The old Loughor Viaduct has been replaced and work is focusing on laying two tracks through Gowerton for the start of services on Monday.
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Low cloud will bring murky conditions with extensive hill fog.
The team, which is manned by volunteers, will operate out of Pontardawe Fire Station in partnership with Mid and West Wales Fire Service.
Dan Biggar has no doubt that Wales remain flrmly in the Six Nations title mix ahead of next Saturday's clash against Scotland.