As we all know the Tawa Flat Deviation was opened in 1937 to replace the entire section of the NIMT from Wellington to Tawa Flat via Johnsonville. Whilst the first section of the route from Wellington to Johnsonville remains as a passenger-only line today (although until the 1980s it also served freight traffic), from Johnsonville to Tawa Flat (latterly Tawa) was closed and lifted.
As I wrote in this article here some years ago and reprinted in 2012, there are some remnants of the line still to be found even though much of it disappeared under the Johnsonville Motorway in the late 1940s. As I don't live in Wellington I have not attempted to trace the features referred to by Nicol Campbell (stormbird) to see what they look like today.
Aerial photography dated from 1946 was used to attempt to determine the existence of any other features which has shown up a couple of overbridges. The rest of the maps that were previously drawn were reasonably accurate (understandably, since most of it was drawn from other source maps).
As we usually do with the NZ Rail Maps we start at the northern most end i.e. Tawa. The junction with the present line being prominent near the end of Duncan St. This road re-uses the railway formation up past through the old Tawa Flat station on the hill.
Here we see part of the curve at Takapu Road. Just past Redwood Station the old line had a bridge over it.
According to Nicol Campbell's account, the old railway along this section between Belmont Gully and Takapu Road is still extant just to the side of the motorway and can be traced on foot.
During construction of the Tawa Flat Deviation a temporary tramway was laid to take rock to a large crusher that was installed above the track. The old line crossed over the top of No.2 tunnel and had an overbridge near that location.
Belmont Gully and the viaduct site are prominent remnants of the old railway route today. There was also an overbridge on the old line about where the present day motorway crosses the route. Nicol Campbell also refers to the formation at the very bottom of this map which he says is a cutting that is still partly extant although most of it was filled in by the subdivision development.
Coming out from Johnsonville the old line deviated slightly to the east of the present terminus and the old station was slightly further north. This station survived for many years post closure of the line north of there; the present terminus dates from about the 1980s/90s due to the original site being redeveloped as a supermarket. The road overbridge is on the site of the original which crossed over the line as it headed north of Johnsonville.
So in summary the tangible remants are a few cuttings. I would certainly like to know about Nicol Campbell's statement as follows:
"The line then cuts across the motorway at a sharp angle and continues along its west side but slightly below road level. It is not continually visible from the motorway but because of the heavy earthworks needed in the hilly country the line can be easily traced on foot as it slowly descends through a succession of cuts and fills."
He is referring to between the Belmont Gully and Takapu Road. What cuttings and fillings exist there today?