Recent years have found an increased demand for obstacle course races and “ninja warrior” style training and events at gyms and athletic facilities. World OCR, the international governing body for obstacle sports, includes a world series and world championships for the discipline.
In this article, Adventure & Obstacle Sports Expert, Ian Adamson, details the design, construction, and maintenance of obstacle courses and their components, as well as common failure modes that can result in injuries.
Obstacle Course Design, Construction, and Maintenance - Expert Article
As with many sports and events, most people are participants as opposed to competitors. Those who use obstacle courses may do so simply for fun, or when training for Ninja competitions, cross country, urban or military activities. American Ninja Warrior (ANW) courses have evolved from home-built obstacles to engineered structures that are commercially produced. Most of the obstacles in gyms are isolated for training purposes, but in some cases, they are joined together for timed competitions or races.
Facilities typically seek to replicate the types of obstacles seen on television. These vary from relatively simple challenges for beginners, to advanced features that require explosive strength and specialized skills. Ninja courses are often described as playgrounds for adults.
Design and Construction
Ninja courses consist of discrete obstacles, commonly built on frames. Obstacle design and construction varies from rudimentary wooden frames to fully engineered metal structures similar to stage truss assemblies.
The strength and consistency of trussing varies greatly, depending on the alloy, tube diameter, wall thickness, cross brace size and spacing, triangulation, weld quality and surface finish. Other common builds use clamped frame scaffolding and bolted wood structures.
Safe obstacle design requires an understanding of the static and dynamic loads, load cycles, wear, and the environmental conditions under which the obstacle will be kept. Knowing the use conditions allows a person with sufficient engineering knowledge and experience to design safe structures, inspection and maintenance schedules, and specify the design life.Obstacle Course Frame Element Failures
A common mistake in obstacle frame design is assuming maximum load conditions are due to static loads. This ignores the amplification of force from people moving through an obstacle, known as dynamic loading. Examples of dynamic loads include centrifugal force (from swinging) and deceleration from jumping. Fatigue is a result of repeated loading and unloading. This can slowly loosen fasteners, change joint geometry, and negatively affect load characteristics, increasing the probability of failure. Certain materials such as aluminum are particularly susceptible to fatigue failure.
If made of wood, certain factors such as nail size and length, screw size/type and length, bolts/washers’ size, fastener patterns, wood hardness and grain direction, triangulation, footings, and wind loads, among others, must be taken into account.
Metal frames subjected to cyclical dynamic loading can experience weld or fastener failure if the forces are improperly calculated. Dynamic loading on obstacles commonly includes repeated (back and forth) swinging on a rope or trapeze-like structure. This pendulum motion causes centrifugal forces far exceeding the body weight of the human and sometimes causes harmonic motion of the entire structure if not damped properly. This combination of forces has the potential to cause component or structural failure of the frame.
Obstacle Component Selection and Safety
The components used in obstacle elements vary from commercially available items such as climbing holds, ropes, cables, climbing rigging and gym equipment, to custom-built wheels, slides, rails and bars. These are commonly attached to frames with webbing, rope, cord, cable, clamps, carabiners, shackles and the like. Industry standard climbing gear and marine grade hardware is necessary to meet the applicable standard and hold up during foreseeable use.
At the time of this article being published, the ASTM International standard on Safety Standards of Obstacle Course Events (subcommittee F24.61) has been put to ballot, but the review process, publication and adoption could take years depending on how each state regulates the activity. In the interim, comprehensive safety guidelines exist and are readily available to designers, manufacturers and owner/operators.
ASTM, ANSI and CE standards can be used to ensure the quality of obstacle frames, and components such as trussing, tubular webbing, climbing rope, wire rope, cable clamps, scaffolding, shackles, etc., as well as proper inspection practices.
Inspection and Maintenance
Structural elements should be inspected for wear and integrity per the applicable standard and on a schedule appropriate for the obstacle’s loading, frequency of use and environmental conditions.
Fasteners should be routinely tightened to the specified torque / force, and the number of load cycles should be logged for welded elements, ropes, cables and webbing. All moving parts should be replaced when wear / performance dictates.
Permanent structures should be disassembled and rebuilt periodically to inspect the frames, connections and fasteners for deformation, wear, corrosion and signs of stress.
OBSTACLE COURSE INJURY INVESTIGATIONS
The Sports and Recreation experts at Robson Forensic are qualified to thoroughly examine whether the standard of care for obstacle courses was met in a situation where an injury has occurred.
For more information, please submit an inquiry.
Adventure & Obstacle Sports Expert
Ian Adamson is an expert in sports and recreation, with particular expertise in obstacle courses and races. He is President of Fédération Internationale de Sports d’Obstacles (FISO), the world governing body for obstacle course racing (OCR) and related disciplines. As a Mechanical Engineer with a master’s degree in Sports Medicine, Ian has applied his technical expertise to develop the standards and best practices relevant to obstacle courses and events worldwide. This includes safety standards and medical guidelines as a member of the Land Based Obstacles working group of ASTM International Committee F24 Amusement Rides and Devices. He also authored and leads the global program for OCR Coach Certification and is an advisor on event formats and obstacles for international multi-sport competitions.