The route has been stopped since June 25, when twelve carriages on a hundreds-meter-long freight train derailed east of Bollebygd.
The cause of the derailment was believed to be a sun curve, a phenomenon where the heat from the sun bends rail tracks.
“The restoration work has gone according to plan. We have replaced nearly 700 meters of track, sleepers, rails and contact wire,” said Malou Klock Strömgren at the Swedish Transport Administration's Western Region in a press release.
The trains will initially run at reduced speed due to the ongoing heat wave.
Other train traffic will also not run as planned for a couple of days, also due to the intense heat.
Scientists have shown that recurring heatwaves are a clear marker of global warming primarily caused by burning coal, oil and gas – and warn they are set to become more frequent, longer and more intense.