The intention was to subsequently extend the line to Tarong, which was connected by rail to Kingaroy and beyond into the Burnett River area.
[10] Mixed trains initially ran four times a week and were replaced in 1929 by a daily rail motor service to Toowoomba.
This provided passenger and farm produce services not only to these towns but also to the surrounding townships of Quinalow, Maclagan and Evergreen.
With negligible track remaining the Oakey-Cooyar branch line could all but be overlooked as a fading scar on the landscape, it retains its significance however through the still intact Muntapa Tunnel.
The Oakey-Cooyar branch line was repeatedly surveyed to arrive at its built route, which had a negligible gradient over its length, but which required the 300m tunnel.