A RAIL line in the Blue Mountains is reopening to freight services following a derailment last month.

A freight train derailed on 14 December on the main western line between Lawson and Linden, damaging around 10 kilometres of track.

Transport for NSW and Sydney Trains repaired broken rail, smashed concrete sleepers and damaged signalling equipment and electrical assets.

Crews have replaced more than18 kilometres of damaged track, installed more than 15,000 new sleepers, 24,000 tonnes of ballast and replaced or repaired 92 pieces of signalling equipment.

Minister for regional transport and roads Sam Farraway said the entire damaged track was rebuilt in “extremely difficult” terrain.

“The Blue Mountains rail line is a critical freight corridor linking east with west,” he said.

“We worked closely with the freight industry during the repair period, opening the adjacent track to allow for diesel freight train movements across this critical supply chain.”

Mr Farraway said full freight access will resume on the Blue Mountains line following once repair works are finished.

“I’d like to thank our rail freight industry, passengers and the local community for their patience and understanding while the repairs were undertaken,” he said.

“I would also like to acknowledge the professionalism of the engineering and trackwork teams who completed the significant repairs to the rail corridor.”

The first train to run on the on the repaired track will be Saturday’s 0349 passenger service from Lithgow to Sydney.