Final Report

Anthropometry of Wheeled Mobility Project

 

Prepared for the U.S. Access Board

December 31st, 2010

Center for Inclusive Design and Environmental Access (IDeA)

School of Architecture and Planning

University at Buffalo

The State University of New York

Buffalo, NY 14214-308
Credits 

Authors

Edward Steinfeld, Arch.D. Co-Project Director

Victor Paquet, Sc.D. Co-Project Director

Clive D’Souza, M.S. Research Assistant

Caroline Joseph, M.Sc.A. Research Assistant

Jordana Maisel, M.U.P. Research Associate

Graphics

Jonathan White, M.Arch. Research Intern Architect 

Heamchand Subryan, M.A., M.Arch., Research Design Associate

Funding for this project was provided by:

U.S. Access Board

National Institute for Disability and Rehabilitation Research, U.S. Department of Education

Acknowledgement 

The authors would like to thank the following people for their foresight in perceiving the 

value of this work:

William Peterson, RERC Project Manager at NIDDR who perceived the need for the 

project and insured that it was part of the RERC on Universal Design’s mission.

Katherine Seelman, Director of NIDRR during the time the project was conceived.

Lois Thibault, Research Director of the U.S. Access Board who saw the value of continuing

the work.

Lawrence Roffee and David Cappozi, Executive Directors of the Access Board during the 

project period.

Marsha Mazz, Director, Office of Technical and Information Services, who managed the 

project for the U.S. Access Board when Lois Thibault retired.

Disclaimer

This report was developed with funding from the U.S. Access Board (contract # TPD-ABA-07-C001). The research was initially funded by the National Institute on Disability and Rehabilitation 

Research (NIDRR), U.S. Dept. of Education (grant #H133E99005). The contents of the report do not 

necessarily represent the policy of the U.S. Access Board or NIDRR, and readers should not 

assume any endorsement by the Federal government.
Contact Information

For further information, contact:

Edward Steinfeld, Director

Center for Inclusive Design and Environmental Access (IDeA Center)

School of Architecture and Planning

University at Buffalo

3435 Main Street, 378 Hayes Hall

Buffalo, NY 14214-3087

716.829.5899 (phone)

arced@buffalo.edu (email)

This document is available free of charge from the IDeA Center website at: 

http://www.udeworld.com/anthropometrics

 Copyright, Center for Inclusive Design and Environmental Access, 2010

Unlimited use of this document for educational and research purposes are permitted without 

written permission but altering the contents and distribution for sale is not allowed without prior 

written permission from the IDeA Center. 
Table of Contents

Executive Summary ................................................................................................................1

1.0 Background ......................................................................................................................7

2.0 Methodology ................................................................................................................ 13

3.0 Study Findings............................................................................................................... 36

4.0 Implications for Standards and Design .................................................................... 81

5.0 Dissemination Activities..............................................................................................114

6.0 Conclusions .................................................................................................................. 127

List of References .............................................................................................................. 133

Design Information and Accommodation Models.........................................................133

Bibliography ...................................................................................................................... 159
Anthropometry of Wheeled Mobility | 1

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 
Anthropometry of Wheeled Mobility | 2

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 | 3

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 | 4

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.
Anthropometry of Wheeled Mobility | 5

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. 
Anthropometry of Wheeled Mobility | 6
Anthropometry of Wheeled Mobility | 7

1.0 Background

Relevance

The standards used to ensure accessibility for people who use wheeled mobility devices (WhMDs)

like wheelchairs and scooters are based on research in anthropometry, the measurement of body 

sizes and physical abilities. 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 WhMD

users in both guidelines were largely derived from the research conducted in the 1970’s 

(Steinfeld et al., 1979). Comments from people who use powered mobility devices indicate that 

increases in space and maneuvering requirements and decreases in reach ranges are needed in 

the Board’s guidelines to accommodate the use of such devices, which are generally larger, 

heavier, and less finely maneuverable than manual wheelchairs. Since the 1970’s, research on the 

anthropometry of WhMD users has been conducted in Australia, the United Kingdom (U.K.) and 

Canada. All of those countries have revised or are revising their standards based on that 

research. 

In 30 years, many changes have occurred in nature of the U.S. population, the characteristics of 

people who use WhMDs and the characteristics of equipment that they use. Many more power 

chairs are in use now than in the 1970’s. Significant advances in wheeled mobility technology, 

health care, public health and demography have occurred that impact the body sizes and 

functional abilities of those who use wheeled devices for mobility. For example, power 

wheelchairs and scooters are often larger in size than manual chairs. In addition, improved health 

care technology has allowed people with more serious disabilities to survive longer than in earlier 

decades. These individuals may have conditions that affect their abilities to maneuver devices in 

small spaces or reach objects. A significantly broader range of devices is now available, from 

highly-adjustable battery-powered wheelchairs to 3- and 4-wheeled scooters with front tillers. 
Anthropometry of Wheeled Mobility | 8

Scooters also are growing in popularity. Yet, the technical requirements in U.S. standards have not 

changed. It is likely that the current U.S. standards do not reflect the actual dimensions and 

abilities of contemporary WhMD users. 

Very few studies of the anthropometry of WhMD users were conducted in the 1980s and 1990s, 

especially in the U.S. In response to this lack of current information, the IDeA Center, with funding 

from the National Institute on Disability and Rehabilitation Research, developed a new set of 

anthropometric measurement methods and a comprehensive anthropometric data set of over 200 

WhMD users was created (Feathers et al., 2002, 2004; Paquet and Feathers, 2004; Steinfeld et 

al., 2005). Rigorous scientific procedures were used in the development of the research methods 

and new software was created to organize and analyze the results. While much was 

accomplished in that study, there were important research needs that were unmet. First, a larger 

sample was needed to provide a more accurate characterization of the anthropometry of WhMD

users. Second, a more diverse sample in terms of ages and WhMD technologies was needed to 

help improve the representativeness of the sample. Third, new dissemination products were 

needed to help ensure that the research findings could be translated to design practice and 

standards development.

Additionally, comparisons of international standards and research were needed to assess the 

adequacy of the current U.S. accessibility standards and help set priorities for improving 

regulations. Comparisons are also useful to identify best practices and differences related to 

cultural factors. Thus, in addition to collecting anthropometric data, we also completed a 

comparative analysis of research and standards on wheeled mobility in the U.S., the U.K., 

Australia and Canada. The analysis was limited to WhMD dimensions, minimum clear floor areas, 

space requirements for maneuvering, knee and toe clearances, and reach limits. 

Objectives 

The objectives of this study, supported by the U.S. Access Board were to:

1. Collect data on an extended sample with a target of a total of 500 individuals.

2. Collect and compare anthropometric research studies on wheeled mobility in Canada, the 

U.K. and Australia, with the U.S. standards and the research results from the current study.
Anthropometry of Wheeled Mobility | 9

3. Develop dissemination products including a final research report, tools for using the 

database and an online educational module.

The scope of the research analysis was limited to key anthropometric issues in accessibility 

standards:

• Unoccupied device width and length

• Clear floor space, or occupied footprint

• Seat height*

• Knee and toe clearances:

o Knee height and depth

o Toe height and depth

• Maneuvering clearances on level surfaces:

o 90-degree turn

o 180-degree turn 

o 180-degree turn around a barrier*

o 360-degree turn

• Reach ranges:

o Forward reach

o Side reach

o Side reach over an obstruction

• Grip Forces*

• Door use 

Note, scope items with asterisks were added by IDeA Center.

Report Organization

This report documents the basic findings of the research and compares them to the national 

standards from the three countries and the U.S. It also compares the research findings to the 

research underlying the standards of these three other countries. Section 2.0 describes the 

methods we used to collect the data and make the comparisons. Section 3.0 describes the 

research results. Section 4.0 discusses the implications of these findings for design and standards 

development. Section 5.0 describes related dissemination and knowledge translation activities, 

and Section 6.0 provides some general conclusions, including recommendations for future research 
Anthropometry of Wheeled Mobility | 10

and knowledge translation activities. The Appendix includes a list of publications on the project 

and a set of information tools for designers and standards makers. 

Units

The scientific practice of anthropometry is conducted using Metric units. However, in the U.S., 

accessibility standards are developed in Imperial units. Thus, in this report, we have used Metric 

units as the primary form for all dimensions. Some tables only have Metric units for space reasons. 

We included Imperial equivalents in parentheses in the text to assist the reader who is familiar 

with the dimensions in the standards. The ADA-ABA and other U.S. standards use a “soft’ 

conversion method in which Metric equivalents are rounded off to the nearest 5 mm except for 

very small values. Thus, in this report, where we refer to values in the ADA-ABA, we use the soft 

conversion to avoid confusion with the original source. Elsewhere, including our recommendations 

for revising the ADA-ABA, we use a “hard” conversion, rounded off to the nearest 1 mm. One 

exception to the Metric units as primary is in Section 3.0 on grip forces, and these dimensions are 

reported in pounds-force (lbf) as they were collected. 

Text Descriptions

To facilitate comprehension of the report by people who use screen readers, we have included 

descriptive captions for all figures and tables, alt tags in digital versions and long text 

descriptions for figures. In Section 3.0, there are graphs of results but, each graph is simply a 

graphic summary of the data in the accompanying table that appears below it. The tables are 

readable by screen readers. Thus, there is no need for a further text description of the summary 

figure since the data is fully accessible to all readers. 
Anthropometry of Wheeled Mobility | 11
Anthropometry of Wheeled Mobility | 12
Anthropometry of Wheeled Mobility | 13

2.0 Methodology 

2.1 Participant Recruitment and Sampling

A sample of 495 WhMD users was recruited for the study. These included sub-samples of manual 

wheelchair users, conventional powered wheelchair users and scooter users. We intentionally 

oversampled powered wheelchair users in order to capture the sizes and space requirements of 

this group. 

It would be useful to know how our sample compares to national estimates of the WhMD

population. The most recent published estimates on the type of device are provided by LaPlante 

and Kaye (2010), and Cooper and Cooper (2003). LaPlante and Kaye (2010) used data from 

the 1994-95 National Health Interview Survey on Disability (NHIS-D). More recent data 

available on the utilization of WhMD’s (e.g. the 2010 U.S. Census Bureau’s Survey of Income and 

Program Participation) do not distinguish between the types of electric WhMDs. Based on 

estimates by LaPlante and Kaye (2010), powered wheelchair users and scooter users each 

comprise about 9% of the WhMD user population not residing in institutions. A representative 

sample of 495 WhMD users would therefore include only 45 powered wheelchair and 45 scooter 

users.

In a review on wheeled mobility demographics, Flagg (2009) cites estimates by Cooper and 

Cooper (2003) on the proportion of mobility devices in the three categories. They estimated 

powered wheelchairs and scooters each to be about 15% of the WhMDs in use. The estimates by 

Cooper and Cooper (2003) were based on their own research and experience in the field, and

include wheelchairs used in institutional settings like long term care facilities, rehabilitation 

hospitals and assisted living facilities. In our research, we recruited from assisted living facilities 

and day care programs for frail older adults but only people who could propel a chair 

independently were eligible to participate.

Based on this larger estimate, a sample of 495 WhMD users representative of the U.S. in terms 

types of WhMD used would include only about 74 power wheelchair and 74 scooter users. Even 

this larger estimate would not allow an accurate characterization of the sizes and functional 

abilities of these user groups in our study, which we expected to be quite diverse and different 

than manual wheelchair users.
Anthropometry of Wheeled Mobility | 14

Our approach allowed us to accurately describe the range of body sizes and functional abilities 

of conventional powered wheelchair users and manual wheelchair users. A sub-sample of scooter 

users was recruited to provide us with preliminary anthropometric data for this group but we 

were not able, despite great efforts, to recruit a large number of scooter users. It should be noted 

that it is possible to manipulate our current sample with the use of statistical simulation methods to 

develop samples that representative in terms of device type, age, and gender (Paquet et al., in 

preparation). 

Data were collected in three different locations to help ensure a diverse sample of WhMD users: 

Buffalo and its suburbs (n=351), Pittsburgh (n=100) and Ithaca (n=44). Researchers at each of 

these sites were trained in the data collection methods and used the same measurement 

equipment to ensure consistency in measurement methods across sites. 

2.2 Key Measurement Variables and Procedures

We selected measurement variables and procedures for measurements based on advice 

provided by experts in anthropometry and ergonomics, human modelers, architects and designers, 

and clinicians. 

The measurement variables include the following:

1. Demographic information and wheelchair description: Approximately 30 

variables recorded with a checklist, along with digital still photographs of the user 

and mobility device.

2. Body and wheelchair dimensions: Approximately 125 locations of body and 

wheelchair points recorded in three dimensions.

3. Reaches and lifts: One-handed maximum reaches recorded at 5 different heights 

in three different directions for up to four different weight conditions (maximum of 

60 reaches total).

4. Maneuverability: Four tasks related to propulsion in confined spaces.

5. Grip Strength: Three repetitions of maximal power grasp recorded for two 

different upper extremity postures and three repetitions of maximal pinch grip for 

two types of finger posture (lateral and thumb-forefinger pinches) (12 

measurements total).

6. Door use: The level of observed effort was rated as participants used three 

different doors.
Anthropometry of Wheeled Mobility | 15

2.2.1 Demographic Information

A survey, checklist and photography were used to capture the demographic and wheelchair 

characteristics for each WhMD user. Demographic variables included: gender, age, disability 

status (category), years with the disability, and years using the mobility aid. Key variables 

associated with the mobility aid included device type (e.g., power chair, scooter), and within each 

type: make, model, age, armrests, footrests, drive wheels, controller, seat support surfaces and 

overall condition of the seating surface. A checklist was used to evaluate these device attributes 

(see Figure 2-1). Digital photographs of the user and device were taken from the front and side 

views to document the wheelchair accessories and configurations of WhMD user. 
Anthropometry of Wheeled Mobility | 16

Figure 2-1. Portions of the checklist used to evaluate wheelchair characteristics.
Anthropometry of Wheeled Mobility | 17

2.2.2 Structural Anthropometry (i.e. Body and WhMD Dimensions)

A three-dimensional (3-D) electromechanical probe (i.e. FaroArm, Faro Technologies Inc.) was 

used to record the 3-D location of body and WhMD device points (Figure 2-2). The 3-D points 

were used to estimate body and WhMD heights, widths and depths and to construct static 3-D 

digital human models of WhMD users.

Figure 2-2. Data collection with an electromechanical probe allows quick and accurate 

measurement of the widths, heights and depths of the body and mobility device 

characteristics.

The 3-D measurements required the measurement of reference points and planes, as well as the 

measurement of key body and WhMD points with respect to the environment. The IDeA Center 

has developed a detailed manual that defines each of the points in 3-dimensions, includes 

illustrations and explains applications for each of the points (Feathers et al., 2004). The reference 

points and planes, body points and WhMD points, and some of their application are listed in 

Tables 2-1 and 2-2. 
Anthropometry of Wheeled Mobility | 18

Table 2-1. Wheelchair and environment reference points and planes, and uses. 

Key Reference Point Use

Floor (defined by multiple reference points) Allows WhMD users to be oriented similarly in 3-D 

digital space.

Wheelchair mid-axle point (defined by the mid-point of 

the left and right wheel hubs)

Allows WhMD users to be oriented similarly in 3-D

digital space.

Seatback plane (defined by four corner points) Informs the 3-D digital model of WhMD and some 

seated body depth measures.

Seat support surface plane (defined by four corner points 

and one point at the interface of the occupant & seat 

surface i.e. compressed seat surface)

Informs the 3-D digital model of WhMD and some 

seated height body measures.

Left and right arm support surface planes (defined by four 

corner points each)

Informs the 3-D digital model of WhMD.

Foot support surface planes (defined by four corner points 

each)

Informs 3-D digital model of WhMD and some 

WhMD length measures.

Anterior most point (foot or foot support surface) Used to measure Occupied Length.

Posterior most point (head, arm, WhMD, or accessory) Used to measure Occupied Length.

Lateral most point, left (arm, leg, WhMD or accessory) Used to measure Occupied Width.

Lateral most point, right (arm, leg, WhMD or accessory Used to measure Occupied Width.
Anthropometry of Wheeled Mobility | 19

Table 2-2. Body points and important anthropometric dimensions associated with each point. 

No. Body Points* (Anatomical Area) Associated Anthropometric Dimensions

1 Vertex of Head Height: Sitting Height, Vertical Head Clearance

Breadth/Width: Head Lateral Location

Angles: Head Tilt (back or forward)

2 Occipital Protuberance 

(occiput)

3 Ectocanthus* Height: Eye Height

Angle: Head Tilt (with contra-lateral side)

4 Tragion* (tragus) Ref. Plane: Frankfurt Plane

5 Infraorbitale* Ref. Plane: Frankfurt Plane

6 Cervicale 

(spinous process of the 7th Cervical 

Vertebrae)

Height: Cervical Height

Joint Center of Rotation (JCR): Lower Neck JCR

7 Acromion* Heights: Height of Shoulder, Acromial Height, sitting

Length/Depth: Length of Clavicle (with sternal notch) 

JCR: Possible Shoulder JCR

8 Deltoid Point* Height: Height of Shoulder Clearances

Breadth/Width: Lateral Measure of Shoulder Clearances

Length/Depth: Shoulder Clearances in Relative Position to the 

Wheelchair, Deltoid Arc

9 Olecranon, Bottom* Breadth/Width: Elbow Clearances

Lengths/Depths: Length of Upper Arm Segment

10 Olecranon, Rear* Breadth/Width: Elbow Clearances

Lengths/Depths: Proximal point for Length of Forearm, Forearm 

position relative to the Wheelchair

11 Medial Humeral Epicondyle* 

(Epicondylus medialis)

Breadth/Width: Elbow Breadth

JCR: Elbow JCR

12 Lateral Humeral Epicondyle* 

(Epicondylus lateralis)

Breadth/Width: Elbow Breadth

JCR: Elbow JCR

14 Stylion* Length: Forearm and Hand Length Calculation

16 Dactylion III * Length: Hand Length Calculation

18 Metacarpophalangeal (MCP) joint,

II*

Breadth/Width: Hand Breadth Calculation

Length/Depth: Palm Length

20 MCP joint, V* Breadth/Width: Hand Breadth Calculation and Reach Measures

21 Sternal Notch 

(Suprasternale, Army, 1988)

Height: Seated Height (one type of measure)

Breadth/Width: Variance from H-Point (skew)

Length/Depth: Upper Chest Thickness from Seat Back, Anterior Neck 

Length

22 Abdominal Point, Anterior 

(omphalion)

Height: Waist height to the floor.

Length/Depth: Clearance Depth for tables, trays, etc.

23 Anterior Superior Iliac Spine* 

(Spina iliaca anterior superior)

Breadth/Width: ASIS Breadth

Angle: Pelvic Tilt
Anthropometry of Wheeled Mobility | 20

JCR: Hip JCR

24 Top of Thigh* Height: Maximum Thigh Height, Thigh Height from Floor

Table 2-2. Body points and important anthropometric dimensions associated with each 

point. (Cont’d)

25 Hip Point, Lateral* Height: Maximum Hip Height

Breadth: Hip Breadth

26 Thigh Point, Lateral* Breadth/Width: Maximum Distance for lateral leg clearance, Seat 

pan width

27 Knee Point Superior* 

(Apex patellae)

Height: Maximum Height of Lower Leg, Knee Clearance Height

28 Knee Point Anterior* Length/Depth: Knee Clearance Depth, Buttock-knee Length, 

Maximum Length of Upper Leg

29 Femoral Epicondyle, Lateral* 

(Epicondylus lateralis)

Breadth/Width: Femoral Breadth (Knee breadth), Knee-knee 

breadth calculation

JCR: Knee JCR

30 Femoral Epicondyle, Medial* 

(Epicondylus medialis)

Breadth/Width: Femoral Breadth (Knee breadth), Knee-knee 

breadth calculation

JCR: Knee JCR

31 Popliteus* Height: Popliteal Height

Breadth: Popliteal Breadth

Depth/Length: Maximum Seat Depth, Upper Leg Length Estimate

32 Malleolus, Lateral* 

(Malleolus lateralis)

Height: Lateral Malleolus Height

Breadth/Width: Lateral Distance between Ankles

Length/Depth: Fibular Length

JCR: Ankle JCR

33 Malleolus, Medial* 

(Malleolus medialis)

Height: Medial Malleolus Height

Breadth/Width: Minimum Distance between Ankles

Length/Depth: Tibial Length

JCR: Ankle JCR

34 Heel Back* Height: Floor to Foot Height

Breadth/Width: Distance between Heels

Length/Depth: Position of Foot in proximity to Wheelchair, Instep 

Length, Functional Leg Length

35 Medial edge of Foot* 

(Distal Termination of Longitudinal 

Arch)

Breadth/Width: Medial measure for Foot Breadth (ball-of foot 

breadth

36 Lateral edge of Foot* 

(5th Metatarsal protuberance)

Breadth/Width: Lateral-lost portion, foot clearance when 

navigating, Ball-of-foot breadth

37 Foot and leg crease* 

(Dorsal foot point)

Height: Foot Clearance Height

Depth: Foot Clearance Depth

38 Toe Tip* 

(Acropodions)

Height: Height of Toe Tip to Floor

Breadth/Width: Distance between Toe Tips

Length/Depth: Distal Measure of Toe-Tip to Wheelchair Reference 

Point.

* indicates points digitized on the left and right side of the body
Anthropometry of Wheeled Mobility | 21

2.2.3 Functional Reach

One-handed reach and lift capability data made at different heights, angles and object weights 

were collected in 3-D. Determining an individual’s 3-D reach envelope required that the reach 

envelope be measured relative to certain environmental, wheelchair and personal features (e.g. 

3-D envelopes measured relative to a point on the floor, forward most portion of a person or 

wheelchair and/or from a reference point on wheelchair’s arm support surfaces). Data can be 

presented in 3-D, in the form of 2-D charts along key planes (e.g. sagittal plane to represent 

forward reach abilities), or described for a standard reach (e.g. maximum forward reach from a 

reference point).

The one-handed lifting tasks required individuals to move weighted cylinders that were empty or 

weighted with filler. Cylinders of 75 mm (3 in.) diameter were chosen because they required 

participants to use one-handed power or lateral pinch grasps, which are commonly used to hold 

and manipulate products. The size of the cylinders was held constant across conditions and 

participants. The four weight conditions were no weight, 1 lb, 3 lb and 5 lb. 

Those individuals unable to grasp and/or lift any of the cylinders above shoulder height did not 

complete the reaches. Further, if a particular weighted canister could not be lifted above shoulder 

height then reaches involving that particular weight were avoided for reasons of participant 

safety.

Reaches and lifts were completed in 15 different directions (3 different angles of asymmetry 

from the orientation of the WhMD at 5 different heights). The angles of asymmetry included 0, 45 

and 90-degrees from the sagittal plane that passes through the acromion process on the 

individual’s dominant side (i.e. forward, asymmetric and side reaches, respectively). The five 

heights were normalized to the individual's vertical reach capabilities so that reaches were 

performed at, above and below shoulder height.

Three-dimensional reach data were collected with the electromechanical probe (FaroArm, Faro 

Technologies). Use of the electromechanical probe required manually digitizing the 3-D location 

of the maximum reach point after the cylinder was positioned (Figure 2-3). The point data were

used to measure reach distances from reference points (e.g. maximum forward reach from the 

front of the WhMD, or maximum side reach from the lateral-most point of the WhMD), and 
Anthropometry of Wheeled Mobility | 22

construct reach envelopes that illustrate the reaching capabilities of the sample in 2-D and 3-D

space.

A computation procedure was developed for performing analyses on reaches that involved 

combining 3-D reach information from the measured WhMD users in relation to a common 

reference plane. For instance, a vertical plane at the anterior-most point was used a reference to 

analyze forward reaches. This is similar to a wheelchair occupant facing a wall such that the 

forward-most aspect of their foot and/or wheelchair was touching the wall. Likewise, a vertical 

plane at the lateral-most point was used as a reference for analyzing lateral reaches, similar to a 

situation where a wheelchair occupant were right alongside a wall. 

The percentage of WhMD users able to reach to or beyond a particular reference plane (either 

forward or lateral) was then computed. The data were analyzed in 100 mm (4 in.) increments 

from the floor. The reference planes could also be moved away or towards the occupant to 

simulate different obstruction depths to estimate the relative increase or decrease in reach 

capability. It should be emphasized that our data depict, in percentages, the reaching 

capabilities of only those individuals who could grasp and lift a particular cylinder above 

shoulder height.

Figure 2-3. Participants moved cylinders in 3 different directions at 5 different heights. Shown 

are forward reaches for two different heights. The electromechanical probe is used to record 

the 3-D location of the maximum reach distances from body and wheelchair reference points.
Anthropometry of Wheeled Mobility | 23

2.2.4 Maneuverability

WhMD users were video recorded while completing the following tasks: 

• 90-degree turn,

• 180-degree turn with no restrictions on length of the maneuver,

• 180-degree with a center barrier, 

• 360-degree rotation within a space with four walls.

The tasks were performed in restricted space conditions with the maneuvering performed within 

the confines of temporary barriers that are made of cardboard. Widths of the restricted space 

were set at a minimum of 750 mm (30 in.) for the 90-degree turn, 750 mm (30 in.) passage width 

for the U-turn with a barrier, and 1300 mm (51 in.) for the 180-degree and 360-degree turning 

activities. 

WhMD users were asked to complete the tasks without touching the walls. The separation 

between walls was increased at increments of 50 mm (2 in.) if passage through the mock 

environment was not cleared without touching the walls (Figure 2-4).

 

Figure 2-4. Two examples of WhMD users completing restricted space experimental conditions.

2.2.5 Grip Strength 

Four types of grip strength measurements for the dominant hand were assessed. These included a 

power grip with the elbow in full extension (i.e. shoulders flexed 90-degrees and upper extremity 

fully extended), power grip with the elbow flexed 90-degrees, lateral pinch (i.e. with the pinch 

gauge between the thumb pulp and the radial aspect of the forefinger), and thumb-forefinger 
Anthropometry of Wheeled Mobility | 24

pinch (i.e. with the pinch gauge between the tips of the thumb and forefinger). These 

measurements are important to the design of and/or standards development for some types of 

hand tools, hardware and electrical controls (e.g. scissors, some types of door latches, knob 

controls). Grip strength was recorded with manual hand and pinch dynamometers (Jamar, Inc). 

WhMD users were required to perform three maximal efforts in each of the four types of grips 

with their dominant hand, with the mean value considered as the maximal force value for analysis. 

Force measurements were not obtained for those WhMD users that were unable to perform a 

grip or exert a grip force, or declined from grip measurements (e.g. due to pain or discomfort in 

the hand). If the person could not complete all three force repetitions, force data for that 

particular grip was not included in the analysis.

Prior analysis of a subset of this data (D’Souza et al., in review) showed maximal power grip 

forces to be greater on average by approximately 1% to 5% with the arm in full extension as 

compared to with the elbow flexed 90-degrees on average across gender and mobility device 

type. In light of this marginal difference, only the power grip data measured with the elbow 

flexed 90-degrees along with data on pinch grips are included in this report. Additional analyses 

of this data to study potential differences in grip strength capabilities by age and medical 

condition that may clinical relevance have also been reported (e.g. Joseph et al., 2010). 

2.2.6 Door Use

Our study of door use had three main objectives all intended to provide groundwork for future 

studies aimed at design guidelines and standards that would make doors more accessible to 

WhMD users: 

1. Identify door use tasks that present WhMD users with the most difficulty, 

2. Evaluate how different aspects of door design effect door use difficulty, and 

3. Identify which WhMD user groups experience the greatest difficulties with doors. 

The door use tasks required the use of three different doors in the building housing the IDeA

Center. Trials in both directions were performed (i.e. from push and pull sides) using a forward 

approach. Each door presented different types of challenges to WhMD users. The door 

characteristics are summarized in Table 2-3.
Anthropometry of Wheeled Mobility | 25

Table 2-3. Characteristics of doors tested.

Door type

Door 1 Door 2 Door 3

Clear opening 825 mm 1040 mm 755 mm

Closer No No Yes

Resistance to open the door ≤ 2 lbf. (9 N) < 2 lbf. (9 N) 7 to 8 lbf. (31 to 36 

N)

Threshold 3 mm 0 6 mm

Latch Yes Yes Yes

Push side clearance > 1525 mm > 1525 mm > 1525 mm

Pull side clearance > 1525 mm > 1525 mm > 1525 mm

Push side latch side clearance 3 in. > 1525 mm > 1525 mm

Pull side latch side clearance 800 mm 406 mm 508 mm

For each trial, use of the door was divided into six task components: Opening Maneuver, 

Operating Latch, Opening, Through Passage, Closing Maneuver and Closing (See Figure 2-5). For 

each phase, the level of difficulty experienced during each task was assessed using a 4 point 

scale and definitions previously developed and tested by Danford and Steinfeld (1999):

1. Minimal effort: The task was performed successfully on the first attempt, without an 

expression of frustration, smoothly without interruption, and in no more time than it would 

take for a member of the general population.

2. Moderate effort: The task was performed successfully on the first attempt, with no more 

than a brief expression of frustration and infrequent pauses or slight difficulties that 

increase the task time slightly as compared to a member of the general population.

3. Maximal effort: The task was performed successfully after multiple attempts, often with 

some expression of frustration and frequent pauses or difficulties that dramatically 

increases task time as compared to a member of the general population.

4. Impossible: The task was not performed successfully or there was a refusal to complete 

the task.

5. Blocked View: The effort could not be assessed due to visual obstruction between 

observer and WhMD user (e.g., door in the way for closing maneuvers, the WhMD user’s 

body orientation with the observer prevents an assessment).
Anthropometry of Wheeled Mobility | 26

 

Figure 2-5. Two examples showing physical requirements of door use for two of the doors used 

by WhMD users.

2.3 Analysis

2.3.1 Comparison of Demographic Characteristics of Our Sample and U.S. Population of 

WhMD Users

The size and functional abilities of WhMD users was hypothesized to differ significantly across 

gender, device type and age of the individual. A comparative analysis between our sample and 

the population of U.S. WhMD users provided information about the generalizability of our 

pooled results with the U.S. population of WhMD users. Demographic information about the U.S. 

population of WhMD users was obtained through summary reports of the 1994-95 National 

Health Interview Survey on Disability (Flagg, 2009; Kaye et al., 2000).

The relative percentages of WhMD users stratified by gender, device type and age categories 

were compared between our sample and the U.S. population of WhMD users. Cases in which our 

sample was not considered representative on these variables suggest a “stratified analysis” (i.e. 

presentation of results for sub-samples, rather than the pooled data set) or other statistical 

modeling methods (e.g. Paquet et al., in preparation) would provide opportunities for a more 

valid application of our results to U.S. standards. Population-based data about percentage of 

WhMDs users with different types of disability were not available for the analyses. 

2.3.2 Comparison of Demographic Characteristics of Subsamples by Data Collection Location

Because each of the data collection sites had access to different sub-populations of WhMD users 

and slightly different methods of participant recruitment, we believed it would be important to 

understand the differences in the demographic characteristics of the sub-samples of each site. 
Anthropometry of Wheeled Mobility | 27

Therefore the relative percentages of WhMD users stratified by gender, device type and age 

categories were compared across the study’s three data collection sites. 

2.3.3 Comparison of Dimensions with Standards and other Anthropometric Studies

The results of our study were compared to the Americans with Disabilities Act Accessibility 

Guidelines (ADAAG) and the Americans with Disabilities Act – Architectural Barriers Act

Accessibility (ADA-ABA) Guidelines for Buildings and Facilities, standards of several countries and 

findings from several other large non-U.S. anthropometric studies of WhMD users. To identify the 

dimensions to compare, we first identified the relevant item in the U.S. standards to identify the 

common underlying anthropometric variables. Our analysis then focused only on those variables. 

The list below identifies the items in the standards and the anthropometric variables which were 

used for comparison: 

• Unoccupied Device Width: Compared to the horizontal distance between the most 

extreme lateral points of the WhMD.

• Unoccupied Device Length: Compared to the horizontal distance between the most 

extreme posterior and anterior points of the WhMD.

• Clear Floor Space Width: Compared to Occupied Width.

• Clear Floor Space Length: Compared to Occupied Length.

• Seat Height, maximum: Compared to the vertical distance measured from the floor to the 

height of the seat support surface when occupied.

• Knee Clearance Height, minimum: Compared to the vertical distance measured from the 

floor to the superior aspect of the right knee.

• Toe Clearance Height, minimum: Compared to the vertical distance measured from the 

floor to the highest point on the right foot (i.e. higher of either the dorsal or distal foot 

point). This measure was only considered for manual and power wheelchair users.

• Knee Clearance Depth, minimum: Compared to the horizontal distance measured from 

the distal aspect of the right knee to the anterior-most point on the occupant and/or 

wheelchair. This measure was only considered for manual and power wheelchair users.

• Toe Clearance Depth, maximum: Compared to the horizontal distance measured from 

the dorsal aspect of the foot (i.e. crease of the foot and lower leg) to the anterior-most 

point on the occupant and/or wheelchair. This measure was only considered for manual 

and power wheelchair users.
Anthropometry of Wheeled Mobility | 28

• Wheelchair Turning Space to make a 90-Degree Turn: Compared to the maneuvering 

clearances required for performing a 90-degree (L-shaped) turn.

• Circular and T-shaped Wheelchair Turning Space: Compared to the maneuvering 

clearances required to make a 180-degree turn in a space confined on three sides.

• Wheelchair Turning Space to make a 180-Degree Turn around an Obstacle: Compared 

to the maneuvering clearances required to make a 180-degree turn around a center 

barrier. 

• Circular and T-shaped Wheelchair Turning Space: Compared to the maneuvering 

clearances required to make a 360-degree turn in a space confined on all four sides.

• Forward Reach Height Lower and Upper Limits: Compared to the measured heights that 

WhMD user could reach beyond the anterior (forward) most point of the WhMD user or 

device.

• Side Reach Height Lower and Upper Limits: Compared to the measured heights that 

WhMD user could reach beyond the most lateral point of the WhMD user or device.

• Side Reach Height Lower and Upper Limits over an obstruction of 610 mm: Compared 

to the measured heights that WhMD user could reach 610 mm beyond the most lateral 

point of the WhMD user or device. 

• Maximum Forces for Hand-operated Controls: Compared to the maximum hand grip 

strength in a power grip, and lateral and thumb-forefinger pinch grips.

In order to accomplish the comparative analysis with the standards and other studies, we 

reviewed ICC/ANSI A117.1 (2003) 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. 

Table 2.4 summarizes Accessibility Standards that were used for the comparisons.
Anthropometry of Wheeled Mobility | 29

Table 2.4 Comparison of Accessibility Standards across Four Countries.

Measurement Dimension

Country & Standards Document

Australia Canada* U.K. USA

AS 1428.2

(mm) B651-04 (mm) BS8300:2001(mm)

ICC/ANSI 

A117.1 (mm 

& in.)

Wheelchair Dimensions

Unoccupied Device Width - 660 - 660 (26)

Unoccupied Device Length - - - 1065 (42)

Seat Height, maximum 480 480 - 485 (19)

Clear Floor Space

Width, minimum 800 750 900 760 (30)

Length, minimum 1300 1200 1350 1220 (48)

Knee and Toe Clearances

Knee Clearance Height, minimum 640-650 680 700 685 (27)

Toe Clearance Height, minimum 280 230 300 230 (9)

Knee Clearance Depth, minimum 230 200 260 280 (11)

Toe Clearance Depth, maximum 190 230 - 150 (6)

Reach Ranges

Forward Reach - Unobstructed 250-1220 380-1220 - 380 (15) -

1220 (48)

Side Reach – Unobstructed 230-1350 230-1400 630-1170 380 (15) -

1370 (54)

Side Reach – between 255-610 

obstruction depth - - - Max. 1170 (46)

Maneuvering Spaces (minimum)

90-Degree Turn - 920 - 915 (36)

180-Degree Turn 1540x2070 1500 1500 1525 (60)

180-Degree Turn around Barrier - - - 1065 (42)

360-Degree Turn 1540x2070 1500 1500 1525 (60)

Hand Force for Operating Controls, 

maximum - - - 5 lb-f.

* This standard also includes an appendix with information on device size and maneuvering spaces 

for power chairs and scooters derived from the UDI research.

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 
Anthropometry of Wheeled Mobility | 30

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. Each of the studies is briefly 

described below. See Steinfeld et al. (2010c) for a more complete summary of each.

In his study, Bails (1983) recruited participants from attendees at disability support centers and 

institutions. Eligible participants were between 18 and 60 years of age and used a manual or 

powered wheelchair. Scooter users were not included in the study. The research focused primarily 

on testing of full-size simulations of elements found in the built environment, such as doorways, 

environmental controls, furniture and fixtures that were configured to meet the Australian 

standards at the time. 

Seeger et al. (1994) studied only device size. About 73% of the 240 individuals in the sample 

lived in nursing homes and other institutions. Forty-five percent were over 65 years old. Eleven 

percent used power chairs and 2% used scooters. Both unoccupied and occupied dimensions of 

device width and length were measured as well as a set of other basic dimensions. Measurements 

were taken manually using conventional measuring tools including a tape measure, steel square 

and spirit level. 

The Department of Environment Transport and the Regions (DETR) (Stait et al., 2000) and the 

Department for Transport (DfT) (Hitchcock et al., 2006) studies were the two most recent in a 

series of three large-scale wheelchair anthropometry surveys conducted in the U.K. The studies 

were limited to the measurement of device size and weight. The DETR survey conducted in 1999, 

recruited participants solely at an exposition of equipment for people who use wheeled mobility 

devices for traveling around the community. The subsequent DfT survey was widened to include 

12 schools and retail centers in the U.K., in addition to the 2005 Mobility Roadshow. Of the 745 

participants in the DETR study whose data was acceptable, 59% used self-propelled manual 

chairs, 9% used attendant powered chairs, 25% used power chairs and 9% used scooters. Nine 

percent of the sample were judged to be 16 years of age or younger. The DfT study sample 

comprised of 1098 adults and 247 children. Among adults, 41% used self-propelled manual 

chairs, 10% used attendant-propelled wheelchairs, 27% used power chairs, and 22% used 

scooters. The DETR study used two photographs of each participant, while the DfT study employed 
Anthropometry of Wheeled Mobility | 31

seven photographs taken with a camera from pre-determined angles after participants wheeled 

into position on a scale. A checkerboard pattern on the floor and wall provided references to 

take measurements off the photographs. Although a wide variety of accessories were observed 

on the devices, they were not measured as part of the width calculation. 

The research used as a basis for revisions to the U.K. BS8300:2001 standards covered clear floor 

area space requirements, knee clearances and maneuvering clearances. A total of 164 

individuals were included in the sample but only 90 participated in the research on space 

allowances. Due to the lack of a full research report, it is not clear how the measurements were 

collected and, in many cases, the landmarks used to define them. From the information available, 

it appears that some scooters and attendant propelled chairs were included in the sample but it is 

not clear whether these individuals were included in the device or body measurements. 

The Universal Design Institute (UDI) study (Ringaert et al., 2001) included a sample of individuals 

recruited from disability and senior organizations in Winnipeg by written invitation. Of the 50 

participants, 35 (70%) used power chairs and 15 (30%) used scooters. The cause of disability for 

individuals in the sample included a wide range of conditions. Device size and maneuvering 

spaces were measured. All dimensions were taken to the extremes of the equipment including any 

object attached to the device like a ventilator. However, the actual landmarks on the devices 

were not well documented. Measurements were made with rulers and tape measures but no 

information is given on the accuracy and reliability of these techniques. Maneuvering trials were 

recorded using overhead video cameras while participants completed standardized movements in 

simulated environments built with plywood floors and wood framed dividers. Measurements were 

later taken off the videotapes although the method used to extract the measurements and the 

reliability of the technique was not described. An observer rating was used to determine 

successful trials.

The common variables were defined graphically in illustrations and with abbreviations, e.g. Knee 

Clearance Height (KCH), Knee Clearance Depth – Upper (KCD), and Extended Depth (ED). In 

many cases, variables underlying the U.S. standards are not included in other standards. Thus, in 

our comparisons, we omitted values for those variables. We did not, however, report variables 

from other standards that are not included in the U.S. standards. 
Anthropometry of Wheeled Mobility | 32

The standards did not always 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 Imperial values found in the U.S. standards. 

We then reviewed the research completed in each study. 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

including our own 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 were 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. 
Anthropometry of Wheeled Mobility | 33

For clarity, we pooled data for all mobility devices. However, this can confound comparisons 

across studies due to differences in the proportion of manual wheelchairs, power chairs, and 

scooters. Therefore, we also provided tabular data stratified by mobility device type.

2.3.4 Analysis of Door Use Difficulty

The measurement of door use performance was designed as a quasi-experimental study that 

involved systematically observing and coding WhMD user performance during door use tasks. It 

therefore required different analysis and comparison approaches.

First, an analysis of the demographic variables for the subset of WhMD users who completed the 

door use tasks was completed to describe the percentages of men and women, and types of 

WhMDs used in this sub-group. The mean, median and range of WhMD user age, occupied width, 

occupied length and maximum power grip were also reported as we thought that these variables 

might help explain the door use performance among the sub-group. 

The level of difficulty experienced for each of the phases of door use was then compared across 

the three different doors and WhMD types for each of the tasks. Specifically, the percentage of 

each of the rating scores (minimum effort, moderate effort, maximum effort and impossible) was 

calculated for each of the three doors and six door use tasks. Those doors and door use tasks 

having a relatively large percentage of scores exceeding minimum effort were identified as 

potentially problematic, and a follow-up analysis of these conditions was performed to determine 

which WhMD user groups had the greatest difficulty with these tasks. 
Anthropometry of Wheeled Mobility | 34
Anthropometry of Wheeled Mobility | 35
Anthropometry of Wheeled Mobility | 36

3.0 Study Findings

3.1 Comparison of Our Sample to U.S. Population of WhMD Users

Our sample of WhMD users was younger in age, had a much higher percentage of powered 

wheelchair users and a somewhat larger sample of male WhMD users than the estimated U.S. 

population of WhMD users (Table 3-1). As stated in the previous section, we deliberately oversampled powered device users in order to be able to accurately describe the anthropometric 

characteristics of this group. The higher frequency of male WhMD users recruited for this study is 

not very surprising as two of our data collection sites (Buffalo and Pittsburgh) recruited some of 

their study participants through VA medical centers that had extremely high percentages of male 

patients. As a result, our overall sample, when compared to the overall population of WhMD

users is likely to have lower upper extremity and torso function, and be somewhat larger (i.e., 

taller, longer arms, wider, etc.). As stated in the previous chapter, these sample differences can 

be accounted for by stratifying the data by WhMD and/or by gender, or through the use of 

statistical modeling methods (Paquet et al., in preparation).

In terms of the medical conditions, Kaye et al. (2000) reported orthopedic impairments of the 

lower extremity (17% when combined with arthritis and other polyarthritis to conform with the 

classification used in the current study), cerebral vascular diseases (e.g. stroke, 11%), and central 

nervous system disorders (8%, including multiple sclerosis and cerebral palsy) as being the most 

frequently reported conditions leading to the use of a WhMD in the U.S. population. The most 

frequently reported medical conditions in our study were found to be central nervous system 

disorders (32%, including multiple sclerosis and cerebral palsy), spinal cord injuries (20%), 

cerebral vascular diseases (16%), followed by orthopedic impairments of the lower extremity 

(12%). The higher prevalence of spinal cord injuries in our study sample is expected given that

two of the study locations recruited substantially through local VA medical centers.
Anthropometry of Wheeled Mobility | 37

Table 3-1. Comparison of the percentages of WhMD users by gender, device type and age 

based on the estimated U.S. population of non-institutionalized WhMD users (Kaye et al., 

2000) and our sample of WhMD users (n=495). 

Age by Device Type % U.S. WhMD User Pop. (Kaye et al., 2000) Overall Sample (n=495)

Male Female Total Male Female Total

Age between 18-64 years

Manual 16% 17% 37% 107 (22%) 62 (13%) 169 (34%)

Power 3% 3% 6% 78 (16%) 58(12%) 136 (27%)

Scooter 2% 3% 5% 10 (2%) 10 (2%) 20(4%)

Total 21% 23% 43% 195 (39%) 130 (26%) 325 (66%)

Age >65 years

Manual 17% 33% 53% 40 (8%) 67 (13%) 107 (22%)

Power 1% 2% 3% 22 (4%) 31 (6%) 53(11%)

Scooter 2% 2% 4% 6 (1%) 4 (1%) 10 (2%)

Total 20% 37% 57% 68 (13%) 102 (21%) 170 (34%)

Total (age >18 years)

Manual 33% 50% 89% 147 (30%) 129 (26%) 276 (56%)

Power 4% 5% 9% 100 (20%) 89 (18%) 189 (38%)

Scooter 4% 5% 9% 16 (3%) 14 (3%) 30 (6%)

Total 41% 60% 100% 263 (53%) 232 (47%) 495 (100%)

3.2 Comparison of Sub-samples across Data Collection Sites

The primary purpose of expanding data collection to different sites was to increase the diversity 

of the overall sample. The Buffalo site, having recruited participants for close to 10 years had a 

relatively diverse sample of individuals recruited through the local Independent Living Center, a 

local VA medical center, and local adult care facilities. The Pittsburgh site recruited primarily 

through a local VA medical center. The Ithaca site recruited through local adult care facilities. 

Not unexpectedly, large differences in WhMD users in terms of gender, age, years with disability 

and device type used were found (Table 3-2). Pittsburgh had a much higher percentage of men 

WhMD users (73%) as compared to Ithaca (57%) and Buffalo (46%). It has been our experience 

that men are more likely to participate in the study, and the Buffalo site specifically targeted 

female WhMD users in our last phase of data collection to improve the representativeness of the

data set in terms of gender. The median age of WhMD users was highest for the Ithaca site (74 

years) followed by Buffalo (57 years) and Pittsburgh (44 years). Ithaca, and Buffalo in the later 

stages of data collection, recruited primarily from adult care facilities in order ensure that older 

WhMD users were well represented in the sample. 
Anthropometry of Wheeled Mobility | 38

The disparities in the time WhMD users had their disabilities can also be explained by the 

differences in sampling approaches across the sites. By concentrating on veterans, the Pittsburgh 

site recruited WhMD users with disabilities for the largest number of median years (20 years) as 

compared to Buffalo (15 years) and Ithaca (10 years). This illustrates that the WhMD users 

recruited by Pittsburgh were more likely to experience their disability at an earlier age than the 

other two sites, while the WhMD users recruited by Ithaca were likely to have first experienced 

their disabilities at a much older age. 

Table 3-2: Gender, age and number of years with disability across sites.

Site

Total

Buffalo, NY Pittsburgh, PA Ithaca, NY

Total Sample size 351 100 44 495

Gender

Women 190 (54%) 23 (23%) 19 (43%) 232 (47%)

Men 161 (46%) 77 (77%) 25 (57%) 263 (53%)

Age in years

Mean (SD) 58.6 (18.0) 43.4 (14.9) 68.6 (19.3) 56.4 (18.9)

Median 57 43.5 74 55

Range 18 - 95 19 - 83 24 - 100 18 - 100

Number of years with disability

Mean (SD) 20.6 (18.5) 20.7 (15.1) 15.6 (17.6) 20.2 (17.8)

Median 15 19.5 10 15

Range 0 - 94 1 - 80 1 - 81 0 - 94

There were also large differences in the medical condition reported as being responsible for the 

need to use a WhMD across data collection sites (Table 3-3). Pittsburgh by far had the largest 

percentage of spinal cord injured WhMD users and lowest percentage of orthopedic injuries and 

deformities. The greater percentage of acute injury related mobility impairments such as spinal 

cord injuries for the Pittsburgh site is expected given that most of its sample was recruited through 

a VA medical center. The Buffalo and Pittsburgh sites each had sub-samples with a diverse set of 

medical conditions.
Anthropometry of Wheeled Mobility | 39

Table 3-3: Reported primary medical conditions among WhMD users across sites.

Data Location

Total

Buffalo, NY Pittsburgh, PA Ithaca, NY

Total Sample size 351 100 44 495

Reported Medical Condition

CNS Disorders (incl. MS, CP) 121 (35%) 26 (26%) 9 (20%) 156 (32%)

Spinal cord injuries 46 (13%) 51 (51%) 4 (9%) 101 (20%)

Orthopedic Injuries or Deformities 67 (19%) 2 (2%) 11 (25%) 80 (16%)

Cerebral Vascular Disease 49 (14%) 2 (2%) 7 (16%) 58 (12%)

Other* 68 (19%) 19 (19%) 13 (30%) 100 (20%)

* “Other” includes amputations, traumatic brain injuries, respiratory diseases and diabetes.

The disparities across the three sites in terms of the percentages of WhMD technologies were 

largest between the Ithaca and the other two sites (Table 3-4). The Ithaca site measured a much 

higher percentage of manual wheelchair users than Pittsburgh and Buffalo, which is not surprising 

given the distribution ages and reported medical conditions for the Ithaca site. 

Table 3-4. Primary mobility device used among WhMD users across sites.

Data Location

Total

Buffalo, NY Pittsburgh, PA Ithaca, NY

Total Sample size 351 100 44 495

Type of Mobility Device

Manual 191 (54%) 50 (50%) 35 (80%) 276 (56%)

Power, combined 135 (39%) 46 (46%) 8 (18%) 189 (38%)

Power, front-wheel drive 25 (7%) 21 (21%) 0 (0%) 46 (9%)

Power, mid-wheel drive 57 (16%) 10 (10%) 3 (7%) 70 (14%)

Power, rear-wheel drive 53 (15%) 15 (15%) 5 (11%) 73 (15%)

Scooter, combined 25 (7%) 4 (4%) 1 (2%) 30 (6%)

Scooter, three-wheeled 21 (6%) 4 (4%) 1 (2%) 26 (5%)

Scooter, four-wheeled 4 (1%) 0 (0%) 0 (0%) 4 (1%)

Some of the research participants could not complete all of the functional anthropometric tests (i.e.

grip strength, reach and maneuvering). The participation rates in these tests were evaluated for 

each of the sites. The participation rates for the reach and grip tests are summarized in Table 3-

5. Participation rates for the reach tests were lowest in Ithaca where the WhMD users tended to 

be much older than those of the other sites. The participation rates for the power grips were 

lowest in Pittsburgh, where there was the highest percentage of WhMD users with spinal cord 

injury.
Anthropometry of Wheeled Mobility | 40

Table 3-5: Participation rates in the functional anthropometric tests for each site.

Data Location

Total

Buffalo, NY Pittsburgh, PA Ithaca, NY

Total Sample size 351 100 44 495

Reach Capability

Able to Pick-place empty canister (%) 261 (74%) 83 (83%) 27 (61%) 371 (75%)

Able to Pick-place 5 lbs. canister (%) 183 (52%) 68 (68%) 15 (34%) 266 (54%)

Able to Exert Hand Grip Force

Power Grip (%) 320 (91%) 80 (80%) 38 (86%) 438 (88%)

Lateral Pinch Grip (%) 305 (87%) 77 (77%) 29 (66%) 411 (83%)

Thumb-forefinger Tip Grip (%) 288 (82%) 73 (73%) 34 (77%) 395 (80%)

3.3 Comparison of Dimensions with Standards and other Anthropometric Studies

3.3.1 Unoccupied Device Width 

The unoccupied widths of devices were similar for the mean and 80th percentile values across 

research findings from different countries (Figure 3-1). Our sample overall had, on average,

larger mean and 80th percentile values for unoccupied device width than other countries. This was 

in part due to the larger percentage of powered wheelchair users and manual bariatric 

wheelchair users that were included in our study.

The unoccupied widths of devices used for the “reference wheelchair” described in the U.S. and 

Canadian standards are smaller than many of the WhMD users in our sample. For example, our 

results for mean unoccupied width are just under the U.S. standard reference wheelchair of 660 

mm (26 in.). But, the widest device measured (a manual wheelchair) was over 300 mm (12 in.) 

wider than the U.S. standard’s reference wheelchair. The U.S. standards, generally accepted by 

the other countries, were derived from manufacturers’ data in the 1970’s and did not include 

many of WhMD technologies that are in use today. 
Anthropometry of Wheeled Mobility | 41

Data Source Sample Size Min 5%ile Mean 80%ile 90%ile 95%ile Max

Seeger et al., AUS

All Device Types* 240 - - 650 - - 715 880

UDI, Canada

Power chairs and scooters* 50 560 - 613 - - 697 810

DfT, U.K.

Self-Propelled Wheelchair 458 393 572 635 - - 707 992

Attendant-Propelled Wheelchair 106 505 538 595 - - 662 719

Electric Wheelchair 294 399 536 605 - - 670 745

Electric Scooter 240 426 478 579 - - 669 840

All Device Types* 1098 393 531 612 - - 692 992

IDeA Center, U.S.

Manual chairs 276 508 575 654 688 710 740 967

Power chairs 189 539 562 635 665 701 738 845

Scooters 30 488 492 610 660 695 730 759

All Device Types* 495 488 563 644 675 705 739 967

* Indicates data plotted in the graph.

Figure 3-1. Unoccupied WhMD width: research findings versus the standards.
Anthropometry of Wheeled Mobility | 42

3.3.2 Unoccupied Device Length 

The unoccupied length of devices could be compared only between our study and the U.K. study 

(Stait et al., 2000). Our findings for mean, 80th percentile and 90th percentile values were 

somewhat larger than those of the comparison study (Figure 3-2). This again was likely due to the 

larger percentage of powered wheelchairs and manual bariatric wheelchairs that were included 

in our study.

The unoccupied lengths of devices used for the “reference wheelchair” described in the U.S. 

standard equals the average value obtained from our overall sample. The mean unoccupied 

length for a powered wheelchair in our sample was 52 mm (2 in.) greater than the unoccupied 

length of the reference chair given in the standards, and the longest unoccupied length measured 

in our study was over 600 mm (23.6 in.) greater than the unoccupied length of the “reference 

wheelchair”! 

There are a few reasons for the disparity in our unoccupied length data and the unoccupied 

length of the “reference wheelchair” currently provided in the standards. First, the available 

WhMD technologies of today are structurally different than those from which the standards were 

derived. For example, powered wheelchairs and scooters are generally longer than manual 

wheelchairs. Second, we measured the unoccupied length of the WhMD while it was in use; thus

devices measured with elevated leg supports would be “lengthened.” Third, many of today’s 

mobility users attach accessories to the back of their device; we included the accessories in our

length measurements. 
Anthropometry of Wheeled Mobility | 43

Data Source Sample Size Min 5%ile Mean 80%ile 90%ile 95%ile Max

BS8300:2001, U.K.

Manual chairs - self propelled 54 700 - - 1090 1124 - 1200

Power chairs 27 700 - - 1160 1190 - 1400

Manual and Power chairs* 81 700 - - 1110 1170 - 1400

Electric scooters 5 1170 - - - - - 1500

IDeA Center, U.S.

Manual chairs 276 686 774 1012 1169 1223 1264 1600

Power chairs 189 681 900 1117 1244 1297 1340 1669

Scooters 30 1025 1035 1208 1283 1369 1435 1439

All Device Types* 495 681 795 1065 1204 1265 1318 1669

* Indicates data plotted in the graph.

Figure 3-2. Unoccupied WhMD length: research findings versus the U.S. standards.
Anthropometry of Wheeled Mobility | 44

3.3.3 Clear Floor Width 

The findings on clear floor width are based on the findings on occupied width from 

anthropometric studies shown in Figure 3-3. Neither the DfT or DETR studies collected data on 

occupied width but did measure the unoccupied device width. The authors argued that individuals 

can bring their arms and legs inboard when entering transportation vehicles and passing through 

doorways. We found, however, that many individuals do not have the physical ability to position 

their upper and lower extremities “inboard”. Moreover, in situations where an individual might 

remain stationery for a relatively long time, for example, at a concert or sporting event, it is 

unrealistic to assume that an individual would keep their upper and lower extremities in such a 

constraining position. The BS8300 research did not report occupied widths larger than 800 mm 

but the BS8300 standard, as we interpret it, requires an additional 100 mm (4 in.) more than that 

for the clear floor area width (900 mm). The BS8300 standard’s developers may have added 

100 mm to provide additional maneuvering room at clear floor areas.

Due to recent revisions, the minimum required clear floor width standard in Australia and the U.K.

now exceeds that in U.S. and Canada (Figure 3-3). The U.K. standard accommodates the 

occupied widths of most everyone in all of the studies, except for a small sample of the largest 

widths measured in our study. Approximately 90% of manual wheelchair users, 85% of scooter 

users and 80% of powered chair users in our sample had occupied widths that were less than the 

U.S. clear floor width standard. Therefore, 10-20% of individuals measured in our study have an 

occupied width that is greater than the U.S. standard of 760 mm (30 in.).
Anthropometry of Wheeled Mobility | 45

Data Source Sample Size Min 5%ile Mean 80%ile 90%ile 95%ile Max

Seeger et al., AUS

All Device Types* 240 - - 690 - - 820 890

BS8300:2001, U.K.

Manual chairs - self propelled 54 560 - - 696 720 - 800

Power chairs 27 560 - - 750 760 - 800

Manual and Power chairs* 81 560 - - 720 750 - 800

Scooters 5 630 - - - - - 700

IDeA Center, U.S.

Manual chairs 276 508 595 685 725 761 786 992

Power chairs 189 574 607 707 765 802 827 1008

Scooters 30 488 516 643 732 810 837 857

All Device Types* 495 488 595 691 742 780 818 1008

* Indicates data plotted in the graph.

Figure 3-3. Clear floor width (occupied width): research findings versus the 

standards.
Anthropometry of Wheeled Mobility | 46

3.3.4 Clear Floor Length 

The mean value of clear floor length for our study (1250 mm or 49 in.) is above the clear floor 

length provided in the U.S. standards (1220 mm or 48 in.). Australian and U.K. have also recently

increased the clear floor length standards (Figure 3-4). The U.K. requirements for clear floor 

length exceed the U.S. by 130 mm (5 in.). The results of our study and other anthropometric 

studies support larger lengths to accommodate the vast majority of occupied WhMD lengths. The 

largest occupied lengths reported in all the anthropometric studies exceed the current standards, 

even the U.K. BS8300 standard of 1350 mm (53 in.). However, the results show that the 95th

percentile values of occupied length are between 1250 mm. (49 in.) and 1480 mm (58 in.). 

The difference between the maximum length in the UDI and Seeger studies and the others is so 

great that they are probably due to the presence of unusually large people and/or devices, or 

measurement error. The maximum length (occupied) recorded in the UDI study, for example, was 

over 2000 mm (6 ft.- 8 in.)! In the case of Seeger et al.’s work, we know that most of the sample 

was recruited from institutions and many may have had extended foot-rests or reclined backs on 

their chairs. No information was provided in the reports to assess whether individuals in either 

study could be considered outliers. For example, since the other studies together included over 

1200 individuals and no other study reported a device as long as 2000 mm (78 in.), such a large 

value is likely a measurement error or a very rare occurrence. In fact, by coincidence, we met an 

individual who served as an advisor and participant in the UDI research. She recalled that there 

was one individual who had a “trailer” attached to her wheelchair that carried ventilator 

equipment which would not be required anymore due to advances in technology.
Anthropometry of Wheeled Mobility | 47

Data Source Sample Size Min 5%ile Mean 80%ile 90%ile 95%ile Max

Seeger et al., AUS

All Device Types* 240 - - 1170 - - 1480 1750

UDI, Canada

Power chairs and scooters* 50 820 - 1168 - - - 2030

DfT, U.K.

Self-Propelled Wheelchair 458 776 864 1068 - - 1254 1534

Attendant-Propelled 

Wheelchair 106 951 1003 1123 - - 1344 1375

Electric Wheelchair 294 633 955 1142 - - 1339 1604

Electric Scooter 240 828 956 1168 - - 1416 1503

All Device Types* 1098 633 893 1113 - - 1339 1604

IDeA Center, U.S.

Manual chairs 276 743 934 1150 1255 1314 1362 1625

Power chairs 189 831 977 1196 1313 1360 1415 1708

Scooters 30 1025 1035 1208 1283 1369 1435 1439

All Device Types* 495 743 960 1171 1280 1340 1386 1708

* Indicates data plotted in the graph.

Figure 3-4. Clear floor length (occupied length): research findings versus the standards.
Anthropometry of Wheeled Mobility | 48

3.3.5 Seat Height 

Height dimension standards for seats prescribed in the Australian, Canadian and U.S. standards 

were very similar (480 mm or 18.9 in., 480 mm or 18.9 in. and 485 mm or 19 in., respectively). 

The values in the current standards for seat height are below the means for people we measured 

and those in the UDI study (Figure 3-5). This is probably due to the increasing use of positioning 

systems, thick cushions and the availability of a wider range of wheel sizes since the 1970’s. 

Comparisons of research findings on the seat heights for power chairs and scooters showed that 

mean seat heights measured in the UDI study were comparable to seat heights for the power 

chairs and scooters of our study; however, the differences grew larger toward the higher 

percentiles. Further, our study findings also revealed that occupied seat heights for manual chairs 

were much lower than seat heights for power chairs and scooters.

The reference points used for measurement can yield quite different results for seat height. The 

height of the seat can be measured at the edge and at the middle, under the cushion, on top of 

the cushion, etc. Thus, specifying exactly how it is measured is important for comparing results. We

computed the occupied seat height by measuring a point underneath an individual’s buttocks using 

an extension of the electromechanical probe that we slipped in from the side between the 

occupant and seat interface. Our results would be different compared to other measurements not 

made in a similar manner.
Anthropometry of Wheeled Mobility | 49

Data Source Sample Size Min 5%ile Mean 80%ile 90%ile 95%ile Max

UDI, Canada

Power chairs and scooters* 50 420 - 528 - - 639 650

IDeA Center, U.S.

Manual chairs 276 414 434 496 530 547 567 608

Power chairs 189 412 465 539 574 599 628 734

Scooters 30 472 475 550 582 595 636 643

All Device Types* 495 412 440 516 556 575 597 734

* indicates data plotted in the graph

Figure 3-5. Seat height: research findings versus the standards.
Anthropometry of Wheeled Mobility | 50

3.3.6 Knee Clearance Height, minimum 

Knee clearance heights for the four sets of standards range from 650 mm (25.6 in.) (Australia) to 

700 mm (27.6 in.) (U.K.) (Figure 3-6). The U.S. standard for knee clearance height is 685 mm (27

in.). The U.K. BS8300 results for knee clearance height suggest that current U.K. standard 

generally accommodates most wheelchair users in that country. In the case of the U.S. and 

Canadian standards, however, the level of accommodation drops to 80% in relation to measured 

knee heights among wheelchair users in their respective countries.

A review of photographs of participants in the IDeA sample indicated that the largest individuals 

are not always the ones who need the greatest knee clearances. Smaller individuals who have 

large thighs, those with high seats and scooter users also have high lap heights. Individuals with 

extended footrests and scooter users have deep knee clearances but not necessarily high knee 

clearances. 
Anthropometry of Wheeled Mobility | 51

Data Source Sample Size Min 5%ile Mean 80%ile 90%ile 95%ile Max

UDI, Canada

Power chairs and scooters* 50 540 - 663 - - 777 800

BS 8300:2001, U.K.

All Device Types* 164 - - - 661 674 691 -

IDeA Center, U.S.**

Manual chairs 268 460 496 596 645 667 689 743

Power chairs 188 488 543 643 685 709 729 870

Scooters 29 553 566 665 712 754 774 785

All Device Types* 485 460 512 618 672 697 717 870

* Indicates data plotted in the graph.

** Does not include individuals with an above-knee right leg amputation (n=6) or with the right leg constrained in 

fully extended position (n=3) such as in an orthopedic cast. 

Figure 3-6. Knee clearance height: research findings versus the standards.
Anthropometry of Wheeled Mobility | 52

3.3.7 Toe Clearance Height, minimum

There is relatively large disparity between the standards for toe clearance height, with the U.S. 

having the lowest (230 mm or 9 in.), followed by Australia (280 mm or 11 in.) and the U.K. (300

mm or 12 in.) (Figure 3-7). Our study suggests that the standards required in each of the 

countries, do not accommodate the vast majority of WhMD users, especially in the U.S. The mean 

toe height for the overall sample of WhMD users in our study was 230 mm (9 in.). 

In particular, the 80th percentile of toe clearance height for manual chairs (276 mm or 10 in.) 

suggests that over 20% of manual chair users exceed the minimum required toe clearance height 

of 230 mm (9 in.). Corresponding clearance heights for power chair users were typically greater 

than manual chair users, and with over half the sample exceeding the minimum toe clearance 

height requirement.
Anthropometry of Wheeled Mobility | 53

Data Source Sample Size Min 5%ile Mean 80%ile 90%ile 95%ile Max

DETR, U.K.

Manual Chairs* - 140 175 - - - 299 350

Power Chairs* - 180 197 - - - 318 340

IDeA Center, U.S.**

Manual chairs* 266 83 94 204 276 304 330 564

Power chairs* 186 84 168 267 320 366 408 535

Manual and Power chairs 452 83 102 230 296 333 365 564

* indicates data plotted in the graph

** does not include individuals with a below-knee right leg amputation (n=10) or with the right leg constrained in 

fully extended position (n=3) such as in an orthopedic cast

Figure 3-7. Toe clearance height: research findings versus the standards.
Anthropometry of Wheeled Mobility | 54

3.3.8 Knee Clearance Depth, minimum 

Knee clearance depths for the four sets of standards range from 200 mm (8 in.) in Canada to 

280 mm (11 in.) in the U.S. (Figure 3-8). None of the comparison studies used for this report 

provided anthropometric information about knee clearance depth. The results of our study suggest 

that a large percentage of WhMD users are not accommodated by the standards. The U.S.

standard on knee clearance depth accommodated just over 50% of our overall sample, and was 

well below the 80th percentile values of maximum knee height for manual wheelchair users (369

mm or 14.5 in.) and power chair users (345 mm or 13.5 in.). Even fewer would be accommodated 

by the standards of the U.K., Australia and Canada. A knee clearance depth of over 400 mm (16

in.) is needed to accommodate close to 95% of our sample’s manual and powered wheelchair

users.

Data Source Sample Size Min 5%ile Mean 80%ile 90%ile 95%ile Max

IDeA Center, U.S.**

Manual chairs* 268 31 116 276 369 402 433 620

Power chairs* 188 23 110 260 345 385 422 487

Manual and Power chairs 456 23 116 270 356 395 424 620

* indicates data plotted in the graph

** does not include individuals with an above-knee right leg amputation (n=7) or with the right leg constrained in 

fully extended position (n=3) such as in an orthopedic cast. 

Figure 3-8. Knee clearance depth: research findings versus the standards.
Anthropometry of Wheeled Mobility | 55

3.3.9 Toe Clearance Depth, minimum 

Toe clearance depths for the standards range from 150 mm (6 in.) in the U.S. to 230 mm (9 in.) in 

Canada (Figure 3-9). None of the comparison studies used for this report provided 

anthropometric information about toe clearance depth. While the Canadian standard 

accommodates over 85% of our WhMD users, the U.S. standard accommodates fewer than 50% 

of our sample. 

Data Source Sample Size Min 5%ile Mean 80%ile 90%ile 95%ile Max

IDeA Center, U.S.**

Manual chairs* 266 71 124 184 208 246 292 502

Power chairs* 186 30 106 164 197 223 261 342

Manual and Power chairs 452 30 111 176 201 236 272 502

* Indicates data plotted in the graph.

** Does not include individuals with a below-knee right leg amputation (n=10) or with the right leg constrained in 

fully extended position (n=3) such as in an orthopedic cast.

Figure 3-9. Toe clearance depth: research findings versus the standards.
Anthropometry of Wheeled Mobility | 56

3.3.10 90-Degree Turn 

While all of the standards compared in this report have requirements for “wheelchair turning 

spaces”, only the U.S. and Canada have requirements specifically for 90-degree or L-Turn 

clearances. These are similar for both countries, 915 mm (36 in.) and 920 mm (36.2 in.) for the 

U.S. and Canada, respectively. 

The width required for all participants to complete a 90-degree turn in our sample was much 

smaller than the UDI findings (Figure 3-10), due to differences in the abilities of people or/and 

WhMD technologies included in each of the studies or due to the different measurement 

procedures employed.

An increase in the 90-degree turning width criterion from 915 mm (36 in.) to 1000 mm (39 in.)

would accommodate at least 95% of our sample. It also appears that there are some manual 

chair, power chair and scooter users who require much larger spaces than the 95th percentile 

values. 
Anthropometry of Wheeled Mobility | 57

Data Source Sample Size Min 5%ile Mean 80%ile 90%ile 95%ile Max

UDI, Canada

Power chairs – CW* - 920 - 964 - - 1062 1120

Power chairs – CCW - 920 - 972 - - 1084 1120

Scooters – CW* - 920 - 1030 - - 1158 1120

Scooters – CCW - 920 - 1025 - - 1145 1120

IDeA Center, U.S.

Manual chairs* 199 750 750 872 950 1000 1000 1100

Power chairs* 150 750 750 883 950 1000 1000 1150

Scooters* 19 800 800 942 1000 1000 1100 1100

All Device Types 368 750 750 880 950 1000 1000 1150

* indicates data plotted in the graph

Figure 3-10. 90-degree turning width: research findings versus the standards.
Anthropometry of Wheeled Mobility | 58

3.3.11 180-Degree Turn 

The mean width required for all participants to complete a180-degree turn in our sample was 

smaller than the UDI findings (Figure 3-10), but our 95th percentile values for power chair and 

scooters users were larger than the maximum values obtained in the UDI study. The disparities are 

likely due to the differences in the studies described previously.

The space requirements for a 180-degree turn are similar across countries, ranging from 1500

mm (59 in.) in the U.K. and Canada to 1540 mm (60.6 in.) in Australia. The U.S. standard of1525

mm (60 in.) accommodates just over 80% of the manual and powered wheelchair users, but less 

than 50% of the scooter users in our sample. An increase in the 180-degree turning width of at 

least 175 mm (7 in.) would be needed to accommodate 95% of manual and powered wheelchair

users and 90% of the scooter users. Again, there are some manual chair users, power chair users 

and scooter users who require much larger spaces than the 95th percentile values, exceeding 500

mm (almost 20 in.) beyond the current U.S. standards!
Anthropometry of Wheeled Mobility | 59

Data Source Sample 

Size Min 5%ile Mean 80%ile 90%ile 95%ile Max

UDI, Canada - 180 deg

Power chairs* 15 1500 - 1563 - - - 1575

Scooters* 35 1500 - 1692 - - - 1925

Power chairs and 

scooters 50 1500 - 1563 - - - 1925

BS8300:2001, U.K.

(Length x Width)

Manual chairs - self 

propelled 54 - - -

1800 x 

1450

1950 x 

1500 - -

Power chairs 27 - - -

2190 x 

1600

2275 x 

1625 - -

Scooters 5

2000 x 

1300 - - - - -

2800 x 

2200

IDeA Center, U.S.

Manual chairs* 198 1300 1300 1428 1500 1700 1700 2300

Power chairs* 140 1100 1300 1450 1500 1700 1700 2100

Scooters* 16 1300 1300 1600 1700 1700 2100 2100

Overall 354 1100 1300 1444 1500 1700 1700 2300

* indicates data plotted in the graph

Figure 3-11. 180-degree turning width: research findings versus the standards.

3.3.12 180-Degree Turn around a Barrier 
Anthropometry of Wheeled Mobility | 60

The U.S. has requirements for a 180-degree turn around a barrier that makes the width of the 

turn-around space dependent on the width of the passageway. If the barrier is less than 1220 

mm (48 in.) wide, the standard calls for a minimum passage width of 1065 mm (42 in.) and a 

minimum turn-around space depth of 1220 mm (48 in.). If the passageway is narrower, the turnaround depth must be1525 mm. (60 in.). 

Our study was the only one of those compared in this report to evaluate 180-degree turning 

performance around the barrier. The results show that the current standards accommodate at 

least 90% of the powered chair users and manual wheelchair users, and almost 80% of the 

scooter users in our sample. However, they also demonstrate that the depth of the turn-around 

space could be reduced if the passageway width is at least 1095 mm. (43 in.).

Data Source Sample Size Min 5%ile Mean 80%ile 90%ile 95%ile Max

IDeA Center, U.S.

Manual chairs* 141 595 695 880 995 995 1095 1295

Power chairs* 105 595 695 887.5 995 995 995 1195

Scooters* 9 895 895 995 1095 1095 1095 1095

Overall 255 595 695 887.5 995 995 1095 1295

* indicates data plotted in the graph

Figure 3-12. 180-degree turning width around barrier: research findings versus the standards.
Anthropometry of Wheeled Mobility | 61

3.3.13 360-Degree Turn

The standards on the space requirements for a 360-degree turn are quite similar across countries, 

ranging from 1500 mm (59 in.) in Canada and the U.K. to1525 mm (60 in.) in the U.S. 

Less than 50% of our manual and powered wheelchair users completed a 360-degree turn within 

the United States standard turning diameter (Figure 3-12). None of our sample’s scooter users 

were able to complete a turn within the U.S. standard. In fact, the tightest 360 turn performed by 

a scooter user was 1900 mm (75 in.) in diameter! The 360-degree turning diameter would have 

to be increased to 2500 mm (a little over 98 in.) to accommodate our entire study sample.

In comparison, the UDI participants utilized a much larger space for the 360-degree turn in which 

no sides were blocked. A diameter of about 4200 mm (165 in.) would be needed to 

accommodate their entire sample. In our sample, scooter users overall require more space but the 

largest values for scooters, power chairs and manual chairs were very close. In the UDI sample, at 

least one power wheelchair user required a much larger clearance for the 360-degree turn (most 

likely the person with the “trailer” mentioned previously). 
Anthropometry of Wheeled Mobility | 62

Data Source Sample Size Min 5%ile Mean 80%ile 90%ile 95%ile Max

UDI, Canada

Power chairs – CW* - 1062 - 1939 - - - 2929

Power chairs – CCW - 1307 - 1957 - - - 2723

Scooters – CW* - 1186 - 2107 - - - 3622

Scooters – CCW - 1340 - 2128 - - - 3608

Power chairs and scooters - CW 41 1062 - 1997 - - 3007 3622

Power chairs and scooters - CCW 37 1307 - 2022 - - 2944 3608

IDeA Center, U.S.

Manual chairs* 185 1300 1300 1650 1900 1900 2100 2500

Power chairs* 139 1100 1300 1605 1900 2100 2100 2300

Scooters* 15 1900 1900 2100 2300 2380 2500 2500

All Device Types 339 1100 1300 1651 1900 2100 2100 2500

* indicates data plotted in the graph

Figure 3-13. 360-degree turning width area: research findings versus the standards.
Anthropometry of Wheeled Mobility | 63

3.3.14 Grip Strength

There were large differences in the percentage of individuals capable of completing the gripping 

tasks and, for those able to complete the tasks, the distribution of the grip strength for the three 

different grips were different between men and women, and across WhMD types (Figure 3-14). 

For power grips, the percentage capable of completing three repetitions of maximal grips 

ranged from 77% (male power wheelchair users) to 100% (male scooter users). Overall, fewer 

WhMD users were able to complete the lateral pinching tasks (e.g. 73-74% of power wheelchair 

users) and thumb-forefinger pinching tasks (e.g. 68-69% of power wheelchair users).

For those individuals able to complete the pinching tasks, the results showed that both the ability 

to perform a grip and the magnitude of maximum grip force are substantially affected by the 

type of hand grip being considered. In particular, the magnitude of maximum power grip forces 

was noticeably greater in a power grip than in a pinch grip. Further, between the two pinch grip 

postures, the data show lateral pinch grips to be marginally greater than thumb-forefinger pinch 

grips. 

Hand grip forces were typically greater for men than women, across users of the three different 

WhMD types. When compared across WhMD types, users of manual chairs typically produced 

the greatest magnitude of grip force, followed by scooter users and then lowest for power chair 

users. An exception to this trend was the lateral pinch grip forces among women. Not included in 

this analysis, are the effects of arm posture (e.g. elbow flexed at 90-degrees vs. an outstretched 

arm) (see D’Souza et al., in review), medical condition and age (see Joseph et al., 2010). 

A comparison with the ADA-ABA permissible force limit for operating controls showed that more 

than 95% of the sampled WhMD users who were able to perform a power grip could exert a 

maximum power grip force exceeding 5 lbf.

However, the 5 lbf force limit substantially exceeds the 5%tile values of grip for the pinch 

postures. For the WhMD users who were able to perform a power grip in this study, 

approximately 25% of the WhMD users could not exert a maximum lateral pinch force that 

exceeded 5 lbf. About 25% of male WhMD users and 50% of female WhMD users could not 

exert a thumb-forefinger grip that exceeded 5 lbf. 
Anthropometry of Wheeled Mobility | 64

Maximum Power 

Grip Force (lb-f)

Sample Size 

(% capable*) Min 5%ile 10%ile 25%ile Mean (SD) 95%ile Max

Men

Manual chair users 131 (89%) 1 27 40 55 75 (31) 129 162

Power chair users 77 (77%) 1 5 12 24 51 (31) 110 123

Scooter users 16 (100%) 25 25 29 47 61 (19) 87** 87

Women

Manual chair users 125 (97%) 12 18 21 30 42 (17) 70 103

Power chair users 72 (81%) 3 9 13 26 37 (17) 66 70

Scooter users 13 (93%) 12 12 13 31 39 (15) 63** 63

* Percent capable indicate the percentage of the sample (grouped by gender and device type) capable of 

successfully forming a hand grip and exerting a force for three repetitions of the prescribed grip postures.

** 95th percentile value same as maximum value due to small sample size.

Figure 3-14. Grip force: research findings versus the standard.
Anthropometry of Wheeled Mobility | 65

Maximum Lateral Pinch

Grip Force (lb-f)

Sample Size 

(% capable*) Min 5%ile 10%ile 25%ile Mean (SD) 95%ile Max

Men

Manual chair users 126 (86%) 1 3 4 8 13 (7) 25 27

Power chair users 73 (73%) 1 3 4 5 10 (6) 22 25

Scooter users 16 (100%) 2 2 3 6 11 (6) 20** 20

Women

Manual chair users 117 (91%) 0 1 2 4 7 (4) 16 20

Power chair users 66 (74%) 1 2 3 5 8 (4) 15 17

Scooter users 13 (93%) 3 3 4 8 9 (2) 14** 14

Max. Thumb-forefinger

Pinch Grip Force (lb-f)

Sample Size 

(% capable*) Min 5%ile 10%ile 25%ile Mean (SD) 95%ile Max

Men

Manual chair users 126 (86%) 1 2 4 6 10 (6) 22 25

Power chair users 68 (68%) 1 2 2 4 9 (6) 20 21

Scooter users 16 (100%) 1 1 2 5 8 (5) 19** 19

Women

Manual chair users 111 (86%) 0 1 2 3 6 (4) 15 24

Power chair users 61 (69%) 1 1 1 3 5 (9) 11 13

Scooter users 13 (93%) 3 3 3 4 6 (2) 12** 12

* Percent capable indicate the percentage of the sample (grouped by gender and device type) capable of 

successfully forming a pinch grip and exerting a force for three repetitions of the prescribed grip type.

** 95th percentile value same as maximum value due to small sample size.

Figure 3-14. Grip force: research findings versus the standard. (Cont’d)
Anthropometry of Wheeled Mobility | 66

3.3.15 Reach

3.3.15.1 Forward reach – unobstructed

A large percentage of WhMD users in our study could not reach beyond the most forward point 

of their WhMDs or foot, and the difference between users of different types of WhMDs was very 

large (Figure 3-15). For example, from among the 371 (75%) WhMD users in our study that 

could perform a reach task, only 78% of the manual chair users, 55% of the power chair users 

and 48% of the scooter users could reach beyond their mobility device or foot for at least one 

point between 600 mm (23.6 in.) and 1100 mm (43.3 in.) from the floor. Lower percentages in a 

forward reach for scooter users partially resulted from having to overcome a greater distance to 

reach over and/or around the front tiller, particularly at lower heights. Forward reaching 

capabilities for the three groups declined rapidly for heights above 1200 mm (47.2 in.) and 

below 600 mm (23.6 in.). Only 32% of our study’s manual wheelchair users, 22% of power chair 

users and 8% of the scooter users could complete forward reaches beyond the mobility device or 

foot at heights of 500-600 mm (19.7-23.6 in.). The lower limit of the U.S. standard would need to 

be raised from 380 mm (15 in.) to at least 600 mm (23.6 in.) in order to accommodate over 70%, 

50% and 38% of our study’s manual wheelchair users, powered chair users and scooter users, 

respectively.
Anthropometry of Wheeled Mobility | 67

% Capable (Forward Reach – Unobstructed)

Height from floor (mm) Manual chair users (n=235) Power chair users (n=110) Scooter users (n=26)

1900-2000 0 0 0

1800-1900 1 0 0

1700-1800 3 1 0

1600-1700 14 6 4

1500-1600 23 21 12

1400-1500 38 31 38

1300-1400 50 39 46

1200-1300 62 44 46

1100-1200 69 54 46

1000-1100 73 55 46

900-1000 76 56 50

800-900 77 57 46

700-800 76 55 38

600-700 71 52 38

500-600 32 22 8

400-500 4 2 0

300-400 0 0 0

200-300 0 0 0

100-200 0 0 0

0-100 0 0 0

Figure 3-15. Forward reach: research findings versus the standard. 
Anthropometry of Wheeled Mobility | 68

3.3.15.2 Side (lateral) reach - unobstructed

For WhMD users in our study that could perform a reach task, over 90% of each of the WhMD

user groups could reach beyond the lateral most point of their WhMDs for heights between 800

mm (31.5 in.) and 1400 mm (55 in.) (Figure 3-16) suggesting a marked improvement over a 

forward reach. Reach abilities began to drop at 600-700 mm (23.5-27.5 in.) and fell 

dramatically for all WhMD user groups at heights of 500-600 mm (19.5-23.5 in.). For heights of 

500-600 mm only 48% of manual wheelchair users, 32% of power wheelchair users and 22% of 

scooter users could complete a reach beyond the most lateral portion of their WhMD. In order to 

accommodate over 90% of the manual and powered chair users, and over 80% of the scooter 

users in our sample, a shift from 380-1220 mm (15-48 in.) to 700-1400 mm (27.5-55 in.) is 

needed. The improvement in side reaching performance with increased lower and upper limits as 

compared to the current standard is likely a function of larger (i.e. higher) WhMDs, and in some 

cases larger individuals who are now able to use WhMDs. 
Anthropometry of Wheeled Mobility | 69

% Capable (Side Reach – Unobstructed)

Height from floor (mm) Manual chair users (n=235) Power chair users (n=110) Scooter users (n=26)

1900-2000 1 0 4

1800-1900 1 0 4

1700-1800 6 8 8

1600-1700 38 27 54

1500-1600 64 56 88

1400-1500 87 84 96

1300-1400 97 94 96

1200-1300 99 95 96

1100-1200 99 96 96

1000-1100 99 96 96

900-1000 99 96 96

800-900 99 95 92

700-800 98 93 81

600-700 91 73 62

500-600 48 32 23

400-500 9 4 4

300-400 0 0 0

200-300 0 0 0

100-200 0 0 0

0-100 0 0 0

Figure 3-16. Side reach, unobstructed: research findings versus the standard.
Anthropometry of Wheeled Mobility | 70

3.3.15.3 Side (lateral) reach – over an obstruction depth of 610 mm

The vast majority of WhMD users in our study that displayed some reach capability could not 

reach at or beyond a 610 mm (24 in.) obstacle, regardless of height (Figure 3-17). There were 

also differences between users of different types of WhMDs. For heights that approximated the 

U.S. standard of 1170 mm (46 in.), only 31% of the manual wheelchair users, 24% of the power 

wheelchair users and 13% of the scooter users could reach 610 mm (24 in.) beyond the most 

lateral point of the WhMD. The results suggest that the recommended maximum depth of 610 mm 

(24 in.) obstruction would need to be reduced significantly in order to accommodate a majority of 

our study’s WhMD users.
Anthropometry of Wheeled Mobility | 71

% Capable (Side Reach – 610 mm obstruction)

Height from floor (mm) Manual chair users (n=235) Power chair users (n=110) Scooter users (n=26)

1900-2000 0 0 0

1800-1900 0 0 0

1700-1800 0 0 0

1600-1700 1 0 0

1500-1600 3 0 4

1400-1500 8 2 12

1300-1400 12 5 12

1200-1300 18 8 27

1100-1200 24 12 31

1000-1100 26 15 31

900-1000 31 15 35

800-900 35 23 27

700-800 33 24 23

600-700 29 19 23

500-600 17 6 0

400-500 0 2 0

300-400 0 0 0

200-300 0 0 0

100-200 0 0 0

0-100 0 0 0

Figure 3-17. Side reach, beyond a 610 mm obstruction: research findings versus the standard.
Anthropometry of Wheeled Mobility | 72

3.3.16 Door Use

A total of 144 WhMD users completed door use tasks for at least one of the doors. In some cases, 

WhMD users were not able to complete tasks involving other doors due to scheduling issues (i.e., 

lack of time) and building renovations. 

The differences in the sub-sample composition compared to the overall sample on demographic 

and anthropometric variables were generally small. Table 3-5 summarizes the descriptive 

statistics for the sub-sample. The sub-sample was on average younger than the overall sample 

(see Table 3-2). The differences in age are not unexpected since latter data collection efforts in 

Ithaca and in Buffalo involved targeting older adults who were not measured at the IDeA Center 

and therefore could not complete the door use tasks. Differences between the gender 

composition, occupied width, occupied length and maximum power grip strength were fairly 

modest. For example, the mean occupied width of the sub-sample was 10 mm (0.4 in.) less than 

the occupied width of the overall sample, and the occupied length of the sub-sample was only 6 

mm (0.2 in.) less than the overall sample (See Figures 3-3 and 3-4).
Anthropometry of Wheeled Mobility | 73

Table 3-5. Descriptive statistics for the sub-sample that completed the door use tasks.

Door type

Door 1 Door 2 Door 3 Total

Push Pull Push Pull Push Pull

Sample size

Subtotal - completed the 

task 144 142 128 128 127 104 144

Total 144 144 144 144 144 144 144

Gender

Women 72 (50%) 71 (50%) 65 (51%) 65 (51%) 59 (46%) 47 (44%) 72 (50%)

Men 72 (50%) 71 (50%) 63 (49%) 63 (49%) 68 (54%) 61 (56%) 72 (50%)

Age in years

Mean (SD) 50.0 

(13.7)

50.2 

(13.7)

50.1 

(14.1)

50.1 

(14.1)

49.5 

(13.5)

49.2 

(13.5) 50.0 (13.7)

Median 48.5 49.5 50 50 49 48.5 48.5

Range 18 - 88 18 - 88 18 - 88 18 - 88 18 - 85 18 - 82 18 - 88

Type of mobility device

Manual 77 (53%) 76 (54%) 68 (53%) 68 (53%) 68 (54%) 56 (52%) 77 (53%)

Power 51 (35%) 50 (35%) 45 (35%) 45 (35%) 45 (35%) 42 (39%) 51 (35%)

Scooter 16 (11%) 16 (11%) 16 (12%) 16 (12%) 14 (11%) 10 (9%) 16 (11%)

Occupied width (mm)

Mean (SD) 681 (65) 679 (62) 682 (66) 682 (66) 680 (63) 681 (58) 681 (65)

Median 671 670 673 673 672 672 671

Range 561 - 932 561 - 856 561 - 932 561 - 932 561 - 856 574 - 856 561 - 932

Occupied length (mm)

Mean (SD) 1165 

(115)

1163 

(112)

1165 

(117)

1165 

(117)

1160 

(115)

1156 

(108) 1165 (115)

Median 1166 1166 1166 1166 1163 1166 1166

Range 743 - 1487 743 - 1487 743 - 1487 743 - 1487 743 - 1482 743 - 1439 743 - 1487

Maximum power grip with arm extended (lbf)

Mean (SD) 54 (34) 55 (34) 54 (35) 54 (35) 56 (35) 57 (37) 54 (34)

Median 48 48 48 48 50 50 48

Range 0 - 162 0 - 162 0 - 162 0 - 162 0 - 162 0 - 162 0 - 162
Anthropometry of Wheeled Mobility | 74

The “Opening Maneuver” and “Operating Latch” door use tasks posed difficulties for very few 

WhMD users, requiring “minimal effort” for more than 85% of the trials (Table 3-6 a-b). Door use 

tasks that were found to present WhMD users with difficulty were “Opening”, “Through Passage”, 

“Closing Maneuver” and “Closing”. For these tasks, a significant percentage of trials were rated 

at “maximal effort” or “impossible” for at least one of the three doors (Table 3-6 c-f). 

WhMD users had more difficulty “Opening” door 3, as compared to doors 1 and 2. Fifty-two 

percent of the pushing trials were rated at “maximal effort” or “impossible” for door 3, as 

compared to 12% for door 1 and 9% for door 2 (Table 3-6 c). Forty percent of the pulling trials 

were rated at “maximal effort” or “impossible” for door 3, as compared to 13% for door 1and 

27% for door 2. The additional effort required of door 3 for the “Opening” task was expected

because door 3 had a mechanical closer that had a resistance of 7-8 lb-f. 

A higher percentage of WhMD users also had greater difficulty with “Through Passage” for door 

3 than doors 1 and 2. Forty-four percent of the pushing trials were rated at “maximal effort” or 

“impossible” for door 3, as compared to 11% for door 1 and 6% for door 2 (Table 3-6 d). 

Eighteen percent of the pulling trials were rated at “maximal effort” or “impossible” for door 3, 

as compared to 14% for door 1 and 11% for door 2. This was expected because of the closer 

and also because door 3 had a 6 mm (1/4 in.) threshold, and was the narrowest of the three 

doors (755 mm or 29.75 in.). The door most often rated as requiring “minimal effort” was door 2. 

It did not have a closer or threshold and was the widest (1040 mm or 41 in.). The presence of the 

closer requires the user to continue to apply pressure to the door while passing through the 

opening. 

The “Closing Maneuver” presented problems to WhMD users for each of the 3 doors studied. 

“Closing Maneuver” was rated at “maximal effort” or “impossible” for 36%, 26% and 100% of 

the pushing trials and 57%, 42%, and 100% of the pulling trials for doors 1, 2 and 3, 

respectively (Table 3-6 e). However, the very high number of “blocked view” trials for door 3 

(103 for pushing and 100 for pulling) is worth noting. Trials for this door were often not 

observable when the participant successfully passed through the door to the space beyond 

because the mechanical closer closed the door while the researcher remained on the side of the 

door where the trial started. Most, if not all, of these trials would have required minimal effort. If 

the “blocked view” trials for door 3 were categorized as either “minimal” or “moderate” effort, 
Anthropometry of Wheeled Mobility | 75

then only small percentage of the trials (19% for pushing) and (4% for pulling) would have been 

rated as “maximal effort” or “impossible” for the “Closing Maneuver). 

Similar results were found for the “Closing” task, although this task was the one likely to be rated 

as “maximal effort” or “impossible” (Table 3-6 f). One interesting finding, however, was that 

“Closing” trials were more likely to be rated as “minimum effort” for door 2 than door 1, despite 

door 2 being 215 mm (8.5 in.) wider than door 1. The difference in rating was therefore more 

likely to have been influenced by the latch side clearance than door size, especially on the pull 

side. Door 1 only had a 76 mm (3 in.) latch side clearance.

Differences in observed ratings of effort were also found between different device types for 

some of the door use tasks. For example, “Closing” trials involving scooter users were more likely 

to be rated “minimum effort” than trials involving manual or powered chairs for doors 1 and 2 

(Table 3-7 a, b). This may be because scooter users in general have greater upper extremity 

function and strength and can more easily close doors than those who use manual or powered 

wheelchairs.
Anthropometry of Wheeled Mobility | 76

Table 3-6 Observed level of effort for each of the tasks (a-f).

a.

Opening Maneuver Push Pull

Door 1 Door 2 Door 3 Door 1 Door 2 Door 3

Minimum effort (1) 92% 94% 92% 88% 94% 92%

Moderate effort (2) 3% 2% 1% 5% 4% 2%

Maximal effort (3) 5% 3% 6% 7% 2% 5%

Impossible (4) 0% 0% 1% 0% 0% 0%

Subtotal sample size (rated) 119 89 101 121 114 92

Blocked view (5) 25 39 26 21 14 12

Missing data 0 16 17 2 16 40

Total sample size 144 144 144 144 144 144

b.

Operating Latch Push Pull

Door 1 Door 2 Door 3 Door 1 Door 2 Door 3

Minimum effort (1) 86% 92% 87% 94% 94% 91%

Moderate effort (2) 5% 4% 5% 4% 3% 5%

Maximal effort (3) 7% 4% 8% 2% 3% 3%

Impossible (4) 3% 0% 1% 0% 0% 1%

Subtotal sample size (rated) 104 106 119 109 103 88

Blocked view (5) 40 22 8 33 25 16

Missing data 0 16 17 2 16 40

Total sample size 144 144 144 144 144 144

c.

Opening Push Pull

Door 1 Door 2 Door 3 Door 1 Door 2 Door 3

Minimum effort (1) 60% 72% 28% 67% 50% 19%

Moderate effort (2) 28% 20% 20% 20% 23% 41%

Maximal effort (3) 9% 9% 39% 13% 27% 37%

Impossible (4) 3% 0% 13% 0% 0% 3%

Subtotal sample size (rated) 141 123 127 140 128 103

Blocked view (5) 3 5 0 2 0 1

Missing data 0 16 17 2 16 40

Total sample size 144 144 144 144 144 144
Anthropometry of Wheeled Mobility | 77

Table 3-6 Observed level of effort for each of the tasks (a-f). (Cont’d)

d.

Through Passage Push Pull

Door 1 Door 2 Door 3 Door 1 Door 2 Door 3

Minimum effort (1) 58% 69% 22% 55% 67% 50%

Moderate effort (2) 31% 25% 33% 30% 22% 32%

Maximal effort (3) 7% 6% 25% 13% 10% 14%

Impossible (4) 4% 0% 19% 1% 1% 4%

Subtotal sample size (rated) 144 127 126 141 127 102

Blocked view (5) 0 1 1 1 1 2

Missing data 0 16 17 2 16 40

Total sample size 144 144 144 144 144 144

e.

Closing Maneuver Push Pull

Door 1 Door 2 Door 3 Door 1 Door 2 Door 3

Minimum effort (1) 37% 45% 0% 21% 33% 0%

Moderate effort (2) 27% 29% 0% 22% 25% 0%

Maximal effort (3) 32% 25% 0% 53% 40% 0%

Impossible (4) 4% 1% 100% 4% 2% 100%

Subtotal sample size (rated) 144 122 24 137 124 4

Blocked view (5) 0 6 103 5 4 100

Missing data 0 16 17 2 16 40

Total sample size 144 144 144 144 144 144

f.

Closing Push Pull

Door 1 Door 2 Door 3 Door 1 Door 2 Door 3

Minimum effort (1) 37% 42% 0% 13% 23% 0%

Moderate effort (2) 17% 31% 0% 11% 16% 0%

Maximal effort (3) 40% 26% 0% 66% 56% 0%

Impossible (4) 6% 1% 100% 10% 5% 100%

Subtotal sample size (rated) 142 125 24 136 122 4

Blocked view (5) 2 3 103 6 6 100

Missing data 0 16 17 2 16 40

Total sample size 144 144 144 144 144 144
Anthropometry of Wheeled Mobility | 78

Table 3-7 Observed level of effort for the “Closing” task by WhMD (a-b).

a. Level of effort for the closing task by type of mobility device

Closing - Push Door 1 Door 2 Door 3

Manual Power Scooter Manual Power Scooter Manual Power Scooter

Minimum effort (1) 33% 35% 56% 42% 37% 53% 0% 0% 0%

Moderate effort (2) 17% 16% 19% 30% 33% 33% 0% 0% 0%

Maximal effort (3) 43% 41% 25% 28% 28% 13% 0% 0% 0%

Impossible (4) 7% 8% 0% 0% 2% 0% 100% 100% 100%

Subtotal sample size 

(rated) 75 51 16 67 43 15 17 5 2

Blocked view (5) 2 0 0 1 2 0 51 40 12

Missing data 0 0 0 9 6 1 9 6 2

Total sample size 77 51 16 77 51 16 77 51 16

b.

Closing - Pull Door 1 Door 2 Door 3

Manual Power Scooter Manual Power Scooter Manual Power Scooter

Minimum effort (1) 12% 11% 25% 18% 24% 43% 0% 0% 0%

Moderate effort (2) 11% 9% 19% 20% 12% 14% 0% 0% 0%

Maximal effort (3) 67% 72% 44% 61% 55% 36% 0% 0% 0%

Impossible (4) 10% 9% 13% 2% 10% 7% 100% 100% 0%

Subtotal sample size 

(rated) 73 47 16 66 42 14 2 2 0

Blocked view (5) 3 3 0 2 3 1 51 39 10

Missing data 1 1 0 9 6 1 24 10 6

Total sample size 77 51 16 77 51 16 77 51 16
Anthropometry of Wheeled Mobility | 79
Anthropometry of Wheeled Mobility | 80
Anthropometry of Wheeled Mobility | 81

4.0 Implications for Standards and Design

4.1 Introduction

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. The U.S. standards are in greater need of change but the basis for many of the 

changes previously made to the standards in Canada, the U.K. and Australia can also be 

questioned in light of the research findings. Findings must be evaluated very carefully when used 

to make changes to standards. In particular, the impact of the methods used in research on 

findings needs to be studied in depth. Yet, the consistency of trends across the various research 

studies is quite good, given the wide variety of methods used. 

One obvious example of the need to revise standards is that WhMD users who require the highest 

knee clearances cannot be accommodated without making some radical changes to the design of 

counters, drinking fountains and other design features where knee and toe clearance is provided

specifically to provide accessibility. Policy makers have to make a decision about who should be 

accommodated by knee and toe clearances or identify alternative solutions like providing side 

access as well as front access or at least one fully accessible unit in a building or department. The 

results clearly provide evidence that adjustable and adaptable counters are a valuable design 

strategy. They suggest that more emphasis should be placed on adjustability and that the range 

of adjustment should be fairly large. 

As a second example, the reach limits also require some significant rethinking. The idea that a 

control or operable hardware located on a plane in front of the user can be accessible with a 

forward reach, regardless of the height, is not substantiated by this research. Knee and toe 

clearance must be provided under the plane of the device so that WhMD users can get closer to 

their target in order to provide an accessible forward reach. The safety problems we noted for 

low side reach questions the use of low side reach limits in accessibility standards. This reach limit 

should be used to identify the low range of safe reach but not to specify the location of all outlets 

or other devices. The result would be that outlets and other devices would all be so high that they 

would be dysfunctional. As an alternative, perhaps one outlet in a room or a work station area 

could be required to be within the safe reach range.
Anthropometry of Wheeled Mobility | 82

A third example is that the reference WhMD that has been used as the basis for standards, as 

depicted in the U.S. ADA-ABA, AS1428 and BS8300:2001 are manual wheelchairs. The 

Canadian standard, however, includes illustrations and data on scooters and power wheelchairs. 

This information can be very valuable to designers who are seeking to ensure full accessibility 

beyond minimum required levels and should be included in all accessibility standards. Designers 

could benefit from more information on device size to plan spaces like storage areas for 

wheelchairs, the design of counter edges in relationship to armrests, spaces, elements not explicitly 

covered by standards and new products. Additional illustrations and data are needed to convey 

the diversity in the devices and their occupants, especially other types of WhMDs. 

To provide realistic guidance for designers, information on wheeled mobility dimensions should 

include occupied sizes as well as device size; both in percentile form, and also include accessories 

as they are used in everyday life. Occupied device sizes are clearly preferable and more useful 

for designers than unoccupied sizes but it is not uniformly provided in the standards. For example,

the U.S. standards are inconsistent, showing occupied length but unoccupied width. Although data 

on device sizes is available from manufacturers, it does not include actual dimensions as set up for 

individuals nor does it provide data on added equipment like seating systems, cushions, control 

boxes, ventilators, carrying baskets and other accessories. The studies reviewed for our 

comparative analysis did not always include accessories as part of their dimensions and 

measurements (e.g. Stait et al., 2000; Hitchcock et al., 2006). A more comprehensive list of key 

findings can be found later in this section.

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 
Anthropometry of Wheeled Mobility | 83

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 
Anthropometry of Wheeled Mobility | 84

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.

4.3 Specific Recommendations

4.3.1 Reference WhMD Users

The original ADAAG included, in its Appendix, only one reference WhMD user – a male in a 

manual wheelchair, while the ADA-ABA does not have any. Our results demonstrate that the 

WhMD population is quite diverse in terms of sizes and functional abilities and that there are 

significant differences between users of different types of WhMDs. Including Reference WhMD 

Users in the document helps designers and officials understand the basis for many design criteria 

in standards and also to address design issues that may not appear in the standards at all. 

Having a set of multiple Reference Users as opposed to one can benefit designers significantly, 

and our data can be used to develop many different Reference WhMD Users. We recommend 

that at minimum three be provided, one each for manual wheelchairs, power wheelchairs and 

scooters. The Reference Users should include plan and elevation drawings and have key 

dimensions coded with a corresponding table of values for each code showing the 5th, 25th, 50th, 

75th and 95th percentile for both men and women. At minimum, the Reference WhMD Users should 

have data on unoccupied and occupied length and width, total occupied height, eye height and 

armrest height. They should also have data on accessories and equipment often attached to 

WhMD.

Three examples illustrate the need for the incorporation of this information in standards:

1. Occupied Height: Information on the occupied height of WhMDs is often needed in 

design of amusement attractions, playground equipment, museum exhibits and 

vehicles. 
Anthropometry of Wheeled Mobility | 85

2. Lines of Sight: Currently, the ADA-ABA has requirements for clear sight lines from 

seating areas reserved for WhMD users. But, there are no anthropometric data 

provided to evaluate compliance with those requirements. Basic data on eye 

height is needed in the standard to help designers determine whether lines of sight 

are adequate. 

3. Armrest height: The height of armrests on WhMD is useful for design of work 

stations, dining areas and other equipment and furnishings that WhMD users 

approach as close as possible. A Reference WhMD User could provide that 

information which is currently unavailable.

Tables showing results from the structural measurements of these three dimensions are provided in 

Appendix 2.

4.3.2 Seat Height

Seat height is an important dimension for establishing the height of built-in seating, toilet heights, 

tub heights, shower seat heights and other transfer related surfaces. Keeping the height of a 

transfer surface close to the height of a wheelchair seat reduces the effort necessary to transfer 

and provides a safer environment, especially in bathing and toilet rooms. However, seat height 

for wheelchair users can be significantly different than comfortable seat height for ambulant 

people. Seat heights for transfer surfaces in the ADA-ABA are 430 mm - 485 mm (17 in. - 19 in.) 

for water closets, shower seats and tub seats and 405 mm - 485 mm (16 in. -19 in.) for pool 

transfer lifts. 

Our research results indicate that a range of seat heights is appropriate to accommodate the 

wide variety of different needs. Ranges for built elements should accommodate ambulatory 

individuals as well because they are the vast majority of the population. Designing only for 

WhMD users would cause discomfort and safety problems for too many people. Our findings 

show that the values of the current U.S. accessibility standards are below the mean values of each 

of the three WhMD user groups. The mean occupied seat heights were 495 mm (19.5 in.) for 

manual chair users, 538 mm (21.2 inches) for power chair users and 549 mm (21.6 in.) for scooter 

users. For the manual chair users, the 5th -95th percentile range was 430 mm - 566 mm (17 in. -

22.3 in.). Therefore, the current accessibility standards are more accommodating to those WhMD

users with low occupied seat heights. If the goal is to accommodate the mean seat height for each 

of the WhMD user groups, a range of 495 mm – 549 mm (19.5 in. - 21.6 in.) is likely to be more 
Anthropometry of Wheeled Mobility | 86

accommodating. An application of these results could be in the design of fixed toilet heights. If the 

goal is to accommodate the 5th percentile occupied manual chair user seat height and the 95th

percentile scooter user seat height, a range of 430 mm - 635 mm (17 in. - 25 in.) is needed. 

Conventional seating heights are within a ranch of 381 mm - 406 mm (15 in. -16 in.) for adults. 

Thus, designing even for the range of WhMD users would cause a problem for everyone else. This 

finding suggests that the solution to the problem should be sought in technology rather than 

building standards, just like it has with ergonomic office chairs. The findings could be applied to 

establish the range of height adjustable seat and support surfaces. Meanwhile, we recommend 

that the current top of the acceptable range be increased to 508 mm (20 in.) and that 

consideration be given to providing an assistive technology solution, a seat riser, in temporary 

lodging settings.

4.3.3 Clear Floor Area

Clear floor area dimensions are the basis for the minimum required size of spaces used by 

wheeled mobility users (e.g. platform/wheelchair lifts) and for spaces/locations that are 

designated for wheeled mobility users such as in seating areas of movie theatres and sports 

stadiums and in securement spaces of vehicles like transit buses. The clear floor area width also 

informs the minimum clearance width for successful passage through corridors, doorways and 

ramps. In some of these applications, adding more space for maneuvering may be required.

The accommodation model (Figure 4-1) illustrates the 50th, 75th, 90th and 95th percentile values 

for the research results computed for occupied length and width across manual chair, powered 

chair and scooter users using data from our study. The 95th percentile dimension values for 

occupied length and breadth provide a reasonable threshold value for determining the 

dimensions for clear floor area length and breadth. Details about the measurement methodology 

and study sample can be found in (D’Souza et al., 2010b; Steinfeld et al., 2010a; 2010b).

To accommodate the 95th percentile values of both occupied width and length requires a 

minimum clear floor area dimensions of 786 mm x 1362 mm (31 in. x 54 in.) for manual chairs, 

827 mm x 1415 mm (33 in. x 56 in.) for powered chairs, 837 mm x 1435 mm (33 in. x 56 in.) for 

scooters. These sets of dimensions are most applicable when the objective is to accommodate one 

of the dimensions, i.e., either occupied length or occupied width. For example, when designing an 
Anthropometry of Wheeled Mobility | 87

alcove at the side of a large open space where the length of a device must be addressed but the 

width is not an issue because there is plenty of room to one side. 

But, one individual may have a very wide occupied length but narrow occupied width. Thus, use of 

results from an analysis that considers both dimensions at once when computing percentiles (a bivariate approach) is more preferable when the goal is to accommodate 95% of the total 

population (see D’Souza et al., 2010b). Using this method, the minimum clear floor area 

dimensions recommended for accommodating 95% of the WhMD users based on a bi-variate 

analysis are: 820 mm x 1420 mm (32 in. x 56 in.) for manual chair users, 850 mm x 1480 mm 

(33.5 in. x 58 in.) for powered chair users, and 860 mm x 1440 mm (34 in. x 57 in.) for scooter 

users.

For applications where all of three types of mobility devices (i.e., manual chair, powered chair 

and scooters) need to be accommodated, the largest of the occupied length and width values 

across the three device categories should be used. Thus, a “universal space” to accommodate 

95% of the total population would be 860 mm x 1480 mm (34 in. x 58 in.). 

The implications of these dimensions are that most of the current dimensions used in the ADA-ABA 

are inadequate for the larger mobility device users, especially power chair and scooter users. The 

basic clear floor space requirement, 760 mm x 1220 mm (30 in. x 48 in.), should be increased. 

However, the required wheelchair seating space sizes in public assembly areas are actually 

about the same size as the “universal space” with one exception, the front or rear entry condition. 

The depth of this space should be increased from 1220 mm (48 in.) to 1480 mm (58 in.), or, to be 

consistent with the side entry condition, 1525 mm (60 in.) required by the ADA-ABA. While this 

would still make it a tight fit for maneuvering into the space for the largest users, it would only 

inconvenience a few people. Requiring some rear or front entry seating areas in each facility 

could be an alternative strategy. 

Where aisles and other spaces adjoin the clear floor area, the real need for the “universal 

space” may be minimal. For example, the occasional very long occupied device can be 

accommodated without too much inconvenience to people passing by or interference with minimum 

egress requirements. Also, where several wheelchair seating spaces are provided at once, it is 

unlikely that all the occupants approach or exceed the 95th percentile in both length and width. In 

other words, a certain amount of overlap with other spaces and between spaces could be 
Anthropometry of Wheeled Mobility | 88

provided to reduce the impact on space utilization without serious consequences. Thus, in the ADAABA clear floor space for two devices, a lower overall width of 1676 mm (66 in.) is probably 

sufficient.

Figure 4-1: Accommodation model depicting the clear floor space for users of manual wheelchairs, 

powered wheelchairs, and scooters.

Long Description: This data provides the minimum dimensions for the rectangular floor area 

required by occupied wheeled mobility devices (i.e., with the occupant seated in their own wheeled 

mobility device) when stationary. Clear floor area dimensions are used for determining the size of 

spaces designated for wheeled mobility users (such as on buses, in movie theaters, sports stadiums). 

The clear floor area width dimension also informs the minimum clearance width for successful 

passage through corridors, doorways, and wheelchair ramps. Currently, the ADA accessibility 

guidelines prescribe a minimum floor area of 760 x 1220 mm (30 x 48 in.) for wheeled mobility 

access. Dimensions are based on length and width measurements obtained from occupied wheeled 

mobility devices as part of the Anthropometry of Wheeled Mobility Study. These data suggest 

minimum clear floor area dimensions of 786 x 1362 mm (31 x 54 in.) for manual chairs, 827 x 

1414 mm (33 x 56 in.) for powered chairs, and 837 x 1435 mm (33 x 56 in.) for scooters when 

needing to accommodate 95% of users.
Anthropometry of Wheeled Mobility | 89

4.3.4 Knee and Toe Clearances

Adequate space without an obstruction under a design element to the floor is essential for WhMD

users to approach sufficiently close in a forward direction to access equipment, controls, goods 

and other items, and to participate effectively in activities such as eating and work. Such 

clearance space is also critical when using building elements like bathroom sinks, drinking 

fountains, kitchen counter‐tops, information kiosks and ATM machines. 

In the current ADA-ABA standards, the clearances for knee and toe space are treated separately. 

But, in other countries, they are addressed together. We believe that they work together and that 

it would be more effective to present them in this way to avoid confusion in design application 

and compliance reviews. None of the standards we reviewed addressed the relationship of knee 

and toe clearances to anatomical and equipment reference points or landmarks. This makes it 

difficult to take anthropometric data and apply it to the existing standards. For example, the 

ADA-ABA has a sloped line indicating the depth of knee clearance at the plane of the knees and 

the depth somewhere above the ankles. But neither top nor bottom landmark is clearly specified. 

In fact, up to now, we did not have research information on the angle of the slope. Moreover, the 

standards do not address this design issue in practical terms. For example, the ADA-ABA has a 

minimum knee clearance depth of 280 mm (11 in.), but the combined knee and toe clearance 

depth required for an individual to bring their torso to the edge of a table or counter is not 

specified. 

Therefore, we developed a new representation method for knee and toe clearances that can be 

related directly to landmarks on the body and device. Four different accommodation models 

were developed depicting knee and foot clearance spaces for different positions of the 

individual in relationship to the built element: 

1. The forward‐most point of the body or equipment touching a facing wall (Anterior‐most 

point as reference);

2. The crease of the foot and lower leg in contact with the built element (Dorsal foot point as 

reference);

3. The forward‐most point of the knee in contact with the element (Distal Knee point as 

reference);
Anthropometry of Wheeled Mobility | 90

4. The forward‐most point of the abdomen in contact with the element (Anterior-most 

abdomen point as reference). 

Shown below are the first (figure 4- 2) and fourth (figure 4-3) accommodation models developed 

for manual wheelchair users. The shaded areas in the figures depict the envelope of the space 

required by a specified proportion of manual wheelchair users. These graphical representations 

provide information on the minimum knee and foot clearance height and depth needed in order 

to accommodate a specific proportion of the sample (e.g. 95%, 90%, 75%, etc.). 

Each model applies to a different design scenario. The designer should select the model that is 

most appropriate for the task or activity to be conducted at a location and physical constraints in 

the environment. For example, a safe under an ATM may restrict the depth of the toe clearance, 

thus the first model would be used. But, in designing a desk for filling out a job application, there 

is no technical reason for restricting the depth of toe clearance but the leading edge of the desk 

should be as close to the abdomen as possible. Thus the fourth model is more appropriate. 

The accommodation models are very useful for designers and product manufacturers. For 

simplicity, it would be good if standards had only one illustration. The following dimensions on 

knee and toe clearances should be used to accommodate 95% of our study sample on all four 

dimensions:

• Toe clearance depth: 127 mm (5 in.) maximum, measured from wall

• Toe clearance height: 356 mm (14 in.) minimum , measured from the floor

• Knee clearance height: 711 mm (28 in.) minimum, measured from the floor

• Knee clearance depth: 305 mm (12 in.) minimum, measured from the leading edge 

of the toe clearance or 406 (16 in.) minimum, measured from the wall if there is no 

separate toe clearance.

• Knee clearance depth for workstations, lunch counters and dining tables: 813 mm 

(32 in.) minimum, measured from the wall.

Knee clearance should not be sloped, in other words, it should be the same depth throughout. 

Toe clearances at cabinets and other locations without knee clearance should be a minimum 127 

mm (5 in.) high but a minimum or maximum limit is not necessary. 

Overlap of toe clearance and turning clearances can be allowed.
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Figure 4-2: Knee and toe clearances with the forward‐most point of the body or equipment 

touching a facing wall (Anterior‐most point as reference)

Long Description: This depicts knee and toe clearance required by manual chair users for forward 

approach to elements in the built environment (e.g., light switches). It references dimensions of 

clearance height and depth to the forward-most point on the person or mobility device (e.g., toe, 

footrest). Shaded areas depict the envelope of space required by the specified percentage of 

people if positioned with the forward-most point touching the wall. Hence, to accommodate a 

particular percentage of users, the side profile of a design element (shown by dotted line) should 

not extend outside the corresponding shaded area.
Anthropometry of Wheeled Mobility | 92

Figure 4-3: The forward‐most point of the abdomen in contact with the element (Anterior-most 

abdomen point as reference). 

Note: In order to accommodate a specified proportion of users (e.g. 95% of the sample), the side 

profile of a design element shown by the dotted line should not extend beyond the corresponding 

envelope (e.g., the solid line marked 95%). For a given design scenario, specific dimension values 

for clearance height and depths can be read off the horizontal and vertical axis of the figure.

Long Description: This depicts knee and toe clearance required by manual chair users for forward 

approach to elements in the built environment (e.g., dining tables). It references dimensions of 

clearance height and depth to the forward-most abdomen point on a person. Shaded areas depict 

the envelope of space required by the specified percentage of people if positioned with the 

abdomen touching an obstruction. Hence, to accommodate a particular percentage of users, the 

side profile of a design element (shown by dotted line) should not extend outside the 

corresponding shaded area.
Anthropometry of Wheeled Mobility | 93

4.3.5 Turning clearance

The ADA-ABA Standards include requirements for a circular turning space, a T shaped turning 

space, a L-Turn (90-degree turn) and a U-Turn (180-degree turn) around an obstacle. In our 

research several turning maneuvers were studied: the 360-degree turn, the 180-degree turn, the 

180-degree turn around a barrier and a 90-degree turn. In confined dead end spaces, a 360-

degree turn should be used as the basis for the minimum space required since individuals often 

move around within small space without actually leaving it. A 180-degree turn is more 

appropriate as a basis for defining a minimum space bounded only on two sides and the 

individual has an open space to use along the axis of the turn. T shaped space is not included 

here because it can be derived from the 90-degree turn to establish the width of the arms of the 

T and the clear floor space to determine the length of each arm. The overall width should be the 

same in both arms. The same values should be used for the 90-degree turn and the T-turn. 

The accommodation models and our recommendations are addressed individually below. In 

general, standards should give some guidance on where each of these turning spaces should be 

used. For example, the 180-degree turn around an obstruction should be used at ramp landings 

rather than the 180-degree unobstructed turn clearance. 

4.3.5.1 90-Degree Turn

This turning clearance is applicable for exterior and interior circulation, aisles in seating areas, 

ramps and other locations. The width of circulation spaces should be wider to accommodate twoway traffic and egress requirements. 

The mean values for scooters in our sample are in excess of the current standards. In addition, less 

than 80% of power and manual wheelchair users in our sample are accommodated by the 

standard. We recommend revising the ADA-ABA standard for 90-degree turning width to 1000 

mm (39 in.) which would accommodate at least 95% of our sample. Figure 4-4 shows the 

accommodation model of the minimum clear width required for the 90-degree turn.
Anthropometry of Wheeled Mobility | 94

Figure 4-4: Accommodation model depicting the minimum clear width required by users of manual 

wheelchairs, powered wheelchairs and scooters to complete a 90-degree turn.

Long Description: This data depicts the amount of space required by users of wheeled mobility 

devices to perform a 90-degree turn ("L-Turn"). The bold dashed line in the table and figure 

indicates the current ADA requirement of a 91.5 cm (36 in.) passage width. Findings from the 

Anthropometry of Wheeled Mobility Study indicate that a width of at least 85 cm (33 in.) was 

required for 50% of the manual and power wheelchair users measured in this study to perform a 

90-degree turn. A width of 100 cm (39 in.) was required in order for 95% of manual wheelchair 

and power chair users to complete the turn, with 95% of scooter users needing a width of at least 

110 cm (43 in.) These data are based on measurements of wheeled mobility users performing 90-

degree turns in a hallway, built with mock walls. The outside wall of the hallway was fixed. The 

other side of each leg had moveable walls. The enclosed space was incrementally increased until a 

user could pass through the turn successfully. The minimum space required for completing a 90-

degree turn within moving or knocking down any of the walls was recorded. Use of multiple short 

turns was allowed in contrast to a single continuous turn.
Anthropometry of Wheeled Mobility | 95

4.3.5.2 180-degree turn

Currently, the ADA-ABA does not have a specific clearance for this type of turn. The 1525 mm 

(60 in.) turning space would be used instead. Our research findings for this turn apply to corridors 

and other circulation spaces are bounded by two parallel walls or three walls. Our findings 

indicated that a width of 1700 mm (67 in.) would accommodate 95% of manual and power 

wheelchair users and 90% of the scooter users. Accommodation of additional scooter users would 

increase this dimension by 18 mm (7 in.) (Figure 4-5).

Figure 4-5: Accommodation model depicting the minimum clear width required by users of manual 

wheelchairs, powered chairs and scooters to complete a 180-degree turn.

Long Description: This data depicts the amount of space required by users of wheeled mobility 

devices to perform a 180-degree turn. The bold dashed line in the table and figure indicates the 

current ADA requirement of a 152.5 cm (60 in.) space for wheeled mobility users to turn around. 

Findings from the Anthropometry of Wheeled Mobility Study indicate that a width of at least 130 

cm (51 in.) was required for 50% of the manual wheelchair users measured in this study to perform 

a 90-degree turn. A width of 170 cm (67 in.) was required in order for 95% of manual wheelchair 

and power chair users to complete the turn, with 95% of scooter users needing a width of at least 
Anthropometry of Wheeled Mobility | 96

210 cm (83 in.) These data are based on measurements of wheeled mobility users performing 180-

degree turns in a dead-end hallway, built with mock walls. The end wall and a second wall of the 

hallway were fixed. The other side of the hallway had a moveable wall. The hallway width was 

incrementally increased until a user could enter the space, turn around, and exit the space 

successfully. The minimum space required for completing 180-degree turn within moving or 

knocking down any of the walls was recorded. Use of multiple short turns was allowed in contrast 

to a single continuous turn.

4.3.5.3 180-degree turn around an obstacle

This type of turn is applicable to turning at a landing where one is reversing direction to move 

back along a parallel path, e.g. at the end aisles in library stacks or supermarkets, at switchback 

ramps or in a terminal queue. The current ADA-ABA standard for the space needed to complete 

maneuver is based on the width of the entry aisle and the width of the intervening obstacle, e.g. 

shelving. In our research, we studied the impact of keeping the depth of the turning area and the 

entry/egress aisle width identical. This provided the opportunity to discover if a wider aisle would 

lead to less required depth in the turning area. This was, in fact, the case. The accommodation 

model depicts the results with the condition that depth is the same as access and egress aisle 

width. We found that a width of 1065 mm (42 in.) for all three dimensions would accommodate 

more than 90% of the manual wheelchair and more than 95% of the power chair users but less 

than 80% of the scooter users. We recommend using this approach in future ADA-ABA standards 

with a minimum width of 1095 mm (43 in.) which would accommodate more than 95% of all 

WhMD users in the sample. This would increase the width slightly but reduce the depth of the 

turning area significantly. When the entry and egress aisles are less than this width, the 360-

degree turn clearances should be provided at the turning area. In effect, this condition is a space 

bounded by three sides and requires a lot more space because WhMD users cannot cut the corner 

like they can with a wider aisle width (Figure 4-6).
Anthropometry of Wheeled Mobility | 97

Figure 4-6: Accommodation model depicting the minimum clear width required by users of manual 

wheelchairs, powered wheelchairs and scooters to complete a 180-degree turn around an obstacle.

Long Description: This data depicts the amount of space required by users of wheeled mobility 

devices to perform a 180-degree turn ("U-Turn") around an obstruction. The bold dashed line in 

the table and figure indicates the current ADA requirements, which vary based on the passage 

width and space available at the base of the turn. Findings from the Anthropometry of Wheeled 

Mobility Study indicate that a uniform width of at least 89.5 cm (35 in.) was required for 50% of 

the manual and power wheelchair users measured in this study to perform a 180-degree turn 

around the obstruction. A width of 109.5 cm (43 in.) was required in order to accommodate 95% 

of all users. These data are based on measurements of wheeled mobility users performing 180-

degree turns around an obstruction, built with mock walls. An obstruction of 11 cm (4 in.) was fixed 

at a central location. Three moveable walls were constructed around the central fixed wall to form 

a U-shaped hallway of equal passage width. The enclosed space was incrementally and uniformly 

increased until a user could pass through the U-turn successfully. The minimum space required for 

completing a 180-degree turn around an obstruction within moving or knocking down any of the 

walls was recorded. Use of multiple short turns was allowed in contrast to a single continuous turn.
Anthropometry of Wheeled Mobility | 98

4.3.5.4 360-degree Turn

Accommodation models for 360-degree turns have been developed for the three types of 

devices based on the results (e.g. Figure 4-7). There are substantial differences between the 

device types. Scooters require the largest turning spaces and manual chairs the least although 

there are some manual chair users that required spaces as large as many power chair users. The 

use of the 95th percentile in the power chair findings would increase the current requirements by 

575 mm (23 in.). The size of the space required for the 95th percentile of scooter users would 

create even larger increases. Thus, due to the potential impact, these findings require some policy 

decisions on who to exclude, or a new way to address this design issue. 

Dimensions for 360-degree turning spaces are used to determine the minimum spaces needed for 

turning around in spaces with only one point of entry. To better represent these situations, we

based our measurements on a square-shaped space rather than circular as the former allows 

WhMD users to use the corners thereby optimizing space utilization. In spaces in which turning 

around is not critical for usability, another basis for determining the minimum floor area can be 

used as in the Fair Housing Accessibility Guidelines which only require a clear floor space outside 

the arc of a swinging door. This strategy is also already used for elevators and toilet stalls in the 

ADA-ABA Guidelines. A second strategy is to provide a turning space in all covered public spaces 

like toilet rooms, laundries and shared kitchenettes to accommodate the 50th or 75th percentile 

and, in addition, require at least one of each type of space somewhere in a building to be large 

enough to accommodate the largest devices. For example, one companion toilet room could be 

required in every building that accommodates both assisted use and the largest devices while the 

other toilet rooms meet less space intensive requirements. The largest turning space could also be 

required in places where the impact of increasing turning spaces is insignificant, for example, in a 

lobby or outdoors. Obviously, better space planning can also be used to avoid dead end spaces 

entirely but that cannot be mandated in a standard. 

The implications of these findings are so significant that the authors recommend starting broad 

discussion of options among stakeholders before a concrete proposal is made to adopt a 

particular strategy. 
Anthropometry of Wheeled Mobility | 99

Figure 4-7: Accommodation model depicting the minimum clear space required by users of manual 

wheelchairs, powered chairs and scooters to complete a 360-degree turn.

Long Description: This data depicts the amount of space required by users of wheeled mobility 

devices to perform a 360-degree turn. The bold dashed line in the table and figure indicates the 

current ADA requirement of a 152.5 cm (60 in.) turn space. Findings from the Anthropometry of 

Wheeled Mobility Study indicate that a square space of at least 160 x 160 cm (63 in.) was 

required for 50% of the manual wheelchair users measured in this study to perform a 360-degree 

turn. A space of 210 x 210 cm (83 in.) was required in order for 95% of manual wheelchair and 

power chair users to complete the turn, with 95% of scooter users needing a space of at least 250 

x 250 cm (98 in.) These data are based on measurements of wheeled mobility users performing 

360-degree turns within an enclosed square space built with mock walls. The enclosed space was 

incrementally varied from a size of 130 x 130 cm (51 in.) to 250 x 250 cm (98 in.) The minimum 

space required for completing 360-degree turn within moving or knocking down any of the walls 

was recorded. Use of multiple short turns was allowed in contrast to a single continuous turn.
Anthropometry of Wheeled Mobility | 100

4.3.6 Reach Limits 

Accommodation models were developed from the research findings for forward and side (lateral) 

reach in an empty 56 grams (2 oz.) cylinder (figure 4-8) and a heavier 2.27 kg. (5 lb.) cylinder 

(see Appendix 3). In our research, only a subset of the individuals in the study sample who could 

lift a no-weight (56 grams or 2 oz.) cylinder above their shoulder were measured for reach limits. 

This insures that the accommodation models are not biased by individuals who have limited 

functional reaching abilities. Using these models, a designer can determine the percentage of 

wheeled mobility users with functional reaching ability that might be expected to reach (without a 

weight) to a 100 mm x 100 mm (3.9 in. x 3.9 in.) target location in space at a given height from 

the floor. The distance in each case can be measured from the location of the hands at the end of 

the reach to any number of reference points on the WhMD user’s body or chair. The 

corresponding percentages are color coded to differentiate regions of reach performance. 

Percentages of reaching ability drop significantly when the object mass is increased from 56 

grams (2 oz.) to 2.27 kg. (5 lb.). With weights that weigh more than 56 grams (2 oz.), we found 

that 20-25% of all three WhMD users could not reach to the same heights as to the no-weight 

condition. The dashed lines in the figures show the current ADA-ABA requirement which specifies a 

threshold value of 1220 mm (48 in.) when reaching to a target located in front of an individual at 

the plane of the toes or front of footrests, or “anterior most point” (for details on the development 

of the models, see D’Souza et al. (2009a).

The design and standards implications of the research findings are as follows:

1. Side reach access is far more preferable to forward reach access, which is quite restricted 

among the wheelchair user population. Targets at locations along the plane of the anterior 

most point will not be within the reach of a majority of wheeled mobility users, even if the 

maximum reach height limit were reduced to shoulder height. 

2. When forward reach is the only alternative, knee clearance should be provided that 

allows an individual to extend their legs and front part of their wheelchair beyond the 

plane on which the target is located. This will allow many more individuals to reach to 

targets in a forward approach. For the accommodation model of forward reach, the 

depth of knee clearance needed to accommodate different proportions of the sample can 

be determined by the columns with negative offset distances and can be interpreted as 

the increase in ‘percent capable’ (e.g. 74% or 88% of the sample) for every 100 mm (3.9 

in.) increase in available toe or knee clearance. 

3. The upper height limit in the current ADA-ABA standard for unobstructed side reach, 1220 

mm (48 in.) will accommodate the 99th, 95th and 96th percentile of manual wheelchair, 
Anthropometry of Wheeled Mobility | 101

power chair and scooter users in our sample. Thus, there is no need to change that 

dimension. However, a large percentage of the sub-sample of individuals who had 

functional reach could not safely reach to the lower limit of 380 mm (15 in.). Our results 

also indicate that the upper limit of reach could be increased for wheeled mobility users 

but this may result in limitations for people of small stature.

4. Standards developers should consider requiring either side reach access to all targets 

within the scope of standards or limiting front reach to locations where knee clearance is 

provided beyond the plane on which the target is located. The lower limit of side reach 

should be increased to 700 mm (28 in.). We recommend that the lower limit only be 

applied to controls and devices that are needed for business services (e.g. recharging 

station for mobile phones or wheelchairs). For long term use in work sites, power strips 

should be used to provide access to outlets. 

5. When designing environments for tasks that require lifting objects, avoid designs that 

require people to reach to objects above counter height. Adjustable storage units that 

building occupants can customize to their own needs can improve usability. Devices like 

sliding shelves that reduce the length of reach tasks are another beneficial strategy.

 

6. Standards developers should give some consideration to the task in relationship to reach. 

Reach limits for storage units where lifting objects are inherent in their use, could be 

different than for other tasks. We believe that this issue requires discussion since there are 

other approaches to accommodating limited reach as noted above.
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Figure 4-8: An accommodation model showing the abilities of the manual wheelchair users to 

complete a forward reach without lifting weight

Long Description: These data depict the reaching abilities of manual chair users represented as 

the percentage of users expected to reach to a target location in the forward reach direction for a 

given (a) height from the floor (shown the vertical axis) and (b) offset distance (shown on the 

horizontal axis) from the forward-most point of the person or wheelchair (e.g., toe, footrest). 

Horizontal distances in the positive range represent offset distance away from the body (or 

barrier depth) when reaching over an obstruction in relation to the forward-most point, and the 

negative range implying that the reach target is brought closer to the person (such as on a table 

with knee clearance). The percentages are color coded to differentiate regions in reach 

performance. The dashed lines indicate the current ADA-ABA requirement.
Anthropometry of Wheeled Mobility | 103

4.3.7 Clear Floor Space for Reaching

Clear floor space dimensions for reaching are different than for seating because they require a 

specific orientation to the target. This type of clear floor space should be used at light switches, 

wall outlets and other wall-mounted elements. Further, they can be applied to the operation of 

windows, access to items on a shelf or countertop, operating a telephone, automatic teller 

machines (ATM), information kiosks, and other places where reaching is required.

The longest reach distance from the WhMD will usually be at the approximate height and lateral 

direction of the shoulder joint. For forward reaches, the longest reach range will also be at the 

level of the shoulder unless the individual has an upper extremity impairment that affects range of 

motion. Reaching across the body will reduce the effective reach distance due to the reduced 

radius of reach. Generally, clear floor space for reaching should take into account how an 

individual will be oriented when reaching and seek to optimize the range of reach. 

About 25% of the individuals in our sample were left-dominant, which is about double the 

frequency of left hand dominance in the population at large (Raymond et al., 1996). Bi-lateral 

access is desirable to insure adequate functional reach to targets, especially given that 

wheelchair users may only have functional reach and gripping ability in one arm and hand. Thus, 

we developed an accommodation model for clear floor space adapted for bi-lateral reach.

Accommodation models were developed for the three wheeled mobility device types, manual 

wheelchair users, powered chair users, and scooter users (figure 4-9). The accommodation models

provide guidance on the dimensions and location for clear floor space in relation to the reach 

target to accommodate:

• left and right hand users, and

• use of a forward or sideways (lateral) approach, when reaching or grasping.

For applications where all of three types of mobility devices (i.e. manual chair, powered chair 

and scooters) need to be accommodated, the largest of the occupied length and width values 

across the three device categories should be used. The models can be used to develop a right 

handed or left handed approach space but using the full space delineated in the model would 

result in a “universal approach space” that will allow all building users to perform tasks in a way 

that is most comfortable, i.e. using the right or left hand, and a forward or lateral approach 
Anthropometry of Wheeled Mobility | 104

direction. The 95th percentile values for the four measurement dimensions provide a reasonable 

threshold values for developing standards. As described above under Clear Floor Space, current 

clear floor space requirements for reaching in the ADA-ABA Standards do not accommodate the 

full range of contemporary wheelchairs.

The following recommendations should be implemented to specify the position of the clear floor 

space more appropriately than as in current standards:

1. Where reaching is critical for completing a task, e.g. an ATM machine, the universal clear 

floor space for reach (see accommodation model) should be provided and centered on 

the target. The size of the space should accommodate the 95th percentile of scooter users 

to accommodate the full range WhMD users. 

2. For all other reach tasks, a square clear floor space, 1430 mm x 1430 mm (56 x 56 in.) 

should be provided, centered on the target. This will allow almost all device users to 

position themselves close to the target using either a front or a side reach and enough 

leeway for most device users to align their shoulder close to an axis on the target. But, it 

does not optimize for handedness.
Anthropometry of Wheeled Mobility | 105

Figure 4-9: Accommodation model depicting the dimensions and positioning of the clear floor space 

required by manual wheelchair, powered chair, and scooter users when using either the right or 

left hand, for both forward and lateral reach.

Long Description: This data depicts the amount of clear floor area required by persons using wheeled mobility 

devices when performing a forward or side reach to a target location (e.g., reaching to a light switch on the wall) 

with either the right or left hand. The accompanying table provides dimensions values for clear floor area to 

accommodate 95% of manual chair (n=276), power chair (n=189), and scooter (n=30) users that were measured as 

part of the Anthropometry of Wheeled Mobility study. The dimensions of clear floor area are based on four 

anthropometry dimensions. These dimensions are: (A) occupied width, the horizontal distance between the side-most 

(lateral-most) points of the wheelchair or occupant on the right and left side; (B) occupied length, the horizontal 

distance from the front-most (anterior-most) point of the wheelchair or occupant to the rear-most (posterior-most) point 

of the wheelchair or occupant; (C)the horizontal distance from the reaching shoulder to the front-most (anterior-most) 

point of the wheelchair or occupant; (D) the horizontal distance from the reaching shoulder to the side-most (lateralmost) point on the opposite (contra-lateral) side of the wheelchair or occupant.
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Although not specified in the ADA-ABA, the position of the clear floor space for reach in 

relationship to the target has been interpreted to be centered on the target. Centering, however,

reduces functional reaching ability since the shortest reach is on an axis through the shoulder joint 

at a 90 or 180-degree reach angle. Centering requires a longer reach across the body. The 

universal clear floor space for reach, shown in the figure above, is designed to accommodate 

bilateral reach, thus it takes the offset of shoulder point to the lateral and anterior most points of 

the clear floor area into account and does not require a cross body reach.

To optimize for handedness using only enough space for a forward reach or side reach, the clear 

floor space has to be offset from either the lateral most edge of the space (front reach) or the 

anterior most edge of the space (side reach):

1. Front reach: Typically, the shoulder joint is about 175 mm (7 in.) inboard from the extreme 

lateral most point of occupied WhMD. This offset should be used for locating the clear 

floor space in relationship to the target. This means that the clear floor space would be 

offset, from the target, a distance of 175 mm (7 in.) to the right for a right-handed 

approach and 175 mm (7 in.) to the left for a left-handed approach. 

2. Side reach: The anterior most edge of the clear floor space needs to be offset to one side 

of the target so that the shoulder is aligned with the reach target or slightly behind it. 

Offsetting the anterior most edge of the space by 1193 mm (45 in.) from the target will 

accommodate the 95th percentile of scooter users and, thus, provide sufficient room for 

everyone else to optimize their reach. 

Note that using the offsets above is not feasible with the current ADA-ABA standard of 760 mm 

(30 in.) x 1220 mm (48 in.). 
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Figure 4-10: Offsets required when positioning the clear floor space in relation to the reach target 

in (a) forward reach, and (b) side reach. 

Long Description: The figure shows two plan views of occupied WhMD, one for lateral and one for 

forward reach, with the target of reach positioned on axis with the shoulder joint of the device 

user. The forward reach plan shows the target offset 175 mm (7 in.) from the outside edge of the 

occupied device and the side reach plan shows the target offset 1193 mm (45 in.) from the 

anterior most point of the occupied device. 

4.3.8 Operating forces

Operating forces are applied with a wide variety of grip forms (see Steinfeld, 1990). In this 

research we measured performance using three common grips – a power grip, lateral pinch and 

thumb-forefinger pinch grips. From these data, we can only make some broad conclusions for 

design and standards based on a large sample of people with relatively severe disabilities. 

Designers should reduce the need for high precision grip postures and/or pinch forces given the 

lack of finger dexterity, motor control or pinching capabilities of persons with disabilities. This can

be achieved by designs that allow operation using alternate grip configurations such as a flat 

hand, fist or a more convenient power grip or hook grip. Broader handles and larger gripping 

surface areas facilitate stronger grips.

When a precision pinch grip is required, a lateral pinch is recommended over a thumb‐forefinger 

tip pinch grip because a lateral pinch grip provides a larger finger contact surface; the grip 

strength capabilities of our sample was higher for lateral pinch grip as compared thumb-
Anthropometry of Wheeled Mobility | 108

forefinger pinch grip. Individuals with limited finger dexterity and strength are also more likely to 

be capable of forming this grip. 

Use of operable parts that require fine grips preferably should not require exertion of lateral 

pinch grip forces in excess of 2 lbf (9 N) to accommodate the vast majority of WhMD users 

having at least some grasping capability. For other types of operable parts, the upper limit for 

operating force should be retained at a maximum of 5 lbf (22 N) to accommodate 95% of the 

sample. 

Further, tasks and products that require operation of controls or object grasping should allow for 

both right‐ and left‐handed operation, given that more than 25% of wheeled mobility device 

users in this study were left‐hand dominant. Adequate clear floor space should be provided to 

access controls and switches from either the left or the right (see previous description of ‘Clear 

Floor Space for Reaching’).

A large proportion of wheeled mobility device users possess functional capabilities in only one 

hand. Hand‐operated products and environmental features for use by the general public should 

be designed acknowledging that grip strength is significantly affected by gender, age and 

disability, and that a sizeable proportion of WhMD users (approx. 12% in our sample) have very 

limited or no grasping ability. 

Grip strength data from our study can help designers employ more inclusive design criteria when 

developing new designs, as well as identify tasks that require pinch grip force exertion that 

exceed the capabilities of most users and need to be redesigned possibly through use of 

technological interventions and assistive devices. For example, many drawers or cabinets require 

tight pinching to open but adding a more ergonomically designed handle and rollers to the 

bottom of the drawer allows it to open with ease.

The ADA-ABA standards currently require operation with only one hand and without “tight 

grasping, pinching or twisting of the wrist”. This is a major step toward reducing demands on 

people with limitations of grip. However, the standards do not require left and right hand 

operation, and the maximum operating force allowed substantially exceeds the abilities of a 

large number of individuals in our sample for objects requiring a fine grip. Moreover, the 

standards preclude the use of a pinch grip, which is desirable to people who are able to use it 
Anthropometry of Wheeled Mobility | 109

effectively. Not allowing such grips at all may create usability problems for even more building 

users than it helps. 

Our findings suggest developing a more detailed approach to grips and grip forces in the 

standards. This should include:

• Identifying maximum operating force requirements based on the types of grips and forces 

exerted.

• For small controls and hardware that normally would be operated with pinch grips, the 

maximum operating force should be 2 lbf (9 N).

• For larger controls and hardware that can be operated with a power grip, the maximum 

force requirements could be retained at 5 lbf (22 N) bearing in mind that this still does not 

address the needs of many WhMD users having very limited or no grasping ability.

• The 5 lbf (22.2 N) maximum force could be retained for operating forces for opening 

doors. This limit was based on the limitations of door closer technology.

• Developing specific requirements for alternative gripping options without precluding 

pinch grips, e.g. flat hand, knuckle push, based on existing research on hand 

anthropometry (e.g. Steinfeld, 1990)

• Retaining the requirement for use by only one hand.

• Utilizing standard terminology from anthropometry in reference to grip forms; the 

standards could list the types of grips and movements, including alternatives to standard 

grip forms that would be allowed. Information of this type is available from a previous 

Access Board study (Steinfeld, 1990; Steinfeld and Mullick, 1990).

Improving standards related to operating forces requires a careful examination of the 

availability of products that would be accessible to this population and the cost implications of 

new requirements. This would identify the limits to feasible improvements to the standards and 

may require adjusting the force limits to address feasible implementation. 

4.3.9 Doorway Design 

We did not obtain quantitative data on performance in our door use research. Thus there are no 

accommodation models for this topic. The results of the door trials identify relationships between 

structural anthropometry and identify needed modifications to current requirements. 
Anthropometry of Wheeled Mobility | 110

The results of the door maneuvering studies confirmed the importance of many common 

accessibility code requirements. They also demonstrated a need to make some improvements to 

standards to provide access for the broad population of wheeled mobility users. The implications 

of the research findings are summarized below:

A wider clear opening than current ADA-ABA standards 815 mm (32 in.) would improve usability. 

Adopting a clear opening width of 860 mm (34 in.) would accommodate the widest occupied 

devices in our sample. This would also be small enough to allow a 91 cm (36 in.) door leaf, a size 

that is already used extensively for accessibility and fire safety. Consideration should be given to 

aligning U.S. requirements with the metric system. For example, a 90 cm door is slightly smaller 

than a 91 cm door but is standard elsewhere in the world and would accommodate our entire 

sample.

The very wide door that was tested 1041 mm (41 in.) clear opening did not increase the difficulty 

of using doors. The findings demonstrate that wider doors are better for accessibility and there is 

no need to put an upper limit on the size of doors in regulations at this time, although doors wider 

than this could pose some problems.

The lack of differences between the findings for the passage task on the pull sides of Doors 1, 

800 mm (31.5 in.) latch clearance, and Door 2, 406 mm (16 in.) latch clearance, demonstrate that 

an 457 mm (18 in.) clearance required in recessed doors is acceptable although we do not have 

data to demonstrate whether the 305 mm (12 in.) latch clearance on other doors is satisfactory. In 

historic preservation, some allowances should be made for difficult renovation issues like the 

recess in Door 3 where the structure of the building would not only make adjusting the recess 

extremely difficult and costly but also would also impact its historic character. 

Closers are not necessarily bad for accessibility. In fact, they reduce the difficulty of the most 

difficult maneuvering tasks, i.e. closing maneuver and closing tasks. Their impact on passage 

through the door indicates that they must be set to the lowest operating force possible to insure 

that they accommodate the broadest population. 

Since the closing maneuver is the most difficult aspect of door use for wheelchair users,

development of a low cost electromechanical closer that would not increase opening force would 

benefit wheelchair users significantly. It should have microprocessor control that would activate the 
Anthropometry of Wheeled Mobility | 111

closer only when a door is closing. When opened, a presence sensor could activate the closing 

cycle when an individual passed through the door. 

Automating frequently used doors that are kept closed and require closers will increase 

accessibility substantially, especially on exterior doors where the operating forces are higher to 

conserve energy and insure positive latching. Requiring at least one automated door at primary 

entries would be highly desirable. This would increase usability for more than 10% of the 

wheelchair users in our sample and have multiple benefits for all building users: eliminating 

difficulty using the latch, enabling the opening maneuver, and eliminating difficulty closing the 

door. In addition, with proper placement of an activator to open the door, it eliminates the need 

for a latch side clearance. 
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5.0 Dissemination Activities

Dissemination activities related to the project have included publications, conference 

presentations, standards development, an online course and knowledge translation activities. 

Some of these activities started prior to the beginning of the current contract and have continued. 

Others have only recently been started.

Completion of reports alone is not sufficient to ensure that the knowledge generated from 

research will be translated to practice. The IDeA Center uses a general model of knowledge 

translation called “knowledge to action” (KtA model) in all its activities (Graham et al., 2006). The 

basic idea of this model is that effective follow up activities are needed to insure that research 

knowledge is applied in the real world. Lane and Flagg (2010) developed a variation of the KtA 

model called the Need to Knowledge (NtK) model in which research is integrated into the 

development process. In this way, research and development activities inform each other and the 

knowledge to facilitate knowledge translation. 

This project is an excellent example of the NtK model in practice. It started as a response to a 

recognized need for information to advance accessible design and standards development. At an 

early stage of the project, the research team gave attention to the future uses of the data that 

would be produced. Data collection was automated and methods of disseminating the database 

in digital form were investigated to facilitate applications of the knowledge. The project have 

short-, intermediate- and long-term goals. The primary short-term goals are to develop a 

prototype database that would serve as the foundation for continued anthropometry research on 

disabled people and produce dissemination products to apply the knowledge discovered. The 

intermediate-term goal is to provide knowledge to improve existing standards. The long-term 

goal is to produce a human modeling application that can be used in computer-aided design in 

everyday practice. 

Other research at the IDeA Center has been investigating the needs for information in the design 

professions, in particular, how designers used knowledge on accessibility and universal design in 

their work (Paquet et al., 2008a; 2008b). This work helped us to understand how designers are 

currently using accessibility information and adjust our dissemination strategy. Through this work 

and our outreach activities, we learned that a database would not in itself produce knowledge in 
Anthropometry of Wheeled Mobility | 115

a form that could be easily adopted in design. Designers want information like that found in 

codes – “Tell us what we should do” they said. Although 3-D design is now common, few 

environmental designers use human modeling software. In some industries, like the transit bus 

industry, even 3-D design is rarely used except in the production process. Moreover, standards 

developers work within the framework of a rigidly defined process in which interested parties 

offer proposals for changes to standards, including precise wording changes, accompanied by 

supporting information. A database alone would not provide information in a form that could be 

used easily in that process. Thus, we decided we had to expand the types of dissemination 

products we would develop to fit more with the way designers and standards developers 

currently work.

We developed a strategy that included several parallel activities:

1. Publication of conference papers and delivery of presentations to disseminate information 

about the project and create a community of interest in the work through face-to-face 

contact.

2. Publication of a series of refereed journal articles to disseminate the findings of the 

research in a form that would be targeted to specific revisions of standards and have high 

legitimacy (through peer review and archival quality) to support proposals for revisions of 

standards.

3. Holding two international workshops that provided a forum in which people from around 

the world exchanged ideas about the anthropometric study methods, digital human 

modeling and the application of anthropometric data in design.

4. Engagement in standards development activities, including the initiation of proposals for 

revisions helped to make the standards development community aware of the knowledge 

discovered in our research and obtain insight into dissemination needs and methods. 

5. Outreach to all stakeholders to develop a community of practice on the topic of 

anthropometry for people with disabilities.

6. Development of software that would facilitate the extraction of information for the 

activities above, facilitate use of the data in human modeling and support the expansion 

of data collection activities to other research groups. 

These activities are described in more detail below.
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Conference Papers and Journals

From the initial stages of the project, when it was funded by NIDRR, the research staff submitted 

and presented papers and presentations to annual and other periodic professional conferences. 

In all cases, our conference papers were peer reviewed and appeared in the proceedings of the 

conferences, if there were formal proceedings. We have presented 24 papers and additional 

presentations in the following associations and conferences:

1. Rehabilitation Engineering and Technology Society of North America (RESNA) annual 

conferences

2. Human Factors and Ergonomics Society annual conferences

3. Digital Human Modeling for Design and Engineering Symposium (annual)

4. International Applied Human Factors and Ergonomics (AHFE) annual conferences

5. INCLUDE (international bi-annual conference of design researchers interested in inclusive 

design)

6. International Conference on Aging Disability and Independence (international bi-annual 

conference)

7. Transportation Research Board annual conferences

8. TRANSED (international bi-annual conference of professionals interested in accessibility to 

public transportation)

9. American Institute of Architects annual conferences

In several conferences, we organized symposia or workshops on the topic of the anthropometry of 

disability. The latest examples were a workshop at the RESNA conference in June of 2010 that 

attracted an audience of about 100 rehabilitation professionals and scientists and a symposium 

at the AHFE. We have received extensive positive feedback on the quality and importance of the 

work.

Conference papers are short in format and thus are usually very focused. After developing 

conference papers, we expanded the papers and developed peer-reviewed articles for scientific 

journals. These articles are the gold standard of research publications because they are archived 

in research libraries and available through online searches. Rigorous peer review procedures 

insure a high quality. Acceptance for publication means that the article has been vetted by other 

experts and has reached or exceeded their standards of quality. We have published 8 peer 
Anthropometry of Wheeled Mobility | 117

reviewed journal articles and have several others in process. We edited two special issues of 

journals that included articles from both our research group and other colleagues working in this 

field. One appeared in the International Journal of Industrial Ergonomics (2004) and the other in 

Assistive Technology (2010). These two issues are now key resources for researchers in the field.

The published papers and journal articles are now available to provide evidence for proposed 

revisions to standards in a concise and carefully documented form. They provide background on 

the methods we developed for conducting the research, the importance of the specific topic to 

people with disabilities, the results of our research and the implications of those results for design, 

standards and policy. Topics addressed include the structural anthropometry methods, the 

functional anthropometry methods, clear floor area, reach, grip force, the interactive database, 

building design applications, transportation applications and the comparison of standards and 

research. The full list of publications is provided in the Appendix.

Workshops

With separate sponsorship from the U.S. Access Board prior to this project, we held two 

international workshops that focused on current issues of applying the anthropometric data of 

individuals with disability to design. These provided venues in which people from around the 

world exchanged ideas about the current issues in the collection of anthropometric data, digital 

human modeling and the applications of the data in design. In each, we also discussed the special 

nature of anthropometry of disability and wheeled mobility users in particular, for example, the 

limitations of using full body scanning due to occlusion of body landmarks by WhMD. 

“The Anthropometrics of Disability” workshop was held in June of 2001 and was attended by 40 

experts in the areas of anthropometry, human modeling, data fusion and population-based 

statistics. Participants included researchers, standards developers, experts in accessible design 

and wheelchair designers. A workshop report that summarizes the workshop’s outcomes is 

available at http://www.udeworld.com/anthropometrics.html. It describes advances in the state 

of the art in anthropometry, the challenges of measuring people with disabilities and 

recommendations made by the experts at the workshop. This report formed the foundation for a 

special issue of the International Journal of Industrial Ergonomics titled “Anthropometry and 

Disability” that was published in 2004.
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“Space Requirements for Wheeled Mobility” workshop was held in 2003. It was attended by 70 

experts from the U.S. and abroad. The participants represented the fields of anthropometry, 

biomechanics, human factors engineering, human modeling, rehabilitation engineering, standards 

development, wheelchair manufacturer and consumer advocacy. A second workshop report was 

produced and is available at http://www.udeworld.com/anthropometrics.html. It provides 

abstracts of commissioned and submitted papers as well as a description of the discussion that 

followed each paper presentation. The presentations made at this workshop formed the basis of 

what eventually became a special issue of Assistive Technology titled “Space Requirements for 

Wheeled Mobility” that was published in 2010.

Standards Development

Task 2 of this contract focuses on engagement in the International Standards Organization’s effort 

to develop an international standard on accessible building design. This task was included in the 

contract because a member of the Committee encouraged us to become involved in their activities 

with the goal of establishing an international research effort to utilize our methodology. The 

budget for the contract, however, only allocated travel funds to attend meetings. The staff effort 

was to be contributed by project staff. We first had to establish a vehicle for participating. We 

obtained approval to work through RESNA, which is the designated organization to represent the 

U.S. in ISO activities related to accessibility. But, after contacting the ISO committee leadership 

and talking to two other members, it turned out that our involvement was not particularly 

welcomed by committee members and leadership. They had almost completed their work and 

were reluctant to open their agenda to another round of development, revision and balloting. 

Thus, we terminated our effort on that task but also did not expend the travel funds allocated to it 

for international travel.

However, the project team has engaged in many other standards development activities: 

1. Revisions to ICC/ANSI A117

2. Development of Standards for Universal Design

3. Development of new accessibility standards in other countries

4. Revisions to ADA regulations on accessible transportation 
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The ICC A117.1 standard initiated a round of revisions in 2003, which only recently has been 

completed. At the beginning of the revision process, the Committee invited Dr. Steinfeld to make a 

presentation of the project at one of its meetings. Early in the review process, based on evidence 

from the initial data collection activities, the staff prepared a series of proposals for changes to 

the existing standard. Dr. Steinfeld made another presentation about the progress of the project 

during the balloting process. The Committee voted to establish a Task Force on Anthropometry to 

consider the implications of the research. Dr. Steinfeld was appointed to this Task Force. However, 

the Task Force had only two meetings, by teleconference. At the first meeting, they decided to 

table our proposals until the current work was completed. At the second meeting, the Task Force 

voted to begin work immediately after they finished the current cycle. Recently, the cycle was 

completed and the plan is now to begin meetings of the Task Force sometime after January 1, 

2011. We expect to work with this Committee over the next three years to develop a process for 

addressing the implications of our findings (see Section 4.0) for accessibility standards used in 

regulatory activities.

In 2008, an effort began to develop universal design (UD) standards through the newly formed 

Global Universal Design Commission (GUDC). The purpose of these standards is to complement 

minimum accessibility standards by providing the incentive of certification for achieving a higher 

level of accessibility and usability. Buildings will be certified based on the incorporation of 

universal design features. Designers will be accredited through an educational program. The first 

version of the GUDC standards, approved this past summer, utilized the findings of this research 

to incorporate higher levels of accessibility for wheelchair users than those that are currently 

incorporated into minimum accessibility standards. To support certification and accreditation 

efforts, the IDeA Center is developing a series of Design Resources summarizing knowledge from 

scientific research. One of the first sets of Design Resources is on the findings of this project. 

Although this is a voluntary effort, we expect that experience with the GUDC standards will 

identify best practice strategies for providing accessibility for the larger devices and individuals 

with more limited reaching and gripping abilities. Documenting these solutions will help to 

advance the field and build a base of support for improving mandatory standards. The first 

building designed with the new standards is under construction and we will be documenting and 

evaluating it over the next two years. 
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Through our dissemination efforts, knowledge about our work has been spreading around the 

world. The Province of Ontario (Canada) started an effort to revise its accessibility standards last 

year. The project team was contacted to provide input into the new standards. A presentation was 

made to the working committee developing policy recommendations. In the coming year, actual 

work on the standards will commence. We expect that the committee will utilize our findings to 

address the need for accessibility for larger devices. This standard will serve as a good model 

for drafting standards in the U.S. standards developers in Ireland are also working on improving 

their standards. They utilized our Design Resources and publications in their work and recently 

informed us that the new standards will incorporate larger turning areas that are based on our 

findings. 

This year the Access Board issued an NPRM on changes to the ADA requirements for transit 

vehicles. We submitted comments on the proposed rules with documentation based on our 

research findings. We are currently conducting additional research and development activities 

through another grant in which we will initially be developing tools for the transportation industry 

that will include the accommodation models and digital models for design of new vehicles. The 

next step will be to develop a “standard of practice” for the industry in accommodating WhMD

users that will include the use of these models as part of the design process. We hope to work 

with the American Public Transportation Association and/or SAE to develop those standards. 

Database Development

Three goals drove the development of the database software: 

1. Provide a flexible tool for standards developers to assess the implications of decisions in 

a “what if” mode.

2. Provide a resource that can support human modeling of wheeled mobility device users.

3. Provide a foundation for future multi-site and international research in this field.

Most anthropometry results are conveyed through tables and two-dimensional illustrations of the 

body. The availability of 3-D anthropometry tools like the ones we used and 3-D computer 

graphics provides the opportunity to develop much more sophisticated design tools that can be 

integrated into the design process for everyday use. Designers are rapidly adopting 3-D design 

software since lower cost products like SketchUp became available and increased competition. 

While most designers are not currently using digital human modeling software to test their designs 
Anthropometry of Wheeled Mobility | 121

for human fit on an everyday basis, there will someday be a market for low cost easy to use 

human modeling tools. Anticipating this eventuality, we developed a database with the ability to 

integrate the data with human modeling and 3-D design software. The 3-D coordinate data for 

each individual are archived as individual datasets in a relational database. This provides the 

ability to retrieve and analyze the data in many ways, including the ability to construct 3-D static 

digital representations of the individual and mobility device (D'Souza et al., 2007; 2010a), as 

well as generate summary statistics on a number of different body and device dimensions (Paquet 

& Feathers, 2004). 

The visual interface software to the database was developed using Microsoft Visual C++ and 

OpenGL (D’Souza et al., 2010a). The software application generates in runtime both graphical 

and numeric displays such as histograms, summary statistics, percentile values, etc. for a sub-group 

of individuals based on user-selected demographic and anthropometric variables (Figure 5-1), or 

digital human models of specific individual cases. These individual cases can be selected from a 

sub-sample using an interactive histogram that helps identify individuals who possess extreme or 

‘outlier’ values for a particular dimension, i.e. starting at the tails of the distribution. This provides 

designers and standards developers with in-depth information on the characteristics and 

functional abilities of certain individuals who present design needs beyond that of the typical 

wheelchair sub-sample.
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Figure 5-1. Example of interactive histogram of an anthropometric dimension (here overall length) that 

allows individuals (listed on the left) to be selected for additional analysis.

The user interface allows designers and standards developers to identify who could successfully fit 

in a clear floor space, or complete a maneuvering or reaching task in a particular environment in 

real time and who cannot (outliers). For example, in Figure 5-1 above, the histogram has two 

vertical lines on each side of the distribution. By sliding the lines right or left, the operator can 

define a target population by manipulating the parameters of the environment, in this case 

occupied length of the device. Data on that selected population appears at the top right as the 

bars are moved.

We have also integrated other information search capabilities. For example, a list of “outliers”, 

cases who are not accommodated by the parameters selected appear in the list at the top left of 

the screen in Figure 5-1. By clicking on any case, a window opens with the data for the individual 

selected. Photographs of that individual and the figure model can be accessed from that new 

screen (Figure 5-2). Using menu driven tools on the screen, operators can define sub-samples to 

analyze by selecting values for variables like age, gender, type of device used, etc., and the 

data for the selected sub-samples immediately appears. The data can be saved for comparison 

purposes. We developed interactive tools like this for device and occupant characteristics, 

maneuvering performance tasks, grip strength and reaching tasks (D'Souza et al., 2009a).
Anthropometry of Wheeled Mobility | 123

Figure 5-2. 3D human model and visualization of reach data of a female power wheelchair user.

Long Description: Figure 5-2 shows a photograph of a female power wheelchair user in the database 

along with the corresponding digital model and superimposed reach envelopes color-coded for different 

object weight conditions. Using 3-D coordinate data for constructing the model helps to create digital 

models that reflect the relative size, position and spatial orientation of individual body size and postures, 

and device size and shape. Reach envelopes are constructed using maximum reach distances recorded 

electromechanically in an object transfer task. These reach distances were measured in 3-D at five 

normalized shelf heights in three different directions (lateral, forward and an intermediate 45 degrees) 

resulting in 15 reach data points for each of four different weight conditions 0 kg, 0.45 kg, 1.36 kg and 

2.27 kg (0, 1, 3, 5 lbs.) to simulate reach and object placement conditions one might attempt during typical 

activities of daily living.

Through data collection activities with two subcontractors, we developed a training program and 

manual to teach other researchers how to collect the data. We also developed error-checking 

software that researchers can use once data is collected from a participant to reduce 

measurement error in the field. Finally, we developed software tools that allow us to complete 

quality assurance on data sets developed by others in order to identify missing data and errors in 

measurement. These can then be used to correct data before adding it to the database or delete 

inadequate data records. This last set of software tools also manages the input of the new data 

set with our existing archive. 

Now that data collection is complete, we will begin conducting other outreach activities that will 

include inviting other researchers to use our data and collect new data sets to add to the archive 

and potentially merge with ours. We will also offer use of the database to standards developers 

and policy makers, including the Access Board. We have considered providing web based access 

to the database but have concluded that it would take significant effort to support it. Thus, we are 

hesitant to make it widely available without having the resources to provide the support needed. 

We have approached human modeling software developers to ascertain their interest in using the 

database to incorporate human modeling of wheelchair users into their programs. One company 

that makes ergonomic modeling software has shown interest but, at this date, they have not been 
Anthropometry of Wheeled Mobility | 124

willing to invest their own funds to develop such applications. We believe that this lack of interest 

indicates that there is not yet a clear market for such a product. Most commercial human modeling 

software are used for biomechanical analysis (e.g. evaluation of low back stress during lifting, 

etc.) and for animation. Thus, commercial tools are focused primarily on those activities, not 

anthropometric fit. We will continue discussions with them and engage discussion with other 

companies. We may also seek funding to develop our own “plug-ins” that can interface with 

commercial programs. 

Online Course

A self-instructional online educational course has been developed to use in continuing education 

and installed on an IDeA Center website (http://www.udeworld.com/training/continuingeducation.html). This course is designed to meet the requirements of the American Institute of 

Architects for online learning (the IDeA Center is an accredited provider). It provides an overview 

of the project, three modules on the findings, implications for design and a link to resources like 

the reference list of publications derived from the project, the Final Report and the collection of 

Design Resources. Completing the evaluation quiz sends an email with results to the IDeA Center 

for review. The online course is designed for expansion by adding more modules. It will be 

managed and administered through the IDeA Center’s online education program. The Access 

Board can also use this program for its own educational efforts. 
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6.0 Conclusions

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 U.S. standards, especially the power chairs and scooters.

9. Knee and toe clearances: 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. 
Anthropometry of Wheeled Mobility | 128

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. The 

database is available for other invited researchers to utilize. The data is also available for use 

by human modeling software developers to augment their databases of people with no 

disabilities. The research team anticipates the development of future research collaborations, 

dissemination activities and standards development activities.

Much was learned about anthropometry of wheeled mobility during the course of this project. Yet, 

much more needs to be discovered. In particular, there is a need to continue gathering data to 

keep pace with developments in practice. A good model is the periodic survey conducted in the 

U.K. (Stait et al., 2000; Hitchcock et al., 2006). While the research methods used in the U.K. 

program (2-D photogrammetry) only provide data on limited landmarks like occupied width and 

length and the features of devices, it can be used to identify trends in equipment used by 

consumers and the need for targeted studies on specific types of devices. 

Having established an extensive database, the need to measure a large number of people with 

three-dimensional methods is now reduced. The current data archives will provide sufficient data 

to answer many research questions. But, the findings show that different data collection sites have 

access to different user groups. Thus another important research activity in this field should be the 

development of a long range data collection effort on a national scale with a diverse set of 
Anthropometry of Wheeled Mobility | 129

research settings. Small numbers of people can be measured by cooperating with clinical settings 

and equipment moved from place to place. Developing a network of data collection settings in 

academic rehabilitation science departments or major clinical settings could also help to improve 

education on accessibility for the rehabilitation professions, an important stakeholder group, and 

build capacity for research. 

Research that would produce longitudinal data on WhMD use would be very useful, especially to 

improve WhMD design and reimbursement policies. The current sample could serve as a 

recruitment pool for such a project. When recruiting individuals, we asked for permission to retain 

their contact information for future research and most participants agreed. Some are already 

participating in other research at the IDeA Center. Our demographic survey results and other 

anecdotal information obtained by WhMD users suggests that wheeled mobility device users 

often have more than one device, use different devices for different purposes and have unmet 

needs for equipment that are not being addressed by current third party reimbursement policies. 

An individual’s needs also change over time with age and stage of life as they pursue different 

social roles and their body changes. In particular, the impact of progressive diseases like MS, ALS,

Parkinson’s Disease and Post Polio Syndrome, on equipment needs requires more information. A 

longitudinal study could identify the long-range experience of consumers of devices. It could also 

explore the needs for consumer education and changes in purchasing policy to improve 

appropriate selection of devices for the environments in which they are used. 

In-depth studies with small samples are needed to understand the interaction of wheeled mobility 

users with the built environment. The resources available in this study were devoted to measuring 

a large sample of individuals. In-depth studies are needed on the performance of WhMD users in 

specific environments such as workstations, paratransit vehicles and taxis, rest rooms on vehicles, 

doorways and ramps. More extensive research on doors than what was conducted in this project 

would be valuable as well. Such studies should examine the effect of learning on task 

performance. Currently, the IDeA Center has in-depth studies underway on short ramps, public 

transit buses and outdoor walking surfaces. We are applying new research methods to collect 

data on participants in motion in order to develop dynamic human models. Many of our research 

participants come from our sample pool and we will complete structural measurements for new 

participants as they are recruited and add those measurements to the database archive. The new 

research will allow us to study the relationships between demographic variables, structural and 
Anthropometry of Wheeled Mobility | 130

functional anthropometric variables, and task performance in motion, similar to what we did with 

the door maneuvering study but including quantitative body motion analysis performance 

variables. 

In dissemination, the research team will continue to publish refereed journal articles based on our 

research. Updates will be made to existing articles on reach, clear floor area, turning space and 

structural measurements. New articles will be completed on door maneuvering, and knee and toe 

clearance. We will also prepare a proposal to a scientific book publisher to produce an 

authoritative book on the anthropometry of wheeled mobility that brings all the articles that we 

and our colleagues at other research centers have written together. This publication will also 

include all the accommodation models. 

The long-range goal of applying the database through human modeling needs continued 

attention. We hope this will occur first through efforts to develop a standard practice on 

accessible design of transportation vehicles. This will include the further development and testing 

of the accommodation models and the development of a series of 3-D virtual manikins that can be 

used to test vehicle designs in virtual 3-D space. Outreach will also be conducted to find a human 

modeling software producer to adopt the database as part of a commercial product. 

In standards development, the first priority will be to work with the Task Force on Anthropometry 

of the ICC/ANSI A117 Committee, the Province of Ontario Committee and the GUDC Consensus 

Standards for Commercial Buildings Committee, all of which have expressed strong interest in our 

findings and recommendations. Working with three standards groups simultaneously, we hope to 

evolve a new approach to the “building blocks” of wheeled mobility anthropometry that can take 

into account larger devices in a cost effective manner.

Another important stakeholder group in the standards field is RESNA’s WC-19 Committee on 

wheelchair standards. The major U.S. wheelchair manufacturers are also involved in this effort. 

This seems to be the most likely venue to engage the industry in developing initiatives to develop 

wheelchairs that provide more accessibility in the built environment and consumer and 

professional education materials to inform customers and rehabilitation practitioners on the 

features they should seek when purchasing equipment. Engaging experts from the manufacturing 

sector and R&D organizations to assess the future of WhMD design is very important both in 

learning what changes may be on the horizon that could affect anthropometry of WhMD and also 
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to help improve the usability of new products within the built environment. RESNA is another good 

venue for this type of effort. 

There is also a need for further education among those in the design professions, consumers and 

those in the rehabilitation science professions. By providing the existing online course to all three 

audiences, we can assess additional educational needs and evaluate its features and content. This 

feedback will be used to make improvements in the current course. It will also help to define the 

priorities for further modules which could include additional design issues, research methodology, 

use of the interactive database, and design applications. This educational work can include 

findings from current targeted research studies underway at the IDeA Center. The present course 

is designed to fit the scope of a self-instructional module but future development could also 

include a longer-range program with instructors for a more extensive and in-depth continuing 

education experience. 
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Appendix One: List of References
Anthropometry of Wheeled Mobility | 133

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Cooper, R. A., and Cooper, R. (2003). Trends and issues in wheeled mobility technologies. 

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D’Souza, C., Steinfeld, E., and Paquet, V. (2009b). Functional reach for wheeled mobility device 

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Anthropometry of Wheeled Mobility | 137

Appendix Two: Design Information and Accommodation Models
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Appendix Two: Design Information and Accommodation Models

Table 1. Research findings on Occupied Height

Type of WhMD user Sample Size Mean (SD) Min 5%ile 10%ile Median 90%ile 95%ile Max

Manual chair users 276 1249 (77) 1020 1123 1144 1253 1347 1376 1459

Power chair users 189 1274 (81) 1000 1140 1153 1281 1373 1392 1492

Scooter users 30 1321 (71) 1218 1220 1242 1316 1434 1477 1513

All Device Users 495 1263 (80) 1000 1130 1152 1267 1360 1385 1513

Table 2. Research findings on Eye Height, measured on the right eye

Type of WhMD user Sample Size Mean (SD) Min 5%ile 10%ile Median 90%ile 95%ile Max

Power chair users 189 1167 (75) 932 1032 1068 1168 1261 1281 1365

Scooter users 30 1210 (68) 1093 1110 1129 1195 1324 1364 1387

All Device Users 495 1152 (77) 898 1021 1049 1155 1248 1269 1387

Table 3. Study findings on Armrest height, calculated as the mean height of the four corner points of the arm 

rest on the right side measured from the floor. The data does not include height measurements from the fifty 

WhMD users that had no right-side armrest.

Type of WhMD user Sample Size Mean (SD) Min 5%ile 10%ile Median 90%ile 95%ile Max

Manual chair users 228 704 (36) 568 650 661 709 748 757 796

Power chair users 189 726 (53) 593 642 666 719 802 816 876

Scooter users 28 745 (43) 677 679 688 735 812 838 843

All Device Users 445 716 (46) 568 645 663 713 781 801 876
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This data provides the minimum dimensions for the rectangular floor area required by occupied wheeled mobility devices (i.e., with the 

occupant seated in their own wheeled mobility device) when stationary. Clear floor area dimensions are used for determining the size 

of spaces designated for wheeled mobility users (such as on buses, in movie theaters, sports stadiums). The clear floor area width 

dimension also informs the minimum clearance width for successful passage through corridors, doorways, and wheelchair ramps. 

Currently, the ADA accessibility guidelines prescribe a minimum floor area of 760 x 1220 mm (30 x 48 in.) for wheeled mobility 

access. Dimensions are based on length and width measurements obtained from occupied wheeled mobility devices as part of the 

Anthropometry of Wheeled Mobility Study. These data suggest minimum clear floor area dimensions of 786 x 1362 mm (31 x 54 in.) 

for manual chairs, 827 x 1414 mm (33 x 56 in.) for powered chairs, and 837 x 1435 mm (33 x 56 in.) for scooters when needing to 

accommodate 95% of users.
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This depicts knee and toe clearance required by manual chair users for forward approach to elements in the built environment (e.g., 

light switches). It references dimensions of clearance height and depth to the forward-most point on the person or mobility device (e.g., 

toe, footrest). Shaded areas depict the envelope of space required by the specified percentage of people if positioned with the 

forward-most point touching the wall. Hence, to accommodate a particular percentage of users, the side profile of a design element 

(shown by dotted line) should not extend outside the corresponding shaded area.
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This depicts knee and toe clearance required by manual chair users for forward approach to elements in the built environment (e.g., 

countertops). It references dimensions of clearance height and depth to the dorsal foot point on a person (e.g., top of ankle). Shaded 

areas depict the envelope of space required by the specified percentage of people if positioned with the dorsal foot point touching an 
Anthropometry of Wheeled Mobility | 137

obstruction. Hence, to accommodate a particular percentage of users, the side profile of a design element (shown by dotted line) should 

not extend outside the corresponding shaded area.

This depicts knee and toe clearance required by manual chair users for forward approach to elements in the built environment (e.g., 

lavatories, drinking fountains). It references dimensions of clearance height and depth to the distal knee point on a person. Shaded 

areas depict the envelope of space required by the specified percentage of people if positioned with the distal knee point touching an 
Anthropometry of Wheeled Mobility | 138

obstruction. Hence, to accommodate a particular percentage of users, the side profile of a design element (shown by dotted line) should 

not extend outside the corresponding shaded area.

This depicts knee and toe clearance required by manual chair users for forward approach to elements in the built environment (e.g., 

dining tables). It references dimensions of clearance height and depth to the forward-most abdomen point on a person. Shaded areas 

depict the envelope of space required by the specified percentage of people if positioned with the abdomen touching an obstruction. 
Anthropometry of Wheeled Mobility | 139

Hence, to accommodate a particular percentage of users, the side profile of a design element (shown by dotted line) should not extend 

outside the corresponding shaded area.

These data depict the reaching abilities of manual chair users represented as the percentage of users expected to reach to a target 

location in the forward reach direction for a given (a) height from the floor (shown the vertical axis) and (b) offset distance (shown on 

the horizontal axis) from the forward-most point of the person or wheelchair (e.g., toe, footrest). Horizontal distances in the positive 

range represent offset distance away from the body (or barrier depth) when reaching over an obstruction in relation to the forwardmost point, and the negative range implying that the reach target is brought closer to the person (such as on a table with knee 
Anthropometry of Wheeled Mobility | 140

clearance). The percentages are color coded to differentiate regions in reach performance. The dashed lines indicate the current ADAABA requirement.
Anthropometry of Wheeled Mobility | 141

These data depict the reaching abilities of manual chair users represented as the percentage of users able to retrieve and place a 5 lb 

weight on a target shelf in the forward reach direction for a given (a) height from the floor (shown the vertical axis) and (b) offset 

distance (shown on the horizontal axis) from the forward-most point of the person or wheelchair (e.g., toe, footrest). Horizontal distances 

in the positive range represent offset distance away from the body (or barrier depth) when reaching over an obstruction in relation to 

the forward-most point, and the negative range implying that the reach target is brought closer to the person (such as on a table with 
Anthropometry of Wheeled Mobility | 142

knee clearance). The percentages are color coded to differentiate regions in reach performance. The dashed lines indicate the current 

ADA-ABA requirement.
Anthropometry of Wheeled Mobility | 143

These data depict the reaching abilities of manual chair users represented as the percentage of users expected to reach to a target 

location in the lateral or sideways reach direction for a given (a) height from the floor (shown the vertical axis) and (b) offset distance 

(shown on the horizontal axis) from the lateral-most point of the person or wheelchair (e.g., elbow, armrest). Horizontal distances in the 

positive range represent offset distance away from the body (or barrier depth) in relation to the lateral-most point, and the negative 

range implying that the reach target is brought closer to the person. The dashed lines indicate the current ADA-ABA requirement.
Anthropometry of Wheeled Mobility | 144

These data depict the reaching abilities of manual chair users represented as the percentage of users able to retrieve and place a 5 lb 

object on a target shelf in the lateral or sideways reach direction for a given (a) height from the floor (shown the vertical axis) and (b) 

offset distance (shown on the horizontal axis) from the lateral-most point of the person or wheelchair (e.g., elbow, armrest). Horizontal 

distances in the positive range represent offset distance away from the body (or barrier depth) in relation to the lateral-most point, 

and the negative range implying that the reach target is brought closer to the person. The dashed lines indicate the current ADA-ABA 

requirement.
Anthropometry of Wheeled Mobility | 145

These data depict the reaching abilities of power chair users represented as the percentage of users expected to reach to a target 

location in the forward reach direction for a given (a) height from the floor (shown the vertical axis) and (b) offset distance (shown on 

the horizontal axis) from the forward-most point of the person or wheelchair (e.g., toe, footrest). Horizontal distances in the positive 

range represent offset distance away from the body (or barrier depth) when reaching over an obstruction in relation to the forwardmost point, and the negative range implying that the reach target is brought closer to the person (such as on a table with knee 

clearance). The percentages are color coded to differentiate regions in reach performance. The dashed lines indicate the current ADAABA requirement.
Anthropometry of Wheeled Mobility | 146

These data depict the reaching abilities of power chair users represented as the percentage of users able to retrieve and place a 5 lb 

weight on a target shelf in the forward reach direction for a given (a) height from the floor (shown the vertical axis) and (b) offset 

distance (shown on the horizontal axis) from the forward-most point of the person or wheelchair (e.g., toe, footrest). Horizontal distances 

in the positive range represent offset distance away from the body (or barrier depth) when reaching over an obstruction in relation to 

the forward-most point, and the negative range implying that the reach target is brought closer to the person (such as on a table with 

knee clearance). The percentages are color coded to differentiate regions in reach performance. The dashed lines indicate the current 

ADA-ABA requirement.
Anthropometry of Wheeled Mobility | 147

These data depict the reaching abilities of power chair users represented as the percentage of users expected to reach to a target 

location in the lateral or sideways reach direction for a given (a) height from the floor (shown the vertical axis) and (b) offset distance 

(shown on the horizontal axis) from the lateral-most point of the person or wheelchair (e.g., elbow, armrest). Horizontal distances in the 

positive range represent offset distance away from the body (or barrier depth) in relation to the lateral-most point, and the negative 

range implying that the reach target is brought closer to the person. The dashed lines indicate the current ADA-ABA requirement.
Anthropometry of Wheeled Mobility | 148

These data depict the reaching abilities of power chair users represented as the percentage of users able to retrieve and place a 5 lb 

object on a target shelf in the lateral or sideways reach direction for a given (a) height from the floor (shown the vertical axis) and (b) 

offset distance (shown on the horizontal axis) from the lateral-most point of the person or wheelchair (e.g., elbow, armrest). Horizontal 

distances in the positive range represent offset distance away from the body (or barrier depth) in relation to the lateral-most point, 

and the negative range implying that the reach target is brought closer to the person. The dashed lines indicate the current ADA-ABA 

requirement.
Anthropometry of Wheeled Mobility | 149

These data depict the reaching abilities of scooter users represented as the percentage of users expected to reach to a target location 

in the forward reach direction for a given (a) height from the floor (shown the vertical axis) and (b) offset distance (shown on the 

horizontal axis) from the forward-most point of the person or wheelchair (e.g., toe, footrest). Horizontal distances in the positive range 

represent offset distance away from the body (or barrier depth) when reaching over an obstruction in relation to the forward-most 

point, and the negative range implying that the reach target is brought closer to the person (such as on a table with knee clearance). 

The percentages are color coded to differentiate regions in reach performance. The dashed lines indicate the current ADA-ABA 

requirement.
Anthropometry of Wheeled Mobility | 150

These data depict the reaching abilities of scooter users represented as the percentage of users able to retrieve and place a 5 lb 

weight on a target shelf in the forward reach direction for a given (a) height from the floor (shown the vertical axis) and (b) offset 

distance (shown on the horizontal axis) from the forward-most point of the person or wheelchair (e.g., toe, footrest). Horizontal distances 

in the positive range represent offset distance away from the body (or barrier depth) when reaching over an obstruction in relation to 

the forward-most point, and the negative range implying that the reach target is brought closer to the person (such as on a table with 

knee clearance). The percentages are color coded to differentiate regions in reach performance. The dashed lines indicate the current 

ADA-ABA requirement.
Anthropometry of Wheeled Mobility | 151

These data depict the reaching abilities of scooter users represented as the percentage of users expected to reach to a target location 

in the lateral or sideways reach direction for a given (a) height from the floor (shown the vertical axis) and (b) offset distance (shown on

the horizontal axis) from the lateral-most point of the person or wheelchair (e.g., elbow, armrest). Horizontal distances in the positive 

range represent offset distance away from the body (or barrier depth) in relation to the lateral-most point, and the negative range 

implying that the reach target is brought closer to the person. The dashed lines indicate the current ADA-ABA requirement.
Anthropometry of Wheeled Mobility | 152

These data depict the reaching abilities of scooter users represented as the percentage of users able to retrieve and place a 5 lb 

object on a target shelf in the lateral or sideways reach direction for a given (a) height from the floor (shown the vertical axis) and (b) 

offset distance (shown on the horizontal axis) from the lateral-most point of the person or wheelchair (e.g., elbow, armrest). Horizontal 

distances in the positive range represent offset distance away from the body (or barrier depth) in relation to the lateral-most point, 

and the negative range implying that the reach target is brought closer to the person. The dashed lines indicate the current ADA-ABA 

requirement.
Anthropometry of Wheeled Mobility | 153

This data depicts the amount of clear floor area required by persons using wheeled mobility devices when performing a forward or 

side reach to a target location (e.g., reaching to a light switch on the wall) with either the right or left hand. The accompanying table 

provides dimensions values for clear floor area to accommodate 95% of manual chair (n=276), power chair (n=189), and scooter 

(n=30) users that were measured as part of the Anthropometry of Wheeled Mobility study. The dimensions of clear floor area are 

based on four anthropometry dimensions. These dimensions are: (A) occupied width, the horizontal distance between the side-most 

(lateral-most) points of the wheelchair or occupant on the right and left side; (B) occupied length, the horizontal distance from the frontmost (anterior-most) point of the wheelchair or occupant to the rear-most (posterior-most) point of the wheelchair or occupant; (C)the 

horizontal distance from the reaching shoulder to the front-most (anterior-most) point of the wheelchair or occupant; (D) the horizontal 

distance from the reaching shoulder to the side-most (lateral-most) point on the opposite (contra-lateral) side of the wheelchair or 

occupant.
Anthropometry of Wheeled Mobility | 154

This data depicts the amount of clear floor area required by persons using wheeled mobility devices when performing a forward or 

side reach to a target location (e.g., reaching to a light switch on the wall) with either the right or left hand. The accompanying table 

provides dimensions values for clear floor area to accommodate 95% of power chair (n=189), scooter (n=30), and manual chair 

(n=276), users that were measured as part of the Anthropometry of Wheeled Mobility study. The dimensions of clear floor area are 

based on four anthropometry dimensions. These dimensions are: (A) occupied width, the horizontal distance between the side-most 

(lateral-most) points of the wheelchair or occupant on the right and left side; (B) occupied length, the horizontal distance from the frontmost (anterior-most) point of the wheelchair or occupant to the rear-most (posterior-most) point of the wheelchair or occupant; (C)the 

horizontal distance from the reaching shoulder to the front-most (anterior-most) point of the wheelchair or occupant; (D) the horizontal 

distance from the reaching shoulder to the side-most (lateral-most) point on the opposite (contra-lateral) side of the wheelchair or 

occupant.
Anthropometry of Wheeled Mobility | 155

This data depicts the amount of clear floor area required by persons using wheeled mobility devices when performing a forward or 

side reach to a target location (e.g., reaching to a light switch on the wall) with either the right or left hand. The accompanying table 

provides dimensions values for clear floor area to accommodate 95% of scooter (n=30), power chair (n=189), and manual chair 

(n=276) users that were measured as part of the Anthropometry of Wheeled Mobility study. The dimensions of clear floor area are 

based on four anthropometry dimensions. These dimensions are: (A) occupied width, the horizontal distance between the side-most 

(lateral-most) points of the wheelchair or occupant on the right and left side; (B) occupied length, the horizontal distance from the frontmost (anterior-most) point of the wheelchair or occupant to the rear-most (posterior-most) point of the wheelchair or occupant; (C)the 

horizontal distance from the reaching shoulder to the front-most (anterior-most) point of the wheelchair or occupant; (D) the horizontal 

distance from the reaching shoulder to the side-most (lateral-most) point on the opposite (contra-lateral) side of the wheelchair or 

occupant.
Anthropometry of Wheeled Mobility | 156

This data depicts the amount of space required by users of wheeled mobility devices to perform a 90-degree turn ("L-Turn"). The bold 

dashed line in the table and figure indicates the current ADA-ABA requirement of a 91.5 cm (36 in.) passage width. Findings from the 

Anthropometry of Wheeled Mobility Study indicate that a width of at least 85 cm (33 in.) was required for 50% of the manual and 

power wheelchair users measured in this study to perform a 90-degree turn. A width of 100 cm (39 in.) was required in order for 95% 

of manual wheelchair and power chair users to complete the turn, with 95% of scooter users needing a width of at least 110 cm (43 in.) 

These data are based on measurements of wheeled mobility users performing 90-degree turns in a hallway, built with mock walls. The 

outside wall of the hallway was fixed. The other side of each leg had moveable walls. The enclosed space was incrementally increased 

until a user could pass through the turn successfully. The minimum space required to perform a complete 90-degree turn within moving 

or knocking down any of the walls was recorded. Use of multiple short turns was allowed in contrast to a single continuous turn.
Anthropometry of Wheeled Mobility | 157

This data depicts the amount of space required by users of wheeled mobility devices to perform a 360-degree turn. The bold dashed 

line in the table and figure indicates the current ADA-ABA requirement of a 152.5 cm (60 in.) turn space. Findings from the 

Anthropometry of Wheeled Mobility Study indicate that a square space of at least 160 x 160 cm (63 in.) was required for 50% of the 

manual wheelchair users measured in this study to perform a 360-degree turn. A space of 210 x 210 cm (83 in.) was required in order 

for 95% of manual wheelchair and power chair users to complete the turn, with 95% of scooter users needing a space of at least 250 

x 250 cm (98 in.) These data are based on measurements of wheeled mobility users performing 360-degree turns within an enclosed 

square space built with mock walls. The enclosed space was incrementally varied from a size of 130 x 130 cm (51 in.) to 250 x 250 cm 

(98 in.) The minimum space required to perform a complete 360-degree turn within moving or knocking down any of the walls was 

recorded. Use of multiple short turns was allowed in contrast to a single continuous turn.
Anthropometry of Wheeled Mobility | 158

This data depicts the amount of space required by users of wheeled mobility devices to perform a 180-degree turn. The bold dashed 

line in the table and figure indicates the current ADA-ABA requirement of a 152.5 cm (60 in.) space for wheeled mobility users to turn 

around. Findings from the Anthropometry of Wheeled Mobility Study indicate that a width of at least 130 cm (51 in.) was required for 

50% of the manual wheelchair users measured in this study to perform a 90-degree turn. A width of 170 cm (67 in.) was required in 

order for 95% of manual wheelchair and power chair users to complete the turn, with 95% of scooter users needing a width of at least

210 cm (83 in.) These data are based on measurements of wheeled mobility users performing 180-degree turns in a dead-end 

hallway, built with mock walls. The end wall and a second wall of the hallway was fixed. The other side of the hallway had a 

moveable wall. The hallway width was incrementally increased until a user could enter the space, turn around, and exit the space 

successfully. The minimum space required to perform a complete 180-degree turn within moving or knocking down any of the walls was 

recorded. Use of multiple short turns was allowed in contrast to a single continuous turn.
Anthropometry of Wheeled Mobility | 159

This data depicts the amount of space required by users of wheeled mobility devices to perform a 180-degree turn ("U-Turn") around 

an obstruction. The bold dashed line in the table and figure indicates the current ADA-ABA requirements, which vary based on the 

passage width and space available at the base of the turn. Findings from the Anthropometry of Wheeled Mobility Study indicate that 

a uniform width of at least 89.5 cm (35 in.) was required for 50% of the manual and power wheelchair users measured in this study to 

perform a 180-degree turn around the obstruction. A width of 109.5 cm (43 in.) was required in order to accommodate 95% of all 

users. These data are based on measurements of wheeled mobility users performing 180-degree turns around an obstruction, built with 

mock walls. An obstruction of 11 cm (4 in.) was fixed at a central location. Three moveable walls were constructed around the central 

fixed wall to form a U-shaped hallway of equal passage width. The enclosed space was incrementally and uniformly increased until a 

user could pass through the U-turn successfully. The minimum space required to perform a complete 180-degree turn around an 

obstruction within moving or knocking down any of the walls was recorded. Use of multiple short turns was allowed in contrast to a 

single continuous turn.
Anthropometry of Wheeled Mobility | 158

Appendix Three: Bibliography
Anthropometry of Wheeled Mobility | 159

Bibliography

Peer-reviewed Journal Publications

D'Souza, C., Steinfeld, E., Paquet, V., and Feathers, D. (2010). Space Requirements for Wheeled 

Mobility Devices in Public Transportation: Analysis of Clear Floor Space Requirements. 

Transportation Research Record: Journal of the Transportation Research Board, No. 2145: 

66-71.

D'Souza, C., Paquet, V., Joseph, C., and Feathers, D. (in review). Hand size and functional grip 

capabilities of wheeled mobility device users. Applied Ergonomics.

Feathers, D., Paquet, V., and Drury, C. (2004). Measurement consistency and three-dimensional 

electromechanical anthropometry. International Journal of Industrial Ergonomics Special 

Issue on Anthropometry and Disability 33(3): 181-190.

Feathers, D. (2005). Digital human modeling and measurement considerations for wheeled 

mobility device users. SAE 2004 Transactions, Journal of Aerospace, Vol. 113-1. SAE 

International.

Koontz, A., M., Brindle, E. D., Kankipati, P., Feathers, D., and Cooper, R. A. (2010). Design 

features that affect the maneuverability of wheelchairs and scooters. Arch Phys Med 

Rehabil 91: 759-764.

Paquet, V., and Feathers, D. (2004). An anthropometric study of manual and powered wheelchair 

users. International Journal of Industrial Ergonomics Special Issue on Anthropometry and 

Disability 33(3): 191 - 204.

Paquet, V., Joseph, C., and D’Souza, C. (In preparation). Use of computerized re-sampling to 

combine data from multiple samples for population-based anthropometric analysis.

Steinfeld, E. (2004). Modeling spatial interaction in anthropometric research. International Journal 

of Industrial Ergonomics 3(265-278).

Steinfeld, E., Maisel, J., Feathers, D., and D'Souza, C. (2010). Anthropometry and standards for 

wheeled mobility: An international comparison. Assistive Technology 22(1): 51-67.

Guest Edited Journal Special Issues

Paquet, V., Eds. (2004). Special Issue on Anthropometry and Disability. International Journal of 

Industrial Ergonomics ,33(6).

Paquet, V., and Steinfeld, E., Eds. (2010). Special Issue on Space Requirements for Wheeled 

Mobility. Assistive Technology, 22(1).
Anthropometry of Wheeled Mobility | 160

Peer-reviewed Conference Proceedings

D'Souza, C., Feathers, D., and Paquet, V. (2007). Constructing Three-Dimensional Models of 

Individuals and Their Wheeled Mobility Devices from Landmark Data. Technical Paper 

2007-01-2494. 2007 Digital Human Modeling Conference, Seattle, WA, SAE Inc.

D'Souza, C., Paquet, V., Steinfeld, E., and Feathers, D. (2010a). Anthropometric Data Visualization 

Tools to Improve Accessibility of Built Environments. 3rd International Conference on 

Applied Human Factors and Ergonomics, 2010 AHFE International, Miami, Florida, Taylor 

and Francis, Ltd.

D'Souza, C., Steinfeld, E., Paquet, V., and Feathers, D. (2010b). Space requirements for wheeled 

mobility devices in public transportation: An analysis of clear floor space requirements. 

89th Annual Meeting of the Transportation Research Board, Washington, DC.

D’Souza, C., Steinfeld, E., and Paquet, V. (2009a). Functional reach abilities of wheeled mobility 

device users: toward inclusive design. 2009 International conference on Inclusive Design, 

INCLUDE 2009, London, UK.

D’Souza, C., Steinfeld, E., and Paquet, V. (2009b). Functional reach for wheeled mobility device 

users: A comparison with ADA-ABA guidelines for accessibility. Rehabilitation Engineering 

Society of North America (RESNA) Annual Conference 2009, New Orleans, June 2009.

Drury, C., Koontz, A., Feathers, D., Kankipati, P., Paquet, V., and Lin, J.-F. (2009). Controllability 

of manual and powered wheelchairs for spinal cord injury users. Proceedings of the 52nd 

Annual Meeting of the Human Factors and Ergonomics Society, September 22-26, 2008.

Feathers, D., Polzin, J., Paquet, V., Lenker, J., and Steinfeld, E. (2001). Comparison of traditional 

and electromechanical approaches for structural anthropometric data collection. 

Proceedings of the Human Factors and Ergonomics Society 45th Annual Meeting (pp. 

1036-1039).

Feathers, D., Paquet, V., and Drury, C. (2002a). Effects of automation of measurement error and 

consistency in anthropometry. Human Factors and Ergonomics Society 46th Annual Meeting, 

Baltimore, MD.

Feathers, D., Paquet, V., and Polzin, J. (2002b). Reliability of structural anthropometric 

measurements with traditional and semi-automated approaches. Proceedings of the 

Human Factors and Ergonomics Society 46th Annual Meeting.

Feathers, D. (2005). Digital human modeling and measurement considerations for wheeled 

mobility device users. In the Digital Human Modeling for Design and Engineering 

Symposium. 2004-01-2135. SAE International.

Feathers, D., and Paquet, V. (2006a). Three-dimensional variability of static anthropometric 

dimensions: Considering anatomy, behavior and process. Proceedings of the Human 

Factors and Ergonomics Society 50th Annual Meeting (pp. 1380-1383).

Feathers, D., and Paquet, V. (2006b). Three-dimensional variability of static anthropometric 

dimensions: Considering anatomy, behavior and process. Proceedings of the Human 

Factors and Ergonomics Society 49th Annual Meeting.
Anthropometry of Wheeled Mobility | 161

Feathers, D., and Steinfeld, E. (2008). Subjective ratings of accessibility using full-scale bathroom 

environments. Proceedings of the Human Factors and Ergonomics Society 52nd Annual 

Meeting. (pp. 723-727).

Feathers, D. (2009). Mitigating anthropometric measurement variation: Applied tolerances for 

static anthropometric landmark digitizations in three-dimensional space. Proceedings of 

the 17th World Congress on Ergonomics: An International Ergonomics Association Triennial 

Congress.

Joseph, C., D'Souza, C., Paquet, V., and Feathers, D. (2010). Comparison of hand grip strength 

between wheeled mobility device users and non-disabled adults. 3rd International 

Conference on Applied Human Factors and Ergonomics, 2010 AHFE International, Miami, 

Florida, Taylor and Francis, Ltd.

Jui-Feng, L., Drury, C., and Paquet, V. (2006). A quantitative methodology for assessment of 

wheelchair controllability. Proceedings of the Human Factors and Ergonomics Society 50th 

Annual Meeting. San Francisco, California: HFES.

Paquet, V., Feathers, D., and Lenker, J. (2001). Three-dimensional measurements, semistandardized postures and clothing: structural anthropometric methods for persons with 

disabilities. Proceedings of Anthropometrics of Disability: An International Workshop, (8-

1)-(8-9).

Paquet, V. (2009). Moving from accommodation to universal design. Proceedings of the 52nd 

Annual Meeting of the Human Factors and Ergonomics Society, September 22-26, 2008.

Steinfeld, E., Paquet, V., and Lenker, J. (2002). New development in the anthropometry of 

wheelchair users. Proceedings of the Universal Design 2002 Conference, Yokahoma, 

Japan.

Steinfeld, E., Paquet, V., and Feathers, D. (2004). Space requirements for wheeled mobility 

devices. Human Factors and Ergonomics Society 48th Annual Meeting, New Orleans, LA.

Steinfeld, E., and Feathers, D. (2006). Space requirements for aging wheeled mobility users. 

Proceedings of the International Conference on Aging, Disability and Independence.

Steinfeld, E., Maisel, J., and Feathers, D. (2006). Wheeled mobility space requirements and 

maneuvering: An International Comparison of Standards and Research. Rehabilitation 

Engineering and Assistive Technology Society of North America Conference, Atlanta, GA.

Steinfeld, E., D'Souza, C., and Maisel, J. (2010a). Clear Floor Space For Contemporary Wheeled 

Mobility Users. 12th International Conference on Mobility and Transport for Elderly and 

Disabled Persons (TRANSED 2010), Hong Kong.

Steinfeld, E., D'Souza, C., Paquet, V., and White, J. (2010b). Clear floor area for wheeled 

mobility users. 3rd International Conference on Applied Human Factors and Ergonomics. 

Miami, Florida, Taylor and Francis, Ltd.
Anthropometry of Wheeled Mobility | 162

Steinfeld, E., Paquet, V., Lenker, J., D'Souza, C., and Maisel, J. (2010c). Universal Design Research 

on Boarding and Using Buses. 12th International Conference on Mobility and Transport for 

Elderly and Disabled Persons (TRANSED 2010), Hong Kong.

Technical Reports

Paquet, V., and Steinfeld, E. (2004). Space Requirements for Wheeled Mobility: An International 

Workshop, Buffalo, NY. Final Project Report to the U.S. Access Board, March, 2004. 

Retrieved December 20, 2010, from http://www.udeworld.com/anthropometrics.

Steinfeld, E., Lenker, J., and Paquet, V. (2002). Anthropometrics of Disability: An International 

Workshop, Buffalo, NY. Final Project Report to the U.S. Access Board, February, 2002. 

Retrieved December 20, 2010, from http://www.udeworld.com/anthropometrics.

Steinfeld, E., Maisel, J., and Feathers, D. (2005). Standards and anthropometry for wheeled 

mobility. Report prepared for the U.S. Access Board, July 2005. Retrieved December 20, 

2010, from http://www.udeworld.com/anthropometrics