Inspect, Repair, & Maintain O-Courses - Fall Safety

Impact Attenuation is defined as: A device, material, or system designed to prevent injury to persons by absorbing impacts through localized material deformation or displacement, to absorb the energy of an impact in a way that reduces the magnitudes of peak impact force and peak acceleration.

Obstacle Courses are inherently dangerous , impact abatement is only intended for lessening potential ground or structure impact-based injuries in the case of an accidental fall.

Existing Guidelines:

Please note that ASTM guidelines (F2479 and F1292 in particular) deal with playgrounds which are rated for use by children/adolescents up to 12 years old for free play which is dramatically different from JROTC usage which is instructor-led and participants are high school-aged young adults. Also, JROTC is a group membership activity that has certain requirements of conduct outlined in waivers signed by participants and guardians if under the age of 18.

Co-Founder Brett Stewart is proudly a voting member of ASTM and proudly a part of actively creating guidelines for obstacle courses as playground recommendations are not applicable.

Obstacle Builders designs and fabricates our elements with cadet safety first and foremost, with proper training and supervision the incidence rate of injury is drastically reduced. 

PLEASE NOTE: If elements are to be used for “free play” playground-type open access and not overseen by an instructor we will decline to fabricate any/all elements.

The US Military has been working to develop a standard whilst greatly overshooting their target by incorporating 18” of rubber mulch across the board. This in and of itself creates multiple more problems than it solves: 

- Exorbitant costs for hundreds of tons of mulch for the average US MIlitary O-Course as well as stacked 6x6 borders plus all the labor and equipment needed 

- Far more importantly is the significant increase in injuries to cadets' and instructors' ligaments and connecting tissues (primarily ankles and knees) from walking, running, landing, etc. on the extremely unstable surface that’s created by 18” of rubber mulch.

Impact Abatement Recommendations

Here are the current recommended common-sense impact abatement guidelines while a formal ASTM guideline is being drafted and ratified:- Mulch should be concentrated in the below amounts in "impact areas” defined as under or 24” - 48” surrounding elements where falls may possibly occur. 

• 4” depth of rubber mulch for impact abatement 5’-7’ fall height
• 5” depth of rubber mulch for impact abatement 8’-10’ fall height
• 6” depth of rubber mulch for impact abatement up to 12’ fall height

Note: "Fall height” above is defined as the height measured by the closest body part to the ground during normal/prescribed instructor-led completion of that element. 

• For example, a 12’ rope climb has a fall height of 5’6” to 6’6" when completed as instructed:
  • Top bar 12’ high
  • Rope connection & knot 12” - 18” below top bar
  • Instructor height marking (the prescribed location where a cadet’s hands should reach for completion of the element as indicated by tape or paint) 6”-8” below knot
  • Cadet’s (average) height such that their feet are the closest body part to the ground 48” below height marking
  • Fall Height: 5’6” - 6’6” = 4” of rubber mulch for impact abatement

We go through each element with our clients and provide recommendations and it is their decision on the size, depth, and number of elements you choose to purchase impact abatement in fall areas. About 80% of our clients nationwide choose to use existing natural surfaces such as grass underneath a majority of their element. Sand is also an option in some cases when the obstacle course is installed in an area that sees heavy rain runoff. Sand will most remain in place whereas mulch will be washed away.
As a final point to be made about impact abatement, for many cadets it creates a false sense of security whereby they abdicate a level of responsibility for conducting themselves appropriately. This is most notable in situations with crash pads, water, and can be applied to overly thick rubber mulch as well. Impact abatement is only intended for lessening potential injuries in the case of an accident only.