Category Archives: motorcycle helmet expert

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

Motorcycle Helmets Provide Inadequate Protection Against Traumatic Brain Injury

Dr. John Lloyd recently conducted a biomechanical study to evaluate motorcycle helmets in terms of their ability to provide protection against traumatic head and brain injuries. Motorcycle helmet testing proves inadequate protection against concussion and diffuse traumatic brain injuries associated.

Motorcycle accident victims account for more than 340,000 fatalities annually, with the United States ranking 8th highest worldwide in the number of motorcycle accident deaths. 75% of all fatal motorcycle accidents involve brain injury, with rotational forces acting on the brain the primary cause of mortality. Current motorcycle helmets are effective at reducing head injuries associated with blunt impact. However, the mechanism of diffuse traumatic brain injury is biomechanically very different.

Samples of 9 motorcycle helmet models, representing full-face, three-quarter and shorty designs were evaluated. Helmets, fitted to an instrumented Hybrid III head and neck, were dropped at 13 mph in accordance with DOT motorcycle helmet testing standards.motorcycle helmet testing

Results show that, on average, there is a 67% risk of concussion and a 10% probability of severe or fatal brain injury associated with a relatively minor 13mph helmeted head impact.motorcycle helmet testing results

In conclusion, motorcycle helmets provide inadequate protection against concussion and diffuse traumatic brain injuries associated with even relatively moderate impact.

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

What Every Rider Needs to Know About Motorcycle Helmets

I am a motorcycle enthusiast and a biomechanics researcher focusing on head and brain injury. Over the years I have performed more than 2600 helmet impact tests. The following are my take-away points for motorcyclists:

Lloyd-Biomechanics Motorcycle Helmets-Figure 2
  1. Helmets are the best protection we have against head and brain injuries. That said, standard certified motorcycle helmets are only 37-42% effective in preventing fatal head injuries. 
  2. Helmets are designed after ancient military helmets to serve as a second skull and thereby protect the head against focal injury.
  3. However, standard motorcycle helmets are not intended to protect against rotational brain injuries.
  4. There are two types of head and brain injuries, which are caused differently:
    • Translational (linear) forces cause focal injuries including cuts, bruises, and skull fractures.
    • Tangential forces cause rotational injuries including concussion, brain nerve damage, and brain bleeding.
    • Translational and tangential forces are generated in every impact
  5. Certified motorcycle helmets do a great job of protecting against focal head injuries.
  6. My research shows that DOT-certified motorcycle helmets reduce the risk and severity of focal injuries by 93 percent. 
  7. Novelty (non-certified) helmets do not offer any significant protection against focal injuries.
  8. It is therefore highly recommended that riders wear a certified motorcycle helmet at all times.
  9. Helmets that offer greater coverage, i.e. open-face (3/4) and full-face helmets, provide the best protection against focal injuries. However, the US DOT standard (FMVSS 218) [i] does not require impact testing of the chin bar, therefore there is no certified protection against facial injuries for full-face helmets that are only certified to the DOT standard.
  10. Generally, certified motorcycle helmets do not protect against rotational brain injuries. In fact, on average, a standard certified motorcycle helmet will actually increase the rider’s risk of concussion, nerve damage (axonal injury), and brain bleeding (subdural hemorrhage) by 19 percent, compared to an unhelmeted head impact.
  11. Rotational brain injuries are the cause of fatalities in two-thirds of all helmeted motorcycle deaths.
  12. It has been shown that, in general, larger and heavier helmets increase the risk of rotational brain injuries, including concussion, axonal injury, and brain bleeding because they generate greater impact-related rotational forces on the brain.
  13. So, what can a safety-minded rider do to minimize their risk?
  14. Revised motorcycle helmet standards are starting to look at brain injury risk. The new ECE 22.06 [ii] and Snell M2025 [iii] standards now measure the risk of rotational brain injury, though the passing threshold is 23% risk of neurologically devastating or potentially fatal rotation brain injury, at a moderate impact speed of 17.5 mph. 
  15. My recommendation is to choose a helmet that meets either the ECE 22.06 or Snell M2025 standard, in addition to whatever standard is mandated in your country.
  16. Choose a lighter, smaller helmet with the desired coverage over a larger, heavier helmet. Not only will this likely provide better protection against rotational brain injuries, but will also generate less wind resistance and be more comfortable on those longer rides.
  17. Consider helmets that incorporate new technologies that are intended to reduce the risk of rotational brain injuries.
  18. Don’t buy a helmet just based on looks, make an informed purchase based on fit and protective performance.
  19. What can motorcycle helmet manufacturer’s do to improve helmet performance?
  20. Current motorcycle helmet designs may be over-engineered to reduce translational forces that cause focal head injuries, resulting in helmets that are larger and heavier, thereby increasing the risk of rotational brain injuries, which are the primary cause of fatality in two-thirds of helmeted motorcycle crashes. Protection against focal injuries is important, but needs to be balanced against increased risk of rotational brain injuries. Manufacturers should evaluate materials that allow the development of smaller and lighter helmets.
  21. A meta-analysis is underway, comparing helmets intended for a variety of activities including motorcycling, skiing, bicycle, off-road, American football, ice hockey and military. Preliminary results suggest that helmets intended for other sports activities may outperform motorcycle helmets at similar impact speeds in terms of protection against both focal head injuries and rotational brain injuries

[i] U.S. Department of Transportation (2013) Federal Motor Carrier Safety Administration Standard No. 218, Motorcycle helmets. Washington, DC.

[ii] United Nations (2021). Uniform Provisions Concerning the Approval of: Protective Helmets, of their Visors and of their Accessories for Drivers and Passengers of Motorcycles and Mopeds. Regulation No. 22-06

[iii] Snell Memorial Foundation. (2024). Standard for Protective Headgear for use with Motorcycles and Other Motorized Vehicles. M2025

Research

Biomechanical Analysis Athletic Protectors

Concussion and Brain Injury Associated with Headrest Impacts in Rear End Car Crashes

Helmeted Motorcyclist Fatality

Motorcycle Pothole Crash

Why all head protection is in need of a redesign

The humble helmet dates back nearly 3000 years and though it has been used prolifically in warfare, it is now most commonly used to provide head protection outside the combat arena. 

However, although applications might have diversified, it is still fundamentally designed and used to provide the same thing.

So when this most traditional of objects is combined with modern sensor technologies, greater test data resolution and analysis, there is bound to be fresh insight.

And this is the case for many conventional designs where sensors, test and measurement technologies are changing conventional thinking into how something has been designed, to how it should be designed.

It sets the scene and means helmet design is on a collision course for further impact protection, specifically in preventing serious brain injury by giving helmet designers greater clarity in to the mechanical forces at play in any particular scenario.

It was this, along with a lifetime of comprehensive knowledge, which enabled biomechanist Dr John Lloyd, research director of BRAINS, to start up a company dedicated to improving current helmet technology and ultimately improve protection for wearers. He aims to shed new light on helmet design, and improve protection against the fundamental causes of concussion and brain injury.

“There are two key forces at play during a head impact,” said Dr Lloyd, speaking at this year’s National Instruments Week in Austin, Texas. “Firstly there are linear forces, these are the ones that cause visible injuries such as bruising and skull fractures. However, the second is the rotational forces. These are the ones that cause invisible injuries such as concussion and brain injury.

“Current helmet testing technologies measure the linear forces. However, at this time, they do not measure the rotational forces, so consequently we have helmets for many sports that do not test against their ability to provide protection against concussions and brain injury.”

Whether it is for riding a bike, horse riding, skiing or indeed for the soldier in the field, the effect of rotational movement is the same. Yet, it is rarely tested for, and even less frequently measured, to see how effective any helmet is in rotation force protection.

Dr Lloyd modified the standard apparatus used for testing helmets (see the rig on page 28), where a head section is raised 2m on a rig and dropped under gravity before it hits a striking plate with an impact force in the region of 4500N. However, instead of using a standard head form, Dr Lloyd replaced it with a standard automotive crash test dummy head and neck section. This way, when the head impacts the striking plate at the bottom of the test rig it will rotate, and the movement measured.

“We had multiple sensors embedded in the centre of mass of this head form,” explained Lloyd. “So, during the impact we were able to measure the linear acceleration as well as the angular motion of the head.

“My measuring apparatus includes sensors from several manufacturers.. The angular rate sensor, for example, that is used to measure the rotational forces is a highly specialised sensor. And, as a result, has its own data acquisition hardware and software.”

Simplifying synchronisation
Trying to integrate all this data from different sensors was a challenge at best. And to make matters more complicated, the peak linear acceleration and peak angular acceleration actually happen at different points in time.

“So while you can just line up the data,” he said, “there is a lag between them. So we need to measure that lag, which is a critical measurement in the research.”

To resolve the problem, Dr Lloyd uses both the National Instruments LabView graphical software and a CompactDAQ to interface with the sensors and provide the necessary synchronisation between the various sensors.

Dr Lloyd modified his apparatus for testing helmets used by American footballers in the National Football League (NFL), to develop understanding of the how spinal and head injuries are caused and improve the design of the standard helmet.

“The results are pretty alarming in terms of how little protection they provide against concussions and traumatic brain injuries,” he said.

“Based on lessons learned from that study, I have developed a new ‘football’ helmet prototype. This uses a patent pending matrix of non-Newtonian materials and when we tested the prototype helmet, on the same apparatus, the result blew me away. Not only did these materials reduce the linear forces but compared to the standard football helmet they actually reduced the rotational forces that cause concussion and brain injury by an amazing 50%.”

The non-Newtonian materials Lloyd has in mind are inexpensive and produce a helmet that is considerably lighter and even said to be more comfortable for those wearing them.

Dr Lloyd is now expanding the concept of reducing rotation forces in helmets in every application and said it can be applied to almost any helmet design to help reduce concussion and brain injuries from sports to leisure and even back to warfare.

Building a rig and conducting the test
A modification to the US National Operating Committee on Standards for Athletic Equipment (NOCSAE) standard test apparatus was used by Dr John Lloyd, research director of US helmet research start-up, BRAINS.

He developed and validated a new helmet test rig to measure the impact of protective headwear to include measurements of both linear and angular kinematics. This apparatus consists of a twin wire fall test system equipped with a drop arm that incorporates a 50th percentile Hybrid III head and neck assembly from HumaneticsATD crash test dummy, as used in the automotive industry.

The aluminium fly arm runs on Teflon sleeves through parallel braided stainless steel wires, which are attached to mounting points in the building structure and anchored into the concrete foundation. The anvil, onto which the head drop systems impacts, consists of a 350mm x 350mm steel based plate.

Both the standard Riddell Revolution Speed US university football helmet, and the prototype BRAINS helmet that incorporates a non-Newtonian matrix, were dropped from a height of 2m onto a flat steel anvil, in accordance with American Society for Testing and Materials (ASTM) standards. This generated an impact velocity of 6.2 m/s (13.9 mph).

Instrumentation: 
A triaxial accelerometer from PCB Piezotronics and three DTS-ARS Pro 18k angular rate sensors (Diversified Technical Systems) were affixed to a tri-axial block installed at the centre of mass in the Hybrid III head form. Data from the accelerometer and angular rate sensors were acquired using National Instruments compactDAQ hardware.

Analysis: 
Data from the analogue sensors were acquired at 10,000Hz, per channel, using LabView and then filtered in Matlab using a phaseless 4th order Butterworth filter with a cut off frequency of 1650Hz. Angular acceleration values were derived from the angular velocity data based on a 5-point least squares quartic equation.

Result:
The result of the new helmet design shows significant improvement in rotational acceleration exerted on the head and neck, cutting the overall force by nearly 50%.

Author
Justin Cunningham

– See more at: http://www.eurekamagazine.co.uk/design-engineering-features/technology/why-all-head-protection-is-in-need-of-a-redesign/66493/#sthash.6Tv5duXE.dpuf