I've explored a few Oakland to McKeesport routes, but I've never tried Ravine ST/Greensprings/Homesville/Skyline, etc. I'll ahve to give it a whirl.
Mostly I go out and back on 837. Through Duquesne, I take 2nd Ave and Patterson. Both Patterson and the end of 2nd that intersects it are closed. You have to watch for broken glass (very little, considering), but the traffic is great!
http://www.bikely.com/maps/bike-path/Rt-through-Duquesne-PA
This is an OK route right now (June 2009) because 837 has a lane blocked off to traffic between Patterson and the bridge.
I saw that there is a ramp that clims up to the trail bridge between Mck and Duquesne, but I did not see if there was a way to access it.
Is there any schedule for the trail between Homestead and McKeesport? The ...um...stuff... with Sandcastle shouldn't affect this section of the trail and for convenience it would be nice to avoid teh 500 ft or so climb.
Mick