The Imbil Tunnel on the Mary Valley Line runs through the divide between Yabba Creek and Kandanga Creek catchments. The tunnel was built during 1914, and the 5-span high level bridge over Yabba Creek was built simultaneously. Once the tunnel and Yabba Bridge were completed the track was laid to the new terminus at The Bluff, which the Railway department named Brooloo, and the final extension (Kandanga to Brooloo) of the Mary Valley Branch Line was opened officially on April 30, 1915.
In the early years, mixed goods/passenger trains ran 6 days/week. Railmotors for passengers commenced running Brooloo to Gympie and return daily from 1928, with the goods train reduced to 3/week or to 5/week in pineapple picking period.
Once Imbil Secondary Department school was opened Imbil and Brooloo children ceased using the line, and bus services were commenced to take Kandanga children to Gympie High School, and as the ferrying of secondary students to Gympie had been the prime role of the railmotor in the 1950s and 1960s, it ceased to run in 1970.
Then only goods trains (pineapples for the Northgate Golden Circle cannery and sawn timber from Imbil, Melawondi and Amamoor mills of Hyne & Son) operated Monday, Wednesday and Friday till 1991. The last Queensland Rail train ran in 1995, and the line was then transferred to the Mary Valley Heritage Railway run by local enthusiasts, who now operate steam locomotives and diesel railmotors on the line as a tourism venture.