Options are being explored for a major redevelopment of the station during its next five-year funding period, which starts in 2019. The plans are likely to see an extension to the Grade II listed building.
Signalling technology in the Cardiff area is already being upgraded and work has also started to electrify the line from Swansea to London.
But with passenger numbers forecast to grow 69% over the next decade and 145% by 2043, the station is not ready for the rising demand.
The remit for the initial design work, by Powell Dobson Architects, has been to integrate the historic elements of the station into a new building with a bigger concourse and improved connectivity to platforms. There will also be more shops, cafes and sandwich bars.
Network Rail says its wants the station to be not just a place people travel through on their way to somewhere else but “a destination in its own right serving the local community emerging around it”.
The site redevelopment proposals also envisage a new multi-storey car park, commercial developments on the existing south side and Saunders Road car parks and an enhanced transport interchange and public realm.