SIMPLIFICATION AND TRANSFORMATION OF
ASTM F1292-09 MEASUREMENT PROCEDURE
FOR FALL ACCIDENT INJURY CRITERIA
Macky KATO1, Yoshie SHIMODAIRA2, Takeshi SATO3 and Hiromi IIDA4
1Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama 359-1192, Japan
2Nagano Prefectural College, 8-49-7 Miwa, Nagano, 380-8525, Japan
3
Jissen Women’s University, 4-1-1 Osakaue, Hino, Tokyo 191-8510, Japan
4Nihon Taiiku Sangyo Co., 2034 Kazama Nagano, 381-0023, Japan

Accidents involving falls from playground equipment can be fatal for children.
While it is necessary to protect children from such accidents, learning about therisk of falling is an essential aspect of playing with the equipment. Therefore,
prevention of injuries resulting from falling is required. The risk of injury can beevaluated by means of the ASTM F1292-09 Head Injury Criterion (HIC) test. This
test can be used to accurately quantify risk; however, the measurement procedure iscomplicated, and thus not easy to apply to many of existing equipment. ASTM
F1292-09 requires simplification, even at a small cost of accuracy; for example, byreducing the number of trials. With this in mind, this study proposes atransformation equation to simplify ASTM F1292-09. Results of both HIC and Gmax from the conventional procedure are in all cases more detailed than those fromthe simplified method. HIC and G-max values for both procedures linearly increase
with fall height. It is therefore possible for the difference in outcomes between theregression equation of the conventional procedure and that of the simplified
procedure to be added to the equation of simplified method as a transformation
equation. This suggests that the combination of the simplified procedure andtransformation equation would be equivalent to conventional ASTM F1292-09,
with the advantage of being more easily and efficiently applied to the evaluation ofexisting playground equipment.

IntroductionMore than 15,000 people are accidentally killed in Japan every year. The number of casualties
through traffic accidents has been decreasing over the last decade. However, the number ofcasualties through accidents in daily life is greater than those caused by traffic accidents. One
such “daily life” accident is falling. Statistic for 2011 show that 6,644 people were killed bytraffic accidents, while 7,165 people were killed by accidents involving falls (MHLW 2012).
Overall, the majority of victims of falls are elderly people, many of whom fall on flat places.
However, younger people are more likely than elderly people to fall from structures, especiallyfrom playground equipment such as slides, climbing frames, and swings, and therefore requireprotection.
Once an accident involving playground equipment happens, caretakers often remove theequipment in order to prevent a fall accident again. However, this response is not always
appropriate. Children need different types of experience while growing up. Awareness of therisk of fall accidents is most important in protecting them from hazardous situations. Even if
they fall from the equipment, the materials on the ground should keep them safe. Ideally, allitems of equipment should be evaluated in terms of safety. Therefore, the evaluation methodshould be easily applied because of the volumes of playground equipment.
HIC and G-max are used as criteria of injury risk. The evaluation methods for the two- 83 -criteria for fall accidents are standardized in ASTM F1292-09. The ASTM F1292-09 evaluation
method requires some preparation and three trials for each measurement. Because it takes a longtime to measure, it is not practical to evaluate many existing items of playground equipment in atown. Thus, the shortened procedure should be adopted for mass evaluation, which would
enable early removal of equipment with an associated risk of injury. In this study, the shortened
procedure to evaluate injury risk of fall accident is suggested as a mass-evaluation method.

MethodA one-package device to measure HIC and G-max, shown in Figure 1, was developed for theevaluation of the impact attenuation of playground surfacing materials (Koitabashi 2006). There
were five levels of fall height: 100, 150, 200, 250, and 300 cm. The impact surface at themeasurement point was bare ground or sand. Depths of sand were at six levels: 6, 8, 10, 12, 14
and 16 cm. The conventional ASTM F1292-09 procedure was compared with the shortened
procedure in this study using regression analysis. In the conventional procedure, the surface at
the impact point must be hardened before the trials. Measurement of HIC and G-max are
repeated three times and the average of the second and third value is recorded as the result of thetrial. On the other hand, the shortened procedure needs just one measurement. Because themeasurement value obtained by the shortened procedure would be smaller than that obtained by
the conventional procedure, it must be appropriately transformed. The regression equation of Gmax and fall height of the two procedures was compared. Differences between them were added
to the measured value of shortened procedure. HIC was also processed in the same way as Gmax.

Figure 1 One-Package Equipment to evaluate impact attenuation (Koitabashi, 2006)

ResultFigure 2 shows samples of the acceleration and attenuation at the moment of impact. The
surface at the impact point was bare ground. The heights were 100 cm and 150 cm. G-max at
100-cm height was 145, which was measured at point in 4.15 msec. G-max at 150-cm heightwas 214, which was measured at point in 3.025 msec. It exceeded the safety margin of G-max
200.

Figure 2 Sample of the variation of acceleration at the moment of impact- 84 -G-max for all conditions increased with height. It could be measured at an earlier point as
the height increased (see Figure 2). Figure 3 shows the result of regression analysis of G-max by
the conventional procedure and the shortened procedure. The measured value in bothprocedures increased with the height. The difference between measurements from theconventional and shortened procedures also increased with the height. This was true for all
conditions of the sand. G-max decreased as the depth of the sand increased. The coefficients ofthe G-max regression equation also decreased as the depth of the sand increased.
Figure 4 shows the result of regression analysis of HIC by the conventional and shortened
procedures. The variations of HIC show the same features as those of G-max. The difference
between the two procedures increased with height, as in the case of G-max, and the coefficientsof the HIC regression equation decreased as the height increased.

Figure 3 G-max and regression equation of bare ground and 16-cm depth of sandFigure 4 HIC and regression equation of bare ground and 16-cm depth of sand- 85 -Figure 5 shows the regression equation of the coefficient difference of G-max and HIC
between the conventional and shortened procedures. The variation of the coefficient differencesof G-max was unsteady. On the other hand, the coefficient differences of HIC decreased as thedepth of sand increased.

Figure 5 Coefficient differences of G-max and HIC
between the conventional procedure and the shortened procedure

Discussion
As the results show, the G-max difference between the two procedures tends to depend on theheight but not depth of sand. Acceleration and attenuation depend on maximum speed at thepoint of impact, and that speed is determined by the fall height, as can be observed in Figure 2.
On the other hand, HIC difference tends to depend on both height and depth of sand. The
evaluation value can be estimated by transformation of the shortened procedure measured value
as follows:
G-max e = x + 0.2h
HICe = x + (0.08d+2.4)hx: measured value, h: fall height (cm), d: depth of sand (cm)The reason for using “centimeter” is that the evaluation and transformation method should
be applicable to practical use. “Centimeter” is normally used to measure depths and heights inJapan. Easy and familiar methods will be enable the investigators to efficiently research
multiple items. The shortened procedure can be used to identify any dangerous objects that needimprovements; however, it is not as appropriate for strict measurement as is conventionalprocedure. Therefore, measurement by means of the conventional procedure should be done toconfirm initial identification of dangerous objects by the shortened procedure.

Acknowledgment
This study was supported by Japan Park Facilitate Association. We are pleasure to acknowledge
the cooperation of the association and the students in Nagano Prefectural College.

References
ASTM (2009). ASTM F1292 - 09 Standard Specification for Impact Attenuation of Surfacing
Materials within the Use Zone of Playground Equipment
Ministry of Health, Labour and Welfare (2012). Vital Statistics of Japan, Retrieved July 5,
2013, http://www.mhlw.go.jp/toukei/saikin/hw/jinkou/geppo/nengai11/dl/gaikyou23.pdf
Koitabashi, T., Kitazawa, S., Henmi, N., Yabuki, D., Hatakeyama, M. & Iida, H. (2006).
Development of an One-Package Equipment for Evaluating the Impact Attenuation ofPlayground surfacing Materials. Research Reports of Nagano Prefecture General Industrial
Technology Center, 1, M41-M46.

- 86 -