what ever happened to this project https://wiki.openstreetmap.org/wiki/Chennai/Bus_Route_mapping_project
We were also thinking about the same. As per the wiki, we can see it was started my a group of OSM hackers and contributors from Chennai and TN and then they made a considerable progress and they went inactive. Not to blame them, it happens most of the time as people’s interest keeps changing.
What we could do at best is, resume from where they left off. That is why I created this thread. Public Transportation at Chennai - OpenStreetMap