ARTC said the loop was extended to allow 1350m trains to stand while a train travelling in the opposite direction passed at regular speed.

“The overall effect will be to reduce transit time and therefore increase capacity on the line,” ARTC said.

The upgrade included the integration of digital central traffic control signals between Boggabri and Emerald Hill.

ARTC said the new system would allow for more efficient train management with digital signals controlled remotely by a network controller in Broadmeadow.

Chief executive officer David Marchant expected capacity improvements between the Gap (near Werris Creek) and Narrabri.

“There will be an increase in the number of train paths and faster cycle times for trains which will increase the capacity of the track and enable the transport of more coal from this growing region,” Marchant said.

“Demand for coal from the Gunnedah Basin is set to grow exponentially by 2012. This investment in new signal technology is part of ARTC’s strategy for the Gunnedah coal corridor to keep ahead of future market demands.”

Whitehaven Coal’s Narrabri project is expected to reach first coal in the December quarter while Idemitsu Kosan’s Boggabri Coal open pit mine produces about 1.5 million tonnes of run-of-mine coal, according to Downer EDI Mining.