Wheeled Mobility space requirements and maneuvering: An International Comparison of Standards and Research

Edward Steinfeld, Arch. D., Jordana L. Maisel, M.U.P., David Feathers, Ph.D.

Center for Inclusive Design and Environmental Analysis
School of Architecture and Planning
State University of New York at Buffalo
Buffalo, New York, United States

ABSTRACT

Advances in wheeled mobility technology and demographic changes suggest that the standards for accessible design include requirements based on the anthropometry of wheeled mobility users may be out of date. Recent research in four countries was reviewed and compared with their accessibility standards to identify needs for improving standards. The analysis highlighted the importance of integrating research with standards development, organizing international collaborations and developing international standards.

Keywords:

anthropometry; maneuvering; wheeled mobility; standards development

BACKGROUND

The standards used to ensure accessibility for people who use wheeled mobility devices like wheelchairs and scooters are based on research in anthropometry, the measurement of body sizes and physical abilities. The anthropometric data on wheeled mobility users that underlies the technical requirements of the ICC/ANSI A117.1 (1998) Accessible and Usable Buildings and Facilities (ICC/ANSI) and the ADA Accessibility Guidelines (ADAAG) were generated from research completed from 1974 -1978 (see Steinfeld, et al., 1979).

In 25 years, many changes have occurred in the body sizes of the U.S. population, the demographics of people who use wheeled mobility devices and the characteristics of equipment that they use. Yet, the standards related to the accessibility of built environments for wheeled mobility users have not changed. Only recently, newer anthropometric data sets on wheeled mobility users in the U.S. has been available (e.g. Steinfeld, et al., 2004; Feathers, et al., 2004; Paquet and Feathers, 2004).

Comparisons of international standards and research are useful to validate methods and to identify best practices and differences related to cultural factors. Presented here is an outline of comparative analysis for research and standards on wheeled mobility in the U.S., the U.K., Australia and Canada. The analysis investigated wheeled mobility device dimensions, minimum clear floor areas, space requirements for maneuvering, knee and toe clearances and reach limits. This paper only highlights the space requirements for maneuvering. A full report is available.

METHODOLOGY

A review of ICC/ANSI A117.1 (1998) was performed. This standard was reviewed because it 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 the Americans with Disabilities Act - Architectural Barriers Act Guidelines (ADA-ABA). Internationally, a review focused on the United Kingdom BS 8300:2001, the Canadian B651-04, and the Australian AS 1428.2 - 1992. 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. We then compared the relevant criteria in all the U.S. standards to identify the common underlying anthropometric variables.

RESULTS

There were many differences in the research studies, including the documentation provided, samples recruited, methods used and data reporting formats. Table 1 provides a summary of the main differences.

Figure 1. (Click image for larger view)

Research and standards are outlined and presented below. Figures 1 and 2 and Tables 2 and 3 show the standards from the four countries related to maneuvering clearances from a wheeled mobility device.

Figures 3 and 4 show key findings from the research. The clearance required for all participants to complete a 90 degree turn by the IDEA sample was much smaller than the UDI findings. An increase in the clear width criterion of 100 mm (4 in.) would be needed to accommodate the entire IDEA sample. However, to accommodate the entire UDI sample, an increase of 300 mm (12 in.) would be needed. The UDI findings at the high end of the range probably reflect the impact of a few participants or devices with very poor turning ability.

Figure 3. (Click image for larger view)

The IDEA protocol included only a 360 degree turn but the UDI study also included a 180 degree turn. The BS8300 reports only the latter but doesn't define it. The IDEA and BS8300 results demonstrated that turning area clearances would have to be increased to 2400 mm (94.5 in.) compared to the current 1500-1525 mm (60 in.) to accommodate their entire samples. To accommodate the UDI sample for a 180 degree turn, the required turning space would only have to be increased to 1925 mm (75.8 in.). However, in the UDI research protocol, the ends of the turn were open, allowing the participants to lengthen out their turn and reduce its width. In comparison, the UDI participants utilized a much larger space for the 360 degree turn, in which no sides were blocked. A space about 4200 mm (165 in.) would be needed to accommodate the entire sample. In the IDEA sample, scooters require more space but the largest values for scooters, power chairs and manual chairs were very close whereas in the UDI sample, at least one power wheelchair user required a much larger clearance for the 360 degree turn. The results support increasing the clearances for 90 degree turns and "wheelchair turning space."

The divergent UDI findings may be related to the lack of an enclosure in the 360 degree turn, errors in correcting for parallax when measuring from video cameras mounted above, or inability to obtain accurate measurements of body parts and devices in motion. On the other hand, the consistency between the BS3800 and the IDEA results may indicate that there is little difference between the clearance needed for 180 and 360 degree turns. But, without information on the BS3800 protocols, this is only a hypothesis.

DISCUSSION

There are several discrepancies across research studies and standards. This was expected as different research methods, interpretations and data treatment were independently performed. Unfortunately, many research methods have not been fully explained to aid in the possible endeavor of replicating these studies.

Across standards, many variables were not shared, nor 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. Since the standards do not define variables clearly, researchers have used 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.

CONCLUSIONS

The research demonstrated that there is a need to revise the standards for wheeled mobility access to reflect the body structure and functional abilities of this population and the devices they use today. Yet, consistency of trends across the various samples is quite good, given the wide variety of methods used.

There is a clear need to develop an international consensus on standards and research methods. Our findings suggest that, at least in the countries included in this study, standards are diverging. There appears to be several reasons for this divergence: 1) differences in the research that supports standards development, 2) differences in how the elements of access are defined, both the terminology used and also in the definitions (or lack thereof) of key variables, 3) use of Imperial units in the U.S. that are not always compatible with typical metric dimensions used in the construction industry. Underlying these reasons is the lack of communication between the researchers and standards developers at the international level.

While standardization may improve the utilization of research findings, it is important to recognize the need for differences in accessibility standards from country to country. There are many good reasons for variation, including cultural differences in stature, differences in economic development and differences in cultural expectations for independence among the population. Yet, there is no reason why the benefits of international standardization can be achieved while still respecting cultural differences. The research conducted here demonstrates several possibilities: standardize the terms and definitions for the variables of accessibility, establish consensus on how to define accessibility in terms of human performance, define a minimum level of accessibility that is accepted at an international level. Any country could exceed the minimum thresholds.

Another important conclusion from this research is very obvious. Research methods have to be improved and documented more thoroughly. There is not enough information in many of the research reports we obtained to judge the quality of the methods used. The reliability of methods needs to be documented. New methods should be compared for validity with older methods. Sample recruitment should be well documented and designed to reduce bias or achieve specific objectives. In general, sample sizes needed to be increased for reliable estimates of the distribution of body size and function that are used to inform the standards.

Finally, there is a need to internationalize this type of research. Standardizing methodologies at an international level and providing funding from international agencies to measure people in countries that cannot afford to do it themselves are two critical needs. Currently, there is very little research on this subject and it is all being completed in developed societies. The aging of the populations worldwide will also increase the need to support independence for the older part of the population. In less developed countries, international agencies are completing massive projects to improve education, health, transportation and housing. It is important that standards from the western world are not blindly applied in these societies without determining whether they are appropriate.

Disclaimer

This paper reports research findings that were supported with funding from the U.S. Access Board (contract # TPD-02-C-0033). The contents of the report do not necessarily represent the policy of the U.S. Access Board and readers should not assume any endorsement by the Federal government.

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