Surface Measurement and Accessibility
Development of Devices and Test Methods
Accessibility Guidelines and Standards
Surface Measurement Devices and Testing Systems
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From the National Center on
Frequently Asked Questions on the Development of a Field
Test Method for Measuring the Firmness and Stability of
The Rotational Penetrometer is a precision instrument for measuring the firmness and stability of ground and floor surfaces, such as trails, playgrounds, and carpets. The Rotational Penetrometer is the only device of its kind-- a reliable, objective, portable instrument for testing surface firmness and stability.
The Rotational Penetrometer's effectiveness has been proven through research. An interlaboratory study was conducted according to ASTM E691, and the Penetrometer was shown to produce repeatable and reproducible measures. These measurements have been shown to correlate with the amount of work required to propel a wheelchair (as measured by ASTM F1951) and the amount of physiological energy required by persons with and without disabilities attempting to negotiate a surface. For copies of the background research, please contact us.
The Rotational Penetrometer can be of value to a wide variety of individuals and organizations-- surface manufacturers, trail managers, school groups, and ADA accessibility consultants, to name a few.
Without the Rotational Penetrometer, surface manufacturers have to ship samples of their product to independent labs for testing, and spend valuable time waiting for results. The cost of purchasing the Rotational Penetrometer is roughly equivalent to the cost of having a single surface tested-- but the Rotational Penetrometer can be used again and again. With the Rotational Penetrometer, manufacturers can repeatedly test their surfaces on-site. The Rotational Penetrometer can also be a useful tool for new product development and for assessing maintenance issues.
Trail managers can use the Rotational Penetrometer to objectively measure the firmness and stability of their trail surfaces, and the Rotational Penetrometer can be used in conjunction with the Universal Trail Assessment Process.
Park and school playground managers can use the Rotational Penetrometer to evaluate potential playground surface systems, to test existing surfaces, and also to test installed surfaces over time, to see how those surfaces stand up to use.
ADA Accessibility Consultants
Independent ADA accessibility consultants could use the Rotational Penetrometer as part of their property assessment process, to measure the firmness and stability of carpets.
A national standard test method for firmness and stability is being developed by the RESNA Standards Subcommittee on Ground and Floor Surfaces. The test method is based upon the Rotational Penetrometer technology.
From the National Center on Accessibility:
Frequently Asked Questions on the Development of a
Field Test Method for Measuring the Firmness and
Stability of Surface Systems
Denise Axelson is currently Chair of this RESNA Standards Subcommittee. If you would like information about the standard or the subcommittee's work, please contact:
(775) 783-8822 voice, or
(775) 783-8823 fax.
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Wheelchair Work Measurement Method
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The Americans with Disabilities Act Accessibility Guidelines (ADAAG) specify that accessible routes must have ground and floor surfaces that are stable, firm and slip-resistant. However, no existing standard test methods are capable of measuring the firmness and stability of surfaces found in outdoor environments. This project will expand the base of knowledge for surface firmness and stability testing, and develop recommendations for surface accessibility guidelines. Measurement tools and methods for assessing surface firmness and stability will be developed under a related Beneficial Designs project. Objective surface accessibility guidelines will improve access for all people, including those with mobility limitations, older persons, families with strollers, and others.
In 1996, a comprehensive literature review was conducted to identify technologies that enable people with mobility limitations to negotiate soft or unstable surfaces. A variety of personal technologies, including modified cane tips, wheelchair accessories, and off-road wheelchairs were found. However, personal technologies only benefit individuals.
Surface treatment techniques used to improve surface firmness and stability were also reviewed. Different types of alternative surfaces, such as mats or grids incorporated into existing surfaces, and alternative surface treatments, which improve the firmness and stability of existing surfaces, were found. These products only increase access in specific areas.
Literature was also reviewed to determine if there was an existing test method that could assess all types of outdoor surfaces for firmness and/or stability. Many test methods that measure penetration resistance, stability, rolling resistance, or water content for a specific type of surface were found, as well as methods that assess the work or energy required to cross a surface, but none were capable of measuring the firmness and stability of other types of surfaces.
Phase II Human Subject Testing
Test surfaces were constructed and human subject testing was conducted in 1998. The study involving 39 subjects was conducted to determine the amount of energy required by persons with and without mobility limitations to negotiate different types of outdoor surfaces and standard ADAAG accessible routes. These energy expenditure measurements have been correlated to objective measures of surface firmness and stability. This research has resulted in recommendations for a surface accessibility standard, including an objective test method and performance specifications.
This project, entitled "Accessible Exterior Surfaces," was funded by the Access Board (US Architectural and Transportation Barriers Compliance Board) through Contract #QA96005001.
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Accessible Exterior Surfaces: Literature Review Technical Article
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Article in PDF format.
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Accessible Exterior Surfaces Technical Article
To obtain a copy of this article, please go to
the PaxPress page to print an order form.
Ground and Floor Surface Firmness and Stability
AMERICAN NATIONAL STANDARDS FOR GROUND & FLOOR SURFACES
Guidelines for surface accessibility are needed to provide non-discriminatory access for people with disabilities. These guidelines would also improve accessibility for all persons, regardless of their abilities. Surface accessibility guidelines would improve access to a vast number of areas, including recreational facilities, playgrounds, beaches, parks, outdoor stadiums, boating and fishing docks, campgrounds, and hiking trails, as well as large buildings such as convention centers, and airports.
Research Related to the Measurement of Firmness and Stability of Surfaces for Accessibility
Extensive research has been conducted with funding from the National Institutes of Health on the development of a portable surface measurement device for objectively measuring the firmness and stability of ground and floor surfaces. This device is called the Rotational Penetrometer. Measures of firmness are obtained by pressing a wheelchair caster into a surface with a given amount of force and measuring the amount of vertical penetration into the surface. Then, the caster is rotated back and forth on the surface and a stability measurement is obtained by measuring the total amount of vertical displacement after rotation. The device has been shown to produce repeatable results that correlate with the amount of work required to propel a wheelchair across the surface.
With funding from the U.S. Access Board (ATBCB), human subject testing was conducted to determine the amount of energy required for persons with and without disabilities to negotiate various outdoor surfaces. The physiological measures (oxygen consumption, heart rate, velocity, and ratings of perceived exertion) and level of difficulty ratings correlated highly with the Rotational Penetrometer measurements. This research resulted in recommendations for the measurement of the firmness and stability of outdoor surfaces.
Standard Development Recommendation
A standard for measuring surface firmness and stability would provide builders, building and landscape architects, site planners, property owners and managers, and others with the objective information needed to build and maintain accessible indoor and outdoor surfaces. It would also provide a means to determine and compare the relative degree of accessibility of access routes and trails in the outdoor environment, and provide individuals with information about surface characteristics (access information) at specific locations.
A RESNA* Standards Subcommittee was formed in June of 1999 to develop a standard for the firmness and stability of ground and floor surfaces. Objective, performance standards are needed for the firmness and stability of recreation trail and outdoor access route surfaces, as well as indoor floor surfaces, including carpet. The subcommittee will develop a performance test procedure for the measurement of firmness and stability of surfaces with a disclosure.
(*RESNA is the
Rehabilitation Engineering and Assistive Technology Society of North America <www.resna.org> and is accredited through ANSI, the American National Standards Institute).