An incredible new £1bn is to transform travel through the valleys in the form of a long awaited metro. South Wales Metro is Transport for Wales' (TfW) answer to London's Tube - an integrated public transport service involving trains, trams and buses, which is currently being constructed in south-east Wales around the hub of Cardiff Central railway station.

The metro will even mimic the London Underground with its own colour-coded map, tap in tap out payment, destination boards telling you how long to the next train and switching lines to get to where you want to go quicker. Those living in the valley towns will be all too familiar with the disruption the works have caused - and will be pleased to hear that the project is estimated to be finished in 2025.

The idea was formally launched in November 2015 with aims for the metro to be a catalyst for transforming the economic and social prospects of South East Wales and the first phase was approved for development in October 2013.

The initial cost estimate for the Metro was £734million, however, this quickly spiralled to be around £1 billion.

The work is particularly focused on what rail bosses call the core Valley lines - these are the lines that connect Cardiff with Aberdare, Coryton, Merthyr Tydfil, Rhymney and Treherbert. These lines will become an important part of the South Wales Metro.

Construction, engineering and infrastructure work is underway to upgrade the rail network so that it's ready for Metro. This includes electrifying around 170km of track, upgrading all the stations and signalling in the Metro network, building at least two new stations and the service will undergo its biggest timetable overhaul for 30 years.

The chnages mean that there will be more weekday and Sunday services than ever before.

• Four trains per hour between Cardiff and the Heads of each Valley (Aberdare, Merthyr Tydfil, Treherbert), with trains every 15 minutes.
• Two of the four services from Treherbert, Aberdare and Merthyr Tydfil will go on from Cardiff to Cardiff Bay.
• Increasing services between Pontypridd and Cardiff to 12 trains per hour.
• Six trains per hour between Caerphilly and Cardiff, a train every 10 minutes.
• Increasing services to six trains per hour travelling to Cardiff Bay.
• More frequent evening services.

• Two trains per hour on Sundays between Cardiff and the heads of each Valley (Aberdare, Merthyr Tydfil, Treherbert).
• Starting in June 2024, the City line will have its first-ever Sunday service. The Coryton line will follow with a Sunday service in 2025.
• The first-ever Sunday service on the Maesteg line, with trains running every two hours, and increasing to an hourly service soon.

Some valley line routes in and out of Cardiff have changed so that when service frequency increases the major station interchanges in the Welsh capital will be able to cope with extra capacity.

Passengers travelling from some stations may be able to change trains at Pontypridd or Radyr to reach their destination quicker, just like they might have to do on a major city subway.

The fleet will include Class 398 battery-electric tram-trains that can operate on both on-street tracks and conventional railways, along with Class 231 bi-mode and Class 756 tri-mode trainsets for conventional railway lines.