Black Bridge, across the River Dulas near Machynlleth, now stands one metre higher after being manually raised using lifting blocks and around eight miles of chain.
The bridge has been raised to alleviate problems caused by flooding. It was closed no fewer than ten times in 2020 for emergency repairs, and a total of 30 times over the last decade.
Engineers decided not to use hydraulics, to ensure there was no twisting or buckling to the 80-tonne girder structure.
Network Rail, which worked together with contractor AmcoGiffen, said the scheme “will improve passenger journeys and secure the future of this vital transport link between Mid-Wales and the rest of the UK”.
The £3.6 million project took six weeks, with engineers on site from May 15-June 26 and the Cambrian line reopening on June 28.