There's a word which is specifically about building construction in progress - "долгострой".
When finishing some building project - building, bridge or road takes more and more time and still far from being finished - it's exactly долгострой.
Quite often it's used not only about building. It can be used for describing state of software development (like here - "Долгострой в разработке ПО: о проблемах управления требованиями") or some political reforms - than it's "политический долгострой".
Still, this term is not universal. The closest you can get is затянувшаяся работа or незапланированно долго затянувшаяся работа.
WIPin russian tech (programming themed) texts, I don't think there is exact equivalent for expressing state of work, which has observable properties, but doesn't have quality of finshed product. – Odomontois Sep 19 '17 at 07:04