How Can "Free" Be Anything but Good? - Building Principles

Camping Magazine, Nov-Dec, 2001 by Rick Stryker

What are the permit and design issues you should consider for constructing a new cabin, health center, or climbing wall at your camp? And beyond construction matters, what are the most innovative site development, maintenance, and facility management objectives to achieve? 'Building Principles, "a new regular column, will appear in every issue to keep you informed of the elements that directly relate to best business practices in facility management.

We've all heard the expression about getting something for nothing. More often than not, you end up with something that's worth what you paid. Like anything else, however, unforeseen circumstances can cost the organization much more in the end than may have been saved. Let's illustrate this condition with a hypothetical example Suppose that the program staff has lobbied for high ropes course elements and a climbing tower for several seasons. After much consideration, the project gets approval. The catch is that the budget is not sufficient to cover all the construction costs. Being the resourceful individual that defines a great career camp person, the program director begins to solicit help and donations from every source imaginable. The most attractive offer comes from a local power company that offers to supply and install utility poles for the supports. (Sound familiar, yet?) The first element will be a zip line.

After the poles are installed by the power company, the ropes course installer comes, places the hardware, and completes the construction of all the elements. The "project "is certified complete by the installer. The staff is trained, camp opens, and the new zip line is the biggest hit in years. Then the unthinkable happens. A support has toppled over, and a camper or staff member has been injured.

Identifying Liability

Who "owns "the liability? Obviously, nobody involved is going to rush to the front of this line! The ropes company will reasonably assert that it had no part in placing the poles. The power company will contend that the poles and labor to install them were a donation. The poles had been placed with the customary and reasonable care associated with the installation of power poles. They had no other directions upon which to base their installation. The prevailing question will be, "Who certified the adequacy of the foundation and structural components of this high-risk attraction?"

Utility-pole versus structure installation

On the surface, this looks very simple, and the applications appear to be obvious. The fact is, though, that the design considerations associated with the installation of utility poles are vastly different from those associated with the installation of a structure. Wooden power poles are installed with the intended use of supporting wires that are mounted either directly to the pole itself or to a crosspiece. It may also be assumed that a transformer (or some other heavy, stationary piece of equipment) will be mounted on the pole at some time in the future. All of these weights ("loads") are still vertical ("dead") and are ultimately held in the air by the interaction between the pole and the soil beneath and around the pole.

Zip-line supports

In the case of a support for a zip line, the loads are highly variable and are comprised of a combination of live and dead loads that are not always acting directly towards the ground. The drawings in Figure 1 are known as "free body diagrams, "and attempt to simplify the systems into sketches that show where and how the forces act on the poles.

Some of the considerations that should be part of the zip-line design include:

* The physical properties of the pole (there are no universal standards for utility pole length, diameter, or strength),

* The physical properties of the soil in which it is embedded (soils vary considerably over surprisingly short distances),

* The live and dead loads that are expected to act on the pole and its foundation,

* The dynamic (active) behavior of the entire system when it is being used as it was intended, and

* The dynamic behavior of the entire system when it is being used as it was not intended.

This last point is one that may be easily overlooked. The potential effects of immediate and long-term misuse or misbehavior of participants should always be a consideration of the designer.

Conducting a Risk Analysis

To illustrate how these factors come into play, consider extreme examples. For instance, it is easy to imagine that if the pole is set in a swamp, the ability of the soil to resist the toppling of the pole is much lower than if the pole is set at the same depth in a well-drained, tightly compacted clay soil. A complete design, then, should be a series of linked, cyclic questions and answers. What if we were to set the pole 30' deep? Is that enough? Perhaps. Is it too much? Perhaps. The answers to these questions depend on repeated and cyclic revisiting of those points listed earlier.

As another example, consider the design requirements of modular playground equipment. The Consumer Product Safety Commission and Underwriters Laboratories test for pinch points and places for limbs and heads to be caught, among other things. We expect nothing less. And yet, in the zip line example, an "attractive nuisance" has been installed with little more than crossed fingers and a desire to make camp more challenging, attractive, inviting, and exciting.