Dunedin’s Railway Rebirth

The original railway line south of Dunedin to the satellite township of Mosgiel, a 15 km length, was a steeply graded and sharply curved single-track route incorporating the Caversham and Chain Hills tunnels. It was opened for traffic between 1874 and 1875. It sufficed only for some thirty years before an improvement project was started to make the route fit for heavier traffic and safer, faster operation. Begun in 1906, the modernisation of the line, realigned and regraded into its present day route, was not completed until 1914. A description of the route changes is in order and described thus:

The reconstruction of the route begins with the 1 in 100 grade embankment approximately opposite the CT (Container Terminal) site. This takes the route over Andersons Bay Road on an overbridge and eliminated the first of sixteen level crossings. Just short of the next bridge at King Edward Street, Kensington Station was raised to the new level, which along with the bridge made the working of this station much more straightforward, without the problems of trains blocking the busy road. Continuing south, the next new bridge was built over Wilkie Road. Between it and King Edward Street a siding into the Hillside Workshops makes a steep descent down the embankment. Soon after Wilkie Road as the line passes behind Carisbrook Stadium, the original route level is joined somewhere near the bridge over South Road. Further on the first major deviation was made when a new tunnel was built through the Caversham Hills at a lower level, easing the gradients, and a longer length; it was also double-tracked from the outset. This deviation placed Caversham Station in a new location. On leaving the new tunnel at the south end, Burnside Station was reached on a new site, followed by Green Island. Abbotsford was then encountered, also on a new site, before the second major deviation was reached. This involved a new Chain Hills double tracked tunnel, twice the length of the original and on much more favourable grades. On reaching the south end of this tunnel, Wingatui Station is encountered on a new site nearly 2 km closer to Dunedin than originally. The rest of the route to Mosgiel involved relatively minor changes.

The Caversham Deviation was examined in my previous posting, “Caversham’s Railways” and is not further referenced here. The geographic impact of this deviation was probably the most significant change of the whole project, due to it passing through an established residential area, and its approximate length. Though the Chain Hills deviation was also of significant length, much of the area through which both lines passed, and still pass, is rural and not impacted significantly. The rest of the rebuilding took place on more or less the original route. There was an undeniable geographic impact from the construction of the large embankment between Dunedin and Caversham stations, the three overbridges and raising of Kensington Station, as well as the doubling of the entire line. In the early 1980s, much of the line was singled in several stages; Dunedin-Caversham was completed first, and Caversham-Wingatui later. At this present time, there is still a double track line from Dunedin almost to Kensington including Andersons Bay Road bridge. All of the remaining bridges that were able to be observed have been reconstructed or modified to single track formation. This includes, as at Wilkie Road, removal of the girders on one side, or as in the case of a bridge near the southern end of the Wingatui Tunnel (possibly Abbots Creek), abandonment in place. In other cases like King Edward Street and South Road, the bridges have been rebuilt as a single track structure. The single track in the two tunnels has been pulled towards the centreline to increase the clearances for modern rolling stock.

At the time that the line was altered, it crossed the Dunedin, Peninsular and Ocean Beach Railway line just north of Andersons Bay Road on a diamond crossing. As rebuilt the crossing is effected by a single span overbridge. With the closure of the DPOBR in 1942 the remnant of this line served nearby private sidings. In the late 1980s there were still tracks as far as Orari Street used to store old locomotives. The overbridge still exists even though the track is now cut back to Strathallan Street and appears disused. Green Island and Abbotsford Stations were both junctions of branch lines (Walton Park and Fernhill respectively) in the 1900s. Both of these lines continued in use regardless of the effects of reconstruction which altered the junctions somewhat. Suburban passenger traffic density was an important justification for the reconstructive work at the time; the singling has followed the demise of these trains in 1982, but some of the stations closed earlier, including Caversham in 1962 although it may have continued as a passenger halt after this date. After 1982 the Southerner was the main regular passenger train to pass over the route but it made no stops between Dunedin and Milton. Passenger trains were operated on the Otago Central Railway until 1976 and I do not know if they made any suburban stops within Dunedin city. The advent of the Taieri Gorge Railway has not resulted in any reinstatement of closed stations for passenger convenience, the trains generally running non stop between Dunedin and Wingatui.

During the course of my time in Dunedin I only examined the line between Dunedin and Burnside, although I rode the route twice and obtained a few photos of Wingatui which are in my Otago Central Railway album. Please refer to the Caversham’s Railways article for the map of the route and changes. I am not going to revise that map for the purposes of this article; but the photos from the Picasa web albums associated with this blog will be shown below with brief captions. You can see the full size photos together with locational information if you visit the General album at nztransportgeography's Picasa site.

Heading south from Dunedin, the first indication that most people would see of the reconstruction is the embankment that climbs at 1 in 100 to get the line over Andersons Bay Road, a thoroughfare that it formerly crossed on the level.Here we can see it near the beginning of the ascent.

The bridge over the former DPOBR just north of Andersons Bay Road. The lower line appears to be disused today and any future reconstructive requirement of the bridge would probably result in its disappearance.

Andersons Bay Road bridge. The piers are most probably original. Soon after its construction, movement was reported in one of the abutments; the extent of any remedial work is unknown.

Kensington station was about here when its site was raised on the new embankment about 1906. The date it was closed is not known to me. There is road access today from what is now the Warehouse site, which was formerly the location of the Caledonian Grounds.

King Edward Road bridge. The original design, on the far side, incorporated access to Kensington station by steps between the tracks. These have been removed with the reconstruction of the abutments and piers for the now-singled bridge. I assume the reconstruction was at least partly necessary in order to widen this road. The bridge must therefore have been extended.

This photo by Ken Devlin of Dunedin shows the double track bridge at King Edward Street being singled sometime in the 1980s. Two of the Craven steam cranes were brought out to do this work. In the centre of the far abutment you can see the access doorway to the stairs which went up between the tracks and gave access to the station which was used for suburban passenger traffic. As we can see the abutments were rebuilt later and there was then no need for this access.

Wilkie Road bridge. The abutments are probably original but one of the two girders has been removed as it is no longer needed for a single track crossing.

This substantial retaining wall was needed for the raised embankment where it passed alongside Wilkie Road. At the far end the overbridge can just be seen; the road doglegs under the bridge then continuing in roughly the same overall direction on the other side of the line. The wall was necessary because there was not enough space between the railway and the road to allow for the usual sloping embankment with a wider foot.

The motorway and rail overbridges at South Road, just north of Caversham. The rail bridge is modern, and having a similar substructure as the highway bridge suggests it was probably built at the same time. As the highway was constructed in the 1980s, it would appear to me that the singling of the rail route had been decided by this time, as the rail bridge must have been built from the outset for the single track. (As detailed in the second “Caversham’s Railways” article, the railway used to be where the highway is now, and was deviated to its present location when the highway was put through. This required a new bridge which was built at the same time as the motorway bridge and therefore used a very similar design)

More pictures of the route can be seen in the Transport Geography album.

Otago Central Railway (phew:)

I have just finished creating my new Otago Central Railway album on pjrdunford Picasa Web Albums. This is an update of an older album on my old railfan website and has nearly 400 photos – the number is not settled as several will be removed tomorrow when I check for duplications. This has been a huge effort, and purely for the general community, not the railfan community; that effort will not be repeated with any of my older photographs. It has only been done this time because of the addition of the large number of new photos from the Taieri Gorge Railway excursion to Middlemarch I rode upon two weeks ago. The preparation of the album has taken around 10 days, which even allowing for the working only of evenings during the week, is a lot of work. For this new album, every picture has been geotagged, all the slides have been rescanned, and the correct dates inserted, all pictures are batch resampled to a width of 1600 pixels which is around three times the size of photos that I normally put into my Picasa albums or more recent websites. By keeping JPEG compression at 50, the entire album takes less than 100 MB of space whilst allowing reasonable picture quality. Just to give you some idea, here are all the steps followed to get the album together:

• Select the source images
  • Scan slides
  • Copy negative scans from CD
  • Copy digital photos from source
  • Geotag source images
    • Use EasyGPS to synchronise recent photos with GPS tracks obtained on board the train.
    • Using either Google Earth/Picasa or Geosetter, geotag all other photos. Google Earth 5 proved troublesome at times and the last 50 photos had to be tagged with Geosetter, which is more work.
  • Date source images
    • This step only applies to scanned images – digitals have the date inserted in the Exif tags. Using Geosetter to set the EXIF date fields.
  • Caption source images
    • Use Picasa to add captions to all images.
  • Batch convert source images
    • Using IrfanView batch processing, resample all images at a width of 1600 pixels and add the overlay text.

And if this sounds like a lot of work, it is. The only steps which can be automated across a group of images are GPS based geotagging, and batch conversion. Every other step is being done one image at a time. However, you see clearly the advantage of using a digital camera, and using GPS. The images don’t have to be scanned, all the date information is already in them, and the GPS can add the positional information in a simple batch process using EasyGPS. Then only captions have to be added individually, and another batch process using IrfanView for resample.

This isn’t an album for my erstwhile railfan associates. It’s an album for friends, family and the general public. Otherwise I wouldn’t have bothered – and the captions don’t contain all the technical data about the railway, they just refer to the location and occasion. These photos cover a spread of over 20 years and the first of them was taken around 22 years ago.

Caversham’s Railways

Caversham is a suburb of Dunedin and I spent a week there recently. It is one of the oldest parts of the city, established in the late 1870s, and has always been bisected by a railway line. The original route south of Dunedin was single track and featured sharp curvature, steep gradients and numerous level crossings. The two tunnels at Caversham and Chain Hills were known for smoke nuisance from the steam engines and in that era their clearances would have fallen below the standards of modern day rolling stock. So it was that only some 30 years later a start was made on duplicating and regrading the railway and eliminating the crossings, which in its day was a major civil engineering and public works project. This post focuses exclusively on the Caversham section because it was here that a new double track tunnel was bored through the hill, almost double the length of the original, and a deviation of the route totalling around 3 km was constructed. I’ll start by referring to the map below and noting particular features of the old route. Another copy of this map showing the photographs which are in my Picasa web albums, appears at the end of this post. I suggest you zoom and drag the maps to see features referred to.

View Larger Map

The first question to determine is what route the old line actually took. We know, of course, where the old tunnel is located, as it still exists. However there is virtually no trace today of the route at the eastern end. The map above shows the old route as an aqua coloured line. It is a reasonable assumption that it actually followed the present highway route because that is roughly on the right level and direction. Where did the two routes join? There are two possibilities:

• Near the South Road overbridges. The road and highway bridges are at the same level. Moreover, the elevation is 30 metres lower over a distance of 1500 metres, corresponding to the 1 in 50 gradient of the old railway at this point.
• Near the Goodall Street bridge and the old Caversham station. There is a difference in the elevation of the railway and present highway, which possibly could be explained by the highway being constructed by building up the formation. If the new route is at an elevation of 27 metres at this location then this would allow the gradient to be maintained. Evidence for this location mainly comes from a statement that this is the position where the lines diverged, and a photo which appears to show a curve and one of the overbridges over the new route, possibly the one at Goodall Street.

The main issues which oppose the latter suggestion and favour the former are:

• The difference in levels. At the eastern portals there is a difference in elevation of 15 metres between the two tunnels, the old tunnel being higher. This means the new tunnel was roughly at 25 metres at its eastern portal, which is lower than the 27 metres mentioned above despite the track being on an upgrade. If the new tunnel was at 25 metres elevation then the junction would be at roughly 17 metres which would not work with the 1 in 50 gradient of the old line up to its tunnel.
• The variation from the deviation map. This document shows that the new and old routes were at the same elevation at a point around 1500 metres east of the old tunnel and just a little east of the latter day station site. The most likely location for this grade crossover is the vicinity of the South Road overbridges as suggested by the former option.

What then is shown by this photo? The bridge could be the Goodall Street overbridge crossing over the new route, but the slope appears to be wrong for this. The piling shown alongside the new track is possibly that referred to in a document on the deviation works which states that such piling was needed to stabilise a slip in the cutting of the new route. Even here a difference in levels is apparent. Despite a statement that Sydney Street was where the lines diverged, this seems impossible to sustain and in fact a significant level difference is mentioned in the same document. The best conclusion that can be drawn from this document is that the lines were already running side by side for a much longer distance, and that Sydney Street was the point at which the new line became more separated horizontally.

Another option which was considered was that the photo shows the South Road overbridge with the two lines crossing on separate bridges, but this appears very unlikely as other details are difficult to match up. The conclusion I have chosen to go with at this stage is that the routes did join somewhere near the South Road bridges. On the map I have chosen to make use of the big curve at this location, but without further research it is quite unclear where the actual junction would have been located and the map shown is really an educated guess. We do know from an old map that the South Road overbridge was part of the original route. Unlike many of the other bridges, the line was not raised at this point.

The second question is where the Caversham station was located on the old route. The railway map drawn at the time the deviation was constructed shows that the station on each route was in a different location from the other route. The present day route’s station site (it closed around 1962) is approximately at the end of Parkside Ave, near the old gasworks. The old route’s station is shown on a 19th century map as being between Catherine St and Laing St. The street called Station Rd is something of a red herring, which may have given access to either site, being roughly halfway between both of them. It is interesting that an old railway overbridge is now located in a reserve alongside the highway near the old station site. This bridge probably came from one of the old stations. This article refers to the location of the station being moved, so it is quite reasonable to assume that there were two separate station locations as a matter of fact.

Continuing west we come to the first of what were five crossings of both routes by suburban streets (shown in light grey, along with part of the old Main South Road). Old maps of Caversham show that these streets coming off what is now Main South Road on the south side of the lines, joined up with streets on the north side, which had the same names then as on the south side, but have been renamed today. Five overbridges appear to have been constructed for the new route, as determined by the remains of abutments still present today, but the advent of the Caversham Bypass has meant that all of them except the Goodall Street structure were removed, presumably along with a significant number of houses. The latter bridge now serves only pedestrians who can also cross the highway on a new structure. The present South Road bridge is probably not original. Just west of it is the bridge that is now called Caversham Place. This was the highway bridge when built, but the motorway bypass rendered it redundant. Beyond this point, the route followed by the highway is original.

At this point both railway routes enter their respective tunnels. The new tunnel was driven by hand through sandstone. Most of it is unlined, which is unusual for a railway tunnel in New Zealand. There is some lining at the portals and for a few short stretches within the main tunnel. The new route was built as double track and originally there were two tracks in the tunnel. In the early 1980s the line was singled, and the rail has been realigned towards the centre in order to improve clearances. The old route veers off the highway to enter an approach cutting right alongside. The footpath alongside the highway is cantilevered over one side of this cutting, which is cut through sandstone (as is the tunnel itself). It is possible to walk through the cutting to the tunnel portal, which is covered with a gate. An excellent view of the portal and cutting can be obtained from the footbridge at the end of Lindsay Road, which crosses over the cutting.

At the western end of the old tunnel, access is blocked off with a high wire fence. The route then crossed what is now Kaikorai Valley Road and curved sharply round past the old Burnside Freezing Works to join the present route at Burnside station. The old Cattleyards station was next to the freezing works. The present tunnel at its western end comes out just east of Kaikorai Valley Road and north of SH1. It then passes under the Kaikorai Valley Road overbridge to enter Burnside station.

Below is the photo map showing the photos in my Picasa albums. The old Caversham railway tunnel is an interesting piece of what might be called “Lost Dunedin”. It has been disused more than 100 years and is tucked away in a hard to find location out of the way in a residential suburb. But it is still in almost the same condition as it was when abandoned in the early 1900s, forgotten but not gone. The tunnel is the main remnant of the deviation; the route on the eastern side has disappeared with the motorway construction, and on the western side there is little to see today.

At the time of writing, a four-laning proposal has been in place for the Caversham Bypass Motorway for some years. It appears the original motorway that follows the old rail route was first constructed in the 1980s. The present section of the motorway following the old rail route, including the South Road overbridge, was only constructed as two lane and a new bridge would be needed for the four-laning. Another aspect of this project is that the road will be pushed out over the top of the approach cutting on the eastern side of the old tunnel. This means that the Lindsay Road footbridge would disappear, although the tunnel itself would not be altered in any way. The change could lead to access to the tunnel cutting being blocked off altogether, as it is at the Burnside end of the tunnel, since the change would make it much more practical to achieve this. At this stage the timeframe for reconstruction of the motorway is unclear and the work might not start for at least five years.

View Caversham's Railways in a larger map

I’ll post another article or two in the next few days covering the Wingatui tunnel deviation and the rest of the route between Dunedin and Caversham. You can see all the photos here.

Online references: 1, 2, 3, 4, 5, 6, 7, 8

A Dunedin man is trying to get the tunnel re-opened for public access. His website is here
Here is an interview that was broadcast on Channel 9 around 2007.