Racing Safety: Head & Neck Restraints
HANS stays with belts until tethers are straight. Driver's head is restrained by tethers when torso is restrained.
By Rich Conklin | Originally published Vintage Voice Magazine, Summer 2004 |
Troubling questions spread throughout the racing community after Dale Earnhardt Sr.’s fatal accident on the final lap of the 2001 Daytona 500. Finding a satisfactory answer to those questions is vitally important to all racing drivers, professional and amateur alike.
By the standards of NASCAR crashes – in which a car often tumbles violently and shreds itself, but the driver walks away relatively unscathed – Earnhardt’s crash didn’t look all that serious. The car remained upright. Nothing flew off. It simply turned into the wall and stopped.
But analysis of that crash taught many racing drivers a new medical term: basilar skull fracture. This fracture of the basilar bone, part of the floor of the skull that holds the brain, is not itself fatal. The cause of death is loss of blood flow to the brain and/or brain trauma due to extreme stretching of the neck or spinal cord.
Racers also discovered an important statistic most hadn’t known: Basilar skull fracture is now the most common cause of death in racing.
Although Earnhardt’s crash didn’t look severe, the deceleration forces on his body were immense. His head and helmet became dead weight, multiplied by negative g’s when the car came to an abrupt stop.
Unrestrained by the driver’s safety harness, his head kept moving forward, stretching his spine and fracturing the basilar bone.
From the Earndhart fatality came a greater understanding in the racing community of the complexities of crash dynamics. Steady advances throughout the 1990’s in roll cage, seat and restraint engineering had left many with a sense that race cars were about as safe as technology could make them. Unfortunately they were wrong.
Tether forces of through forehead and center of head without increasing neck loading. Injuries to head swinging it counteracted as soon as the torso is restrained. HANS tethers align with head weight, for robust head support.
There remained one technology that, although it had existed since the mid-1980s, hadn’t been widely adopted throughout the racing world. That technology is generally termed head and neck restraints – devices designed to stop the head from whipping violently forward, thus preventing basilar skull fractures.
Not long after Earnhardt’s accident, head and neck restraints became mandatory safety equipment for all drivers in NASCAR, Champ Car, Formula 1 and the SCCA Speed World Challenge.
Beginning in 2005, head and neck restraints will be strongly recommended safety equipment for all VARA drivers. Various types of restraint systems are now widely available from a number of sources, including HANS, Hutchens, Safety Solutions, Isaac and G-Force.
Driver Safety Is a System
It’s important to understand two things about head and neck restraints. First, these devices function as part of a system of safety features, including the roll bar, roll bar padding, seat, safety harness, window net and helmet. To optimizing your chances of surviving a high-g impact, all of this equipment must be designed and installed carefully, and examined regularly. It’s the whole system – not any one component of it – that will ultimately five you the best chance of surviving a serious crash.
The second key point is that head and neck restraints are primarily intended to protect the driver in frontal collisions, where deceleration forces cause the head to whip violently forward. To help prevent injury in side-impact collisions, other devices and strategies are required. Top-of-the-line racing seats from the manufacturers such as Recaro, Cobra, and Sparco feature deep wings that limit side-to-side head movement. Net also help to limit lateral head movement.
The goal is to restrain body segments so that they move with each other in a crash, reducing loading between them. Head and neck restraints are simply designed to force the head to move with the body, thus reducing the load on the neck.
In an effort to educate club members about driver safety systems, VARA invited Dr, Robert P. Hubbard, a pioneer in developing head and neck restraints, to speak at the club’s California Speedway event in late July.
Dr. Hubbard, a professor at Michigan State University’s Biomechanical Design Research Lab, began developing what is known as the HANS device in the mid-1980s a the urging of his brother-in-law, veteran professional sports car racer Jim Downing.
After Earnhardt’s death, open-wheel racers were among the first to embrace HANS, That same year, Mauricio Guglmin hit the wall twice at Texas, sustaining a 66g frontial hit with a 36g left side impact, which broke the front of the tub before incurring another 120g rear impact.
Without HANS, this incident probably was life threatening. But although Gugelmin had major diffuse pain, he suffered no specific injuries. The HANS was not visibly damaged except for slight fraying of the tethers. His helmet was slightly damaged due to contact with the edge of the cockpit.
In 2002, at an IRL race in the Kentucky Speedway, Richie Hearn crashed into the outside wall at racing speed. The measured chassis acceleration was 138g frontal, 40g lateral. Hearn suffered a broken foot, but no apparent head or neck injuries.
General Recommendations
In addition to research pertaining specifically to his own product, Dr. Hubbard offered the VARA audience a range of recommendations for improving driver safety systems, based on more than 20 years of research and extensive analysis of crash data.
One of his surprising findings is that the widely used foam horse collar actually increases loads on the head and neck in a crash. As a result, VARA has rescinded its earlier requirement that neck collars be worn by drivers who do not use a specifically designed head ad neck restraint system.
The complexity of crash dynamics makes it a challenge t oeffectively incorporate driver safety systems in vintage racing cars. Unlike NASCAR or the IRL, where driver environments are basically identical, vintage racing involves a wide variety of very different cockpit configurations. On top of these differences are individual drivers choices in roll bar and cage construction, seat construction and mounting, cockpit padding and other factors that make each car unique.
The maker of the HANS device strongly recommended that all cars incorporate a six-point racing harness, not the five-point type with a single sub strap. Hubbard stressed the advantages 3-inch shoulder belts over 2-inch belts, recommending that belts be installed to run horizontally from the mounting points to the driver’s shoulders, with no more than 3 inches between their inner edges.
He also recommends that anyone contemplating a new roll cage follow the state of the art. For the production sedans, that’s the SCCAs build specs for World Challenge Touring Cars (available at www.scca.org). Roll bar padding also should meet SFI specifications.
D-Cel device, made by Hutchens, is based upon the principle of neck protection as an essential by product of core body anchoring.
Different Devices One Goal
The various head and neck restraint devices available to racers take different approaches to the same goal: restraining the head and helmet sufficiently in a crash to prevent large neck loads that could result in a basilar skull fracture.
The most widely publicized –and the most expensive—is the HANS, which consists of a light weight yoke over the driver’s shoulders, held in place by the car’s shoulder harness and attached to the helmet with a pair of tether straps. The tethers provide some slack for the drivers normal head movement in racing, while restraining its forward movement in a crash.
Approaches vary among the competing designs. G-Force also utilizes a yoke, while the Isaac System link the driver’s helmet to the car’s shoulder belts through small detachable shock absorbers. Most other devices connect the helmet to a harness of straps on the driver’s body.
HANS device anchors to shoulders and utilizes scientifically proven principle tethers that attach to the helmet. Helmet connection points are critically important.
An obvious consideration in the selection of a head and neck restraint device is cost. Body harness designs such as D-Cel and Hutchens cost less initially than the HANS, but their harness must be replaced every two years to guard against degradation. Although the short HANS tethers also require replacement, they cost only about $25.
One concern expressed by the drivers is that HANS, Isaac and some others require that the helmet be drilled to attach hardware for the restraints. Helmet manufacturers say that such drilling technically voids the helmet warranty, although the mounts do not compromise the structural integrity of the helmet.
To avoid the complications, G-Force makes helmets with built-in anchors for its restraint system, and the next generation of helmets from sparco will come pre-drilled for tether attachments.
Manufacturers of the other types of safety equipment are recognizing the growing popularity of head and neck restraints. Sparco’s next generation of belts will be tapered specifically to work with the HANS device, and new seats from such makers as Sparco and Recaro also are designed to accommodate the HANS correctly.
VARA’s heightend emphasis on head nad neck restraints this year was initiated by president Craig Hibbard, promted in part by the fatal crash of a late-model sports car racer at Buttonwillow. Hibbard is hopping to continue the education process by invirting other safety industry experts to address VARA members at future events.
Device Sources
Here’s a brief list of the head and neck restraints currently on the market which are approved by SCCA Pro Racing. More information is available at the manaufatureres web sites lised below, and there’s plenty of intra-club conversation taking place on VARA’s internet message board (at www.vararacing .com).
Correct placement of the helmet connector to shoulder yoke tether on HANS Device is essential.
HANS Device was the first head-and-neck device to meet FIA compliance standards.
D-Cel Harness
Manufacturer: Safety Solutions
Price: $425
How it works: Basically a body harness that tethers to the helmet via cables, the D-Cel relies on the driver’s pelvis as its anchor and is totally independent of the cars lap and shoulder belts. The D-Cel is popular with endurance racers who need to make quick driver changes.
G-Force SRS-1
Manufacturere: G-Force Racing Gear
Price: $275 (plus helmet)
How it works: This system is designed specifically for the use with G-Force’s latest helmets (priced from $270), which have attachments embedded at the factory. A single cable runs between these attachments around the back of the helmet, where it connects to a yoke that is held under the car’s shoulder straps. A reinforcing reaction rod operates in conjunction with the short connecting strap.
HANS Device
Manufacturere: Hubbard/Downing Inc.
Price: from $850
How it works: A fiberglass carbon fiber and Kevlar yoke fits over the drivers shoulders, held in place by the cars shoulder straps. Two short tethers attach the helmet to the yokes high collar to keep the head upright and aligned with the torso in a collision. A range of recline angles is availavle, from production-car upright to open wheel reclining.
Hutchnes Device
Manufacturere: Safety Solutions
Price: from $325
How it works: A body harness that connects to the car’s lap belt anchors this system. Cables connect the helmet to the harness shoulder straps so that head and neck loads are transferred to the lap belt. NASCAR drivers were among the early adopters of the Hutchens, in part due to the ease with which drivers wearing the device can get in and out of their race cars.
Isaac System
Manufacturere: Isaac, L.L.C.
Price: from $720
How it works: The device uses small shock absorbers linked to each side of the hekmet to take up the forces acting on the head and neck. Isaac claims the device permits normal head movements while counteracting sudden forward movements, as well as those due to side impact. Quick-release pins conncet the shock absorbers to the helmet mounts.
Simpson System
Manufacturere: Simpson Performance
Price: from $450
How it works: This is a version of the D-Cel harness licensed to Simpson, using Simpson’s platinum webbing.
Tucker Helmet Harness
Manufacturer: Teamtech Motorsports Equipment
Price: $250
How it works: Another body harness concept, the Tucker was originally designed for monster truck drivers. It is anchored by a broad strip which wraps around the drivers waist like a weightlifters belt. The car’s safety harness holds the Tucker tightly in place. The helmet is secured via tethers attached to the D-Rings.
Weight Device Pro
Manufacturere: Over 40 Racing Motorsports Accesories
Price: $150
How it works: Jay Wright, an SCCA racer, created this inexpensive device which also utilizes a body harness. Three straps wrap around the helmet, looking into the eyeport at either side. A seatbelt buckle from a stock vehicle connects to a tongue on the back of the body harness. The model approved by SCCA Pro Racing is the preassembled version that requires the full body harness.
