A fleet of 270 trains will undergo a £55m modernisation to improve travel for passengers.
The five-year project will see upgrades to Southern, Gatwick Express and Great Northern trains including real-time passenger information screens.
Govia Thameslink Railway (GTR) and Porterbrook, the owner of the trains, will also equip carriages with environmentally friendly LED lighting.
The improvements will give "a better on-board experience", GTR said.
Trains to benefit from "Project Aurora" include 214 on the Southern network between London, Surrey, Sussex and the south coast, and 56 on Great Northern or Gatwick Express routes.
While parts of the fleet are just five years old, most trains have been in service for between 15 and 20 years.
GTR's engineers will install features including on-board real-time information through media screens, USB and power points and passenger counting technology.
The trains will also be fitted with an upgraded data recorder that will help predict and diagnose faults and streamline maintenance.
New forward-facing CCTV cameras will also help GTR and Network Rail investigate incidents that have delayed services.
GTR's engineering director, Steve Lammin, said: "Taking on board our passengers' feedback, this multi-faceted upgrade by our own team at Selhurst Depot will provide a better on-board experience and more reliability."
Mary Grant, Porterbrook chief executive, said: "We are committed to helping GTR meet the needs of its travelling customers."
The first completed upgrade is scheduled for autumn.
source: BBC News