with Paragraph 188.8.131.52.
5.1. Place the head restraint into any position meeting the requirements of Paragraph 5.1.1 of this
5.2. Measure the torso line angle with the three dimensional H-Point machine defined in
5.3. Fold or retract the head restraint to any position in which its minimum height is less than that
specified in Paragraph 5.1.1. of this Regulation or in which its backset is more than that
specified in Paragraph 5.1.5. of this Regulation; and
5.4. Again measure the torso line angle.
PROCEDURE FOR VALIDATION OF THE H-POINT AND R-POINT
RELATIONSHIP FOR SEATING POSITIONS IN MOTOR VEHICLES
The procedure described in this Annex is used to establish the H-Point location and the actual
torso angle for one or several seating positions in a motor vehicle and to verify the
relationship of measured data to design specifications given by the vehicle manufacturer.
For the purposes of this Annex:
2.1. "Reference data" means one or several of the following characteristics of a seating position:
2.1.1. The H-Point and the R-Point and their relationship,
2.1.2. The actual torso angle and the design torso angle and their relationship.
2.2. "Three-dimensional H-Point machine (3-D H machine)" means the device used for the
determination of H-Points and actual torso angles. This device is described in Annex 13;
2.3. "Centre plane of occupant (C/LO)" means the median plane of the 3-D H machine
positioned in each designated seating position; it is represented by the coordinate of the
H-Point on the "Y" Axis. For individual seats, the centre plane of the seat coincides with the
centre plane of the occupant. For other seats, the centre plane of the occupant is specified
by the manufacturer;
2.4. "Three-dimensional reference system" means a system as described in Annex 11;
2.5. "Fiducial marks" are physical points (holes, surfaces, marks or indentations) on the vehicle
body as defined by the manufacturer;
2.6. "Vehicle measuring attitude" means the position of the vehicle as defined by the
coordinates of fiducial marks in the three-dimensional reference system.
3. PROCEDURE FOR H-POINT AND ACTUAL TORSO ANGLE DETERMINATION
3.1. The vehicle is preconditioned at a temperature of 20° C ± 10° C to ensure that the seat
material reaches room temperature.
3.2. The vehicle is at the measuring attitude defined in Paragraph 2.6. of this Annex.
3.3. The seat, if it is adjustable, is adjusted first to the rearmost normal driving position, as
indicated by the vehicle manufacturer, taking into consideration only the longitudinal
adjustment of the seat, excluding seat travel used for purposes other than normal driving
positions. Where other modes of seat adjustment exist (vertical, angular, seat back, etc.)
these will be then adjusted to the position specified by the vehicle manufacturer. For
suspension seats, the vertical position is rigidly fixed corresponding to a normal driving
position as specified by the manufacturer.
3.9. Tilt the back pan forward against the forward stop and draw the 3-D H machine away from the
seat back using the T bar. Reposition the 3-D H machine on the seat by one of the following
3.9.1. If the 3-D H machine tends to slide rearward, use the following procedure. Allow the
3-D H machine to slide rearward until a forward horizontal restraining load on the T bar is no
longer required i.e. until the seat pan contacts the seat back. If necessary, reposition the
3.9.2. If the 3-D H machine does not tend to slide rearward, use the following procedure. Slide the
3-D H machine rearwards by applying a horizontal rearward load to the T bar until the seat
pan contacts the seat back (see Figure 13-2 of Annex 13).
3.10. Apply a 100 ± 10 N load to the back and pan assembly of the 3-D H machine at the
intersection of the hip angle quadrant and the T bar housing. The direction of load application
is maintained along a line passing by the above intersection to a point just above the thigh bar
housing (see Figure 13-2 of Annex 13). Then carefully return the back pan to the seat back.
Care must be exercised throughout the remainder of the procedure to prevent the
3-D H machine from sliding forward.
3.11. Install the right and left buttock weights and then, alternately, the eight torso
weights. Maintain the 3-D H machine level.
3.12. Tilt the back pan forward to release the tension on the seat back. Rock the 3-D H machine
from side to side through 10° arc (5° to each side of the vertical centre plane) for three
complete cycles to release any accumulated friction between the 3-D H machine and the
3.12.1. During the rocking action, the T bar of the 3-D H machine may tend to diverge from the
specified horizontal and vertical alignment. The T bar must therefore be restrained by
applying an appropriate lateral load during the rocking motions. Care is exercised in holding
the T bar and rocking the 3-D H machine to ensure that no inadvertent exterior loads are
applied in a vertical or fore and aft direction.
3.12.2. The feet of the 3-D H machine are not to be restrained or held during this step. If the feet
change position, they should be allowed to remain in that attitude for the moment.
3.12.3. Carefully return the back pan to the seat back and check the two spirit levels for zero position.
If any movement of the feet has occurred during the rocking operation of the 3-D H machine,
they must be repositioned as follows:
3.12.4. Alternately, lift each foot off the floor the minimum necessary amount until no additional foot
movement is obtained. During this lifting, the feet are to be free to rotate; and no forward or
lateral loads are to be applied. When each foot is placed back in the down position, the heel
is to be in contact with the structure designed for this.
3.12.5. Check the lateral spirit level for zero position; if necessary, apply a lateral load to the top of
the back pan sufficient to level the 3-D H machine's seat pan on the seat.
DESCRIPTION OF THE THREE-DIMENSIONAL H-POINT MACHINE
(3-D H Machine)
1. BACK AND SEAT PANS
The back and seat pans are constructed of reinforced plastic and metal; they stimulate the
human torso and thigh and are mechanically hinged at the "H" Point. A quadrant is fastened to
the probe hinged at the H-Point to measure the actual torso angle. An adjustable thigh bar,
attached to the seat pan, establishes the thigh centreline and serves as a baseline for the hip
2. BODY AND LEG ELEMENTS
Lower leg segments are connected to the seat pan assembly at the T bar joining the knees,
which is a lateral extension of the adjustable thigh bar. Quadrants are incorporated in the lower
leg segments to measure knee angles. Shoe and foot assemblies are calibrated to measure the
foot angle. Two spirit levels orient the device in space. Body element weights are placed at the
corresponding centres of gravity to provide seat penetration equivalent to a 76 kg male. All joints
of the 3-D H machine should be checked for free movement without encountering noticeable
Dimensions of the 3-D H Machine Elements and Load Distribution
(Dimensions in millimeters)