The £13m project will deliver a new, 271m-long second platform and a fully-accessible steel footbridge, with sandstone clad lift towers, for the East Lothian station.
Engineers will be on-site at Dunbar from next Tuesday establishing a project office and compound ahead of the start of construction work at the station.
Throughout May work will take place to clear vegetation and redundant structures and track to make way for the new infrastructure.
Construction work on the project will be ongoing from May until early 2020, with the new platform being operational from December 2019.
The new platform will provide increased capacity and improve operational flexibility as currently all northbound and southbound services have to use the same platform.
Northbound stopping services will use the new platform once it is constructed and it will also allow train companies on the East Coast Main Line to operate more services on the route in the future.
Matthew Spence, Network Rail route delivery director for Scotland, said: “The new platform will mean extra capacity at Dunbar and create opportunities for more services to stop in the future.
“The new infrastructure, which will be fully accessible, will also include a choice of materials and paint colours that are designed to be considerate to the historic station building.”
More information on the project can be found at: www.networkrail.co.uk/DunbarStation.