There is some general discussion here: 
http://www.ala.org/tools/ada-and-libraries . From that site:


"8.1 General. In addition to the requirements of section 4, the design 
of all public areas of a library shall comply with 8, including reading 
and study areas, stacks, reference rooms, reserve areas, and special 
facilities or collections."


They also indicate a preference for at least 42 inch spaces, but I am 
unsure as to enforcement and would gather that this only applies to new 
construction/renovation.

       Joel


On 8/3/16 9:40 AM, Angela R Cope wrote:
>
> I'm searching through the Maps-L archives to see if we've talked about 
> this before. There is lots of talk of how high to stack map cabinets 
> and then finding reference to the space and equipment article from 
> 1961. Is there a newer article on map library space planning than this 
> one: /Map Libraries: Space and Equipment/ by Catherine I. Bahn, */SLA 
> Geography & Map Division Bulletin/*, v. 46, pp. 3-17 (1961)
>
>
> Does it say anything in the 1998 Maplibrarianship : an introduction by 
> Mary Lynette Larsgaard?
>
>
> Best of luck.
>
>
> Angie
>
>
>
> ------------------------------------------------------------------------
> *From:* Maps-L: Map Librarians, etc. <[log in to unmask]> on 
> behalf of Joel Kovarsky <[log in to unmask]>
> *Sent:* Wednesday, August 3, 2016 7:02 AM
> *To:* [log in to unmask]
> *Subject:* Re: [MAPS-L] Best Practices - Aisle Width between map cases
>
> I have a question. Is any decision here in the USA impacted by library 
> compliance with the Americans with Disabilities Act? I gather most of 
> the distances being discussed comply with that standard, but is there 
> an exemption for stacks not used by most public clients?
>
>         Joel Kovarsky
>
>
> On 8/3/16 12:39 AM, Brendan Whyte wrote:
>>
>> We've just installed 10,000 drawers of 1m deep bespoke US-made cases 
>> (with proud handles additional to the 1m depth) in a compactus with 
>> 1.01m aisles (case front to case front, ignoring handles).
>>
>> A standard sized user [i.e. non-obese/non-American] can stand behind 
>> the open drawer to remove/reshelve maps, and the drawers themselves 
>> are less deep than the 1m cabinet, so can be removed from the cases 
>> by two people, one each side of the drawer.
>>
>>
>> The aisle width was intended to allow drawers to be physically 
>> removed/replaced, but still maximise rows of cases and minimise aisle 
>> width. (and fit sensibly in our stack space which is studded with 
>> pillars).
>>
>>
>> Brendan Whyte
>>
>> National Library of Australia
>>
>>
>> ----------------------------------------------------------------------
>>
>> Date:    Tue, 2 Aug 2016 02:26:04 +0000
>> From:    Kathy Stroud <[log in to unmask]>
>> Subject: Best Practices - Aisle Width between map cases
>>
>> All,
>>
>> It seems I've seen this somewhere but I can't locate it.  Is there a 
>> best practice distance for placing map cases facing each other 
>> (what's the aisle width between map cases with drawers opening facing 
>> each other?)  We're going through re-envisioning our map space and 
>> I'll hoping for numbers to add weight to my estimates.  I already 
>> know that a 40" aisle is not going to be adequate for a 40" deep map 
>> case.  It would be impossible to get drawers in and out when needed 
>> and be difficult to work around fully opened drawers.  My gut feeling 
>> tells me that 48" is the minimum and 56" would be ideal.  This is an 
>> area that is open access to patrons so it's not just the librarians 
>> that need to be able to maneuver in the space.
>>
>> Anyone have any authoritative sources?
>>
>> Thanks in advanced,
>>
>> Kathy
>>
>