You can view my fork here: https://github.com/l0g1x/gazeboosm of tashwins gazeboosm fork (she had unmerged changes into upstream).
I currently took out everything except roads as I have a similar need. I also changed the texture of the road to a simple color for now as the default road texture with lines did not visually merge nicely at intersections, junctions, etc.. It also seems that the osmapi does not give osm node data only from within the boundary box specified. I fixed this and now the outFile.sdf loads alot quicker (within 1 second for me).
Working on it now, so hopefully by tonight ill implement a cubic hermite spline to be applied to the roads/road interections/road junctions to make the roads alot smoother. However, i think this should be done from within the gazebo source for Road2d.cc. But maybe it might be better to already supply smoother points from a higher level (like gazebo_osm)
EDIT: I should also mention that the option of using data from google maps i think is out of the question as it is in their terms of service agreement. Reference here: https://support.google.com/maps/answe...
EDIT2: (June 29th) So i have made some progress with implementing a hermite spline to an individual road, however its not perfect and theres still a couple of bugs, but they dont affect the generation of the world file, just the output of the roads once you launch the world has few hickups; primary one being checking if a road contains at least 3 points so that a spline can be applied. Im just learning about splines, but i have a good grasp on it after working on it for past couple of days and reading couple books. Hopefully the ticket to revive the package gets bumped so there is more support for osm with gazebo.