In first look, it will be a bad decision of Railway. 1900 or more i.e.20,000/- (Average 10 Sleeper Coaches) 3AC Economic class coaches are required, it will take at least 05 years to manufactured. So in every year average 300 to 400 trains can be converted in AC train as per the priority decided by the the railway authority. In my observation in 1st phase only Golden Quadrilateral track route trains will be converted in fully AC train. A, B & C grade city/ town wise train will convert in the later stage. Hope concerned Railways authority will mange this issue very efficiently.