Wednesday, 11 August 2010

The Waiau Branch – Part 3 : Weka Pass

This article is revised from the original that was published on the Railways of New Zealand website.

The division of the gradient diagram and the locations of photos are purely for the purpose of allocating the coverage of the series of articles and bear no relation to the physical boundaries of the “Weka Pass Railway” organisation. This website is not and does not purport to be any kind of official representation of the Weka Pass Railway Inc.

Since 1983 the Weka Pass section of the Waiau Branch has been the home of the Weka Pass Railway. Just past the summit at 7 miles 22 chains (11.8 km) there is a road overbridge (No. 2) and a small bridge crossing a creek (No. 1). No.2 bridge was in a poor state of repair even in its NZR days and Railways looked at eliminating it in 1982. However it is understood that the Weka Pass Railway is no longer responsible for this bridge. The WPR began operating its own trains in 1984, reaching Waikari Crossing in 1985. However the entire Weka Pass line had to be closed temporarily in 1986 due to damage caused partly by bad weather and accumulation of deferred maintenance from NZR days. The line was re-opened to the 5.5 km peg in April 1987, and in stages after that. In 1988, track was lifted in the Waikari cutting where the formation was in poor condition from slipping, so that the cutting could be filled in and the grade and a yard area levelled. Within a couple of years, however, the formation was in a similar waterlogged condition again and more slips had come down, so that extensive remedial work was needed. This work was necessary due to the fact that the track at Waikari crossed an area of blue papa, a notoriously unstable soil type responsible for many problems in railway construction throughout New Zealand.

At approximately 10 to 10.5 km, a location known today as "Herberts Crossing", there was originally a lengthy curved wooden viaduct, beneath which passed the main road and a small stream. The viaduct was on a level grade and curved on a 12 chain radius, was 266 feet long and 40 feet high. It cost £1994 to build in 1882. In the early to mid 1930s the road was deviated to somewhere near its present location over a new concrete culvert, allowing the viaduct to be filled in, which was begun by a contractor in 1936 and finished by NZR the following year. It is possible to walk down into the trees in this area and find abutments for the small bridge where the road crossed the stream as well as the culvert which carries it under the present railway embankment and road.

It took some 12 years for the Railway to be reopened to Waikari which occurred at the official opening in September 1999.


The gradient diagram pertaining to the section of the line which this page addresses. We can see that in the diagram, the line levels out for a short distance before resuming this climb. This small level piece was the site of the former viaduct, as it has often been observed in New Zealand that many of the larger bridge structures are built on the level. The line then resumes its inexorable climb to reach the summit (VC = Vertical Curve) before beginning the descent into the Waikari station. The present day terminus of the Weka Pass Railway is roughly at the point where the gradient eases from 1 in 80 to 1 in 100, although for WPR purposes the line was built up to ease the gradient to 1 in 200 at the terminus.