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According to Architectural Graphic Standards, Tenth Edition, stairways “...are the site of accidents resulting in approximately 4,000 deaths and one million injuries requiring hospital treatment annually in the United States.” No wonder, then, that several mathematical formulas have been developed to help minimize stairway tripping hazards. Most notably, these formulas regulate the ratio of the height of the riser to the depth of the tread for the contiguous steps of any given stairway. In addition, various other restrictions are imposed... all with the aim of assuring safe and comfortable stairways.
Now then, when an exterior stairway spills out onto a sidewalk with an appreciable slope, it is not possible (without the use of the techniques which this new Method teaches) to obtain a uniform ratio of riser-to-tread, thereby possibly introducing a serious tripping hazard. In any stairway it is most important for that ratio to be consistent. The mind of the pedestrian using a stairway is very quick to implant the expectation of an ensuing constant biomedical rhythm, which predicts just how high the next step will be. To encounter even a slight difference can result in tripping.
This new Method will teach how to design safe stairways from sloping sidewalks as well as how to design minor modifications to the normal geometry of individual steps of existing offending stairways that interface with sloping surfaces. It will also show how to redesign the sidewalk itself so that an interfacing stairway will be safe from tripping hazards, and it will explain how pre-cast concrete steps can be modified to conform with the safe-step parameters that this Method employs.
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