Standards and Anthropometry for Wheeled Mobility

2.0 Methodology

We reviewed ICC/ANSI A117.1 (1998) Accessible and Usable Buildings and Facilities, which serves as the model for the technical requirements in the federal guidelines in the U.S., the Americans with Disabilities Act Accessibility Guidelines (ADAAG) and its eventual replacement, the Americans with Disabilities Act – Architectural Barriers Act Guidelines (ADA-ABA). For the United Kingdom (U.K.), we reviewed BS 8300:2001 Design of Buildings and Their Approaches to Meet the Needs of Disabled People – Code of Practice. For Canada (CA), we reviewed B651-04 Accessible Design for the Built Environment. For Australia (AUS), we reviewed AS 1428.2 – 1992 Design for Access and Mobility Part 2: Enhanced and Additional Requirements – Buildings and Facilities.

Since the findings of anthropometric research are often voluminous, journal articles and book chapters do not usually include a full documentation. Thus, we obtained the original research reports from Ringaert, et al. (2001) from Canada, Stait et al. (2000) from the United Kingdom, Bails (1983) and Seeger et al., (1994) from Australia. The research underlying BS8300:2001 in the U.K. was summarized in an Annex to the standard itself but we were unable to obtain a more comprehensive report that described the details of the methodology.

We first compared the relevant criteria in all the U.S. standards to identify the common underlying anthropometric variables. Our analysis then focused only on these variables. The common variables were defined graphically in illustrations and with abbreviations, e.g. Knee Clearance Height (KCH), Knee Clearance Depth – Upper (KCDU), Knee Clearance Depth – Lower (KCDL) and Extended Depth (ED). In many cases, variables underlying the U.S. standards are not included in other standards. Thus, in our comparisons, we simply omitted values for those variables. We did not, however, report variables from other standards that are not included in the U.S. standards.

The standards did not use the same variables (or parameters), terminology or measurement conventions. For example, the U.S. standards include both Imperial and “soft” conversions to Metric units, but all the other standards are in Metric units only; there are at least three different terms used for a “wheelchair turning space,” and the U.K. standards report reach ranges for both a “maximum” and “minimum” reach while the U.S. standards have only one range delimited by a minimum and a maximum value. These differences present several problems to researchers. For example, the definition of a “wheelchair turning space” determines the protocol used to study the clearance needed. Different results are obtained if that space is bounded or unbounded or whether the protocol calls for a smooth continuous turn or includes a series of smaller movements or allows either. Since the standards do not define variables clearly, researchers have made their own interpretations and developed different protocols to study the same variables. Thus, to make comparisons, we standardized all the values from standards and research as much as possible based on a common definition of variables and measurement conventions. We reported the U.S. values in both Imperial and Metric units but did not convert the other countries’ values to Imperial nor did we do “hard” conversions of the U.S. Imperial values.

We then reviewed the research completed in each country since 1980; the year after the research of Steinfeld et al. (1979) was published. In many cases, this required some interpretation because the research studies did not always use the same terms or definitions as the standards in the respective country. Different approaches were also used to report findings. Some results were reported in percentiles. Other results were reported as minimum or maximum values. Still others were reported as the “percentage of subjects accommodated” – those who could perform a task at a certain criterion level. We devised a graphic method to compare the results of the research studies to each other and to the standards. Most of the studies reported at least a minimum or maximum value and a mean value for each variable studied. These three points were displayed on a graph and coded by study. Where available, percentile data was added to the graph in between the minimum and maximum values and the mean to provide more detail. All the values for each study that represented a distribution were connected by line segments.

Some studies focused on a very limited set of variables. Because of the methodology used in the IDEA Center anthropometry research, however, we were able to compute results for all the variables and all relevant statistics. Thus our results appear in all the analyses and can be compared to all the standards.