Their is something called Public Private Partnership which have worked in Karachi at least in the form of K Electric and fortunately Karachi have perfect ingredient to support such venture which is Corporate Business Environment....Its only Will of Govt. that is the real question mark in Reviving this Project....probably for the best, its not building which is difficult, maintaining it is, It will be a nightmare in corrupt Pakistani govt. it will costs billions to maintain such a project.
remember karachi circular railway was a well functioning system and it was closed because of rising costs and corruption in 90s. so even if its rebuild same would happen., if not today after a decade. and we will end up paying 2.6 billion dollars
the only solution is if its privately build and privately maintained