I had to add a vertical grab bar in a toilet compartment a couple years back even if I showed the building official the 2010 ADA manual, for some reason they go by the ANSI book.

There is no clear answer, I would say ask your building dept. and go with that.

If showering with a friend, the vertical grab bar might appear on its own!   :o)

ANSI ICC 117.1-2009 is the current accessibility standard referenced by my local jurisdiction's building code (OBC), and I believe the International Building Code as well. 117.1 requires vertical grab bars in accessible stalls.

Odd thing is, if ADAAG has stricter standards than 117.1, the ADAAG standards should be followed instead of 117.1. Never run into this though, so I'm not sure what those standards would be.

ANSI A117.1 is included, by reference, in the IBC.  Therefore any jurisdiction adopting/modifying the IBC is likely enforcing the 117.1. 

2010 ADA is a federal law.  It is not, technically, a building code.  It may be adopted as an accessibility standard by a jurisdiction.  Otherwise, compliance is mandatory, simply because it is a law. 

In the event that one standard is more stringent than the other, you always use the more stringent one.  Most codes and standards have verbiage to this effect.  And, most jurisdictions have some wording in their rules/laws to that effect.  

+1 to Andrew.Circle and senjohnblutarsky. 

It surprises me how many architects think ADA is in the code and have never heard about ANSI 117.1. 

For Seattle, here is the code referencing ANSI 117.1. Also note the big box with a note about ADA at the top of the page.

http://www.seattle.gov/dpd/cs/groups/pan/@pan/documents/web_informational/s047850.pdf

Thanks for the answers! I've gotta follow ANSI here it appears. The state of WA requires you to use ANSI first and then the federal ADA laws. Just like ya'll said!

@citizen: I'll make sure they know that a shower partner is always a substantial substitution to a vertical grab bar ;)