Updated population-level estimates of child restraint practices among children aged 0-12 years in Australia, 10 years after introduction of age-appropriate restraint use legislation.

OBJECTIVE: Optimal child passenger protection requires use of a restraint designed for the age/size of the child (appropriate use) that is used in the way the manufacturer intended (correct use).This study aimed to determine child restraint practices approximately 10 years after introduction of legislation requiring correct use of age-appropriate restraints for all children aged up to 7 years. METHODS: A stratified cluster sample was constructed to collect observational data from children aged 0-12 years across the Greater Sydney region of New South Wales (NSW). Methods replicated those used in a similar 2008 study. Population weighted estimates for restraint practices were generated, and logistic regression used to examine associations between restraint type, and child age with correct use accounting for the complex sample. RESULTS: Almost all children were appropriately restrained (99.3%, 95% CI 98.4% to 100%). However, less than half were correctly restrained (no error=27.3%, 95% CI 10.8% to 43.8%, no serious error=43.8%, 95% CI 35.0% to 52.7%). For any error, the odds of error decreased by 39% per year of age (OR 0.61, 95% CI 0.46 to 0.81) and for serious error by 25% per year (OR 0.75, 95% CI 0.60 to 0.93). CONCLUSION: The findings demonstrate high levels of appropriate restraint use among children across metropolitan Sydney approximately 10 years after introduction of legislation requiring age-appropriate restraint use until age 7, however, errors in the way restraints remain common. IMPLICATIONS FOR PUBLIC HEALTH: Given the negative impact incorrect use has on crash protection, continuing high rates of incorrect use may reduce effectiveness of legislative change on injury reduction.

Differences in participant characteristics and observed child restraint use between population-based and restraint fitting service samples.

OBJECTIVE: To compare characteristics and restraint use between a population-based and fitting service sample of child restraint users. METHOD: Characteristics of the two samples were compared using chi-squared tests. Differences in errors in restraint use observed in the two samples were modeled using logistic regression. RESULTS: There were significant differences in child age (p < 0.001), and restraint types (p < 0.001) between the two samples, with more younger children in the fitting service sample. Controlling for differences in restraint type, the odds that adult participants were female were 61% less in the fitting service sample than in the population-based sample (OR 0.39, 95%CI 0.21-0.71). The odds that adult participants perceived a large risk associated with restraint misuse (OR 3.62, 95%CI 1.33-9.84), had a household income in the highest bracket (OR 3.89, 95%CI 1.20-12.62) and were living in areas of highest socioeconomic advantage (OR 2.72, 95%CI 1.22-6.06) were approximately three times higher in the fitting service sample. Overall, more participants had errors in restraint use in the population-based sample (p = 0.021). However, after controlling for restraint type, securing errors were three times more likely (OR 3.34, 95%CI 1.12-10.2), and serious installation errors were almost twice as likely (OR 1.91, 95% CI 1.09-3.39) in the fitting service sample. CONCLUSIONS: While less resource intensive, convenience and/or fitting service samples may be less representative than population-based samples. Given the need for efficiency, methods that combine randomized population-based invitations to participate in restraint fitting check day events across geographically representative areas may be useful for ongoing surveillance of child restraint use.

Child restraint headrest and belt routing design features and their association with child passenger behavior and restraint misuse.

OBJECTIVES: Ergonomic design of child restraint systems (CRS) may facilitate optimal travel behavior and crash protection of child passengers during motor vehicle trips. However there have been few studies examining the relationship between CRS design and child passenger travel behavior. The aim of this study was to examine whether associations between CRS design features and child passenger behavior exist during real-world, everyday vehicle trips. METHODS: Video from a naturalistic driving study (NDS) was analyzed in this study. Families drove an instrumented study vehicle for approximately two weeks with at least one child aged between one and eight years traveling in their own forward-facing (FF) CRS or belt positioning booster (BPB). Video for one child passenger was randomly selected from each trip for analysis. Video was coded for five-second epochs at nine time points (5%, 17%, 25%, 30%, 50%, 53%, 75%, 89% and 95% of trip length). Two types of child passenger travel behaviors were identified by manual review of the video and audio recordings: (i) optimal/suboptimal head position and (ii) correct/incorrect use of the internal harness/shoulder belt. Video screenshots were used to characterize CRS design features. Random effects logistic regression models were used to examine the associations between specific CRS design features and the travel behaviors of interest, whilst accounting for clustering of data by child and trip. RESULTS: Suboptimal head position was associated with the absence of a height adjustable headrest and a narrow headrest wing width in FFCRS. Incorrect harness use in a FFCRS was associated with the absence of an adjustable headrest, in addition to headrest features such as wing width and depth. In BPBs, a reduction in suboptimal head position was associated with the absence of a sash belt guide, however no restraint design features were associated with incorrect shoulder belt use. CONCLUSIONS: Some CRS design features may influence undesirable child passenger travel behavior. These early findings support enhanced and user-centric CRS design as a likely important mechanism to improve child passenger safety.

Can Age or Height Define Appropriate Thresholds for Transition to Adult Seat Belts? An Analysis of Observed Seat Belt Fit in Children Aged 7-12 Years.

This study aimed to investigate associations between demographic, anthropometric and vehicle factors and the fit of adult seat belts in children aged 7-12 years in passenger vehicles. Seat belt fit was assessed by inspection of 7-12-year-old children in their own cars. Logistic regressions examined associations between anthropometric and vehicle factors on achieving good seat belt fit. There were 40 participants included in the analysis, with 16 (40%) having good overall belt fit. The odds of achieving good overall seat belt fit increased by 15% (OR 1.15, 95% CI 1.04-1.27) with every centimeter increase in height and increased by 5% with every one-month increase in age (OR 1.045, 95% CI 1.001-1.10). Controlling for vehicle factors, neither age or height was significantly associated with overall good belt fit, and the discriminatory power of models including these metrics to predict good belt fit was 73% (AUC 0.73, 95% CI 0.55-0.91) and 74% (AUC 0.74, 95% CI 0.58-0.91). The results suggest that taller and older children have a better chance of achieving a good seat belt fit. However, with variations in seat geometry between vehicles, no single simple metric clearly defines an appropriate transition to the adult seat belt.

Paediatric off-road vehicle injury in rural and regional Australia.

OBJECTIVE: Off-road riding of quad bikes and motorcycles is common among children across rural and remote Australia, but is a significant source of injury and hospitalisation. An in-depth analysis of paediatric off-road vehicle crashes was undertaken to inform injury prevention countermeasures by characterising injury patterns and sources of injury. DESIGN: This is a prospective in-depth case series. PARTICIPANTS: Participants are children aged 16 and under who have been hospitalised due to injury sustained from the use of an off-road motorcycle or quad bike in New South Wales, Australia. INTERVENTIONS: Crash investigation techniques (medical data, structured interview, vehicle and crash site inspection) were used to ascertain details of the crash event, protective gear, injury information and contributory factors. RESULTS: Thirty children were recruited, 27 boys and 3 girls, ranging in age from 4 to 16 years, having crashed on off-road motorcycles (n = 27) or quads (n = 3). Most (73.3%) were participating in unstructured social riding. A total of 67 separate injuries were observed, with overall Injury Severity Scores between 1 and 35. There were high rates of wearing helmets and motorcycle-specific garments. The most commonly injured areas were the upper and lower extremities. The most common sources of injury were from impacting the ground, obstacles/other riders or the vehicle. CONCLUSION: This study demonstrates the patterns of riding and injury in rural paediatric off-road vehicle riders, occurring despite high rates of helmet/protective gear use. This underscores the need for investigation into the injury mitigation and fit properties of protective gear and the inherent risks for physically and developmentally maturing children.

Restraint Factors and Child Passenger Deaths in New South Wales, Australia.

Inappropriate or incorrect use of child restraints can influence crash injury outcome. This study examined the role of restraint factors in child passenger deaths and the effect of legislation requiring appropriate restraint systems up to 7 years old. Data for child (0-12 years) passenger deaths occurring in New South Wales (NSW) from 2007 to 2016 were collected by the child death review team including photographs, reports of in-depth crash investigation, witness reports and medical reports. Restraint use, type of restraint, appropriateness of the restraint for the age of the child and correctness of restraint use were examined. The primary contributor to death was determined in each case. Sixty-four child passengers died in NSW during the data period. Twenty-nine (29/64, 45%) were properly restrained. Thirteen children (13/64, 20%) were unrestrained. In 20 cases (20/64, 31%), children were using a restraint that was either inappropriate for their age (6) or not used correctly (14). Restraint factors were a primary contributor in 22 (22/64, 34%) child deaths. Compared to pre-legislation, appropriate restraint use was more common post-legislation (13/22. 59% vs. 30/42, 71%). However, incorrect use was also greater (3/22, 14% vs. 11/42, 26%). Interventions targeting increasing restraint use and reduction of common 'use' errors are needed to prevent further restraint factor-related deaths.

User-driven design of child restraint information to reduce errors in use: a pilot randomised controlled trial.

BACKGROUND: Incorrect use of child restraints is a long-standing problem that increases the risk of injury in crashes. We used user-centred design to develop prototype child restraint instructional materials. The objective of this study was to evaluate these materials in terms of comprehension and errors in the use of child restraints. The relationship between comprehension and errors in use was also explored. METHODS: We used a parallel-group randomised controlled trial in a laboratory setting. The intervention group (n=22) were provided with prototype materials and the control group (n=22) with existing instructional materials for the same restraint. Participants installed the restraint in a vehicle buck, secured an appropriately sized mannequin in the restraint and underwent a comprehension test. Our primary outcome was overall correct use, and our secondary outcomes were (1) comprehension score and (2) percent errors in the installation trial. RESULTS: There was 27% more overall correct use (p=0.042) and a higher mean comprehension score in the intervention group (mean 17, 95% CI 16 to 18) compared with the control group (mean 12, 95% CI 10 to 14, p<0.001). The mean error percentage in the control group was 23% (95% CI 16% to 31%) compared with 14% in the intervention group (95% CI 8% to 20%, p=0.056). For every one point increase in comprehension, there was an almost 2% (95% CI -2.7% to -1.0%) reduction in errors (y=45.5-1.87x, p value for slope <0.001). CONCLUSIONS: Consumer-driven design of informational materials can increase the correct use of child restraints. Targeting improved comprehension of informational materials may be an effective mechanism for reducing child restraint misuse.

Energy attenuation performance of impact protection worn by motorcyclists in real-world crashes.

OBJECTIVE: Laboratory studies have demonstrated that impact protectors (IP) used in motorcycle clothing can reduce fracture severities. While crash studies have reported IP are associated with reduced likelihood of soft tissue injury, there is little evidence of their effectiveness in reducing fracture likelihood. This discrepancy might be related to IP quality. There are mandatory requirements for IP supplied with protective clothing in Europe, but not elsewhere. This study examines the energy attenuation performance of IP used by Australian riders. METHODS: IP were harvested from clothing worn by crashed riders admitted to hospital. The IP were examined and energy attenuation properties were determined using EN 1621-1 test procedures. Impact injury was identified from medical records and defined as fractures, dislocations, and avulsions that occurred following impact to the rider's shoulders, elbows, hips, and/or knees. Fisher's exact test was used to examine the relationship between meeting the EN 1621-1 energy attenuation requirements and impact injury. The association between the average and maximum transmitted force, and impact injury was examined using generalized estimating equations. Motorcycle riders were recruited as part of an in-depth crash study through three hospitals in New South Wales, Australia, between 2012 and 2014. Riders were interviewed, and engineers conducted site, vehicle, and clothing inspections. Clothing was collected, or identical garments were purchased. RESULTS: Clothing was inspected for 62 riders. Of these, 19 wore clothing incorporating 76 IP. Twenty-six of these were impacted in the crash event. Almost all impacted IP (96%) were CE marked, and most (83%) met Level 1 energy attenuation requirements of EN 1621-1 when tested. Of the 26 impacted IP, four were associated with impact injuries, including midshaft and distal clavicle fractures and a scapula and olecranon fracture. No associations between meeting EN 1621-1 requirements and impact injury were found (p = 0.5). There was no association between average force transmitted and impact injury (95% CI: 0.91-1.24); however, as maximum force transmitted increased, the odds of impact injury increased (95% CI: 1.01-1.2). These results indicate a high probability of impact injury at 50 kN, the limit of maximum transmitted force specified in EN 1621-1. CONCLUSION: The allowable transmitted force of EN 1621-1 may be too high to effectively reduce the probability of impact injury. This is not surprising, given human tolerance levels that are reported in literature. Reducing the force limit below the reported fracture tolerance limits might be difficult with current technology. However, there is scope to reduce the EN 1621-1 maximum limit of 50 kN transmitted force. A reduction in the maximum force limit would improve rider protection and appears feasible, as 77% of tested IP recorded a maximum force <35 kN. This level of transmitted force is estimated to be associated with <20% probability of impact injury. While the performance of IP available to Australian riders is not regulated, most IP was CE marked. The results indicate a significant association between maximum transmitted force, tested according to EN 1621-1 procedures, and impact injury. Further investigation of the EN 1621-1 requirements may be warranted. This work will interest those targeting protective equipment for motorcyclists as a mechanism for reducing injury to these vulnerable road users.

Further development of Motorcycle Autonomous Emergency Braking (MAEB), what can in-depth studies tell us? A multinational study.

OBJECTIVE: In 2006, Motorcycle Autonomous Emergency Braking (MAEB) was developed by a European Consortium (Powered Two Wheeler Integrated Safety, PISa) as a crash severity countermeasure for riders. This system can detect an obstacle through sensors in the front of the motorcycle and brakes automatically to achieve a 0.3 g deceleration if the collision is inevitable and the rider does not react. However, if the rider does brake, full braking force is applied automatically. Previous research into the potential benefits of MAEB has shown encouraging results. However, this was based on MAEB triggering algorithms designed for motorcycle crashes involving impacts with fixed objects and rear-end crashes. To estimate the full potential benefit of MAEB, there is a need to understand the full spectrum of motorcycle crashes and further develop triggering algorithms that apply to a wider spectrum of crash scenarios. METHODS: In-depth crash data from 3 different countries were used: 80 hospital admittance cases collected during 2012-2013 within a 3-h driving range of Sydney, Australia, 40 crashes with Injury Severity Score (ISS)>15 collected in the metropolitan area of Florence, Italy, during 2009-2012, and 92 fatal crashes that occurred in Sweden during 2008-2009. In the first step, the potential applicability of MAEB among the crashes was assessed using a decision tree method. To achieve this, a new triggering algorithm for MAEB was developed to address crossing scenarios as well as crashes involving stationary objects. In the second step, the potential benefit of MAEB across the applicable crashes was examined by using numerical computer simulations. Each crash was reconstructed twice-once with and once without MAEB deployed. RESULTS: The principal finding is that using the new triggering algorithm, MAEB is seen to apply to a broad range of multivehicle motorcycle crashes. Crash mitigation was achieved through reductions in impact speed of up to approximately 10 percent, depending on the crash scenario and the initial vehicle pre-impact speeds. CONCLUSIONS: This research is the first attempt to evaluate MAEB with simulations on a broad range of crash scenarios using in-depth data. The results give further insights into the feasibility of MAEB in different speed ranges. It is clear then that MAEB is a promising technology that warrants further attention by researchers, manufacturers, and regulators.