A section of a railway line is set to reopen after it suffered extensive damage during a storm in the summer.
A half-mile stretch of the Heart of Wales line at Llandrindod Wells, Powys, was damaged by landslips and flooding after Storm Francis in August.
Network Rail said it had taken several measures to bolster the resilience of the line.
A section of the line at Llangennech, Carmarthenshire, is still closed after a freight train derailed.
That section of track will remain closed until the new year.
Bill Kelly, Network Rail's Wales route director, said he was "really proud" of the engineers who repaired the section of line so that it could reopen on Tuesday.
"They have completed a mammoth task, and we are extremely pleased to reopen the line and to begin serving all of the communities who rely on this route," he said.
Lisa Dennison, development manager for the Heart of Wales line, said: "The communities along The Heart of Wales line have been very hard hit by recent line closures and reduced services, the knock-on effect has been massive.
"That is why we are so delighted to have the northern section back open and to see trains running again - it's what the towns and villages need right now. "
Alexia Course, from Transport for Wales, said services were currently in place for "essential journeys only" due to the ongoing 'firebreak' lockdown in the country.