Motor vehicle crash expert Dr. John Lloyd has served attorneys nationwide for 25+ years in biomechanics, human factors, helmet testing and motorcycle accident expert
A motorcycle accident involves a higher degree of complexity than typical automobile collisions, requiring detailed motorcycle crash analysis to determine causes and contributing factors. Two aspects considered paramount for motorcycle crash analysis include injury biomechanics and human factors ways to appreciate how the rider’s body responded in a crash and how human behavior affects the outcome of accidents.
The Role of Biomechanics in Motorcycle Crash Analysis
Motorcycle biomechanics is the study of how forces interact with the body in the crash. The study provides an understanding of rider kinematics (post-impact tmotion), injury patterns, helmet performance, and effectiveness of protective gear.
Understanding Rider Kinematics
A motorcycle crash includes multiple forces acting on its rider. Hence, a motorcycle crash expert analyzes:
The ejection or throw angle of the rider from the motorcycle
Impact points on the rider’s body
Influence of speed, angle, and surface conditions on injury
Dr. John Lloyd utilizes his expertise in biomechanics to analyze how those impact forces cause injuries, thereby providing key information in accident investigations and law cases.
Performance of Helmet and Protective Gear
Another part of the motorcycle crash analysis is the evaluation of helmet protection. The aspects considered by the motorcycle crash experts include:
Damage sustained by the helmet and forces due to the impact;
Compression of the liner and protection of the skull;
Compliance with safety standards (DOT, ECE, Snell).
Dr. Lloyd’s work in motorcycle biomechanics may help decide whether or not the helmet successfully prevented head injuries and brain injuries or that design defects resulted in injury.
Injury Causation and Severity Assessment
A biomechanical assessment allows experts to correlate accident dynamics and specific injuries. Such evaluations may include:
Fractures and soft tissue injuries
Head and spinal trauma
Injury severity as a function of the crash scenario
Through the analysis of injury biomechanics, the expert can determine whether safety systems were appropriate or if other factors contributed to injury causation.
FAQs
How have biomechanics been useful in analysis?
Motorcycle biomechanics establish how forces acted on the motorcycle rider’s body, which explains the injury patterns and the level of effectiveness of protective gear, including helmets
What is the importance of human factors in accident reconstruction?
Motorcycle human factors studies how rider perception, reaction time, and decision-making can help understand if human error played a role in the crash.
Is there an analysis of motorcycle crashes that can reveal a defective helmet?
Yes, helmet inspection in the course of the analysis can indicate defects in design or manufacture that could have contributed to head injuries.
Conclusion
The interlinking of motorcycle biomechanics and motorcycle human factors is vital for accurate motorcycle crash analysis. Dr. John Lloyd, a professional in these fields, investigates injury causation, helmet effectiveness, and rider behavior in crashes based on scientific methodology. His knowledge will illustrate to legal teams, insurance companies, and accident victims the multifaceted dynamics of motorcycle accidents, leading to an accurate evaluation of such cases.
Motorcycle accidents are some of the most difficult to analyze. Motorcycle crashes involve unique dynamics due to the complexity of the vehicle, and when coupled with rider and environmental factors, they become more complicated to analyze than a typical car accident. Unlike occupants of a car, who are usually protected by the vehicle frame in the event of a crash, riders are often ejected from the motorcycle and directly exposed to impact forces, requiring a multi-disciplinary analysis.
The physics, biomechanics, and human factors involved in these accidents necessitate that specialty professionals be consulted for matters involving motorcycle crash analysis and motorcycle accident reconstruction.
The Complexities of Motorcycle Crash Analysis
Motorcycles differ from cars due to their two-wheeled structure, center of gravity, and rider control for balance. Some of the factors that add to the complexities surrounding motorcycle accident analysis include:
Traction: Wet or slippery road conditions, tire grip, and sudden braking can all lead to skidding and loss of control.
Rider Ejection Dynamics: Cars are designed with seat belts and airbags to protect passengers. Ejections during motorcycle collisions generate a multiplicity of injury patterns and complicate the analysis of forces and impacts.
Few Onboard Systems: Motorcycles are not often equipped with event data recording systems. The information from these systems is extremely useful in typical automobile accident reconstruction. Without such technology motorcycle accident reconstruction and analysis requires a greater reliance on physical evidence and expert insight.
Why an Accident Reconstruction Expert is Important
An accident reconstruction expert works fundamentally in determining liability in a motorcycle crash. Such experts apply scientific principles to recreate the accident site, considering:
Motorcycle Speed and Motion Analysis: Experts calculate impact speed based on tire marks, dispersed debris patterns, and footage from surveillance cameras.
Impact-Injury Correlation: Experts analyze rider injuries to reconstruct how the crash happened and determine if the rider’s protective gear was effective in mitigating impact forces.
Environmental Conditions: How the road surface, visibility, and weather conditions affect accident causation.
Human Factors Analysis: Knowledge of rider reaction time, the decision-making process, and potential distractions prove valuable in determining the sequence of events leading to the crash.
Frequently Asked Questions (FAQs)
How long does motorcycle accident reconstruction take?
It depends on how complicated the crash is. A simple case may require a week of investigation, while a major case may involve more extensive trial preparation.
Can reconstruction be used for cases in court?
Absolutely! Expert motorcycle crash analysis can provide critical evidence for lawsuits and help insurance companies, attorneys, and courts achieve justice for their clients.
What would be the qualifications of a motorcycle accident reconstruction expert?
Experts often have backgrounds in engineering, biomechanics, or law enforcement. Accredited certification in accident reconstruction as well as experience with motorcycle handling and operation are also key qualifications.
Final Thoughts!
Motorcycle accidents require specialized analysis skills because they are usually far more complicated than typical automobile crashes. Trained accident reconstruction experts can determine the cause of a motorcycle crash, thereby identifying the liable party and aiding the courts in seeking justice.
Dr. Lloyd is a recognized authority in motorcycle accident and human factors analysis, with more than 30 years of experience as an expert witness. His understanding of motorcycle crash dynamics makes him an expert of experts.
In the United States there are 11 million motor vehicle accidents each year, more than 400,000 of which result in death. The most common injuries resulting from automobile accidents are to the head, brain, neck, and low back. The evaluation of such cases often involves a team of experts, including accident reconstruction, biomechanics and human factors experts.
As an expert witness in biomechanics and human factors as well as a certified accident reconstructionist for motorcycle crashes, automobile accident, and truck collisions, r. John Lloyd is a highly qualified testifying expert witness.
Accident Reconstruction
First the accident reconstructionist evaluates the physical evidence from a crash scene, including skid marks, gouges and other roadway markings, along with crush information from the vehicles along with their final rest positions. This evidence is used to calculate the change in velocity of the subject vehicles.
Biomechanical Analysis
The complete anatomy of the crash (pre and post impact vehicle speeds, whether or not seat belts were worn, faulty airbags, etc.) is conveyed to the biomechanics expert.
Biomechanists use this information to determine occupant kinematics (motion of the vehicle occupants in response to the impact), kinetics (forces acting on various body parts as a result of the collision) and injury mechanisms. This can include the impact to the head and forces transmitted to the brain, blunt trauma to the low back, and shear forces to the cervical vertebrae. Findings are used to determine whether impact locations and forces provide a causal explanation for claimed injuries. Hence the biomechanist can provide rationale as to whom was at fault for the sustained injuries.
As an expert witness in biomechanics and human factors as well as a certified accident reconstructionist for motorcycle crashes, automobile accidents, truck collisions, in addition to bicycle and pedestrian accidents, Dr. John Lloyd is highly valued expert for the evaluation of motor vehicle crashes.
An expert on motorcycle crashes can reconstruct these accidents for the courts, insurance companies, and legal teams. Here is the process of how a motorcycle crash expert conducts accident reconstruction.
The Process of Motorcycle Accident Reconstruction
Motorcycle crash experts start from a systematic perspective in reconstructing any accident. To that end, multiple phases of investigation occur: evidence collection, analysis of impact forces, and human factors. Below are the basics of how a crash assessment is reconstructed by an authority such as Dr. John Lloyd:
Scene Investigation and Data Collection
The first step of any reconstruction should be an extensive investigation of the crash site. A motorcycle crash expert would collect crucial data, including:
Skid marks and tire tracks
Road condition”s depression, dry, gravel, and uneven
Vehicle damage and final resting position
Witness statements and video footage, if any
Weather and light during the time of the crash
3D mapping of the scene using a professional drone
Analyzing Motorcycle Dynamics and Impact Forces
The motorcycle helmet expert studies various parameters. Dr. Lloyd conducts a biomechanical reconstruction as a basis for analyzing the rider’s pre and post-collision movements. The effects of helmet protection and the pattern of injuries give an impression of what forces were in play.
Human Factors and Rider Behavior Analysis
Human factors are very important in accident reconstruction. Factors studied by Dr. Lloyd include:
Perception and reaction time of the rider
Visibility and knowledge of the road
Hazards such as fatigue, distractions, or impairment
Evasive maneuvers attempted by the rider
An expert in motorcycle accidents can determine whether rider error, vehicle defects, or environmental factors contributed to the causation of an accident.
Computer Simulations and Expert Testimony
Advanced, 3D physics-based computer simulation allows experts like Dr. Lloyd to reproduce motorcycle accidents with high accuracy. Such reconstructions are not only informative to the legal team and adjusters but are also very useful at trial to illustrate the collision sequence.
In doing so, Dr. Lloyd works as an expert witness, presenting these conclusions in court and supplementing them with scientific explanations for court-related purposes.
FAQs – Motorcycle Crash Expert
Can accident reconstruction determine fault in a motorcycle crash?
Yes, a motorcycle crash expert studies many aspects to determine liability, including vehicle speeds, road conditions, and rider behaviors.
Why is helmet analysis important in accident reconstruction?
Helmets save lives, and experts like Dr. John Lloyd analyze the damage to a helmet to determine the levels of head impact forces and possible injuries to the brain.
Final Thoughts!
Accident reconstruction uses a detailed process and requires various specialization in biomechanics, human factors, and vehicle dynamics. Dr. John Lloyd, a well-known motorcycle crash expert, uses a scientific approach to establish causation in various motorcycle accidents. His expertise helps legal teams and insurance companies better understand these often complicated cases.
The following is a case study in which biomechanics expert, Dr. John Lloyd, evaluated the risk of concussion and brain injury associated with headrest impact in rear end crashes.
Headrest Impact Test Apparatus:
In accordance with prior published test methods[1],[2],[3], a test apparatus was constructed to evaluate the biomechanical protection afforded by an exemplar automobile headrest against head and brain injuries during occipital head impacts in a simulated rear-end motor vehicle collision.
The apparatus involves a pendulum arm, attached by bearing housings to a weighted base. The upper body, including neck and head of a 50th percentile Hybrid III crash test dummy was mounted to the pendulum arm. Data acquisition was initiated by triggering an electromechanical release mechanism, allowing the mannequin to fall, under acceleration due to gravity, until the crash test dummy impacted the headrest and backrest (Figure 1).
Figure 1: Test apparatus
The fundamental elements and principles of this testing have been utilized in other laboratories. By utilizing a Hybrid III neck, the head impact tests are more realistic, causing head rotation at the axis between the head and neck, which produces measures of head and brain angular kinematics. The methods presented herein are based upon standardized test methodologies and published research.
Instrumentation
Four PCB Piezotronics tri-axial accelerometers (model # 356A01) were mounted in an X,Y,Z array at the center of mass of the Hybrid III headform, along with a tri-axial angular rate sensor produced by Diversified Technical Systems (composite Figure 2).
Figure 2: Sensor installation in Hybrid III headform
Sensor Calibration:
All sensors were calibrated by the manufacturer. Verification of calibration of the linear accelerometers was performed prior to testing using a calibration shaker. Results indicate that the sensors were operating in the specified frequency range and output (Figure 3).
Figure 3: Pre-test verification of linear accelerometer sensors
For the angular rate sensor, a simple validation method was devised in which the sensor was affixed to a digital goniometer that was rotated through a 90-degree angle. Using LabVIEW software, the integral of angular rate was computed, reflecting concurrence with the digital goniometer for all three planes of motion (Figure 4).
Figure 4: Pre-test validation of angular rate sensor calibration
Headrest Impact Testing:
The mannequin head was raised from the headrest in 2-inch increments from 2 inches to 30 inches, generating head impact speeds from 1 to 25 miles per hour. Two headrest positions were evaluated, along with two different Hybrid III necks representative of a stiff and relaxed neck (Figure 5), for a total of sixty tests.
Figure 5: Test apparatus with Hybrid III loose neck and headrest in lower position
Data Acquisition and Analysis:
Data from the analog sensors were acquired in accordance with SAE J211 [4], using a National Instruments compact DAQ data acquisition system and LabVIEW software (National Instruments, Austin, TX). The raw data was then filtered in MATLAB (The MathWorks, Natick, MA) using a phaseless eighth-order Butterworth filter with cutoff frequencies of 1650 Hz and 300Hz for the linear accelerometers and angular rate sensors, respectively.
Angular acceleration values for sagittal, coronal and axial planes were computed from the angular velocity data using the 5-point central difference by least squares method (Equation 1):
Equation 1: Five-point central difference by least squares method
Angular acceleration vales were also derived from the array of linear accelerometers, by the mathematical method documented by Padgaonkar et al [5].
Linear velocity was calculated by integrating linear acceleration. Mathematical methods were performed using Matlab to compute characteristic values from variables of interest. Figure 6, below illustrates peak linear acceleration and angular velocity associated with a 6.8 mph occipital head impact against a headrest.
Figure 6: Linear acceleration and angular velocity associated with headrest impact
It is noted that the major component of linear acceleration was in the X-axis (anterior-posterior), while the major component of angular velocity was in the sagittal plane, as expected.
Linear acceleration values were used to calculate Maximum Pressure (Equation 2), Gadd Severity Index (GSI) (Equation 3), and Head Injury Criterion (HIC15) (Equation 4).
Equation 2: Maximum Pressure
Equation 3: Gadd Severity Index
The Head Injury Criterion (HIC) is an empirical measure of impact severity describing the relationship between the linear acceleration magnitude, duration of impact and the risk of head trauma (Equation 4).
Equation 4: Head Injury Criterion
where a is resultant head acceleration, t2-t1 < 15 msec
With reference to the Figure 7, below, the HIC value is used to predict the risk of head trauma: Minor –skull trauma without loss of consciousness; nose fracture; superficial injuries Moderate – skull trauma with or without dislocated skull fracture and brief loss of consciousness. Fracture of facial bones without dislocation; deep wound(s) Critical – Cerebral contusion, loss of consciousness for more than 12 hours with intracranial hemorrhaging and other neurological signs; recovery uncertain.
Figure 7: Probability of specific head trauma level based on HIC value
Peak angular velocity was determined as the maximum angular velocity related to peak linear acceleration impact time. Angular velocity values were used to derive Maximum Principal Strain (MPS) (Equation 5), Cumulative Strain Damage Measure (CSDM) (Equation 6), and Brain Rotational Injury Criterion (BrIC) (Equation 7).
Equation 5: Maximum Principal Strain
Equation 6: Cumulative Strain Damage Measure
An analysis method validated by Takhounts [6] establishes physical injury criteria for various types of traumatic brain injury and uses Anthropomorphic Test Device (ATD) data to establish a kinematically based brain injury criterion (BrIC) for use with ATD impact testing. This method was utilized to express risk of diffuse brain injury according to the revised AIS scale [7] in terms of peak angular head kinematics, where:
Equation 7: Brain Rotational Injury Criterion
Headrest Impact Results:
A summary of key results is presented in Table a-d, below. The driver was aware of the pending impact, as he depressed the accelerator in an attempt to avoid the collision in the moments prior to the crash. In rear end collision tests involving human subjects, volunteers instinctively tensed their neck muscles as a protective response. Given that the driver anticipated the crash his neck muscles were likewise expectedly tense as an instinctive protective response. Therefore, the results most consistent with the subject case are presented in Tables a and b. Rows highlighted in green are consistent with change in velocity experienced by the driver during the subject crash.
Table a: Summary of test results – Neck – Stiff; Headrest – lower position
Table b: Summary of test results – Neck – Stiff; Headrest – upper positio
Table c: Summary of test results – Neck – Loose; Headrest – lower position
Table d: Summary of test results – Neck – Loose; Headrest – upper position
Skull Fracture
With reference to Ono 8, none of the impact tests approached the occipital skull fracture threshold of 140 g for impacts lasting longer than 7 milliseconds. Therefore, vehicle headrests provide excellent protection against acute skull fractures at impact speeds below 25 mph.
Traumatic Head Injury
With reference to Figure 7 and Tables a-d, maximum recorded HIC values were consistent with a 5 percent or less risk of moderate traumatic head injury. Whereas, the HIC value computed at impact speeds similar to the crash was only 3.4, at which the risk of minor or moderate traumatic head injury is negligible.
Mild Concussion
With reference to Figure 8 below, the risk of an occupant sustaining a mild concussion in a rear-end collision producing a change in velocity of 6.25 mph (range 5.4 to 7.2 mph) can be determined based on the following calculation: Risk AIS-1 = 31.744*ln(x) + 6.1748 (R2=0.67). The risk of and AIS-1 mild concussion, without post-concussion syndrome, in such an impact is 64.3% (range 59.7 to 68.8%).
Figure 8: Risk of mild concussion (AIS-1) associated with headrest impact
Severe Concussion
With reference to Figure 9, below, the risk of an occupant sustaining a severe concussion in a rear-end collision producing a change in velocity of 6.25 mph (range 5.4 to 7.2 mph) can be determined based on the following calculation: Risk AIS-2 = 0.198e0.234x (R2=0.85). The risk of severe concussion in such an impact is 0.85% (range 0.70 to 1.07%).
Figure 9: Risk of severe concussion (AIS-2) associated with headrest impact
Traumatic Axonal Injury:
Figure 10, below, is adapted from Margulies et al. 20 in which thresholds for axonal injury were developed and published based on mathematical modeling, animal testing and physical experiments. Results from occipital head impact against an exemplar headrest at a speed of 6.2 miles per hour are represented, indicating that rotational head and brain kinematics associated with such impact are well below scientifically-accepted thresholds for traumatic axonal injury.
Figure 10: Scientific Thresholds for Axonal Injury
Figure 11, below was generated from data presented in Tables a through d, to present the risk of traumatic axonal injury associated with head impact against an headrest.
Figure 11: Risk of traumatic axonal injury (AIS-4) associated with headrest impact
Results show that the risk of an occupant sustaining traumatic axonal injury in a rear-end collision producing a change in velocity of 6.25 mph (range 5.4 to 7.2 mph) can be determined based on the following calculation: Risk AIS-4 = 0.0271e0.2391x (R2=0.85). The risk of traumatic axonal injury in an impact of the magnitude experienced by the driver is 0.12% (range 0.10 to 0.15%).
Conclusions
Biomechanical testing of head and brain injury risk associated with occipital head impact against a headrest, in accordance with published methods, shows a significant risk (59.7 to 68.8%) of AIS-1 mild concussion, without post-concussion syndrome, in a 6.2 mph rear-end collision. However, the risk of an AIS-2 severe concussion in such an impact decreases to 0.70 to 1.07%, and the risk of traumatic axonal injury is only 0.10 to 0.15%. Moreover, the mechanical traumatic axonal injury is not consistent with a sagittal plane impact.
References
[1] Caccese V, Lloyd J, Ferguson J (2014) An Impact Test Apparatus for Protective Head Wear Testing Using a Hybrid III Head-Neck Assembly. Experimental Techniques.
[2] Lloyd J & Conidi F. (2015). Brain Injury in Sports. Journal of Neurosurgery. October.
[3] Lloyd J. (2017). Biomechanical Evaluation of Motorcycle Helmets: Protection Against Head and Brain Injuries.Journal of Forensic Biomechanics.
[4] SAE (2014) J211/1. Instrumentation for Impact Test – Part 1 – Electronic Instrumentation. Society of Automotive Engineers International, Surface Vehicle Recommended Practice, Warrendale, PA.
[5] Padgaonkar AJ, Krieger KW and King AI. Measurement of Angular Acceleration of a Rigid Body using Linear Accelerometers. J Applied Mechanics. Sept 1975.
[6] Takhounts EG, Craig MJ, Moorhouse K, McFadden J (2013) Development of Brain Injury Criteria (BrIC). Stapp Car Crash Journal 57: 243-266.
[7] Abbreviated Injury Scale (2008) Association for the Advancement of Automotive Medicine, Des Plaines, IL.
