Thanks. People in Bd have less knowledge on the preparation of time schedule of a large civil work. On the other hand, the govt. authorities keep on promising the completion on certain year without first consulting the construction schedule.
So many works are needed to complete an MRT, like getting land for Right of Way (RoW), bringing in construction machines and materials there, selecting the sub-contractors and vendors, continuous surveying, doing earth works, placing crushed stones or concrete, laying sleepers, and finally laying the steel lines. Simultaneous other works involve building of railway stations, signal system with control rooms and many other facilities. Then comes the electricity supply process and many hundred other jobs.
So, whatever the govt. authority says I am not the one to believe any part of MRT will be finished at the end of 2019. However, since Japanese are involved they certainly have prepared a construction schedule already and they are working accordingly. I have not seen the schedule. I believe that no part will be ready for use before 2022, as you have said.