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Safety Hazards of Stairs, Ramps, and Single-Step Risers
By Dr. Gary Presswood, PE | April 20, 2008
Stairs, ramps, and what are called “single-step risers” are safety hazards to pedestrians if not properly constructed. Much of my professional experience has been in evaluating these elements for attorneys and property owners, often the result of an unfortunate accident where a surprised patron fell and sustained injuries.
Typically, I find that handrails are missing or improperly installed, or the stairway or ramp was improperly designed, constructed, and/or maintained. Slippery surfaces also contribute to pedestrian falls especially when the edge of a step includes a metal border.
Stairways are generally considered to be constructed of two or more risers. To clarify, a step consists of a “riser” (the vertical edge of the step) and the tread depth or “run” of a step. Normally a stairway is defined as having two or more risers; however, the newer building codes (since 2000) have included a single-step riser as within the definition of a stairway.
Steps are typically required to be 4 - 7 1/2″ in height (depending on the building codes and at least 10″ in depth. The variance in height and tread depth is also a critical element of stairways in most building codes. Finally, most stairways are required to have at least one handrail. A single handrail, or handrails on each side, or no handrails for that matter, is a function of the intended use of the stairway. For example, many short height, private stairways are not required to have handrails. It’s best to review the local building codes for clarification. (Don’t forget to use the correct edition since building codes are revised ever so often.)
Single-step risers are simply a vertical change from a lower level to a higher level (and conversely higher to lower), the result of a single step up (or down). The problem with single-step risers is that they are smaller elements than multiple step staiways and are often not seen because of their relatively short duration, the lack of magnitude in height transition, or the lack of contrast from one level to another. Also, single-step risers often are not required to have handrails as do stairways and ramps. Handrails provide an added visual element to a change in level and serve to warn pedestrians of a transition in the walkway.
Single-step risers are now included within the definition of stairway.
Ramps are used more and more, likely the result of the 1990 passage of the Americans with Disabilities Act (ADA). This federally mandated Act essentially extended civil rights protection to disabled persons. Ramps then are required (by the Federally mandated ADA and most building codes) as a means of changing from one level to a higher (or lower) level without the use of stairways. Of course, this has limitations (height, width, purpose, etc.); however, the general idea is to provide a safe means of travel for all pedestrians regardless of mobility status.
Ramps are required by the ADA and most local builiding codes to have a slope no steeper that 1 : 12 (read, “one to twelve”). This simple means that for every unit in height (say, each inch), the slope must extend at least 12 siimilar units horizontally. (A 10″ high change in level would require a ramp at least 10′ in length-10″ X 12 = 120″ or 10′.)
Ramps are generally required to have handrails on at least one side (most often on both sides) and dependant on the exit requirements, a center handrail may also be required. Handrails are useless unless they are installed at the proper height (often at 30″ - 34″) and of the configuration usable by a “grasping hand” (normally this is understood to be about 1 1/2″ in diameter or similar shape).
Safety is everone’s concern. No one likes to be injured as a result of a fall, and no one appreciates being held responsible for someone’s injuries. My best advice is to inquire of a qualified expert engineer or architect if there is any question regarding walkway safety .
Topics: ADA, Building Codes, Construction Defects, Falls, Safety |