Amusement Ride Safety and G-Forces

G-forces refer to the force of gravity, and one G is equal to the normal pull of earth’s gravity on the body. Amusement ride designers have collected and studied relevant data on g-forces for years, subsequently applying this biodynamic knowledge to the design, manufacture and construction of rides. While technological advances have led to the development of faster and more thrilling rides, overall g-force levels have not dramatically changed in the past two to three decades because riders’ tolerance levels have not changed.

When discussing the effects of g-forces on a person who is on a ride, one must consider the duration of the g-force, as well as a multitude of other variables. When it comes to the higher–g sections of amusement rides, exposure often lasts fractions of a second. Therefore, the rider does not experience any adverse effects because the force is extremely brief. Blackouts and other health issues associated with Gs require exposure to g-forces which are either greater in magnitude or of much longer duration than those achieved by today’s amusement rides.

A study by Murray Allen, MD, Ian Weir-Jones, P. Eng, Ph.D., and several other doctors and engineers was published in the November 1994 edition of Spine. The study “found that in one event of daily activity, the vector acceleration of 10.4 g was experienced uneventfully.” We go through our everyday lives with our bodies exposed to far greater gravitational pull than that of any amusement park ride; we just don’t realize it, or even think about it.

Examples of everyday gravitational forces:

Sneeze 2.9
Cough 3.5
Crowd jostle 3.6
Slap on back 4.1
Hop off step 8.1
Plop down in chair 10.1

MYTH: Higher level g-forces (Gs) on rides are overly dangerous, with blackouts possible at a level of just 6 Gs. The industry is pushing the envelope in this regard, without any parameters or guidance, and there are numerous cases of brain injury stemming from amusement rides.

REALITY:

No fewer than five independent scientific reviews have comprehensively analyzed the issue of amusement ride g-forces, and all five have reached the same conclusion: the rotational accelerations experienced by the head during rides pose no risk of brain injury to the general populace.
We welcome this science-based work, in place of the random anecdotal accounts that had previously dominated the debate over this issue.
It is clear from this thorough analysis that a focus simply and strictly on the matter of g-forces or height or speed is wholly inadequate when discussing the physical experience of riding a roller coaster or any other ride.
Instead, the interaction between ride and rider is a complex one, yet these reviews have authoritatively demonstrated that the dynamic characteristics of that interaction are far below even the minimum levels associated with brain injury.
Amusement ride manufacturers have collected and studied relevant data on g-forces for years, subsequently applying this biodynamic knowledge to the design and construction of rides to make them as safe as possible.
While technological gains have led to the development of bigger rides, overall g-force levels have generally not changed that much in the past two or three decades because riders’ tolerance levels haven’t changed – people are the same today as they were in 1970.
Instead, the very technological and design improvements which have allowed for a more thrilling and faster ride have simultaneously helped produce an even safer ride in all aspects, including Gs.
Additionally, ASTM International has now incorporated g-force limits into its ride safety standards that guide the amusement industry. The ASTM process is the most appropriate one for the task, given the independent organization’s 30-plus-year history in developing this exacting set of standards in partnership with the industry, consumer groups, and government entities.
A key point to remember about this issue is that equally important to the magnitude of g-forces is their rate of onset and their duration, as well as a multitude of other variables. When it comes to the higher-g sections of amusement rides, exposure lasts but a few seconds at most, and often fractions of a second, so before a rider feels any adverse effect, the force is already past.
In marked contrast, blackouts and other health matters associated with Gs require exposure to g-forces which are either greater in magnitude or of much longer duration than those achieved by today’s rides.