Designed to give access to Lake Rotorangi picnic area and water ski course. The Tangahoe Valley Tunnel is the only one in South Taranaki.
Built in 1928, it stretches 160 metres long. Two teams of diggers started digging, one from either end, upon reaching each other they were found not to be quite in line. The floor level is still today uneven even after some adjustment. The Gothic arch gave the tunnel stability but no one knew it was on a fault line. A series of tremors shook the roof down and it closed to the public in 1986.
A replacement channel through a Papa bank was dug which was more often than not closed by slips – causing endless problems for irate land owners.
In 1996 the STDC decided to reopen the tunnel and work began the following year. The $250,000 repair job turned out more difficult than expected with 25,000c metres of fill needing to be shifted just to get to the tunnel.
Supposedly this fill came from the channel previously cut from the hill; a further 10,000 c metres of soil had to be moved just to find the portal. The most critical stage followed – that of drilling and ramming home more than 1,000 metres of rock stabilising bolts.
Today the well preserved Tangahoe Tunnel serves South Taranaki not only as an old world attraction but as an historic monument and a tribute to those men who built and restored it.
As you drive in from the west on the left hand side is a plaque commemorating the reopening by Mayor Mary Bourke in May 1997, easy to miss if you don’t know it’s there.
At the other end, another plaque just inside the tunnel records the Guniting of the tunnel by P. W Batchelar Ltd. It’s worth looking at.