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Truncated domes: function and location.............

JPohling

Sawhorse
Joined
Aug 16, 2011
Messages
1,584
Location
San Diego
I wish the photo turned out better! This is the POT from the sidewalk to the front entrance at our little Target store that I walk past every day just shaking my head.. There are 7 instances of where you will encounter detectable warnings on your adventure across the parking lot. Should only be 2. This is what happens when people that do not understand how visually impaired people use these warnings. The first section of domes at the sidewalk edge indicates your in a vehicular way and then a few feet later you hit the next set and for the impaired now believe you are no longer in the vehicular way. But this is now crossing the drive aisle! And it repeats its contradiction all the way to the front door. Terrible misuse of detectable warnings. I see this all the time where they believe more is better. It is just confusing and potentially dangerous.
 

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Here is regular ramp being built that goes down and ends in a vehicle way. It looks like the code does not require detectable warnings like a curb ramp does. Is this right?
 
Here is regular ramp being built that goes down and ends in a vehicle way. It looks like the code does not require detectable warnings like a curb ramp does. Is this right?
Rick, no picture to look at but whenever you have a flush curb condition on a POT that crosses a vehicular way detectables are required. walkway, ramp or curb ramp
 
Rick, no picture to look at but whenever you have a flush curb condition on a POT that crosses a vehicular way detectable's are required. walkway, ramp or curb ramp

Detectable warnings are not mentioned in ICC/ANSI !117.1 - 2006 section 405 Ramps. There is no curb here. No sidewalk ether. Bottom of ramp goes directly into driveway from a door landing. Detectable warnings are only mentioned and required in section 406 Curb Ramps. Please explain why would I be even looking in the Curb Ramp section if I do not have a Curb Ramp.
 
It is a risk management issue, if provided they must comply but at a minimum they are not required except by local amendment.
 
Detectable warnings are not mentioned in ICC/ANSI !117.1 - 2006 section 405 Ramps. There is no curb here. No sidewalk ether. Bottom of ramp goes directly into driveway from a door landing. Detectable warnings are only mentioned and required in section 406 Curb Ramps. Please explain why would I be even looking in the Curb Ramp section if I do not have a Curb Ramp.

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If I am understanding correctly you have a ramp or sloping walkway from the door landing that goes directly into drive aisle without a curb. That would require detectable warnings as it is either a curb ramp or a blended transition leading to a hazardous vehicular area
 
The photo below is a retail parking lot in California that utilized the accessible parking loading/unloading aisles to do double-duty as the accessible POT from the public sidewalk to the front door. As a result, it has 4 different detectable warning in less than 100'.
This is because each parking lot drive aisle is "vehicular way", and each row of blue-striped ADA parking stall loading spaces is not a vehicular way.
Coming up from the public sidewalk (bottom of photo), warnings #1 and 3 let you know each time you are about to cross a drive aisle.
In the other direction, when exiting the building (top of photo), warnings #4 and 2 tell you when you are about to cross a drive aisle.​

I asked a friend who is 100% blind how he keeps track of whether the warnings are telling him he's entering vs. leaving a vehicle area. He said at his school for the blind they teach that detectable warnings are generally worthless and confusing and should not be relied upon at all.


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You are correct Rick....Hardly ever required by IBC/ANSI....Unless it has been "ramped" up in the later editions..(pun fully intended)

The curb ramp section of ANSI says "where the warnings are provided" not that they need to be....Just "raised marked crossings", which means if they don't mark them, they are good...
 
The photo below is a retail parking lot in California that utilized the accessible parking loading/unloading aisles to do double-duty as the accessible POT from the public sidewalk to the front door. As a result, it has 4 different detectable warning in less than 100'.
This is because each parking lot drive aisle is "vehicular way", and each row of blue-striped ADA parking stall loading spaces is not a vehicular way.
Coming up from the public sidewalk (bottom of photo), warnings #1 and 3 let you know each time you are about to cross a drive aisle.
In the other direction, when exiting the building (top of photo), warnings #4 and 2 tell you when you are about to cross a drive aisle.​

I asked a friend who is 100% blind how he keeps track of whether the warnings are telling him he's entering vs. leaving a vehicle area. He said at his school for the blind they teach that detectable warnings are generally worthless and confusing and should not be relied upon at all.


View attachment 6825
locations 2 and 3 should be eliminated. Don't get me started on diagonal curb ramps!! I have rescued several blind people from the center of intersections after they use the curb ramp for orientation and are now walking diagonally across the intersection!
 
New construction. Sidewalk is level with driveway at parking lot. They used white paint on the black top driveway to mark a crossing to the accessible parking spaces. No detectable warning was installed. Would it be ok if I told them to go over the markings with black paint, then they would not need the detectable warning?

ICC/ANSI A117.1-2009
406.12 Detectable Warnings at Raised Marked
Crossings. Marked crossings that are raised to the
same level as the adjoining sidewalk shall be preceded
by a detectable warning 24 inches (610 mm) in depth
complying with Section 705. The detectable warning
shall extend the full width of the marked crossing.
 
I wish the photo turned out better! This is the POT from the sidewalk to the front entrance at our little Target store that I walk past every day just shaking my head.. There are 7 instances of where you will encounter detectable warnings on your adventure across the parking lot. Should only be 2. This is what happens when people that do not understand how visually impaired people use these warnings. The first section of domes at the sidewalk edge indicates your in a vehicular way and then a few feet later you hit the next set and for the impaired now believe you are no longer in the vehicular way. But this is now crossing the drive aisle! And it repeats its contradiction all the way to the front door. Terrible misuse of detectable warnings. I see this all the time where they believe more is better. It is just confusing and potentially dangerous.

I don't agree that this is a misuse. They are placed to alert people when they are entering and leaving vehicular traffic crossings. I think that is an appropriate use for detectable warnings (truncated domes). See A117.1-2009 section 406.14. A117.1 doesn't explicitly call for them at such level crossings, but such crossings are not unlike a curb cut-through as illustrated in Figure 406.11(a).
 
Not really my area of expertise but it seems to me that the domes at the interface between the sidewalk and the parking lot should be the last set of domes. The path and the entire parking lot is prone to vehicular traffic. A second set of domes as shown in the picture would confuse a blind person and lead them to believe that they have exited the area of vehicular traffic.
 
The photo below is a retail parking lot in California that utilized the accessible parking loading/unloading aisles to do double-duty as the accessible POT from the public sidewalk to the front door. As a result, it has 4 different detectable warning in less than 100'.
This is because each parking lot drive aisle is "vehicular way", and each row of blue-striped ADA parking stall loading spaces is not a vehicular way.
Coming up from the public sidewalk (bottom of photo), warnings #1 and 3 let you know each time you are about to cross a drive aisle.​
In the other direction, when exiting the building (top of photo), warnings #4 and 2 tell you when you are about to cross a drive aisle.​

I asked a friend who is 100% blind how he keeps track of whether the warnings are telling him he's entering vs. leaving a vehicle area. He said at his school for the blind they teach that detectable warnings are generally worthless and confusing and should not be relied upon at all.


View attachment 6825
When the loading zones are used as the POT from the PROW, I do not see an issue with it.
When It is just loading zones , they should not be placed in the LZ. IMPO
 
Code Chronicle, my example and several posted after it are a complete misuse of truncated domes and can endanger the blind. no detectable s should be used within the parking area typically. There could be a highly unusual situation that calls for it but not the situation that I showed.

And Mark, I fully agree that is seriously wrong
 
I also agree with Mark and JPohling. The image in the original post is very explicitly against current CBC requirements (mentioning CBC because the OP is in San Diego).

11B-502.4 Floor or Ground Surfaces (this is for access aisles)
Parking spaces and access aisles serving them shall comply with Section 11B-302. Access aisles shall be at the same level as the parking spaces they serve. Changes in level, slopes exceeding 1:48, and detectable warnings shall not be permitted.

Even if it wasn't explicitly against code (maybe it was compliant when it was built?), it seems like a poor design imo. The detectible warning is to indicate that the person is either entering or leaving a hazardous area. A parking spot is still a hazardous area (there's still moving cars around you. You aren't exactly in a safe location).

It would be different if there were, say, concrete islands that were raised above the vehicle way. I've been called out for missing those before...
 
There is so much misinformation about the purpose and use of the detectable warnings, it is hard for contractors, and even professionals, as to the use and placement.
 
The rumble strips are there as a warning for visually impaired persons. Could it be that the damage caused but the domes at shopping centers outweighs any perceived benefit? The surface is slippery when wet, resulting in a slip and fall. The domes shake shopping carts/dollies causing product to spill out. Women twist their ankles.

A friend that remodels big box stores tells me that he has witnessed all of that and he's there for a limited duration. I make sure that the Crown Royal is secure for the ride from Costco to the truck. How many blind people are traversing parking lots unaccompanied?
 
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