Transport for Wales (TfW) advance with work on the South Wales Metro with work set to take place between Merthyr Tydfil and Pontypridd.
The railway line between Merthyr Tydfil and Pontypridd will be closed from 23rd October to 27th October whilst engineering work takes place.
This work forms part of the preparations to introduce brand new electric tram-trains.
A replacement bus service will be put in place between Merthyr Tydfil and Pontypridd while work take place.
The three-quarters of a billion-pound project is funded in part by the European Regional Development Fund through the Welsh Government.
This will allow quicker and more regular services between Cardiff and the heads of the valleys.
Engineers will conduct complex work during the closure including repositioning signals, installing and testing new equipment, realigning the track and installing the overhead line equipment system.
The scale of this project will require work to take place 24 hours a day making railway closures unavoidable.
Overhead lines will power the new tram-trains reducing journey times between Merthyr Tydfil and Cardiff city centre.
The introduction of tram-trains will also allow TfW to increase the frequency of services to four every hour.
Karl Gilmore, TfW’s Rail Infrastructure Director spoke on the importance of the work on South Wales Metro.
Mr Gilmore said: “We have a significant amount of work to carry out to create the South Wales Metro.
“This includes the biggest upgrade to the ageing Core Valley Lines infrastructure to this scale since it was first built.
“So that we can deliver the faster, more frequent and greener services the people of the South Wales valleys deserve.
“While work is taking place, we’ll do everything we can to work responsibly by ensuring our sites are well managed and our people are considerate to our neighbours.”
Investment in South Wales Metro will provide greater access to jobs, leisure and other opportunities for the people of Wales.