Comment by asdff

A mezzanine level is expensive and only serves to delay people. It doesn't get more people into more trains. Only more frequent and longer trains can do that, and that is dependent on the length of the platform and how many trains can move through a given tunnel an hour, the mezzanine is extraneous. It makes people not want to take the train by introducing bottlenecks by making you go through another set of stairs or escalator. But I'm sure the expenses associated with the mezzanine lines a bunch of people's pockets, so I wouldn't expect sensible design to come into fold anytime soon in our contractor-graft based country.