The time frame depends on whether investors are qualified for conducting geo-technical survey and preparing conceptual plans or they have to outsource the tasks.
In this website, only guidance for two-step construction designing is presented in accordance with Article 23.2.b of Decree 59/2015/ND-CP on construction project management.
Under circumstances where one-step construction designing is required, investors only have to produce detailed construction plans and techno economic feasibility reports for their application of construction permits.