Anthropometry of Wheeled Mobility Project: Final Report

4.2 Applications of Findings in Design and Standards Development

It is unrealistic to assume that standards and designs should accommodate every single individual in the world. A decision always has to be made to draw the line somewhere because there are diminishing returns in terms of benefits and increased costs associated with expanding the target population for design. Even dimensions that accommodate our entire sample might not accommodate someone who is larger or smaller than the people we measured.

The recommendations in this section, in most cases, are based on accommodating all but 5% of the WhMD sample we studied. We believe that this is a reasonable target and a cost effective approach because it will benefit everyone in most cases, even people without disabilities. Also, the changes required are often minimal and the cost is usually only a small percentage of total building costs, if any. It generally means increasing dimensions in existing standards by 2‒6 inches. However, there are some cases in which the implications are much broader, for example, length of clear floor area, knee and toe space clearances, 360-degree turning space, and front reach limits. In these cases, we believe that the existing knowledge base at the time that the standards were developed led to guidelines conceived in a way that is not appropriate for the current era. At the time, standards developers had limited data on a limited population. Since that time, the problem has been compounded by significant changes in the population and mobility technologies. Thus, rather than making revisions to design criteria that are based on ideas that are completely obsolete, in our recommendations we sought to identify innovative solutions to provide increased accessibility without a major cost impact. In other cases, we deferred making recommendations for further study, and when possible we have proposed several options that could be considered.

The decision to adopt these recommendations is really up to others. Policy makers and standards developers could decide that some of our recommendations are not cost effective. In other words, for the cost required, they would benefit a relatively small group of people. But, it is important that those involved in such decisions be fully informed about the impact of their decisions. To help stakeholders understand the implications of the findings and of the decisions they might make based on our work, we have prepared charts that demonstrate the degree to which our sample is accommodated by any particular dimension listed in the current accessibility standards. These “accommodation models” provide easy to use tools for standards developers and design professionals; in particular, they help to understand the degree to which their decisions will exclude use by some part of the WhMD user population.

We developed separate accommodation models for the three types of WhMDs covered in our study so that stakeholders can understand the differences and similarities across device types. In our research, we oversampled power wheelchair users in order to better characterize their sizes and functional abilities and to more accurately identify differences in performance between that group and the others. Manual wheelchair users represent a much larger proportion of the entire population of WhMD users than either power chair users or scooter users. Thus, accommodating a larger proportion of the latter two groups has less of an impact overall than accommodating a larger proportion of manual chair users. The full set of charts is found in Appendix 3. In addition to these accommodation models, we have also developed an interactive software application that allows stakeholders to access the entire dataset in a variety of useful ways. This tool could be very useful to standards developers and designers with the assistance of our research team. It is described in the next section (5.0) in more detail.

The design and standards implications of our findings are presented below. By organizing all the implications in one place, readers who are not interested in the research details can obtain a comprehensive understanding of the results.