Inner city tram. Initially a museum line that got modernized and after much biching and digging, then extended by 400m, getting it closer to the subway.
Currently stalled by street renovation work that was meant to be done in the 1990s. The anti-tram lobby in the city hall played this card in a last bid to stop construction.
It will be extended another 400m but everything else is in limbo.
I reckon the abstract line map tries to depict the current situation where it has been shortened by 200m in preparation for the upcoming extension. The western terminus was a single-track contraption.