Documentation:FIB book/The Capabilities of The Head and Neck Support (HANS) Device in Reducing Acute Head and Cervical Spine Injuries During High-Velocity Impacts in Motorsports

Overview

Figure 1: The head and neck support (HANS) (1) is a frontal head restraint device consisting of two straps (2) that are fixed at the helmet (3) Shoulder support (4)

The Head and Neck Support (HANS) device is a safety system primarily used in motorsports to reduce the risk of severe head and neck injuries during crashes. It works by anchoring the helmet to a rigid shoulder brace, thereby limiting the relative motion between the head and torso during rapid deceleration of 45 G. The device can bee seen in Figure 1. Before the introduction of the HANS device, severe craniovertebral junction (CVJ) injuries were the leading cause of death in high-speed motorsport crashes. Since the device became mandatory, fatalities from CVJ injuries have been reduced to nearly zero.

Over the past few years, the popularity of motorsports, especially in Formula 1, has grown rapidly. With high-speed crashes being a common occurrence, it is crucial to continue improving safety measures.

Introduction & Significance

Motorsports involve extremely high speeds and subject drivers to a wide range of loading conditions. During rapid deceleration events, usually resulting from a collision with another vehicle, barriers, or roll overs, the driver's body is restrained by the cockpit structure, roll cage and harnesses that wrap around the pelvic region and upper torso. However, the driver's head is still free to move relative to the body, which generates high loads at the CVJ that often severely injure the driver. To mitigate these fatal injuries, the HANS device was introduced to transfer these large loads from the neck area to the forehead, which is a much stronger region of the body.

Historical context

The original design was developed in the 1980s by both Dr. Robert Hubbard, a biomechanical engineer who specialized in the principles of the human skull, and Jim Downing, an engineer and professional racecar driver as the 5-time IMSA champion. Their ambition was driven by the loss of a friend in a racing crash, where Hubbard and Downing realized that the basilar skull was vulnerable to fractures. Jim Downing was the first IMSA driver to wear the HANS device in 1986, followed by Paul Newman as the second in 1988. After a decade of research and development, the HANS device was officially on the market in 1991. The HANS device was slow to gain traction until a series of high-profile deaths in professional racing (namely, Ronald Ratzenberger and Ayrton Senna) throughout the 1990s sparked the interest in safety. By the early 2000s, Championship Auto Racing Teams (CART) had announced that the HANS device be required for all oval track races, from which stricter rules and regulations were set in place, shifting the culture of motorsport safety from reactive to preventative.

Epidemiology

From an epidemiological perspective, the HANS device's performance has been nearly perfect. Since the HANS device has been adopted by the motorsport industry, fatal injuries regarding the CVJ area in major racing leagues have dropped to virtually zero. According to an article, A revolution in preventing fatal craniovertebral junction injuries, not a single case of a fatal CVJ injury was reported since the rule requiring the HANS device in professional auto racing was implemented . In contrast, drivers before the year 2001 were at constant risk of these injuries, as CVJ injuries were the most common cause of death in these high-speed sports . This trend demonstrates a strong epidemiological correlation between the introduction of the HANS device and the near disappearance of major head and cervical spine-related injuries in professional motorsports.

Social Effects

From a social perspective, the HANS device has reshaped the motorsport culture, as well as the public's and professionals' understanding of safety in these high-risk sports. Fatal crashes were originally perceived as tragic but unavoidable, an inherent risk of the sport. Today, with the addition of incredible safety equipment and features like the HANS device, Halo cockpit protection and improved barriers, such accidents are viewed as unacceptable and preventable tragedies. HANS device not only saves the individuals, but also positively impacts the ethical standard in motorsports by promoting better designs of helmets, restraint systems, and even other consumer automotive safety technologies that were inspired by motorsport research.

Biomechanical Design

Figure 2: HANS device secured by 5-point-seatbelt

The body of the device is manufactured with carbon reinforced composite material to ensure a high -trength performance. The device is horseshoe or "U" shaped, which acts like a collar surrounding the head and neck, and is placed over the shoulder of the user. The centre of the "U" is partially extruded to follow the shape of the helmet and two tether straps are attached to the helmet. The connection of the straps are not pinned to the device, so the driver can turn their head freely left to right while driving. In practical application, the two belts (orange from the illustration Figure 2) lay on top of the device collar (shown in yellow), clamping the HANS device securely against the driver’s torso. During a crash, these belts play a crucial role by anchoring the device to the upper body, creating an alternative load path for crash forces that would otherwise be transmitted through the cervical spine.

In a frontal impact, the driver’s head tends to continue moving forward due to inertia, while the torso is rapidly decelerated by the seat belts. Without protection, this disparity in motion creates high tensile and shear forces in the cervical vertebrae, particularly at the C1–C2 complex and lower cervical segments, which are regions that are highly susceptible to injuries.

The HANS device redirects these forces. When the head pitches forward, the tethers become tensioned, limiting the distance the helmet can travel. Instead of the neck absorbing the full load, the tension force is transferred through the tethers into the rigid arms of the device. From there, the energy is dispersed into the clavicles, scapulae, and upper thoracic cage, structures far better suited to handle compressive loading. Because the HANS rests on the broad bony surfaces of the shoulders, the crash forces are distributed across a larger anatomical area, greatly reducing peak stresses. This redirection of force prevents the cervical spine from experiencing the dangerous combination of axial tension and forward shear that historically caused basilar skull fractures and CVJ injuries.

The device is designed not to fully immobilize the head and neck, but rather to restrict excessive movement, particularly the severe motion caused by high-deceleration events like frontal collisions.

Experimental & Theoretical Studies

The effectiveness of the HANS device in reducing neck loads during frontal impacts has been demonstrated through both computational modelling and controlled experimental testing. The illustration in Figure 3 visually summarizes these effects, showing the substantial decreases in neck tension, axial loading, and shear forces when comparing scenarios without and with the HANS device.

Experimental Sled-Test Studies

Early sled-tests by Hubbard, Downing, and colleagues used anthropomorphic test devices (ATDs) in frontal crash simulations to quantify neck loading reductions. They referenced established injury thresholds for severe craniovertebral junction (CVJ) injury—specifically axial neck tension above 740 lbs and forward shear above 700 lbs.

Their results showed that, in a 40 mph, 36° right-frontal impact, the ATD experienced approximately 1,350 lbs of total neck loading without HANS, which decreased to about 296 lbs with the device. Axial neck tension dropped dramatically from 1,120 lbs to 210 lbs, while neck shear reduced from 750 lbs to 210 lbs. These reductions, averaging roughly 80%, provided compelling biomechanical evidence for the device’s protective capability.

Additional tests were conducted across multiple motorsport seating configurations, including Formula 1, IndyCar, NASCAR, and rally-car environments. Later studies confirmed similar decreases in cervical axial loads and shear forces, even when using different harness configurations such as 5-point belt systems. The consistency of these findings across both computational and experimental methods ultimately led to the widespread adoption and later mandatory implementation of the HANS device throughout high-speed motorsport disciplines.

A further series of experimental sled-tests by Gramling and Hubbard compared the HANS device to an FIA-prototype Formula One airbag system under identical crash conditions. Using a Hybrid-III ATD in an F1 monocoque sled, they evaluated frontal and 30° oblique impacts and found that both systems reduced head and neck loads from injurious levels to well below threshold values. Notably, the HANS device not only limited axial tension and shear but also prevented head rotational accelerations observed in baseline tests, particularly in angled impacts (9000–13000 rad/s²). While the airbag sometimes reduced forward head excursion more effectively, it introduced chin-loading risks and inconsistent restraint timing, making HANS the more reliable and biomechanically robust solution. These findings further reinforce the HANS device’s consistent protective benefit across varied crash orientations and test configurations.

Theoretical Studies

Computational studies later reinforced the experimental findings. In the computational study Effectiveness of the Head and Neck Support (HANS) Device in Frontal Impacts of CART Cars, a detailed CAE model was constructed using MADYMO to evaluate the biomechanics of a 50th-percentile male Hybrid-III dummy seated in an open-wheel race car environment. The model included the complete driver restraint system: cockpit geometry, 6-point harness, helmet, and head-neck-torso linkage. A scanned geometric representation of a typical HANS device was converted into a finite-element mesh and integrated into the simulation.

A frontal impact pulse, derived from prior sled test data, was applied to compare two conditions: a driver without the HANS device and one with the HANS device. Performance was evaluated using Injury Assessment Reference Values (IARVs) for a mid-sized male, including Head Injury Criterion (HIC ≤ 1000), upper-neck flexion/extension moments (190 Nm / 57 Nm), axial tension (3.3 kN), and shear (3.1 kN).

The results showed large reductions in cervical loading when the HANS was used. Peak upper-neck fore-aft shear decreased from 2.38 kN to 0.65 kN, a reduction of more than 3.5 times, and axial tension dropped from 3.32 kN to 0.04 kN, essentially eliminating tensile overload of the cervical spine. Although the HIC value was unexpectedly higher in the HANS condition (531 vs. 285), it remained well below the threshold corresponding to a <2% probability of fatal head injury. Overall, the simulations confirmed that the HANS device provides a controlled alternative load path from the head to the upper torso, preventing excessive tensile and shear forces from being transmitted through the cervical vertebrae.

Figure 3: Biomechanical schematic showing neck forces during frontal impact, with and without the HANS device.

Issues and Controversies Surrounding the HANS Device

Research addressing the limitations and controversies associated with the HANS device and the experimental methods used throughout its validation remain relatively scarce. This scarcity is largely attributed to the device’s widespread adoption and demonstrated effectiveness in preventing fatal and severe head/cervical spine injuries following its introduction in the early 2000s . The primary function of the HANS device is to reduce head and neck injuries by eliminating large head motions with respect to the upper thorax, and this was achieved with notable success in its first iteration.

Despite subsequent modifications to the HANS device to fit drivers of varying anthropometric characteristics, such as adjustments in tether length and collar fitment for different shoulder and neck sizes, no changes in the injury preventative nature of the device was observed. A retrospective study conducted in 2001on 26 drivers from CART series exemplified this adaptability and robustness. The cohort exhibited considerable variability in driver stature and mass, ranging from 59kg at 168cm in height, to 102kg at 183 cm in height. In addition, each driver had their own unique adjustments made to their harnesses, bucket seats and headrests. This led to a heterogeneous testing population for the HANS device but also one that would allow researchers to gain insights to potential variables that would decrease its effectiveness and spark conversations about important safety limitations. However, with no serious head injuries or cervical fractures reported in 21 incidents, apart from 1 grade 3 concussion, there was very little to investigate apart from HANS material fatigue and collar cracks in certain high g-force cases. Another retrospective analysis from the same period (2000-2001) similarly reported zero fatalities and zero instances of cervical fractures or dislocations in 28 documented racing incidents involving 33 CART drivers. The limited number of injuries observed has reduced further inquiry into the devices potential limitations.

A point of discussion is the limited volume of publicly available experimental data on the HANS device. Much of the foundational research in the open literature was conducted either by, or in close collaboration with, Robert Hubbard the principal inventor of the HANS system. While this concentration of authorship is not unusual in the development of highly specialized safety equipment, it naturally raises questions regarding potential bias, as the primary researcher has an interest in demonstrating the device’s effectiveness. However, this does not substantially weaken the overall evidence base. Subsequent independent investigations, including epidemiological studies from FIA and other motorsport bodies, and later ATD sled tests performed by other academic groups have consistently replicated the core biomechanical findings. These external validations reinforce confidence in the protective performance of the HANS device and help mitigate concerns about early publication bias.

Early Validation Experimental Methods

Despite the strong practical evidence supporting the HANS device effectiveness, few apects of its safety performance have remained open for discussions and debates. One area of critique concerns the physical tools and methodologies employed during the restraint device’s initial validation, particularly with the sled-based collisions simulations. It can be seen in literature that the Hybrid III 50^th percentile male anthropometric test device (ATD), a standard crash test dummy designed to replicate the average male adult in frontal collisions, was used for the majority of the HANS collision simulations. Although the Hybrid III has enhanced biofidelic responses at higher impact velocities, due to the stiffer nature of its mechanical neck, there are limited studies performed on its ability to properly recreate physiological and viscoelastic head and neck responses at motorsport level decelerations and under specific motorsport restraint mechanisms .

Additionally, reported empirical data on the Hybrid III was found to be stiffer in axial compression compared to cadaveric specimens, potentially influencing the measured compressive response of the neck under HANS tether engagement. There is one instance in particular where researchers modified the lower neck bracket of the Hybrid III in order to handle the extremely high neck loads when simulating a frontal stock car crash. Although this ATD modification likely enhanced mechanical durability and ensured test repeatability by preventing unwanted material bending or yielding, the new bracket can artificially stiffen the part of the ATD that would simulate the junction between the lower cervical spine and the upper thoracic/torso region, decreasing biofidelity. However, the outputted test results continued to support the superior performance of the HANS.

Conflicting Findings

Computational models of the HANS device have generally agreed with most of the physical sled test and ATD data found in literature. Most noticeable similarities were observed with the reductions in upper neck shear and axial tension, and slight increases in imparted axial compression and flexion moments, likely resulting from altered load paths induced by the tethering system. However, discrepancies emerged when comparing head injury criterion (HIC) outcomes with Hybrid III ATD tests for the 50^th percentile male as the computer model predicted a slight increase in the HIC. These differences were attributed to potential variations in model contact parameters, though some researches have proposed that the increased HIC value could be caused by the sudden application of force to the helmet, resulting in the driver forehead impacting the inner padding.

Future Work

Areas for Further Investigation

Following the demonstrated success of the HANS device, further research into its biomechanical nuances have been limited. While the overall function and injury prevention capabilities are well established, several parameters influencing its performance remain insufficiently explored.

One such factor is the influence of friction, which occurs between the race suit, the HANS shoulder collar, and harness straps. To date, this element has been only been examined through computational models rather than physical experimental test. Simulations suggest that maintaining a low coefficient of friction (~0.2) between these different material interfaces minimised neck shear, axial tension and extension moments. However, computational models under the same testing parameters show that higher friction values (~0.6) have been associated with lower HICs. This suggest a rather complicated relationship between head loading and frictional resistance which is open for further discussion.

Another parameter of interest is tether design. Since the relative slack and adjustment of the HANS tethers can be modified at the drivers discretion, it can be worth looking into the effect of certain tether material types, lengths and stiffness', so that drivers can better understand the balance between comfort and safety. Experimental work has shown that stiffer tethers can increase neck extension moments and axial compressive forces to higher IARVs, reducing the protective effect of the device. Another factor to this would be to examin the effect that rain and other external factors can have on the effect of the tethers and HANS device.

Sex-Based Biomechanical Differences

Research on the HANS device has predominantly been centred around male anthropometry, with limited attempts at investigating its performance among female motorsports athletes. It has been observed that differences in anthropometry and mass distribution in both females and males can impact the way the body interacts with restraint mechanisms in vehicles, impacting injury severity and type. The standard Hybrid III 50^th percentile male crash dummy, that is often used in motorsport crash reconstruction and HANS testing, roughly corresponds to a 90-95^th percentile female in terms of body weight and overall posture. This raises concerns regarding the device's applicability across different body types.

Additionally, the differences in the head and neck physiology between males and females can likely lead to different neck responses under HANS tethering engagement which has yet to be looked into. It has been studied in the past that females tend to have lower neck strength values and smaller segmental support areas, likely caused by smaller vertebral dimensions and differences in ligament structural components. However, these findings are influenced by the relative size of the individual as well and cannot be generalised to all female occupants and drivers. Additional research involving female specific biomechanical models can be performed to determine whether past and present configurations of the HANS device provide the same level of protection across sexes.

Case Studies- Effectiveness

Recent case reports and epidemiological analyses up to 2025 continue to demonstrate the real-world effectiveness of the HANS device in professional motorsport. Large-scale reviews of Formula 1 injuries attribute the marked decline in serious head and neck trauma since the early 2000s in part to the introduction of HANS-type frontal head restraints, while forensic investigations of fatal crashes highlight that incorrect or absent HANS use is a key factor when craniovertebral junction injuries still occur.Data from major racing series and FIA safety reports further show that, since such devices became mandatory, catastrophic basilar skull and CVJ injuries have been virtually eliminated, with no recorded skull-base fracture deaths in top-level motor racing during the HANS era. Overall, the recent findings and available studies further reinforce the early evidence demonstrating the HANS device’s life-saving effectiveness, confirming its critical role in preventing fatal head and neck injuries across modern motorsport disciplines.