The Dellfield Line (previously known as the Museum Line) is a branch of the Downtown Line serving the Dellfield area, and is part of the NotchRail network. It was constructed after the City Museum Commitee convinced the NotchRail Corporation to build a railway line to the City Museum.

In 2068, as part of Project Revolution, the Dellfield Line was amalgamated with the Downtown Line. The branch was duplicated and all but Dellfield Park received an extra platform.

The line was formerly coloured lavender in NotchRail's timetables and other promotional materials. Now it is coloured orange like the Downtown Line.