Category Archives: motorcycle crash expert

Motorcycle crash expert Dr. John Lloyd has served attorneys nationwide for 25+ years in biomechanics, human factors, helmet testing and motorcycle accident expert

Motorcycle Crash Expert

Motorcycles are considerably more complex to operate than cars, and riders are significantly more vulnerable to potentially devastating injuries. Motorcycle crashes may be caused by a number of factors, including rider error or inexperience, excessive speed, other driver distraction, carelessness or inattention, roadway or mechanical defects, and weather related hazards. For these reasons, a motorcycle crash expert is critically important in a motorcycle crash case.

Dr. Lloyd’s interest in motorcycling began at the age of 13, when he built his first motorcycle and learned to ride. Since that time he has amassed many years of technical expertise. In addition to holding a PhD in Ergonomics (Human Factors), with a specialization in Biomechanics, John holds several certifications in motorcycle accident reconstruction.

Based on his 38+ years of riding and advanced training as a motorcyclist, he is one of a few experts who have been admitted in court to testify regarding motorcycle handling and operation.

Motorcycle Crash Expert

Using his FAA part 109 pilot’s license, Dr. Lloyd can fly drones to generate 3D forensic maps of crash scenes for reconstruction purposes. Based on his PhD in human factors / ergonomics, John is qualified to address human factors issues including line of sight analysis, perception response time (PRT), distracted driving and impairment. Given his extensive experience as a senior researcher in biomechanics, with a specialization in head and brain injury biomechanics, including research and development of helmets, Dr. Lloyd is also uniquely qualified to opine on injury biomechanics and motorcycle helmet protection issues.

With combined expertise as a motorcyclist, accident reconstructionist, biomechanist, and human factors expert, Dr. Lloyd is often called upon to provide expert witness testimony in motorcycle accident cases. Such cases have included solo motorcycle accidents, motorcycle v auto accidents, motorcycle crashes due to roadway defects as well as accidents attributable to mechanical failure or maintenance.

Links to several of Dr. Lloyd’s articles pertaining to motorcycle accident reconstruction and biomechanical evaluation of motorcycle helmets are presented below:

Please call Dr. Lloyd at 813-624-8986 or email DrJohnLloyd@Tampabay.RR.com to discuss how he can be of help to you with your case.

Motorcycle Pothole Crash

Motorcycles are highly sensitive to changes in roadway conditions. Potholes can destabilize a motorcycle, causing the rider to lose control. The following is a case in which a rider claimed he was traveling at only 15 miles per hour, when he came upon a large pothole in the roadway and lost control. The motorcycle fell to the right, with the right foot peg penetrating the rider’s leg, leading to a near amputation of his right foot. Dr. Lloyd was retained to investigate the cause of the motorcycle pothole crash.

Test Instrumentation

An exemplar Honda CBR 929RR motorcycle was acquired and instrumented with accelerometers installed on the front axle, rear axle and handlebars:

Diagram of test instrumentation used in a motorcycle pothole crash scenario, showing sensors and equipment designed to measure impact forces, rider response, and helmet performance during the crash.

Data acquisition was controlled using a National Instruments cDAQ 9178 and acquired at 10 kHz per channel on a Windows tablet running LabVIEW software:

Illustration of test instrumentation in a motorcycle pothole crash, featuring sensors and devices that capture data on impact, speed, acceleration, and rider safety during the collision.

Pothole Crash Testing

Using the instrumented motorcycle, Dr. Lloyd constructed an exemplar pothole in an open parking lot using ramps to investigate how the length and depth of the pothole affected stability of the motorcycle. In addition to sensors, testing was recorded using high speed and standard video, as well as GoPro cameras mounted on the motorcycle

Image of pothole crash testing by Dr. Lloyd, using an instrumented motorcycle, sensors, and cameras to study the impact of pothole length and depth on stability.

Results

Based on analyses and physical evidence, that the speed of the motorcycle while crossing the roadway defect was likely 14 -18 miles per hour. At such speeds, the front and rear suspensions have a tendency to approach maximum compression. along with substantial deformation of the tires.

Conclusions

Dr. Lloyd determined that the motorcycle crash was caused due to the motorcycle accelerating as it crossed the pothole. When the rear wheel crossed the fore edge of the defect it lost contact with the roadway and the rear wheel speed increased without resistance. Upon contact with the aft edge of the roadway defect the rear wheel was at a higher rate of speed than the rest of the motorcycle, causing the motorcycle to unexpectedly wheelie.

Please call Dr. Lloyd at 813-624-8986 or email DrJohnLloyd@Tampabay.RR.com to discuss how he can be of help to you with your case.

Motorcycle Accidents and Brain Injury

To consider whether a motorcycle helmet might reduce the risk of brain trauma in a motorcycle accident it is first important to understand the two primary mechanisms associated with traumatic brain injury – impact loading and impulse loading, according to motorcycle helmet expert, Dr. John Lloyd.

John Lloyd motorcycle helmet expert linear head injuryImpact loading involves a direct blow transmitted primarily through the center of mass of the head, resulting in extracranial focal injuries, such as contusions, lacerations and external hematomas, as well as skull fractures. Shock waves from blunt force trauma may also cause underlying focal brain injuries, such as cerebral contusions, subarachnoid hematomas and intracerebral hemorrhages.
John Lloyd motorcycle helmet expert rotational brain injury

Whereas, impulse or inertial loading caused by sudden movement of the brain relative to the skull, produces cerebral concussion. Inertial loading at the surface of the brain can cause subdural hemorrhage due to bridging vein rupture, whereas if affecting the neural structures deeper within the brain can produce diffuse axonal injury (DAI).

Epidemiology Studies

Two major epidemiologic studies into the causation of motorcycle accidents have been conducted in North America and Europe: the Hurt Report and the MAIDS report. The Hurt Report showed that failure of motorists to detect and recognize motorcycles in traffic is the predominating cause of motorcycle accidents. Seventy-five percent of accidents were found to involve a motorcycle and a passenger vehicle, while the remaining 25% of accidents were single motorcycle accidents. Two-thirds of motorcycle-car crashes occurred when the car driver failed to see the approaching motorcycle and violated the rider’s right-of-way. Findings indicate that severity of injury increases with speed, alcohol motorcycle size and speed.

The MAIDS study (Motorcycle Accidents In Depth Study) is the most recent epidemiologic study of accidents involving motorcycles, scooters and mopeds, which was conducted in 1999 to investigate motorcycle accident exposure data across five European countries. Key findings show that passenger cars were the most frequent collision partner (60%), where 69% of the drivers report that they did not see the motorcycle and the predominance of motorcycle accidents (54.3%) occurred at an intersection.

In 1995, the European Commission Directorate General for Energy and Transport initiated a Cooperative Scientific and Technical Research (COST) program to investigate Motorcycle Safety Helmets. Several agencies from Finland, the United Kingdom, France and Germany participated in this study, which compiled and analyzed data from 4,700 motorcycle fatalities in Europe, each year. The COST report documents that 75% of all fatal motorcycle accidents involve head injury. Linear forces were present in only 31% of fatal head injuries, while rotational forces were found to be the primary cause in over 60% of cases. Within the scope of this study experiments were performed using drop tests with accelerometers to measure linear and rotational accelerations of the brain and skull mass associated with different types of impacts. These tests confirmed rotational acceleration to be a primary cause of brain injury in helmeted motorcycle accidents.

While the motorcycle helmet is currently the most effective means of protection for riders, data suggests that motorcycle helmets are only 37-42% effective in preventing fatal injury. By reducing the effects of blunt trauma to the head it is generally believed that risk of brain injury, including concussion, axonal injury and hematoma would also be reduced. However, the mechanisms of head and brain injury are very different. New research shows that these mechanisms are poorly coupled, contrary to previous beliefs.

Summary

  • Motorcycle helmet expert report that rotational forces acting on the brain are the underlying cause of traumatic brain injuries.
  • Motorcycle helmets, including those certified under DOT and SNELL standards are designed to mitigate forces associated with linear acceleration.
  • According to motorcycle helmet expert, helmets are not currently certified under either DOT or SNELL standard against their ability to protect against the angular / rotational forces.
  •  Epidemiologic evidence from the COST-327 report  indicates that motorcycle helmets do not provide adequate protection against closed head and brain injuries

New Research

Motorcycle helmet expert Dr. John Lloyd recently published a new study: Biomechanics of Motorcycle Helmets: Protection Against Head and Brain Injury. Testing proves that motorcycle helmets provide inadequate protection against concussion and severe traumatic brain injury associated with even relatively minor head impact