We go inside the Severn Tunnel as it closes for major renewal work
Water and salty air inside the tunnel mean the tracks have to be replaced every ten years.
Water and salty air inside the tunnel mean the tracks have to be replaced every ten years.
The Severn Tunnel was temporarily closed on Wednesday evening following an incident in which passengers reported seeing "flames" from the windows.
The 130-year-old Severn Tunnel will close for six weeks from Monday to upgrade it in preparation for a fleet of new electric trains