A computational simulation study of the influence of helmet wearing on head injury risk in adult cyclists

Analysis of the consequences of car to micromobility user side impact crashes

INTRODUCTION

The strong rise in modes of travel commonly referred to as micromobility has changed the mobility patterns and lifestyles in cities worldwide, especially after the COVID-19 pandemic. It has led to a significant increase in the number of crashes involving these types of vehicles, especially bicycles and stand-up e-scooters. The risk of crashes is higher at intersections where motor-vehicles perform a turning maneuver crossing a bike lane.

METHOD

The consequences of a passenger car-to-micromobility vehicle side-impact crashes, considering both bicycle and e-scooter, were studied based on the results of the simulation of several scenarios with PC-Crash software. Two injury criteria were applied: Head Injury Criterion (HIC15) and 3 ms chest acceleration criterion.

RESULTS

When motor-vehicle speed is lower than 50 km/h, the 3 ms chest acceleration never exceeds the 60 g threshold. However, at 50 km/h, it is close to 50 g in the case of e-scooter rides. At this speed, HIC15 is considerably greater than 1000, both for bicycles and for e-scooters, and the safety margin of 700 is exceeded at 45 km/h for e-scooters.

CONCLUSIONS

In case of motor vehicle-to-micromobility vehicle side-impact crash, riding a bicycle is safer than riding an e-scooter since the observed HIC15 experienced by the cyclists is lower than that experienced by the e-scooter rider when motor vehicle speed is greater than 30 km/h.

PRACTICAL APPLICATIONS

To reduce micromobility users injury risk at intersections, motor vehicle speed limit should be equal or lower than 40 km/h. At this impact speed, the activation of hood or bumper airbags could be justified.

Numerical Reconstruction of Cyclist Impact Accidents: Can Helmets Protect the Head-Neck of Cyclists?

Cyclists are vulnerable road users and often suffer head-neck injuries in car-cyclist accidents. Wearing a helmet is currently the most prevalent protection method against such injuries. Today, there is an ongoing debate about the ability of helmets to protect the cyclists' head-neck from injury. In the current study, we numerically reconstructed five real-world car-cyclist impact accidents, incorporating previously developed finite element models of four cyclist helmets to evaluate their protective performances. We made comparative head-neck injury predictions for unhelmeted and helmeted cyclists. The results show that helmets could clearly lower the risk of severe (AIS 4+) brain injury and skull fracture, as assessed by the predicted head injury criterion (HIC), while a relatively limited decrease in AIS 4+ brain injury risk can be achieved in terms of the analysis of CSDM0.25. Assessment using the maximum principal strain (MPS0.98) and head impact power (HIP) criteria suggests that helmets could lower the risk of diffuse axonal injury and subdural hematoma of the cyclist. The helmet efficacy in neck protection depends on the impact scenario. Therefore, wearing a helmet does not seem to cause a significant neck injury risk level increase to the cyclist. Our work presents important insights into the helmet's efficacy in protecting the head-neck of cyclists and motivates further optimization of protective equipment.

Head impact kinematics and injury risks during E-scooter collisions against a curb

E-scooters as a mode of transportation is rapidly growing in popularity. This study evaluates head impact conditions and injury risk associated with E-scooter crashes. A multibody model of E-scooter falls induced by wheel-curb collision was built and compared with an experimental E-scooter crash test. A total of 162 crash scenarios were simulated to assess the effect of fall conditions (E-scooter initial speed and inclination, obstacle orientation, and user size) on the head impact kinematics. The forehead hit the ground first in 44% of simulations. The average tangential and normal impact speeds were 3.5 m/s and 4.8 m/s respectively. Nearly 100% of simulations identified a risk of concussion (linear acceleration peak >82 g and rotational acceleration peak >6383 rad/s2) and 90% of simulations suggested a risk of severe head injuries (HIC>700). This work provides preliminary data useful for the assessment and design of protective gears.

A Method for Evaluating Brain Deformation Under Sagittal Blunt Impacts Using a Half-Skull Human-Scale Surrogate

Trauma to the brain is a biomechanical problem where the initiating event is a dynamic loading (blunt, inertial, blast) to the head. To understand the relationship between the mechanical parameters of the injury and the spatial and temporal deformation patterns in the brain, there is a need to develop a reusable and adaptable experimental traumatic brain injury (TBI) model that can measure brain motion under varying parameters. In this effort, we aim to directly measure brain deformation (strain and strain rates) in different brain regions in a human head model using a drop tower.

METHODS

Physical head models consisting of a half, sagittal plane skull, brain, and neck were constructed and subjected to crown and frontal impacts at two impact speeds. All tests were recorded with a high-speed camera at 1000 frames per second. Motion of visual markers within brain surrogates were used to track deformations and calculate spatial strain histories in 6 brain regions of interest. Principal strains, strain rates and strain impulses were calculated and reported.

RESULTS

Higher impact velocities corresponded to higher strain values across all impact scenarios. Crown impacts were characterized by high, long duration strains distributed across the parietal, frontal and hippocampal regions whereas frontal impacts were characterized by sharply rising and falling strains primarily found in the parietal, frontal, hippocampal and occipital regions. High strain rates were associated with short durations and impulses indicating fast but short-lived strains. 2.23 m/s (5 mph) crown impacts resulted in 53% of the brain with shear strains higher than 0.15 verses 32% for frontal impacts.

CONCLUSIONS

The results reveal large differences in the spatial and temporal strain responses between crown and forehead impacts. Overall, the results suggest that for the same speed, crown impact leads to higher magnitude strain patterns than a frontal impact. The data provided by this model provides unique insight into the spatial and temporal deformation patterns that have not been provided by alternate surrogate models. The model can be used to investigate how anatomical, material and loading features and parameters can affect deformation patterns in specific regions of interest in the brain.

Effect of different helmets against ground impact based on the in-depth reconstruction of electric two-wheeler accidents

Skull fracture and brain injury are frequent head injuries in electric two-wheeler (ETW) accidents, and the type of helmet and impact conditions affect the effectiveness of the helmet in protecting the rider's head. The purpose of this study was to conduct in-depth reconstructions of rider's head-to-ground impacts in ten ETW accidents by using a multi-body system combined with a finite element approach and to evaluate the effect of two typical full-face helmets (FFH) and one half-coverage helmet (HCH) through head accelerations and intracranial biomechanics injury metrics in ground impacts. The results showed that all three helmets reduced the risk of skull fracture in most cases, however, FFH performed better due to its wider protection area. In addition, three helmets showed varying degrees of overall reduction in measuring all indicators of brain injury. Although the effectiveness of the helmets on angular acceleration was largely influenced by the angle and location of impact, it was certain that wearing an FFH was more likely to reduce rotational head movements than an HCH, and that the FFH also offered the better advantage in reducing diffuse axonal injury (DAI) risk due to its better resistance to ejection in a crash.

Helmet Use in Preventing Head Injuries in Bicycling, Snow Sports, and Other Recreational Activities and Sports

Bicycling, snow sports, and other recreational activities and sports are important activities to keep children and youth active as part of a healthy lifestyle. These activities can be associated with serious and fatal head and facial injuries. Helmets, when worn correctly, are effective in decreasing head injuries and fatalities related to these activities. Legislation for helmet use is effective in increasing helmet use in children and, ultimately, in decreasing deaths and head and facial injuries. A multipronged strategy employing legislation, enforcement of laws, and medical clinicians and community programs is important for increasing helmet use to decrease deaths and injuries from recreational sports.

Bicyclists injured by automobiles: helmet use and the burden of injury

Background

Given the widespread use of bicycles on public roadways, bicyclists injured in automobile collisions present a familiar problem to trauma centers worldwide. The aims of this study are to characterize the current injury patterns and to quantify independent risk factors for preventable injury and death, with a focus on helmet utilization and traumatic brain injuries.

Methods

This is a retrospective study using the American College of Surgeons Trauma Quality Improvement Program database for the period 2010 to 2016. Data were abstracted for bicyclists ≥16 years of age injured by an automobile. The primary outcome of interest was mortality. The secondary outcomes included intracranial, facial, and cervical spine injuries, as well as polytrauma. We used multivariate logistic regression to identify risk factors associated with outcomes.

Results

Of the 980 955 cases in the database, 7159 (0.73%) were bicyclists involved in a collision with an automobile. The median age was 45 years and 85% of patients were male. Polytraumatic occurrences accounted for 58% of injuries. Helmet use was reported in 25.4% of cases, a rate that did not change significantly during the study period. Helmet utilization was higher in those aged >65 years and in patients located in the West and Northeast regions of the USA. Helmet use was associated with an overall lower incidence of all reported forms of intracranial injuries. Overall mortality was 7.4%. Independent risk factors associated with mortality included age >65, lack of helmet use, head injury, and abdominal injury.

Discussion

Bicyclists injured in collisions with an automobile are at high risk of severe injury and mortality. Preventive strategies should target older bicyclists, helmet utilization, and increasing helmet accessibility for all bicyclists using roadways.

Level of evidence

Level IV.

Evaluation of the head protection effectiveness of cyclist helmets using full-scale computational biomechanics modelling of cycling accidents

INTRODUCTION

Cycling is a popular choice for urban transportation. Helmets are important and the most popular means of head protection for cyclists. However, a debate about the effectiveness of helmets in protecting a cyclist's head from injury continues.

METHOD

We employed computational biomechanics methods to analyze the head protection effectiveness of nine off-the-shelf-helmets for two typical impact scenarios that occur in cycling accidents: cyclist's head impacting a kerb (kerb-impact) and cyclist skidding (skidding impact) on the road surface. We conducted drop tests for all nine analyzed helmets, and used the test data for validation of the corresponding helmet finite element (FE) models created in this study. The validated helmet models were then used in the full-scale computer simulations (FE analysis for the skull, brain and helmet, and multibody dynamics for the remaining segments of the cyclist's body) of the cycling accidents for cyclists wearing a helmet and without a helmet.

RESULTS

The results indicate that helmets can reduce both the peak linear acceleration of the cyclist head center of gravity (COG) and the risk of cyclist skull fracture. However, higher rotational acceleration of the head COG was predicted for cyclists wearing helmets. The results obtained using the injury criteria that rely on the brain deformations (maximum shear strain MPS and cumulative strain damage measure CSDM) suggest that helmets may offer protection in all the analyzed cyclist impact scenarios. However, the predicted level of protection varies for different helmets and impact scenarios with appreciable variations in the predictions obtained using different injury criteria. Reduction in the maximum principal strain (MPS_0.98) for helmeted cyclists was predicted for both impact scenarios. In contrast, wearing the helmet reduced the CSDM only for the skidding impact scenario. For the kerb-impact scenario, no clear influence of the helmet on the predicted CSDM was observed.

A Biomechanical Evaluation of a Novel Airbag Bicycle Helmet Concept for Traumatic Brain Injury Mitigation

In this study, a novel expandable bicycle helmet, which integrates an airbag system into the conventional helmet design, was proposed to explore the potential synergetic effect of an expandable airbag and a standard commuter-type EPS helmet. The traumatic brain injury mitigation performance of the proposed expandable helmet was evaluated against that of a typical traditional bicycle helmet. A series of dynamic impact simulations on both a helmeted headform and a representative human head with different configurations were carried out in accordance with the widely recognised international bicycle helmet test standards. The impact simulations were initially performed on a ballast headform for validation and benchmarking purposes, while the subsequent ones on a biofidelic human head model were used for assessing any potential intracranial injury. It was found that the proposed expandable helmet performed admirably better when compared to a conventional helmet design-showing improvements in impact energy attenuation, as well as kinematic and biometric injury risk reduction. More importantly, this expandable helmet concept, integrating the airbag system in the conventional design, offers adequate protection to the cyclist in the unlikely case of airbag deployment failure.

Nonfinancial conflict of interest in peer-review: Some notes for discussion

Strong beliefs can influence the way we deal with emotionally charged topics. Researchers, editors, and reviewers are not an exception. Declaring such nonfinancial conflict of interest when handling or reviewing submitted articles is often obligatory; however, the declaration is not a license to submit a biased review with personal insults or to break the journal's guidelines. This kind of poor practice can be a clear sign of the seriousness of conflict of interest. In this article, I argue that hostile, unethical, and biased behavior of reviewers and editors often arises from a serious nonfinancial conflict of interest, which should not be ignored or undermined.

A study on the cyclist head kinematic responses in electric-bicycle-to-car accidents using decision-tree model

Due to the high frequent traffic accidents involving electric bicycles (E-bike), it urgently needs improved protection of cyclists, especially their heads. In this study, by adjusting the initial impact velocities of E-bike and car, initial impact angle between E-bike and car, initial E-bike impact location, and body size of cyclist, 1512 different accident conditions were constructed and simulated using a verified E-bike-to-car impact multi-body model. The cyclist's head kinematic responses including the head relative impact velocity, WAD (Wrap around distance) of head impact location and HIC₁₅ (15 ms Head Injury Criterion) were collected from simulation results to make up a dataset for data mining. The decision tree models of cyclist's head kinematic responses were then created from this dataset and verified accordingly. Based on simulated results obtained from decision tree models, it can be found as follows. 1. In the E-bike-to-car accidents, the average head impact relative velocity and WAD of head impact location are higher than those in the car-to-pedestrian accidents. 2. Increasing the initial impact velocity of car can increase the cyclist's head relative impact velocity, WAD of head impact location, and HIC₁₅. 3. The WAD of cyclist's head impact location is also significantly affected by the initial impact angle between E-bike and car and body size of cyclist: the WAD of head impact location becomes higher with increasing initial impact angle between E-bike and car and body size of cyclist. 4. The effects of initial E-bike impact location on the WAD of cyclist's head impact location is not significant when initial E-bike impact location is concentrated in the region of 0.25 m around the centerline of the car.

A study on cyclist head injuries based on an electric-bicycle to car accident reconstruction

OBJECTIVE

In China, the electric-bicycle (E-bike) has become one of the most common modes of travel. However, the safety of E-bike has not received sufficient attentions, especially in the area of protection of the cyclists' head.

METHODS

In this study, an E-bike-to-car accident was reconstructed using MADYMO and LS-DYNA software and head injuries of the cyclist were analyzed. A multi-rigid body model in MADYMO and a head to windshield impact finite element (FE) model using LS-DYNA were separately developed to achieve objectives of the work.

RESULTS

Kinematic responses of the cyclist were predicted by the multi-rigid body model to obtain the best reconstructed results compared to those given in the accident report, and the instantaneous linear and angular relative velocities at the onset of contact between the head and windshield, which were used as input loading conditions to the FE model, were obtained. The maximum principal strain (MPS) of skull, and intracranial pressure (ICP), von-Mises stress and MPS (Maximum principal strain) of brain tissue were predicted by the FE model for the head injuries analyses.

CONCLUSIONS

The results of accident reconstruction in this study case showed that: (1) The head impact region on the windshield in the E-bike-to-car impact accidents is higher than that in the pedestrian-to-car impact accidents. (2) The skull MPS, ICP, von-Mises stress and MPS of strain can accurately predict the head injury risk, location, etc. (3) The directly impact force caused the skull fracture, and the tensile inertial force torn bridge vein resulting in the subdural hematoma on the opposite side of impact in this accident. (4) The models developed in this study were validated against the reconstructed accident and can be used for further study on head injuries of E-bike's cyclist and helmet design.

Protection performance of bicycle helmets

INTRODUCTION

The evaluation of head protection systems needs proper knowledge of the head impact conditions in terms of impact speed and angle, as well as a realistic estimation of brain tolerance limits. In current bicycle helmet test procedures, both of these aspects should be improved.

METHOD

The present paper suggests a bicycle helmet evaluation methodology based on realistic impact conditions and consideration of tissue level brain injury risk, in addition to well known headform kinematic parameters. The method is then applied to a set of 32 existing helmets, leading to a total of 576 experimental impact tests followed by 576 numerical simulations of the brain response.

RESULTS

It is shown that the most critical impacts are the linear-lateral ones as well as the oblique impact leading to rotation around the vertical axis (ZRot), leading both to around 50% risks of moderate neurological injuries. Based on this test method, the study enables us to compare the protection capability of a given helmet and eventually to compare helmets via a dedicated rating system.

Race and Insurance Status as Predictors of Bicycle Trauma Outcome in Adults

BACKGROUND

Race and insurance status have been shown to predict outcomes in pediatric bicycle traumas. It is unknown how these factors influence outcomes in adult bicycle traumas. This study aims to evaluate the association, if any, between race and insurance status with mortality in adults.

METHODS

This retrospective cohort study used the National Trauma Data Bank Research Data Set for the years 2013-2015. Multivariate logistic regression models were used to determine the independent association between patient race and insurance status on helmet use and on outcomes after hospitalization for bicycle-related injury. These models adjusted for demographic factors and comorbid variables. When examining the association between race and insurance status with outcomes after hospitalization, injury characteristics were also included.

RESULTS

A study population of 45,063 met the inclusion and exclusion criteria. Multivariate regression demonstrated that black adults and Hispanic adults were significantly less likely to be helmeted at the time of injury than white adults [adjusted odds ratio of helmet use for blacks 0.25 (95% CI 0.22-0.28) and for Hispanics 0.33 (95% CI 0.30-0.36) versus whites]. Helmet usage was also independently associated with insurance status, with Medicare-insured patients [AOR 0.51 (95% CI 0.47-0.56) versus private-insured patients], Medicaid-insured patients [AOR 0.18 (95% CI 0.17-0.20)], and uninsured patients [AOR 0.29 (95% CI 0.27-0.32)] being significantly less likely to be wearing a helmet at the time of injury compared with private-insured patients. Although patient race was not independently associated with hospital mortality among adult bicyclists, we found that uninsured patients had significantly higher odds of mortality [AOR 2.02 (AOR 1.31-3.12)] compared with private-insured patients.

CONCLUSIONS

Minorities and underinsured patients are significantly less likely to be helmeted at the time of bicycle-related trauma when compared with white patients and those with private insurance. Public health efforts to improve the utilization of helmets during bicycling should target these subpopulations.

Bicycle helmets - To wear or not to wear? A meta-analyses of the effects of bicycle helmets on injuries

A meta-analysis has been conducted of the effects of bicycle helmets on serious head injury and other injuries among crash involved cyclists. 179 effect estimates from 55 studies from 1989-2017 are included in the meta-analysis. The use of bicycle helmets was found to reduce head injury by 48%, serious head injury by 60%, traumatic brain injury by 53%, face injury by 23%, and the total number of killed or seriously injured cyclists by 34%. Bicycle helmets were not found to have any statistically significant effect on cervical spine injury. There is no indication that the results from bicycle helmet studies are affected by a lack of control for confounding variables, time trend bias or publication bias. The results do not indicate that bicycle helmet effects are different between adult cyclists and children. Bicycle helmet effects may be somewhat larger when bicycle helmet wearing is mandatory than otherwise; however, helmet wearing rates were not found to be related to bicycle helmet effectiveness. It is also likely that bicycle helmets have larger effects among drunk cyclists than among sober cyclists, and larger effects in single bicycle crashes than in collisions with motor vehicles. In summary, the results suggest that wearing a helmet while cycling is highly recommendable, especially in situations with an increased risk of single bicycle crashes, such as on slippery or icy roads.

A STUDY ON MOTORCYCLISTS HEAD INJURIES IN CAR–MOTORCYCLE ACCIDENTS BASED ON REAL-WORLD DATA AND ACCIDENT RECONSTRUCTION

Accident data had shown that as one of the most vulnerable road users, the risk of motorcyclist casualties due to head injuries is extremely high in motorcycle accidents. The objective of this study was to analyze motorcyclist head injury based on epidemiological statistical analysis and car–motorcycle accident reconstruction using real world accident data, and obtain a comprehensive understanding about safety effects of helmets on motorcyclists head injury. In epidemiological data analysis of this study, odds ratios (ORs) was applied to identify differences in injuries between helmeted and unhelmeted motorcyclists. Two vehicle–motorcycle collisions with detailed information were reconstructed by using PC-Crash simulation and MADYMO reconstruction. Furthermore, the head injury reconstruction using MADYMO outputs as boundary conditions was accomplished and analyzed with respect to 1st principal strain, Von Mises stress, coup pressure, countercoup pressure at the cerebrum. The results indicated that unhelmeted motorcyclists were more likely to suffer head injury, serious and fatal injury, and tend to take equal responsibility or more. 1st principal strain was reduced from 0.44 to 0.25 for Case 1, and from 0.16 to 0.10 for case 2 when including a helmet. Von Mises stress were reduced from 30.37[Formula: see text]kpa to 19.51[Formula: see text]kpa for Case 1 and from 3.42[Formula: see text]kpa to 3.03[Formula: see text]kpa for case when including a helmet, which meant a reduction of the risk of concussion. But the motorcyclist in Case 2 experienced a lower percentage increase in coup pressure and countercoup pressure. This study provided comprehensive knowledge on motorcyclists head injuries and the effectiveness of helmets as well as contributing to develop the injury prevention measures and protection devices of motorcyclists.

Bicycle helmet effectiveness is not overstated

OBJECTIVE

The objective of this study was to discuss the challenges in estimating bicycle helmet effectiveness from case-control studies of injured cyclists and to estimate helmet effectiveness from cases and available exposure data.

METHODS

Data were extracted from studies of cyclists in Seattle; Victoria and New South Wales, Australia; and The Netherlands. Estimates of helmet use were used as exposure to compute relative risks for Seattle and Victorian data. Cycling distance data are routinely collected in The Netherlands; however, these data cannot be disaggregated by helmet use, which makes it unsuitable for estimating helmet effectiveness. Alternative controls were identified from larger cohorts for the Seattle and New South Wales cases.

RESULTS

Estimates of helmet effectiveness were similar from odds ratios (ORs) using hospital controls or from relative risks (RRs) using helmet use estimates (Seattle: OR = 0.339, RR = 0.444; Victoria: OR = 0.500, RR = 0.353). Additionally, the odds ratios using hospital controls were similar when controls were taken from a larger cohort for head injury of any severity (Seattle: OR = 0.250, alt OR = 0.257; NSW: OR = 0.446, alt OR = 0.411) and for serious head injury (Seattle: OR = 0.135, alt OR = 0.139; NSW: OR = 0.335, alt OR = 0.308). Although relevant exposure data were unavailable for The Netherlands, the odds ratio for helmet effectiveness of those using racing, mountain, or hybrid bikes was similar to other estimates (OR = 0.371).

CONCLUSIONS

Despite potential weaknesses with case-control study designs, the best available evidence suggests that helmet use is an effective measure of reducing cycling head injury.

School transportation mode, by distance between home and school, United States, ConsumerStyles 2012

INTRODUCTION

Motor-vehicle crashes are a leading cause of death among children in the United States, and almost one-fourth of all trips by school-aged children are trips to and from school. This study sought to determine how children (5-18years) travel to and from school and, among those living ≤1mile of school, to explore the role of school bus service eligibility on school travel mode.

METHODS

We used national 2012 survey data to determine prevalence of usual school travel mode, stratified by distance from school. For those living ≤1mile of school, multivariable regression was conducted to assess the association between bus service eligibility and walking or bicycling.

RESULTS

Almost half (46.6%) of all children rode in passenger vehicles (PV) to school and 41.8% did so for the trip home. Results were similar among those living ≤1mile (48.1%, PV to school; 41.3%, PV to home). Among those living ≤1mile, 21.9% and 28.4% of children walked or bicycled to and from school, respectively. Ineligibility for school bus service was strongly associated with walking or bicycling to school [adjusted prevalence ratio (aPR: 5.36; p<0.001)] and from school (aPR: 5.36; p<0.001).

CONCLUSIONS

Regardless of distance from school, passenger vehicles were a common mode of travel. For children who live close to school, the role that school bus service eligibility plays in walking or bicycling deserves further consideration.

PRACTICAL APPLICATIONS

Given the large proportion of children who use passenger vehicles for school travel, effective interventions can be adopted to increase proper child restraint and seat belt use and reduce crash risks among teen drivers. Better understanding of conditions under which bus service is offered to children who live close to school could inform efforts to improve pedestrian and bicyclist safety for school travel.

The casualties from electric bike and motorized scooter road accidents

OBJECTIVE

The objective of this study was to describe demographic and injury characteristics of hospitalized injured patients involved in e-bike and motorized scooter accidents at a national level in Israel divided by different road user groups: riders and pedestrians.

METHODS

This was a retrospective study based on data from the National Trauma Registry, between January 1, 2013, and December 31, 2015. All hospitalized casualties due to the involvement of an e-bike or motorized scooter were included. The type of hospitalized road user was further categorized and described by different variables.

RESULTS

During the study period, the Israel Trauma Registry identified 795 hospitalized patients due to an e-bike or motorized scooter accident, with a dramatic 6-fold increase from 2013 to 2015. Although the majority of the injured patients were riders, 8% were pedestrians. Among the total casualties, 33% were children aged 0-14 years and among pedestrians 42% were children and 33% were seniors (ages 60+). Five persons died in hospital, 3 riders and 2 pedestrians.

CONCLUSIONS

E-bike and motorized scooter riders represent the majority of patients hospitalized due to related traffic incident. This finding questions the social and economic advantages of electric-powered 2-wheeled vehicles.

Bicycle helmet use among persons 5years and older in the United States, 2012

INTRODUCTION

In 2013, injuries to bicyclists accounted for 925 fatalities and 493,884 nonfatal, emergency department-treated injuries in the United States. Bicyclist deaths increased by 19% from 2010 to 2013. The greatest risk of death and disability to bicyclists is head injuries. The objective of this study was to provide estimates of prevalence and associated factors of bicycle riding and helmet use among children and adults in the United States.

METHOD

CDC analyzed self-reported data from the 2012 Summer ConsumerStyles survey. Adult respondents (18+years) were asked about bicycle riding and helmet use in the last 30days for themselves and their children (5 to 17years). For bicycle riders, CDC estimated the prevalence of helmet use and conducted multivariable regression analyses to identify factors associated with helmet use.

RESULTS

Among adults, 21% rode bicycles within the past 30days and 29% always wore helmets. Respondents reported that, of the 61% of children who rode bicycles within the past 30days, 42% always wore helmets. Children were more likely to always wear helmets (90%) when their adult respondents always wore helmets than when their adult respondents did not always wear helmets (38%). Children who lived in states with a child bicycle helmet law were more likely to always wear helmets (47%) than those in states without a law (39%).

CONCLUSIONS

Despite the fact that bicycle helmets are highly effective at reducing the risk for head injuries, including severe brain injuries and death, less than half of children and adults always wore bicycle helmets while riding.

PRACTICAL APPLICATION

States and communities should consider interventions that improve the safety of riding such as policies to promote helmet use, modeling of helmet wearing by adults, and focusing on high risk groups, including Hispanic cyclists, occasional riders, adults, and children ages 10 to 14.

Correlates of Helmet Use Among Recreation and Transportation Bicyclists

INTRODUCTION

Helmet use prevents injury and mortality if a bicyclist is in a collision while riding. This cross-sectional study sought to identify domain-specific (recreation versus transportation) correlates of helmet use among U.S. adult bicyclists, using nationally representative data from 2012.

METHODS

This analysis, conducted in 2015-2016, utilized data from the 2012 National Survey of Bicyclist and Pedestrian Attitudes and Behaviors, administered for the National Highway Traffic Safety Administration. Bivariate logistic regressions identified sociodemographic, behavioral, and environmental correlates of helmet use among U.S. adult bicyclists. Backwards elimination procedures selected final multivariate models for bicyclists' helmet use in both domains.

RESULTS

Among recreation cyclists, helmet use was significantly associated with income ($30,000-$75,000, OR=1.79, 95% CI=1.04, 3.10; ≥$75,000, OR=2.34, 95% CI=1.38, 3.97), safety training (OR=2.94, 95% CI=1.46, 5.93), not riding at dark (OR=1.92, 95% CI=1.24, 2.98), feeling threatened while riding (OR=2.24, 95% CI=1.12, 4.45), and using bike lanes/paths (OR=2.04, 95% CI=1.42, 2.93). Helmet use among transportation riders was significantly associated with education (less than high school, OR=2.45, 95% CI=1.13, 5.32; post-high school, OR=3.55, 95% CI=1.96, 6.42), income ($30,000-$75,000, OR=2.11, 95% CI=1.17, 3.8; ≥$75,000, OR=2.33, 95% CI=1.26, 4.27), unemployment (OR=0.29, 95% CI=0.11, 0.76), not using electronics while riding (OR=2.3, 95% CI=1.41, 3.75), safety training (OR=3.19, 95% CI=1.44, 7.07), and injury while riding within the past 2 years (OR=2.81, 95% CI=1.14, 6.94).

CONCLUSIONS

Correlates of helmet use among bicyclists are domain specific. Although confirmatory longitudinal studies are needed, findings suggest that interventions to increase bicyclists' helmet use consider riding domain.

An Analysis of Technology-Related Distracted Biking Behaviors and Helmet Use Among Cyclists in New York City

Bicycling is becoming an increasingly utilized mode of transportation in New York City. Technology-related distracted bicycling and helmet use are behaviors that can impact bike safety. The aims of this study were twofold: (1) to determine rates and types of technology-related distracted behaviors among bicyclists in the borough of Manhattan in New York City; and (2) to assess the rate of bicycle helmet use among these cyclists. Bicyclists in five popular riding areas in Manhattan were observed for a total of 50 h using a digital video camera during summer months in 2014. Videos were coded and enumerated for the total number and gender of cyclists, type of bicycle, number wearing headphones/earbuds and/or using a mobile phone, and whether the cyclist was wearing a helmet. Almost 25,000 cyclists were observed across the five selected locations (n = 24,861). Riders were almost four times more likely not to wear a helmet on rental bikes as compared with non-rentals (Citi Bike(®) OR 3.8; 95% CI 2.5, 5.9: other rental OR 3.8; 95% CI 3.0, 4.9). Significantly increased odds of not wearing a helmet were observed for females relative to males (OR 1.4; 95% CI 1.1, 1.8) across varied times and locations. Overall, rates of technology-related distraction were low, with headphone use being most prevalent. Males were more likely to wear headphones/earbuds (OR 2.0; 95% CI 1.4, 2.9), as were cyclists on Citi Bikes relative to other rental bikes (OR 2.2; 95% CI 1.3, 3.6). Findings from this study contribute to the growing literature on distracted biking and helmet use among bike share program riders and other cyclists and can inform policymakers and program planners aiming to improve bicycle safety in urban settings.

The influence of lower extremity postures on kinematics and injuries of cyclists in vehicle side collisions

OBJECTIVE

A cyclist assumes various cyclic postures of the lower extremities while pushing the pedals in a rotary motion while pedaling. In order to protect cyclists in collisions, it is necessary to understand what influence these postures have on the global kinematics and injuries of the cyclist.

METHOD

Finite element (FE) analyses using models of a cyclist, bicycle, and car were conducted. In the simulations, the Total Human Model of Safety (THUMS) occupant model was employed as a cyclist, and the simulation was set up such that the cyclist was hit from its side by a car. Three representative postures of the lower extremities of the cyclist were examined, and the kinematics and injury risk of the cyclist were compared to those obtained by a pedestrian FE model. The risk of a lower extremity injury was assessed based on the knee shear displacement and the tibia bending moment.

RESULTS

When the knee position of the cyclist was higher than the hood leading edge, the hood leading edge contacted the leg of the cyclist, and the pelvis slid over the hood top and the wrap-around distance (WAD) of the cyclist's head was large. The knee was shear loaded by the hood leading edge, and the anterior cruciate ligament (ACL) ruptured. The tibia bending moment was less than the injury threshold. When the cyclist's knee position was lower than the hood leading edge, the hood leading edge contacted the thigh of the cyclist, and the cyclist rotated with the femur as the pivot point about the hood leading edge. In this case, the head impact location of the cyclist against the car was comparable to that of the pedestrian collision. The knee shear displacement and the tibia bending moment were less than the injury thresholds.

CONCLUSION

The knee height of the cyclist relative to the hood leading edge affected the global kinematics and the head impact location against the car. The loading mode of the lower extremities was also dependent on the initial positions of the lower extremities relative to the car structures. In the foot up and front posture, the knee was loaded in a lateral shear direction by the hood leading edge and as a result the ACL ruptured. The bicycle frame and the struck-side lower extremity interacted and could influence the loadings on lower extremities.

The protective effect of a helmet in three bicycle accidents--A finite element study

There is some controversy regarding the effectiveness of helmets in preventing head injuries among cyclists. Epidemiological, experimental and computer simulation studies have suggested that helmets do indeed have a protective effect, whereas other studies based on epidemiological data have argued that there is no evidence that the helmet protects the brain. The objective of this study was to evaluate the protective effect of a helmet in single bicycle accident reconstructions using detailed finite element simulations. Strain in the brain tissue, which is associated with brain injuries, was reduced by up to 43% for the accident cases studied when a helmet was included. This resulted in a reduction of the risk of concussion of up to 54%. The stress to the skull bone went from fracture level of 80 MPa down to 13-16 MPa when a helmet was included and the skull fracture risk was reduced by up to 98% based on linear acceleration. Even with a 10% increased riding velocity for the helmeted impacts, to take into account possible increased risk taking, the risk of concussion was still reduced by up to 46% when compared with the unhelmeted impacts with original velocity. The results of this study show that the brain injury risk and risk of skull fracture could have been reduced in these three cases if a helmet had been worn.

Bicycle helmets are highly protective against traumatic brain injury within a dense urban setting

BACKGROUND

New York City (NYC) has made significant roadway infrastructure improvements, initiated a bicycle share program, and enacted Vision Zero, an action plan to reduce traffic deaths and serious injuries. The objective of this study was to examine whether bicycle helmets offer a protective advantage against traumatic brain injury (TBI) within a contemporary dense urban setting with a commitment to road safety.

METHODS

A prospective observational study of injured bicyclists presenting to a Level I trauma centre was performed. All bicyclists arriving within 24 h of injury were included. Data were collected between February, 2012 and August, 2014 and included demographics, imaging studies (e.g. computed tomography (CT)), injury patterns, and outcomes including Glasgow Coma Scale (GCS) and Injury Severity Score.

RESULTS

Of 699 patients, 273 (39.1%) were wearing helmets at the time of injury. Helmeted bicyclists were more likely to have a GCS of 15 (96.3% [95% Confidence Interval (CI), 93.3-98.2] vs. 87.6 [95% CI, 84.1-90.6]) at presentation. Helmeted bicyclists underwent fewer head CTs (40.3% [95% CI, 34.4-46.4] vs. 52.8% [95% CI, 48.0-57.6]) and were less likely to sustain intracranial injury (6.3% [95% CI, 2.6-12.5] vs. 19.7% [14.7-25.6]), including skull fracture (0.9% [95% CI, 0.0-4.9] vs. 15.3% [95% CI, 10.8-20.7]) and subdural hematoma (0.0% [95% CI, 0.0-3.2] vs. 8.1% [95% CI, 4.9-12.5]). Helmeted bicyclists were significantly less likely to sustain significant TBI, i.e. Head AIS ≥3 (2.6% [95% CI: 0.7-4.5] vs.10.6% [7.6-12.5]). Four patients underwent craniotomy while three died; all were un-helmeted. A multivariable logistic regression model showed that helmeted bicyclists were 72% less likely to sustain TBI compared with un-helmeted bicyclists (Adjusted Odds Ratio 0.28, 95% CI 0.12-0.61).

CONCLUSIONS

Despite substantial road safety measures in NYC, the protective impact of simple bicycle helmets in the event of a crash remains significant. A re-assessment of helmet laws for urban bicyclists is advisable to most effectively translate Vision Zero from a political action plan to public safety reality.

Adult headform impact tests of three Japanese child bicycle helmets into a vehicle

The head is the body region that most frequently incurs fatal and serious injuries of cyclists in collisions against vehicles. Many research studies investigated helmet effectiveness in preventing head injuries using accident data. In this study, the impact attenuation characteristics of three Japanese child bicycle helmets were examined experimentally in impact tests into a concrete surface and a vehicle. A pedestrian adult headform with and without a Japanese child bicycle helmet was dropped onto a concrete surface and then propelled into a vehicle at 35 km/h in various locations such as the bonnet, roof header, windshield and A-pillar. Accelerations were measured and head injury criterion (HIC) calculated. In the drop tests using the adult headform onto a concrete surface from the height of 1.5m, the HIC for a headform without a child helmet was 6325, and was reduced by around 80% when a child helmet was fitted to the headform. In the impact tests, where the headform was fired into the vehicle at 35 km/h at various locations on a car, the computed acceleration based HIC varied depending on the vehicle impact locations. The HIC was reduced by 10-38% for impacts headforms with a child helmet when the impact was onto a bonnet-top and roof header although the HIC was already less than 1000 in impacts with the headform without a child helmet. Similarly, for impacts into the windshield (where a cyclist's head is most frequently impacted), the HIC using the adult headform without a child helmet was 122; whereas when the adult headform was used with a child helmet, a higher HIC value of more than 850 was recorded. But again, the HIC values are below 1000. In impacts into the A-pillar, the HIC was 4816 for a headform without a child helmet and was reduced by 18-38% for a headform with a child helmet depending on the type of Japanese child helmet used. The tests demonstrated that Japanese child helmets are effective in reducing accelerations and HIC in a drop test using an adult headform onto a relatively rigid hard surface, i.e., simulating a road surface or concrete path. However, when the impact tests are into softer surfaces, the child helmet's capacity to decrease accelerations is accordingly reduced. Impacts into the windshield, while below the critical HIC value of 1000, indicated higher HIC values for a headform with a child helmet compared to an adult headform without a child helmet. The unpredictable nature of the results indicates further research work is required to assess how representative the stiffness of an adult headform is when compared to an actual head.