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Evaluation of Detectable Warning Surfaces
FINAL REPORT
Prepared for the Sacramento Regional Transit District
March 1997
Crain & Associates, Inc.
Accessible Design for the Blind
Mobility and Wayfinding Consultants
120 Santa Margarita Ave.
Menlo Park, CA 94025
(415) 323 - 3444
RECOMMENDATION
RT should use a specification based on Armor Tile as the preferred product
for use in retrofitting all existing stations and installation in planned
future stations.
The evaluation has identified only three products which, based on the
tests conducted and reported experience, are known to be in full
compliance with the requirements of ADA and Title 24 of the California
building code. They are Armor Tile, manufactured by Engineered Plastics,
Inc., Pathfinder, manufactured by Carsonite International, and Detectable
Warning Mat, manufactured by Detectable Warning Systems. Carsonite
International declined to participate in field tests, saying its product
was not appropriate for outdoor use; therefor it was eliminated from
further consideration. Since then, Carsonite has withdrawn its product
from manufacturing. Armor Tile and Detectable Warning Systems product were
both determined to have good performance with respect to detectability by
blind travelers and visibility to travelers with limited vision. However,
Armor Tile is preferred for reasons on safety, durability of installation,
long-term cost, and aesthetics.
CONCLUSIONS
The evaluation shows that Armor Tile is clearly the preferred product for
use at RT based on the available information and the field tests. Armor
Tile's good ratings and compliance with Title 24 depend crucially on the
sound difference between it and the adjoining platform. This sound
difference appears to depend primarily on the way the product is
installed, rather than the material of which it is made. High Quality also
showed some sound difference, also apparently as a result of its
installation. However, this difference was inconsistent and not
sufficiently reliable to be used for purposes of detection.
Table C.4 -
Surfaces which were judged easiest to detect.
| Surface |
Number |
Reasons |
| Armor Tile |
15* |
could
hear the difference in all kinds of weather; pitch difference; easy
to detect under foot; loudest; could hear even if distracted; sound
different from the others; echo-y; hollow sound; best for cane. |
| High Quality |
1 |
louder; bumpier; distinct sound |
| Interlock |
0 |
|
| Detectable
Warning Systems |
6* |
more certain under foot; I'm sure I'd hear it; sound difference; best under foot;
feels different- grabs cane |
| No choice |
1 |
|
* Three
participants identified both Armor Tile and Detectable Warning System as
being easiest to detect.
Participants were also asked to identify, by number, the surface they found most difficult
to detect. Table C.5 shows the number of participants who identified each
surface as most difficult to detect. and the reasons given for the difficult detectablility of that surface.
Table C.5 - Surfaces which were judged most difficult to detect.
| Surface |
Number |
Reasons |
| Armor Tile |
0 |
|
| High Quality |
2 |
less pronounced;
feels more like platform; feels like bumps are lower |
| Interlock |
10 |
flat bumps
are hard to detect under foot; most similar to platform; feels like
concrete; no sound difference; not secure-feels rocky; feels like
other rough surfaces; same sound as platform |
| Detectable Warning Systems |
4 |
not detectable
under foot; In noisy conditions I'd miss it; would walk past it
if I didn't hear it; doesn't have great sound; worried about it
expanding and contracting |
| No choice |
3 |
|
* Three
participants did not identify any surface as being hardest to detect.
Click here for the full report (PDF:
3.2M) |
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