There is no transit directions in iOS 6 Maps because it came from Google Map however nice thing is that Apple allows third-party developers who make transit apps to work with this map from iOS 6 .

 

 

Which it means when you request for transit directions from the Maps, third-party transit apps screen will show up and help you to get there. If you do miss Google Map, you can type maps.google.com in Safari from your iPhone. For full detail, click the link below.

http://www.maclife.com/article/news/reminder_no_transit_directions_ios_6_maps