# Are truncated domes allowed in an accessible parking access aisle?



## Yikes (Feb 17, 2021)

ADA/CBC 11B-502.4 for accessible parking stall access aisles says:  "Changes in level are not permitted.  Exception: slopes not steeper than 1:48 shall be permitted."

Questions:

1.  Are truncated domes in a detectable warning system per ADA / CBC 11B-705 allowed in the striped access aisle? Or do they constitute a "change in level" that is not allowed?  Note that the elevation difference is less than 0.25".




2.  If a dome that is 0.18" high is NOT allowed, then what are the allowable construction tolerances (surface texture) on an accessible stall and access aisle?


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## Paul Sweet (Feb 18, 2021)

I've never seen truncated domes in a parking lot.  They are usually at the curb ramp just before you enter the parking lot.


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## ADAguy (Feb 22, 2021)

This is a grey area up for revision to the CBC this code cycle. Construction tolerance is limited to 2% crossslope max and no vertical rise exceeding 1/4"


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## mtlogcabin (Feb 22, 2021)

Why in the world would you put truncated domes in an accessible parking stall access aisle. What is the purpose/reason?


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## Yikes (Feb 22, 2021)

mtlogcabin said:


> Why in the world would you put truncated domes in an accessible parking stall access aisle. What is the purpose/reason?


Good question.  In this instance, the head of the parking stall's striped aisle is the 4th side of a 3-way "T" intersection walkway system.  Long story short, this intersection cannot be altered under present circumstances.  My concern is that a blind person on the walkway will come to this intersection, and if the intersection is filled with domes, they won't know which of the 3 pathway options is the "hazardous vehicular way".


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## mark handler (Feb 23, 2021)

Yikes said:


> ADA/CBC 11B-502.4 for accessible parking stall access aisles says:  "Changes in level are not permitted.  Exception: slopes not steeper than 1:48 shall be permitted."
> 
> Questions:
> 
> ...


IMHO
No, they can interfere with the loading and unloading of wheelchairs and can be a tripping hazard to those using mobility devices and mobility problems.


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## steveray (Feb 23, 2021)

I can think of a lot of reasons to not have them there, but not one that code would prohibit them from being there...It is not a change and level and they are required on some accessible routes so they are obviously allowed....It does not sound like a raised marked crossing, why are they there at all?


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