Hello.
We would like to inform you about the crowdsourcing project Wikiroutes (http://wikiroutes.info/en/) - an open database of Public Transit routes. There are already 20 000 routes in 500 cities over the world.
Its advantages over similar web-services is in the visual display of routes paths. Any Wikiroutes user can participate in adding and updating data, making the transit information on Wikiroutes sometimes more up-to-date than on the official websites.
There is still no data on Public Transit in New Delhi. You can help other passengers by adding information about the routes you know or use on daily basis.
All information about how to add and edit new routes can be found in Wikiroutes manual.
The web-site also has an optimal route search engine.