Kenneth E. Lawrence
|
October 28, 2002 |
Engineered Plastics Inc
Williamsville, New York 14221
We would like to make public comment on the dome size and spacing as permitted
under the new ADAAG and by the Draft Guidelines for Accessible Public
Rights-of-Way.
Our research on the small diameter truncated domes, spaced farther apart,
indicates that there would be a loss of slip resistance, both wet and dry, as
measured by industry standard test method, ASTM C1028-89. “Determining the
Static Coefficient of Friction of Ceramic Tile and Other Like Surfaces by the
Horizontal Dynamometer Pull- Meter Method”. In layman’s terms, this reduced slip
resistance is a result of the reduced surface area in contact with the sole of a
shoe. For example, man’s shoe (size 11) is approximately 4” wide, which if
placed on a center of a dome, would not extend across to reach the adjacent
domes on either side, leaving the sole of the shoe to rest on only one single
row of two domes, which are, in total, less than one square inch. This problem
could be further compounded with a smaller shoe, and in particular a woman in
high heels whose sole might be expecting to gain a sure footing on the top of a
single dome.
While slip resistance can be defined and measured the issue of balance and
stability is more subjective. However, with the premise of the location and size
of the sole of shoes as mentioned in slip resistance, the stability for all
pedestrians, and in particular the elderly or people with other disabilities may
find the surface unstable, rocky and lead to losing one’s balance. Previous
studies on Detectable Warning Surface design had indicated that stability was a
consideration when spacing or designing the tactile surface.
In addition to the previous safety concerns that a wider spaced, small diameter
dome would raise the issue of wear resistance is also a significant concern.
With fewer domes, the sole of one’s shoe is impacting on fewer dome surfaces,
therefore increasing the load and or friction transfer up 100 % as compared to
the narrower spacing. This increased friction and load transfer will cause a
much higher rate of wear, which will significantly reduce the Detectable Warning
Surfaces useful life, adding significant life cycle costs and possible safety
issues if the product is not replaced as it wears.
Our firms experience, in both transit and pedestrian crossing applications over
the past twelve (12) years using the tighter spaced tops of domes is that, with
over a million square feet of product in service, we have had no verbal or
written complaints with regard to slip resistance and or stability. We question
the wisdom of changing from the current standards to a new design, which does
not have years of practical use in all of this country’s diverse weather
conditions.
Engineered Plastic’s concerns do not stem from self-interest to maintain the
status quo, as our Armor-Tile Detectable Warning Surface Tile Systems are
available in the new In-Line Dome pattern, spaced 1.66” apart, which are
permitted by ADAAG and by the Draft Guidelines for Accessible Rights of Way.
We trust our comments will be considered in the spirit in which they are made,
to enhance the accessibility of all individuals with Disabilities without
compromising the safety of all individuals.
Yours truly
Kenneth E. Lawrence
Vice-President
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