These are the A.D.A. Accessibility Guidelines Pertaining to Ground and Floor Surfaces (Appendix 4.5.1)
People
who have difficulty walking or maintaining balance or who use crutches,
canes, or walkers, and those with restricted gaits are particularly
sensitive to slipping and tripping hazards. For such people, a stable
and regular surface is necessary for safe walking, particularly on
stairs. Wheelchairs can be propelled most easily on surfaces that are
hard, stable, and regular. Soft loose surfaces such as shag carpet,
loose sand or gravel, wet clay, and irregular surfaces such as
cobblestones can significantly impede wheelchair movement.
Slip
resistance is based on the frictional force necessary to keep a shoe
heel or crutch tip from slipping on a walking surface under conditions
likely to be found on the surface. While the dynamic coefficient of
friction during walking varies in a complex and non-uniform way, the
static coefficient of friction, which can be measured in several ways,
provides a close approximation of the slip resistance of a surface.
Contrary to popular belief, some slippage is necessary to walking,
especially for persons with restricted gaits; a truly "non-slip"
surface could not be negotiated.
The
Occupational Safety and Health Administration recommends that walking
surfaces have a static coefficient of friction of "0.5". A research
project sponsored by the Architectural and Transportation Barriers
Compliance Board (Access Board) conducted tests with persons with
disabilities and concluded that a higher coefficient of friction was
needed by such persons. A static coefficient of friction of "0.6" is
recommended for accessible routes and "0.8" for ramps.
It
is recognized that the coefficient of friction varies considerably due
to the presence of contaminants, water, floor finishes, and other
factors not under the control of the designer or builder and not
subject to design and construction guidelines and that compliance would
be difficult to measure on the building site. Nevertheless, many common
building materials suitable for flooring are now labeled with
information on the static coefficient of friction. While it may not be
possible to compare one product directly with another, or to guarantee
a constant measure, builders and designers are encouraged to specify
materials with appropriate values. As more products include information
on slip resistance, improved uniformity in measurement and
specification is likely. The Access Board's advisory guidelines on Slip
Resistant Surfaces provides additional information on this subject.