One of the best applications in recent times I have came across, RIDLR is a must and very useful app in every smartphone. it has almost all cities transportation integrated services. including all local and bus services.
Most people know m-idicator which is the popular transportation app for mumbaikars, but Ridlr including mumbai and all metro cities it provides accurate details about train and bus services, the ui has to be admired for smooth and clean navigations. even it has got map integration you can calculate the estimated time to reach your destination. install the app if you travel frequently, recommended 4/5.