Wainuiomata Tunnel

The Wainuiomata Tunnel was planned to improve access to the Wainuiomata Valley in the Wellington region of New Zealand’s North Island as part of a scheme to commence residential development there in the 1930s. Construction started in 1932 but was halted a couple of years later when only partly completed due to a lack of funds brought about by economic depression. The tunnel was never opened to road traffic, and other than a brief stint of military service during World War II, remained unused until sold in 1975. Thereafter it was completed as a utility tunnel, initially carrying only a water pipe, but later other services were added.

Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).