Over the years, various alterations were made to the line as branch lines and goods yards opened and subsequently closed. One of the most important additions was the Rosewater Loop, which opened on 14 November 1915. The Rosewater Loop was built to help alleviate congestion at Port Dock yard. It linked at Port Adelaide "A" Junction with a new route to Glanville via the Commercial Road viaduct and Ethelton and helped divert all through trains away from the Port Dock bottleneck. This relatively new addition to the railway infrastructure became the main line.