Foundation and preparation works have commenced on the $48 million Toowoomba Range rail upgrade in Queensland.

The project will involve increasing the height of 11 rail tunnels on the Toowoomba and Little Liverpool Ranges, enabling the transport of containerised freight by rail from the Darling Downs and South West Queensland Regions directly to the Port of Brisbane.

"Foundation and preparation works have commenced with further preparation works to be undertaken during a scheduled track closure of the western rail line at the end of February. The first tunnels will be lowered during a major track closure in April," Transport Minister Mark Bailey said.

"The lowering of 11 rail tunnel floors on the Toowoomba and Little Liverpool Ranges will create the clearance necessary to transport 9'6" high cube freight shipping containers via rail, increasingly being used to export goods."

BMD Constructions worked on the detailed design and investigation works for the project.

"BMD Constructions, which has local offices in Toowoomba, and design partners WSP Parsons Brinckerhoff, have completed the detailed design for the project, and Queensland Rail will continue to work with BMD Constructions during the construction phase," Bailey said.

"Now that construction has started, we anticipate the work will take approximately 12 months to complete.

"This project will lower 11 heritage listed railway tunnel floors, including two tunnels on the Little Liverpool range at Laidley and nine tunnels on the Toowoomba Range.

"The tunnels are stone and brick lined and were constructed in the 1860s on Australia's first main rail line through the Great Dividing Range. This project will strike a balance between maintaining the heritage status of the tunnels, while providing the modern day upgrade that is required."