Tuesday, 13 April 2010

The Ngatapa Branch Tunnels Mystery

The Ngatapa Branch, at first glance, is one of the great enigmas of railway construction in New Zealand. It was originally conceived to be the route south from Gisborne towards Napier. Work began on the line as late as 1911 and tracklaying to the eponymous terminus was completed in 1914, although the Waipaoa River bridge was not completed until the following year. Beyond Ngatapa some formation work was carried out, and it has always been rumoured or stated in various publications that one or more tunnels were constructed as part of this work. However, not one single person to my knowledge has ever produced a photo of any of these tunnels or proof that they exist today. What we do know as a matter of public record is that work was started beyond Ngatapa after the end of World War 1 (the Waikura section) and also at Frasertown near Wairoa which was the other end of the planned route. But the route beyond Ngatapa itself was found to be unstable and so the works were stopped in 1920, and in 1924 it was decided that it would be impossible to continue with this line of the railway. Thereafter the completed 12 km railway was operated by NZR as a branch line for seven years until it closed in 1931.
The NZ Railway and Tramway Atlas 4th Edition has shown three tunnel locations. With a bit of help from Google Earth and Geoff B, it is possible to work out that the corresponding locations (and the route beyond Ngatapa) are as shown in the map below:

View Larger Map
Note that Ngatapa railway station is the circular dot symbol at right. The route shown beyond Ngatapa in aqua is that which is easy to determine by the earthworks that were constructed. That which is in green corresponds to the NZRTA 4th edition route, as do three of the square symbols for the three tunnels shown on that route. What is important to note that there is no obvious trace of these tunnels today. There are two likely explanations:
  • the tunnels were never constructed, or
  • the incompleted or partly completed tunnels have collapsed.
Here we must make reference to the above map in conjunction with statements that “the Waikura section was found to be unstable”. It is very easy to see the broken nature of the country around the line in this area and Geoff’s photos back this up. This is a very poor type of soil that slips very readily, NZR/PWD would have had their work cut out for them if the railway had ever gone that way. In such circumstances the collapse of the tunnel works without a trace if they were incomplete is entirely possible, by that I mean if they had not been lined. If the tunnels had been completed there is likely to have been at least portals remaining, probably more, even if the lining had collapsed at some point. The fact of land instability is well established, being corroborated by A L R Merrifield, a fomer NZR civil engineer. The picture above just confirms it. If the tunnels had been built that would have occurred around 90 years ago.
So I think it is safe to say that there is no trace of these tunnels to be found today.
Here for the sake of completeness is the Frasertown section:

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Finally, here are both ends of the line shown on a map together:

View Larger Map

References / Sources:
“New Zealand Railway and Tramway Atlas”, 4th Edition (p.12). Quail Map Co, 1993.
Historic Poverty Bay and the East Coast, N.I., N.Z.”. J A Mackay, Gisborne, 1949.
“Exploring New Zealand’s Ghost Railways”, 2nd Edition (p.22-23). D B Leitch & B Scott, Grantham House Publishing, 1998.
“Of Stone, Steel And Skill”, A L R Merrifield. Chapter from “Steel Roads of New Zealand” (p.111), G S Troup (ed.), Reed Books, 1973.
New Zealand Rail Maps – Northern – PNGL_Other_xxxxxx.kmz. P J R Dunford, 2009.
Thanks to Geoff B, who went to Ngatapa and hunted out the tunnel locations (and a lot more).