Anthropometric data of the 3 and 6 year-old child regarding the position of the safety belt

Serre, Child anthropometry regarding safety belt

Anthropometric data of the 3 and 6 year-old child regarding the position of the safety belt T. SERRE*†, L. LALYS‡ and S. LECOZ† † Laboratoire de Biomécanique Appliquée UMRT24 IFSTTAR-Université de la Méditerranée Faculté de médecine Nord, Bd. P. Dramard, 13916 Marseille, France ‡ CNRS-UPR2147, Paris, France

Abstract

This anthropological study intends to describe first the morphological characteristics of 3 and 6 years old children, and then to evaluate the safety belt position regarding the children seated in a car with different Child Restraint System (CRS). This work is based on a measurement survey which allowed to acquire anthropometric data in two approaches: somatologic data, including dimensions in standing and sitting positions (14 measurements) biometric data on the same subjects seated in a car with different restraint systems (15 measurements) The survey was conducted in a school located in the northern part of France, after obtaining compulsory authorizations from the relevant authorities. 71 children have been measured (33 three year-old and 38 six yearold). The car used for the survey is a Peugeot 308 and the backseat has been measured. The two CRSs which have been used and measured are: a child seat (CRS1) which belongs to the European standard group 1 (children weight between 9 to 18 kg) and a booster which belongs to the groups 2 and 3 (15 to 36 kg). Children of 3 years old have been measured in the CRS1 and CRS2. Those of 6 years old have been measured in the CRS2 and without CRS. Standard anthropometric tools have been used: height gauge, sliding calipers, tape measure, scales. For each age, the main percentile values of all dimensions of the children morphology have been provided. Several measurements of the belt position regarding morphological anatomical points of the child in the car with the different Child Restraint Systems (CRSs) have been performed. This allows to check the suitability of the belt regarding the morphology of the child in a r estraint system. The European mass classification appears as not relevant for 75% of the 3 year-old because they can be both in th CRS1 and CRS2 according to their weight. The 95 percentile of the 3 year-old appears to be out of the limit and can only be in the booster seat. As for the 6 year-old, if all the children fit in the booster seat according to their th th weight, children between the 5 and the 25 percentile could also be placed in a child seat. This work has been performed within the European Project CASPER “Child Advanced Safety Project for th European Roads” co-funded by the EC under the 7 Framework Program (http://www.casper-project.eu (http://www.casper-project.eu). ). Keywords: Measurement, Children, Anthropometry, Posture, Seatbelt

1. Introduction

European transport policy intends to reduce by half the number of fatalities on the road, and considers that approximately half of the 1200 children killed on European roads could have been saved in 2007. Moreover 80000 children are injured per year and it is not acceptable for different aspects (ethical, economic, etc). Safety issues concerning the children involved in car accidents are in consequence fundamental.

*Corresponding author. Email: [email protected]

Use of Child Restraint System (CRS) is the main measure to protect children in a vehicle (Alonzo et al., 2005). As so, numerous researches were conducted the past years thanks to European Project such as CHILD and CREST. The main results show more specifically an incorrect use of restraints because of inappropriateness or misuse CRS (Campbell et al., 1997; Morris et al., 2000) and variability of child anatomy (Burdi et al., 1969). Those CRSs must be designed according to the particular morphology of the child - who is not

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an adult of little size from an anatomy point of view- (Burdi et al., 1969; Floret, 1999; Huang and Reed, 2006), its variability and eventually its growth (Bull et al., 2002). In addition, a CRS that obtains good results in term of protection could be less efficient in another car (Reed et al., 2008). This issue is partially resolved with Isofix system (Kappoor et al., 2005). However, this concerns only groups 0 and 1(birth to 10kg and 9 to 18kg). The European legislation divides CRSs in 4 groups. The second group (15 to 25kg) and the third one (22 to 36kg) present important differences in the fitting with the child morphology (IIH, 2008, 2009; Reed et al., 2009) and with the rear seat (Bilston and Sagar, 2007). The weight overlap is made to provide the transition between each CRS easier. The choice of such a predictor to graduate is criticized since premature graduation was observed (Anderson and Hutchinson, 2007) as well as a gap in the graduation between a forward facing system and a booster for the 3 or 4-year-old (Serre et al., 2009). Mismatch between a system and the child implies a decrease protection (Durbin et al., 2003, 2005). Mostly for practical reasons, none research focused on all of those factors. In most of them, child variability is not studied or updated in favour of backseats and CRSs geometry confronted to old anthropometric databases, typically Snyder’s (Snyder et al., 1975, 1977) or to dummies, ignoring secular growth trend (Smith and Norris, 2001, 2004) and variability of child (Serre et al., 2005). This study offers to acquire new anthropometric data of 3-year-old children in a CRS forward facing system 5-points (group 1-2) and in a booster seat (group 2-3) in a car. Confrontation between anthropometry, special measurements involving the belt and CRSs geometry should help to precise the gap already observed. This study also considers the 6-year-old children because numerous researches are focused on this age. But these previous researches are mainly based on dummy use or on old anthropometric databases. So it appeared interesting to obtain better knowledge of the actual variability of this age. In particular it was shown that the real variability and morphology of the child pelvis could increase biofidelity of crash dummies (Reed et al., 2009) and eventually to help in the prediction of booster-backseat transition (Ebel et al., 2003). The goal of this paper is to answer the following question: which CRS is better for the 3year-old? 5-points forward facing or booster system? What about the 6-year-old child, booster or not?

2. Materials and Methods

This work has been performed within the European Project CASPER “Child Advanced Safety Project for European Roads” co-funded by the EC th under the 7 Framework Program

Figure 1 - Backseat dimensions

2.1. Sample

The survey was conducted in a school located in the northern part of France, after obtaining compulsory authorizations from the relevant authorities and of the CASPER ethical board committee (CNIL, IFSTTAR ethic committee, Education Authority, Headmaster, parents). So ethical rules have been strictly observed. During the classical anthropometric measures, children stayed fully clothed, preferably with lightly ones and shoes off, while they wore their usual seasonal clothes when measured in the car. At least two researchers were needed. The school nurse was attending during some sessions and the parents have been invited to watch if they wanted to. In that way, familiar faces were around the children in order to allay them. The campaign took place according to the French school schedule, during 4 full days. The measurement protocol has been established in order no to be too long. 15 minutes maximum length appeared as acceptable both for children and for the pedagogical program of the school teachers. To respect their necessary nap time, 3 years old children have been measured only in the morning sessions. 71 children have been measured. A Chi-square test has been performed and confirmed sex ratio was unbalanced (See Table 1). Table 1 – Sample

2.2. Car and CRS measurements

The car used for the survey is a Peugeot 308 which is a medium size vehicle with 5 seating positions. The following measurement have been performed on the backseat (See Figure 1, measurements are reported in Table2 of the Results section)

Two CRSs have been used and measured: (See Figure 2 and the corresponding values in Table3 of the Results section)

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•

•

CRS1 BEBECONFORT Trianos safeside, which belongs to the European standard groups 1-2-3 but has been used in the group 1 (9-18 kg) configuration. In this case, the CRS is restrained by the seatbelt and the child is restrained using a 5-points harness. CRS2 GRACCO Booster, which belongs to the European standard 2 and 3 and is usable for children between 15 and 36 kg.

Figure 4 – Measurements involving the restraint system (depending on the age of the child - 20 to 29)

Figure 2 – CRS1 (left) – Harness system and CRS2 (right) simple booster seat

2.3. Anthropometric measurements

The measurement protocol was a two-steps procedure. First a set of 14 standard measures was proceeded in standing and sitting position (see figure 3). Concerning the sitting position, children were seated on a chair against a wall in order to have an angle of 90° between the thigh and the back (see figure 3). The head was oriented in order to have the Francfort plane in a horizontal position. Then additional measurements into the car in real restraint conditions were performed (see Figure 4). Children of age close to 3 years have been measured in the CRS1 and in the CRS2, and the 6 years old ones have been measured in the CRS2 and on the rear bench of the car. Standard anthropometric tools have been used: height gauge, sliding calipers, tape measure, scales. Standard measurements have been selected based on literature (Serre and al., 2009, 2006; Bartoli and al. 2006).

Figure 3 – Standard measurements (taken for every child1 to 19)

Figures 3 and 4 illustrate all the dimensions and the below list describes these 29 di mensions: In standing and sitting position: 1. Stature 2. Sitting height 3. Acromion-seat height 4. Knee-heel height 5. Buttock-heel length 6. Thorax depth 7. Abdominal depth 8. Bi-acromial width 9. Thorax width 10. Abdominal width 11. Bi-trochanter width 12. Thigh length 13. Sternum length 14. Weight In car and CRSs: 15. Manubrium height 16. Navel height 17. Iliac crest height 18. Elbow height 19. Transverse neck diameter 20. Thigh height at the belt navel 21. Distance between the two belts at the acromion level 22. Distance between the two belts at the navel level 23. Diagonal belt height at the shoulder level 24. Diagonal belt height at the mi-clavicle level 25. Diagonal belt height at the sternum level 26. Diagonal belt at the iliac crest level 27. Ventral belt height 28. Diagonal belt distance from the navel 29. Diagonal belt distance at the mi-acromion-sternum level from the opposite acromion

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The measurement order list has been proceeded in order to manage measure tools in the better way. A turnaround of the operators was set up in order to alternate measuring operations and results recording. The data acquisition was performed by qualified operators in the anthropological field and experienced in taking children's measurement. 3. Results 3.1. Car and CRS measurements

Following measurements of the car and the CRSs have been collected (See Tables 2 and 3). Table 2: Car rear bench dimensions

3.2. Anthropometric measurements

A t-test has been processed on a previous database of about 2000 french children (Bartoli et al., 2006) to evaluate the influence of the gender on the measurements. For each standing and sitting measurement, p value showed no significant difference. As so, results have been merged without any distinction between female and male. The database has been statistically processed and th th th th th for each dimension, the 5 , 25 , 50 , 75 and 95 percentiles values have been calculated. The minimal, maximal, mean and standard deviation are indicated too in the Tables 4 and 5.

Tables 3: CRSs dimensions (mm and degrees)

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Table 1 – Measurements of the 3 year-old

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Table 2 – Measurements for the 6 year-old

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4. Discussion

Based on these measurements, several preliminary results can be highlighted: Results of children’s weight have to be confronted with legislative standard groups. First, the European mass classification appears as not relevant: 75% of the 3 year-old can be both in CRS1 and CRS2 according to their weight, while it’s known that children of this age are better protected in harness systems than using a simple booster cushion both in th frontal and side impacts. The 95 percentile of the 3 year-old appears to be out of the limit and can only be in the booster seat (see figure 5).

anthropometric data. More specifically, most of the existing and available data have been mainly collected in standard positions and so appear as not suitable to the real restraint conditions. Concerning the seatbelt position, diagonal belt at the mi-clavicle level appears as too high regarding the real clavicle position. Indeed, for the 3 year-old th in the CRS2 for the 50 percentile, the acromionseat height (which is similar to the clavicle height) is clearly higher than the height of the seatbelt at this level (31 mm of difference). As for the 6 yearth old, it is also higher for the 50 percentile (23 mm) in the CRS2 and much higher in the backseat (58 mm). The lower part of the seatbelt has to fit at the iliac crest level. For the 3 year-old, the ventral belt in the CRS2 is always close or below the iliac crests level. For the 6 year-old, the same pattern appears in the CRS2 while in the backseat ventral belt is slightly above the iliac crest for the smallest percentiles, and close for the higher ones. In the CRS1, the harness straps (at their maximal th position) are below the acromion level at the 50 percentile and higher.

Figure 5 - Weight confronted to legislative classification groups.

As for the 6 year-old, if all the children fit in the booster seat according to their weight, children th th between the 5 and the 25 percentile could also be placed in a child seat (see figure 5).

From an ergonomic point of view, CRSs width is always larger than each percentile of the bitrochanter width of the children that they are supposed to restrain. 5. Conclusion

Another observed phenomenon is that thoracic and abdominal depths show important differences in the measurement according to the fact that the child is simply seated or installed in a car. They appear to be smaller in restraint systems and in the rear bench than in standard sitting position.

The objective of this work was to provide the main characteristics of the anthropometry of children aged of 3 and 6 years old and allow evaluation the suitability between restraint systems and children morphology. Dimensions in standing and sitting positions have been reported in order to give a general overview of the children external geometry. Additional measurements in car and CRSs have been taken to verify the suitability of the belt regarding the children morphology. Preliminary results already highlighted some interesting points: • Differences between a same measure in sitting position and in a CRS or in the backseat possibly revealed changes in the child external morphology and so issues in the CRSs designing. • The European mass classification do not seems to be relevant because the seatbelt appears as bad designed for some children even if they are seated in the good CRS regarding their weight.

This shows the importance of developing tools (human models for example) which fit with correct

Further analyses have to be conducted to check the suitability of the belt in several anatomical points

Moreover it appears interesting to compare some dimensions which have been measured both in classical sitting position (90° backseat) and in a CRS. In particular the acromion-seat height is an important dimension to evaluate if the position of the seatbelt is correct because it has a heavy influence of the quality of the protection of children. Results show that this measurement is shorter in the standard position than for the situations using CRS2 or the car rear bench. So, it seems to be very important to choose the good dimension for designing CRS system for example.

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and to calculate its ideal position considering our sample. These data can be used to develop numerical child body model using scaling technique. Also, data could be used for improvement of test procedures, dummies (and associated models), cars and CRS designs. Acknowledgement

This work has been performed within the European Project CASPER “Child Advanced Safety Project for European Roads” co-funded by the EC th under the 7 Framework Program (http://www.casper-project.eu). Authors would like to thank the headmaster of the school Mr HuotMarchand, parents of the children and the children. References

Anderson RWG, Hutchinson TP (2007). The feasibility of aged-based criteria for child restraint selection. ESV conference, Paper 07-02220, 10p. Alonzo, F., Brun, F., Djidi, E., Gonon, M., Javouhey, E., Khann, N., et al. (2005). L'enfant victime de l'insécurité routière : bilan, prévention et perspectives. Bron: Compte rendu de la Journée spécialisée du 13 octobre 2004. Bartoli C, Lalys L, Serre T, Brunet C, Leonetti G, 2006 - Upper limb anthropometry for children aged from 3 to 15 years. Journal of Biomechanics. Vol.39, Supp 1, pS79. Bilston, L. E., & Sagar, N. (2007). Geometry of Rear Seats and Child Restraints Compared to Child Anthropometry. In A. I. King, J. W. Melvin & L. W. Schneider (Eds.), Stapp Car Crash Journal, Vol 51 (Vol. 51, pp. 275-298). Bull, M. J., Agran, P., Garcia, V., Gardner, H. G., Laraque, D., Pollack, S. H., et al. (2002). Selecting and using the most appropriate car safety seats for growing children: Guidelines for counseling parents. Pediatrics, 109(3), 550-553. Burdi, A. R., Huelke, D. F., Snyder, R. G., & Lowrey, G. H. (1969). Infants and children in adult world of automobile safety design - pediatric and anatomical considerations for design of child restraints. Journal of Biomechanics, 2(3), 267-&. Campbell, H., Macdonald, S., & Richardson, P. (1997). High levels of incorrect use of car seat belts and child restraints in Fife--an important and underrecognised road safety issue. Inj Prev, 3 (1), 17-22. Durbin, D. R., Chen, I., Smith, R., Elliott, M. R., & Winston, F. K. (2005). Effects of seating position and appropriate restraint use on the risk of injury to children in motor vehicle crashes. Pediatrics, 115(3), E305-E309. Durbin, D. R., Runge, J., Mackay, M., Meissner, U., Pedder, J., Wodzin, E., et al. (2003). Booster seats for children: closing the gap between science and public policy in the United States. Traffic Inj Prev, 4(1), 5-8.

Ebel, B. E., Koepsell, T. D., Bennett, E. E., & Rivara, F. P. (2003). Too small for a seatbelt: Predictors of booster seat use by child passengers. Pediatrics, 111(4). Floret, D. (1999). Safety of children as car passengers: integrate their specificities. Archives De Pediatrie, 6 (3), 247-250. Huang, S., & Reed, M. P. (2006). Comparison of child body dimensions with rear seat geometry. SAE technical paper series , 10. IIHS. (2008). Too big for her child restraint, she needs a booster that fits. 43(8), 7. Status report of the Insurance Institute of Highway safety IIHS. (2009). Which booster is best for me? Status report of the Insurance Institute of Highway safety . 44(11), 7. Kapoor, T., Altenhof, W., & Howard, A. (2005). The effect of using universal anchorages in child restraint seats on the injury potential for children in frontal crash. [Article]. International Journal of Crashworthiness, 10(3), 305-314. Morris, S. D., Arbogast, K. B., Durbin, D. R., & Winston, F. K. (2000). Misuse of booster seats. Inj Prev, 6 (4), 281-284. Reed, M. P., Ebert, S. M., Sherwood, C. P., Klinich, K. D., & Manary, M. A. (2009). Evaluation of the static belt fit provided by belt-positioning booster seats. Accident Analysis and Prevention, 41(3), 598-607. Reed, M. P., Sochor, M. M., Rupp, J. D., Klinich, K. D., & Manary, M. A. (2009). Anthropometric specification of child crash dummy pelves through statistical analysis of skeletal geometry. Journal of Biomechanics, 42(8), 1143-1145. Serre, T., Lalys, L., Brunet, C., Bartolli, C., Christia-lotter, G., & Leonetti, G. (2005). 3 and 6 years old anthropometry and comparison with crash dummies. SAE , 5. Serre, T., Thouvenin, S., Brunet, C., Lalys, L., Bartolli, C., & Leonetti, G. (2009). Comparison between new data on children anthropometry and CRS dimensions. Enhanced Safety of Vehicles, 7. Smith, S., & Norris, B. (2001). Childata : Assessment of the validity of data. Nottingham: University of Nottingham, Product Safety and Testing Group. Smith, S. A., & Norris, B. J. (2004). Changes in the body size of UK and US children over the past three decades. Ergonomics, 47 (11), 1195-1207. Snyder, R. G., Schneider, C. L., Owings, C. L., Reynolds, H. M., Golomb, D. H., & Schork, M. A. (1977). Anthropometry of infants, children and youths to age 18 for product safety design. Bethesda: Consumer Product Safety Commission. Snyder, R. G., Spencer, M. L., & Schneider, L. W. (1975). Physical characteristics of children as related to death and injury for consumer product safety design. Bethesda: Highway Safety Research Institute.

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Anthropometric data of the 3 and 6 year-old child regarding the position of the safety belt

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