If it’s PennDOT, which I think it is, you can fix the problems by going to this web form: http://www.dot.state.pa.us/penndot/districts/district11/d11ccc.nsf and entering a description of the issue. Be sure to mention the ADA compliance issues. I’ve gotten problems fixed using that form. (Absurdly, it only works with Internet Explorer, but whatever.)
Basically, what happens is PennDOT hires a contractor, who does a crap job, and if nobody complains they don’t have to fix it. So complain.
I saw the parkway ramp spillout onto Bates there (page 14 of the PDF, coded SR 8006) and complained about lack of safe ADA compliant crossability of that sidewalk. Not holding out any real hope, but was worth a form submit.
Per the map, Penn is a state road east of Target (as PA-380–coded SR-0400…loooong story–and then PA-8), and between 31st St Bridge and Butler St (as SR-2122), but from Downtown to 31st and from Butler to Centre it’s a city road.
As for relative black-hole-ness, I’ve found the 311 twitter account (@Pgh311) pretty responsive…