Anthropometry of Wheeled Mobility Project: Final Report

Executive Summary

Anthropometry is the study of human body characteristics and abilities. Wheeled mobility devices (WhMDs) that are used by people with disabilities include manual wheelchairs, power chairs and scooters. Standards for accessible design include many requirements based on the anthropometry of WhMD users. Key requirements apply to clear floor area, knee and toe clearances, maneuvering clearances, reach limits, grip force requirements and door usability factors. Reference information is also often included on the characteristics of mobility devices like illustrations and dimensions of unoccupied or occupied wheelchairs. This reference information often forms the basis of requirements like clear floor area. Thus, they are as important as the requirements themselves.

The anthropometric data on WhMD users that underlies the technical requirements of the ICC/ANSI A117.1 (1998) Accessible and Usable Buildings and Facilities (ICC/ANSI) were generated from research completed from 1974 −1978 using a research sample that included about 60 individuals who used wheelchairs (see Steinfeld et al., 1979). In 1982, the U.S. Access Board developed the first Federal guidelines for facility accessibility in the U.S. Under the Americans with Disabilities Act of 1990 (ADA), the Board continued this work, publishing the ADA Accessibility Guidelines (ADAAG) in 1991 which were updated in 2004 by the ADA and ABA Accessibility Guidelines for Buildings and Facilities (ADA-ABA Standards). The latter was adopted in place of the ADAAG by the Department of Justice in 2010. Provisions for WhMDs in both guidelines were largely derived from the research conducted in the 1970’s (Steinfeld et al., 1979). Research in other countries, comments from the public, and demographic, social and technological trends indicate that there is a need for new current information on the anthropometry of WhMD users to bring standards up to date. Recognizing this need, the National Institute on Disability and Rehabilitation Research initiated a research study through the Rehabilitation Engineering Research Center on Universal Design at the IDeA Center, University at Buffalo, SUNY, to obtain the needed information in 2000. The initial research activities developed new anthropometric measurement methods and collected data on over 200 WhMD users. In 2006, the U.S. Access Board funded this project to expand the database and develop it further.

This report documents the research conducted at the IDeA Center from the initiation of the project in 2000, including analysis of data on a sample of almost 500 individuals who use WhMDs. Our findings are compared to those in three other countries and to the current standards in all four countries. Many differences exist in both the standards and research studies. Although details of the research results differ from study to study, trends in the data support the need to make many important revisions to the U.S. standards. This report provides a description of the research, an analysis of the results and a discussion of the implications.

The research included the collection of demographic information and WhMD characteristics, and the measurement of structural and functional anthropometry. The demographic and WhMD characteristics were recorded for approximately 30 variables using a checklist, along with digital still photographs of each WhMD user. The structural anthropometric measurements required the measurement of the body and devices size at rest. The methods incorporated the use of a 3-dimensional (3-D) digitizing arm that allowed us to capture the location of body and device landmarks in three dimensions. This technology provided data that we used to develop static 3-D human models. Conventional structural and functional measurements can be also be derived from the 3-D information. The functional anthropometric measurements required measuring reaching ability, grip strength and the minimum space needed for turning. Reaching performance was measured in 3-D with the digitizing arm; grip strength was measured with conventional hand dynamometers; and maneuvering was measured through systematic measured observations of performance and video analysis. We also measured performance during door use tasks via the use of observational rating scales.

We selected measurement variables and procedures for measurements that were based on advice provided by experts in anthropometry and ergonomics, human modelers, architects and designers, and clinicians. Preliminary studies were completed at the University at Buffalo, SUNY to assess and demonstrate the accuracy and reliability of the measurement method. Focus groups with WhMD users were also conducted to ensure that the protocols for the research, which involved intimate contact with the body, were acceptable to the participants. Institutional Review Board approval for the research activities, including recruitment methods and confidentiality, was obtained at three universities.

Software was developed to facilitate expansion of the database and data collection at multiple sites. This software included quality assurance routines to identify errors in datasets and routines to merge other data sets into the database. Most of the research participants came from the Buffalo metropolitan area. But, two other research sites were contracted to provide data during Anthropometry of Wheeled Mobility the research activities to increase the diversity of the overall sample, test the software and test the feasibility of sharing methods. The expansion of the database was quite successful. Thus the database can be augmented over time with new data collection activities.

Data were collected for a total of 495 WhMD users to ensure a diverse sample of WhMD users: Buffalo and its suburbs (n=351), Pittsburgh (n=100) and Ithaca (n=44). The quality assurance software was used to check the quality of the 3-D data collected at each of the sites. All of the acceptable demographic, WhMD and anthropometric information was compiled in a database.

Prototype software was developed to allow designers and standards developers to access the data using a graphical interface. For example, a user can set parameters for width of occupied device and identify the extent of participants accommodated. Menus also provide the ability to display frequency distributions and percentile data for each variable and to access case data. Menu driven settings enable the user to select different groups for analysis, e.g. males or females, to compare the results.

Although the interactive database provides a significant resource for researchers and standards developers, our dissemination activities and other research demonstrated that this tool is unlikely to be utilized by most designers, particularly architects, interior designers and landscape architects. Thus, we also developed information tools in the form of graphic representations of the results that are more consistent with reference materials these professionals utilize in practice. These tools are available on the IDeA Center’s website under design resources (http://udeworld.com/dissemination/design-resources.html). An online educational module has also been completed to explain the research and introduce these design tools to professionals.

This report includes results of analyses of data on the basic aspects of wheeled mobility anthropometry. The topics covered include: selected dimensions of unoccupied and occupied devices, knee and toe clearance, reaching abilities, gripping strength and turning spaces. We also completed a study on the usability of several doors for a sub-sample of our participants. This study provides information on the effectiveness of current standards in meeting the needs of WhMD users.

Dissemination activities included the publication of 8 refereed journal articles, 24 refereed conference papers and one encyclopedia article. Standards development activities have been Anthropometry of Wheeled Mobility initiated with four standards development organization in the U.S., Canada and Ireland. An online self-instructional course on the research has been completed and is now available for the public. A textbook on universal design, under contract with a major commercial publisher, is under development and will include a section describing the research and its implications.

The key findings of the research are:

1. Sample composition: There are important differences in the sample based on recruitment methods. This emphasizes the importance of multi-site studies for this population.

2. Diversity: There are often large differences in the body and chair sizes and in the functional abilities of manual chair, power chair and scooter users, and men and women.

3. Measurement parameters: There are no generally accepted and shared definitions of variables for both anthropometric research and standards development, which impedes integration of research and practice.

4. International comparison: Different countries use different approaches to developing standards based on anthropometry. None of the standards reviewed had a comprehensive and explicit approach to evidence based practice.

5. Landmarks: Some dimensions in standards do not correspond to clear measurement landmarks on the body and device, creating barriers in translating research findings to standards development.

6. Reference WhMD: The U.S. standard reference wheelchair does not represent the sizes of unoccupied wheelchairs in our sample well. Contemporary wheeled mobility devices are much more diverse in size and features than the reference wheelchair.

7. Clear floor space: A large minority of participants in our research would not be accommodated by the current U.S. standard for clear floor space, especially for length. The people excluded include those who use any of the three types of WhMD. Other countries have already increased the clear floor space used in their standards.

8. Seat height: Seats for a majority of our sample have seat heights above that shown in the reference wheelchair in the U.S. standard, especially the power chairs and scooters.

9. Knee and toe clearances: The current U.S. standards for knee and toe clearances do not accommodate a majority of participants in our sample.

10.Maneuvering clearances: A significant proportion of WhMD users, scooter users in particular, are not accommodated by current maneuvering clearances in U.S. standards, although the proportion differs for different clearances. In particular, the current standards do not accommodate most of our sample for completing a 360-degree turn. There are also a small number of participants in all categories who require much larger clearances than current standards provide.

11. Reaching ability: A significant percentage of WhMD users have very limited functional reaching abilities.

12. Reach limits: A majority of WhMD users cannot complete a forward reach to the minimum forward reach height in U.S. standards on a vertical plane in front of their anterior most point (toes or device). The current high side reach limit accommodates WhMD users. The low reach limit, as defined, is currently inappropriate for safety reasons.

13.Operating forces: The maximum operating force in the current standards is too high for the majority of WhMD users.

14. Door usability: The usability study confirmed many of the existing clearance requirements for doors but also identified the need for improving some others, especially the door clearance width. Findings support the increased use of automated doors and the development of improved closer technologies.

The research findings highlight the importance of integrating research with standards development, organizing research collaborations and the need to develop standardized research methods. Now that a foundation of tools and procedures has been developed and extensively tested for systematic scientific research in this field, the cost of implementing future research using these methods is significantly reduced.

There is still much knowledge to be gained from further analysis of the data collected. We intend to continue to analyze and publish the results of this work. We will continue to reach out to human modeling software companies to augment their databases of ambulant people with our database of WhMD users. The research team anticipates the development of future research collaborations, dissemination activities and standards development initiatives to advance the work that has already been completed.