The Hamilton-Koroit Line was a branch line running south west from the Portland Main Line at Coleraine Junction near the town of Hamilton, to the town of Koroit, where it joined the Port Fairy line. Opening in 1890, the line was 84 kilometers long and completely single track apart from at stations. Since closure in 1977, the track has been completely removed and reserve rights mostly sold as well, with very little trace of railway left.
The entire line was opened on 22 August 1890 with the purpose of transporting produce and timber from Victoria's south into the port at Portland and through the rest of Western Victoria. Initially, the line had two separate connections to the Ararat–Portland line, with a secondary branch existing between Penshurst and Dunkeld. However, this short-lived section was closed to traffic on 24 March 1891, and was eventually ripped up.
Most of the trains that ran on this line were carried mixed traffic, and usually ran from Melbourne to Koroit via the Port Fairy Line, before continuing to Hamilton. Declines in both passenger and freight traffic caused smaller stations along the line to close during the 1950s and '60s, and eventually the line was closed completely on 12 September 1977 along with the Dennington–Port Fairy section of the Port Fairy line.
Koroit-Hamilton Line railway line