This new viaduct and redoubling of the railway through Gowerton will remove the current bottleneck created by the stretch of single line and provide capacity to run more trains in the future.
This project joins a number of other rail improvement projects in South and West Wales that will help deliver better journeys and boost economic growth in the area.
As well as making it easier to travel to and from West Wales, they will help to boost local employment opportunities.
More top news
Some clear spells to start the night but the cloud will thicken bringing patchy rain for some!
Carwyn Jones was "received in Audience" by the Queen today. The initial handshake was photographed but their conversation remains private.
The actress has lent her voice to the school's production of Hans Christian Andersen's The Little Match Girl.