The scheme included a complex operation carried out over the Easter weekend to slide the new two-track and 235m-long structure into position.
"The challenge was to deliver a new 235m rail viaduct, constructed in an environmentally sensitive area over a fast flowing estuary with minimum disruption to the railway,” said Carillion senior project manager Jon Kite.
The new river substructure was constructed adjacent to and under the existing live railway whilst the new viaduct was being launched and constructed alongside.
“In a 249-hour possession we demolished the existing railway viaduct, constructed new abutments, slid the new one sideways into position and completed the permanent way works to connect to the track on the original alignment."
Carillion's replacement of the 104-year-old Loughor Viaduct was completed alongside work by Colas Rail and Morgan Sindall to double the width of an 8.4km stretch of the railway.
Both schemes were funded jointly by Network Rail and the Welsh Government in partnership with South West Wales Integrated Transport Consortium.
