Dunedin City Council Votes To Mothball Dunedin Railways As Complete Close Down of Business

We have already blogged twice recently about the direction Dunedin City Council is taking with Dunedin Railways, which has suggested the closure of Dunedin Railways in its current form. This week we obtained the minutes of the DCC meeting a month ago where they discussed the options for Dunedin Railways and made the decisions.

Dunedin City Holdings Ltd (DCHL) prepared a special report for this meeting and presented it to the full Council. The meeting was conducted via audio visual link due to Covid-19 restrictions.

The report has stated that DRL's revised financial forecasts for the year ending 2020 show a net loss of $1,332,862, compared with a pre-Covid forecast loss of $578,579. DCHL had investigated future business prospects with the view that the impacts of both international and domestic tourism market collapse would be substantial. It determined that the Council should consider 3 options as follows:

1.     Close the business (DCHL Recommendation)
2.     Mothball for around 18 months with a view to re-opening train services on the Taieri Gorge line.
3.     Mothball with  view to exploring alternative options for company assets.

Option 2 would entail retaining only 7 staff, to maintain track and rolling stock assets and perform administrative functions, at estimated cost of $900,000 per year, which shareholders would have to fund

DCHL expressed its concern that Option 2 did not address the significant deferred maintenance bill on the Taieri Gorge line, estimated at $1 million per year for all of the next 10 years (total $10 million). This would also have to be funded by shareholders.

Option 3 would see the Taieri Gorge line closed permanently to heavy rail trains. This removes the need to fund the $10 million maintenance bill. Five staff would be retained in the short to medium term for asset maintenance.

The report clearly states with Option 3 that "A key component of this option is to discontinue rail activity on the Taieri Gorge line in view of the cost of deferred maintenance".

The Council voted for option 3 on a 14-1 division, committing to provide the ongoing funding for the next 18 months to support the close down of the company. DCHL indicated that their next steps included engaging with OETT. Following that conversation, OETT chose to sell their shareholding of the company to DCC. We do not know anything at this time as to the significance of the OETT decision but it would appear likely they wished to recover some of their investment in DRL and exit their involvement in the business. It is not clear whether they recovered their full equity or capital from the sale or took a loss.

The question now is as to the future of the operation. We expect that DCHL will look to dispose of most of its existing rolling stock on the open market, or as scrap. There is likely to be little interest in Dunedin in any other organisation acquiring this rolling stock, given the small rail heritage community there.

The bigger questions relate to the in ground assets - the Taieri Gorge track and structures, the stations at Pukerangi and Sutton, and the railway precinct at Middlemarch. We are of the view that there is a future possibility for an alternative ultralight rail tourist operation over the Taieri Gorge line, similar to Forgotten World Adventures' business on the former SOL. Since sections of the DCHL report that was released have been redacted, we do not know if this has been one of the alternative options DCHL is exploring. And since OETT has sold their shareholding in the company, we do not know if they have an interest in any alternative uses of the Taieri Gorge line. If an ultralight rail operation is not possible, then converting the corridor to an extension of the existing Rail Trail is a possibility that will keep it accessible to the public forever. The railway precinct at Middlemarch is well developed and it should be possible to retain it as part of Middlemarch as a whole. Our impression is that DCHL are focused on future options for Dunedin Railways whilst at the same time closing down Taieri Gorge, so we do not think they are looking at any particular option for the TGR.

Currently DCHL / DRL are still going through a staff consultation process and discussing possible options for the future of the line and it is difficult to know if any of the alternatives that are being considered will become viable. We are not commenting on these for now.

Taieri Gorge Railway unlikely to continue commercially

Last week we blogged about Dunedin Railways being mothballed. Since then various pieces of information have been published. Based on what has been released to date, we see it as unlikely that the Taieri Gorge line can be continued in its present form as a commercial operation between Wingatui and Middlemarch. We have no viewpoint about the rest of Dunedin Railways' services.

The Taieri Gorge Railway consists of the first 64 km of the old Otago Central Branch railway and came into being initially as a train service run on the line when it was part of the NZR network. Otago Excursion Train Trust (OETT) inaugurated the Taieri Gorge Limited back in 1987 as a Dunedin-Pukerangi daily service and was subsequently able to raise sufficient funding to finance 50% of the purchase of the Wingatui-Middlemarch section of the OCB. This was then reformed as Taieri Gorge Railway Ltd in 1990, the other half of the initial capital being matched by funding from Dunedin City Council.

We know very little about the financials of the early years of operation as there was no cruise ship market back then as it did not develop in NZ until more recent times. But it is probably correct to say that the operation at best broke even in the early period of its life. In the mid 1990s additional capital injections were needed and a higher proportion, if not all, came from Dunedin City Council with the net result that they increased their shareholding to 72% reducing OETT's holding to 28%.

It was always going to be a tough ask in the south of New Zealand to be able to run a 64 km tourist railway and although income from cruise ship services and running extra trips to Oamaru and Palmerston as well as charter tours must have helped the finances, this has to be balanced against the ageing of most rolling stock which includes the fleet of diesel locomotives that are now more than 50 years old and the original wooden carriage fleet which in more recent times has been steadily upgraded to more modern steel sheathed designs. 

Some of DRL's operations run over the Kiwirail network and this requires considerable additional expense in certification and maintenance standards as well as direct operational costs which for the excursion train market around NZ has resulted in severe cut backs since the 1980s. We also understand from information released that there is a considerable maintenance backlog on the Taeri Gorge line, which is always going to be more expensive in upkeep, in the shorter term because of the topography (hills and a steeply sided gorge) it passes through, and in the longer term because of the many viaducts in this section which will eventually need a lot of money spent on them. The big floods in the Taieri catchment a couple of years did a great deal of damage to the line which must have cost a lot to repair.

So what could happen in the future for DRL? We have no idea whether the operation can be made viable as a cruise ship tourism operator with the key issue being it could be many years before this business builds up again to where it was last year. The future for the Taieri Gorge Line is, regrettably, likely to be either as an ultralight rail vehicle operation (golf carts or rail bikes) such as we see in other parts of the country. It is possible that the section from North Taieri to Pukerangi or from Pukerangi to Middlemarch could be developed as a heritage railway if enough support can be found in the Dunedin area. 

Here, there are certainly questions; we have noted that OETT has chosen to completely sell out of its 28% shareholding, which seems to indicate a limited future for them as a whole, and even before that, rail heritage in Dunedin in general was struggling. A heritage operator could run cruise ship trains with volunteers (Gisborne City Vintage Railway is one heritage railway that works in that market) but keeping the entire line open to Pukerangi could be a hard ask. A lot depends on Dunedin City Council's attitude, and whether Dunedin Railways as a whole continues to operate. The worst case scenario is to convert the line into an extension of the Otago Central Rail Trail.

Taieri Gorge Railway mothballed; OETT selling out its shareholding

It's been reported in the ODT today that Dunedin Railways is to mothball its operations due to the COVID-19 caused economic recession. 80% of their business comes from overseas tourism, notably cruise ship visits to NZ, which is naturally hugely affected by COVID-19, and it is difficult to run the trips under current lockdown conditions which also curtail domestic tourism.

In addition, the company chairman is quoted in the news reports as saying the company has high running costs and its operations are financially challenging with there being $10 million of deferred maintenance costs on the Taieri Gorge Railway.

At the same time as the mothballing has been announced, Otago Excursion Train Trust (OETT), the joint founder of Dunedin Railways (which started as Taieri Gorge Railway Ltd in 1990) has decided to sell its 28% shareholding in Dunedin Railways to Dunedin City Holdings Ltd (DHCL) which owns the other 72% of Dunedin Railways currently. DCHL is in turn 100% owned by Dunedin City Council (DCC).

OETT originally held a 50% shareholding in DRL/TGRL but this has been reduced over the past 30 years to 28% due to the need for further capital investment into DRL that has been met largely by DCHL. It is well known that since it became a minority shareholder there has been much angst at OETT over their reduced influence on the operations of DRL. However it is not known exactly why OETT has decided to sell out at this stage and we will try to find out if they are willing to comment about this. One possible issue, however, can be found in a statement on OETT's news page that further capital investment in DRL is needed in rolling stock and track maintenance. Shareholders are normally expected to be able to finance the businesses they own and it may well be the case that OETT would not be in a position to finance any additional capital themselves. 

This means that the era of DRL being in rail heritage ownership has come to an end and we don't like the implications of that. Local government entities have a penchant for running their infrastructure assets into the ground, or appropriating them for other unrelated projects. There has been a change in emphasis on DRL since the new board chairman was elected who has stated that they expect DRL to produce a financial return. This is due to the politicians demanding more income and dividends from all of DHCL's trading enterprises. The earlier proposal to mothball the line from Pukerangi to Middlemarch is an example because the most obvious solution is to rip the line up and sell the land to raise money. Under a profit focused DHCL this is exactly what could happen.

Closure of Taieri Gorge Railway from Pukerangi to Middlemarch proposed

The big news in rail heritage this week is that Dunedin Railways has proposed to stop running trains from Pukerangi to Middlemarch on the Taieri Gorge Railway. The decision was announced on 5th December. The next day, Dunedin City Council said they had received no prior warning of the decision and that they would require a period of public consultation before allowing the decision to go ahead.

Currently, trains between Pukerangi and Middlemarch operate, on average, about every two to three weeks, but in practice, trains are only run during the peak tourist season, so that the actual frequency during that season is higher, but operations will stop completely during the cooler period of the year. This frequency is much lower than the Taieri Gorge Limited trains to Pukerangi which are at least daily year-round and can be run more often than once a day during the busiest times. Dunedin Railways, among other reasons, has cited the low demand for the Middlemarch trains compared to the costs of maintaining the track among the reasons for stopping the Middlemarch service. This service is the only one that meets the end of the Otago Central Rail Trail, and Middlemarch is the only actual township served by the Taieri Gorge Railway as there are no other population centres west of Wingatui. Middlemarch is within the boundaries of Dunedin City and this is one of the reasons it was chosen to be the terminus of the Taieri Gorge Railway when the line was purchased from the Government in 1990.

There are many questions that need to be asked, including the commercial aspect of the decision. Dunedin Railways was effectively founded by the Otago Excursion Train Trust, a non-profit heritage operator, in partnership with Dunedin City Council. Originally they each held a 50% share of the company. However because of a requirement to inject additional capital into the company at various stages, OETT's shareholding has dwindled to 28% at the time of writing this, with Dunedin City Council (formally Dunedin City Holdings) having a majority shareholding of 72%. This implies OETT did not have the means to provide the additional capital at the time it was needed. Due to the minority ownership position that OETT are in, they do not have much ability to influence the business culture of Dunedin Railways. This leaves DCH in the position of being able to direct DRL into more of a commercial focus than perhaps some would like. The problem is that DCH is being pressured by DCC to focus on producing divendends out of its commercial holdings. Whilst we have no information to confirm specifically that DCL has pressured DRL to produce a dividend from Dunedin Railways, it remains a possibility that Dunedin Railways is being pressured to increase the financial return out of its operations.

OETT's position appears to be one of discontent about its minority shareholding position with the company. We have not had this officially confirmed, but have sighted OETT newsletters that have strongly implied this being the case. It is known that a Memorandum of Understanding between OETT and DRL took many months to negotiate before finally being confirmed relatively recently. It is also known that OETT are attempting to negotiate some sort of case that they have called a special general meeting of their members to discuss and that OETT have had difficulty in getting agreement from Dunedin Railways management on projects that they have wished to fund on the railway. But for the record, OETT have declined to comment in any shape or form about the situation relating to Dunedin Railways or anything at all to do with the Middlemarch issue.

It does appear to us that if the Railway does get closed beyond Pukerangi that the best option would be for OETT to step in and take it over, as well as the Middlemarch rail heritage precinct. The next step could be to lease the line to be operated with light vehicles for a daily operation to meet the train at Pukerangi, for people arriving or departing Middlemarch on the rail trail. We believe it is unlikely that the 18 km of line could be maintained for normal heavy rail operations and therefore light vehicles (golf carts?) would require less maintenance. This option would have the advantage of providing a daily connection that is not currently possible with the present irregular services. Some sort of special vehicle to carry bicycles would be needed.

We understand Dunedin City Council is currently consulting on the matter and everyone should take the opportunity to submit to their process. We will post more details of this as soon as we have them.

Otago Central Railway [61BB]: Alexandra-Cromwell 25: Cromwell Gorge Survey

Last time we wrote about the Cromwell Gorge section that we have been remapping. We chose to redo the aerial mosaics down this section from scratch for various reasons, but a part of that has been the discovery that the original placement of the historical photos in some places was most probably incorrect in that the alignment for the old railway was too far into the present hydro lake.

For various reasons it is extremely difficult to overlay historical aerial photos in steeply graded terrain like this gorge which has steep sides and that is primarily because of perspective distortion with terrain which is not directly below the camera lens and that is a key reason why the process called orthorectification is used by Linz and others to get aerial photos that are geometrically corrected for using in map work. We don't have that option with the old maps, so the placement is a lot of guesswork. But we have found some historical aerial photos taken between 1980 and 1992 through the Gorge and they are confirming some errors in some of the original aerial layers that were produced. A part of the issue would be with the lower resolution base layers that were used at the beginning.

Right now we are just checking with aerial photos from the late 1980s through the area to confirm the alignment and make a few readjustments where necessary to ensure the result is as good as it possibly can be. This will mean a couple more days work before having something to redo the mapping with. We did get a 1991 survey scanned for evaluation back in 2017 but didn't draw too many conclusions from it. But having reasonably good coverage of a few areas helps a lot.

Ultimately the only real way would be to have access to original survey plans or drawings that plotted the new highway route in the Gorge compared with the existing route. Maybe these exist in Archives somewhere. The issue for our maps isn't that a particular aerial photo is uncertain as to its longitudinal placement along a particular part of the Cromwell Gorge; it is mainly the question of how to align things across the width of the Gorge with limited referential viewpoints and various distortions.

We had hoped to progress this work further this week but various time commitments have prevented that. We have also been working on maps of Christchurch City this week.

Otago Central Railway [61AA]: Alexandra-Cromwell 24: Cromwell Gorge Survey

So here we have the first post on the Otago Central Railway for 2019. Last week I started redoing the Cromwell Gorge maps using the same 1962 historical survey images as previously, except this time sourced from Retrolens. They are a slightly higher quality, but the main change is harmonising everything with the other surveys by using the 0.4 metre tiles instead of the old 0.75 metres and also using the 1972 images of both Clyde and Cromwell stations which helped to fix a few issues. I have now finished off the survey and am about to produce the map tiles for use in Qgis. As a result some of the already concluded and drawn maps will need to be altered slightly as I have reached some slightly different conclusions about the position of the railway in relation to the hydro lake.

These images of Cromwell were produced last week and shared on Facebook.

Apart from the new mosaics of the section through the Gorge I am also putting all the station layouts for Omakau-Cromwell together into another Gimp project and the Cromwell and Clyde station maps will be tied into the CG maps so that everything joins together properly.

Project Diary 2019-05-17

We try to post at least once a week depending on what we are doing in this project. Most of the posts are about specific volumes or regions we are working on. Other times there will be a progress report for the whole project like there was last week. This week it will just be a diary entry because whilst we have been doing a lot of map work this week, not a lot of it has related specifically to NZRM.

This week the majority of our time has been taken up with getting a complete set of maps for Christchurch City. This meant downloading a lot of stuff from Land Information New Zealand, because they have a 3.5 GB limit for the estimated size of each download. As it happens, it is more like 5 GB actual download in a lot of cases. But it meant that at a pixel spacing of 0.075 metres, there are a LOT of layers for the whole city. It works out to something like 60 GB. If you have a few dollars you can get them to courier the data layers to you. With the fact we don't have any spare cash to spend, we just settled for splitting up the city layers into a series of downloads to get all of it. There are some overlaps which means we don't quite have the expected efficiency and because we inadvertently got some gaps between downloads we had to make some extra downloads to be able to fill in those gaps.

So we now have Christchurch City covered for 2018 (central only), 2015 (whole city), 2011 just after the quake (central only) and c.2010 (actually between 2004-2010 and for some reason the dates aren't more precise) which again is the whole city. We also have some historical retrolens layers to overlay at some point. We did consider downloading all the 2011 imagery and in fact did set up a series of downloads in Linz but haven't actually executed those downloads because that imagery is at 0.1 metre pixel spacing and while it is very good it is also just after the quakes so it does have limits. But it is a shame that there isn't high resolution imagery before then that can be downloaded. Even 0.3 metres would be better than the 0.75 metres 2004-2010 stuff.

As far as the NZRM project actually goes the work this week has been on the Otago Central line. First up is to redo the Cromwell Gorge section with the Retrolens scans of survey 1452 which are distinctly sharper than the original ones we paid for a few years ago, and then particular stations. At the moment Omakau-Cromwell is being considered as one Gimp project covering a number of stations. It is separate from the Cromwell Gorge mosaics because of differing resolutions. The Cromwell Gorge part was originally done at 0.75 metre base imagery because that was all that was available for the whole section, but in 2017 the full area became available at 0.4 metres. But initially all that we did was scale the 0.4 metres to 0.75 metres and overlay it with the 0.75 metre stuff. Now we have scaled the 0.75 metre base to 0.4 metres so as to be able to use this scale base imagery for the Gorge section.

Otago Central Railway [47J]: Current delay in OCR maps

The current effort on NZ Rail Maps to map the Otago Central Line started in November of 2017 - about 18 months ago. It was at that time with the first of the posts in series 47 that we started the widespread use of the LINZ background imagery and bringing in historical imagery with the mosaic projects. We had at that time hoped to complete the set of maps for the entire line by a series of deadlines which eventually stretched out to the end of 2018.

Since the beginning of this year we decided to temporarily set the Otago Central line aside and work on other projects. One of the reasons for this is that LGGA are still scanning the aerial images for that area and adding new stuff all the time. Rather than doing an area then finding there is new stuff and going back to add it is a good enough reason for deferring the completion of work on maps for railways in Otago.

We just recently discovered LGGA have found survey 1452 which is State Highway 8 that we have used for the Cromwell Gorge has been added so we are currently poring over that to see if their scans are better quality than what we already have. Another example is patiently waiting until finally the one and only good quality scan of Ida Valley became available which was late last year.

We don't quite know when Otago Central will be completed but it is still very much under consideration and being worked on behind the scenes from time to time.

Project development: Work programme for 2019

In my last few posts I have talked about the PNGL mapping I am working on. I have just about completed downloading the base aerial photography, and are working on mosaics for almost every station on the line. This is Volume 5 of the 12 volume map series and the PNGL and its branches is the entire content for it.

I have also been working on Volume 12 with Otago Central Railway and Kingston Branch (and its branches) maps being developed which will be the entire content of Volume 12. This of course particularly the Otago Central has been a key focus for the past couple of years.

The intention for 2019 is to complete both of these volumes more or less simultaneously which is going to be the majority of the work on the whole maps project. These two volumes when complete will add to the existing Volume 7 which was completed a year or two ago which is for the Nelson region. 

I will also republish all diagrams for all existing lines in 2019 but there is not expected to be any other volumes progressed substantially in 2019. The diagrams will be available only as images, as PDFs are only produced for completed map volumes in their entirety. But with the images being hosted on Google Photos, it will be possible to download a complete set and use them offline. All of the map resources will be accessible from the Wordpress site. At the moment not much is listed there but I will get onto it over time. Each line will have its own sub page with historical and current information about the lines / routes as well as linking to the maps covering that line.

Beyond 2019 there is currently increasing competition for my time from other interests and therefore it is difficult to predict how much work will be done on other areas of the maps or other priorities other than those listed above. The maps project will always be an interest but I expect that my current record time commitment which involves work almost every day of the week at present, will change over time to having less time available to produce. So I'm not confident the maps will continue at the same pace as they have in the last two years, beyond next year.

As I alluded to previously, Volume 12 and Volume 5 have got special treatment compared to other volumes, in being given a higher priority and having greater use of historical resources in production of the maps. Due to the lower priorities I don't expect the same treatment for the other map volumes. Every map will have base aerial photography based maps and diagrams produced, but there won't be the same level of historical imagery and station detail to be found in other volumes.

Otago Central Railway [64C]: Middlemarch-Ranfurly 3 - Ranfurly 1

Ranfurly using the 1973 aerial survey as a background. Ranfurly is a nice little railway precinct with virtually all the buildings intact except for the first goods shed and the first engine shed, and is a complete contrast to Alexandra where only the station platform remains.

At the moment I am busy downloading all the base aerial photography for Napier-Gisborne which is slowing down Volume 12 stuff a bit but it is coming together and I will be revising some more of the Central stuff over the weekend.

Otago Central Railway [64B]: Middlemarch-Ranfurly 2 - Waipiata 1

It's two months since I started a series for the Middlemarch to Ranfurly section of the OCR. There weren't at that stage any maps in production for the series. Since that time I have gone back and redone some of the earliest maps with new higher resolution coverage which has thrown the whole schedule back. Right now however I am quickly putting some mosaics together for a number of different stations while I am also updating all the maps as quickly as I can. So I hope to get a fair bit done over the holiday period in terms of progress on a number of the different maps and catch everything up a bit. I had spent quite a lot of time over the past week or so looking at other areas but right now it is just Central I have decided to focus on.

This map is an overview of Waipiata in 1975. Although only just south of Ranfurly, Waipiata was still open at that stage and in fact stayed open almost to the end of the line's closure in 1990, although only as a crossing station. There seems to have been a major stock yards there at the time although not today. Of the railway features you can see in the picture, what remains today is the loading bank and the left hand house. The goods shed was relocated to a site across the main road and a small part of the station building is nearby in Komako Road. A private crib made up of a refurbished wooden carriage and guards van is also in Komako Road.

Otago Central Railway [61Z]: Alexandra-Cromwell 23 - 2nd Clyde Station 2

Last time I posted the 1972/77 aerial photos of Clyde station had some problems that needed to be fixed. It looks like the aerial images of a 1977 survey were significantly distorted, perhaps the plane that took the photos was not level. Anyone who has used a data projector knows about keystone adjustments you have to make because the lens is not exactly square on to the screen and the shape of the picture is distorted. The same thing will happen when an aerial survey is made and the plane is not level either laterally or longitudinally or maybe the camera is not mounted properly in the plane. Aerial photography generally uses a special plane with a camera mounted in the bottom of it looking straight down. There are other distortions that are caused by varying terrain height and on the modern aerial photography we get from Linz they run it through a computer program called orthorectification to mathematically correct these issues caused by different ground level heights, however the Retrolens photos are just straight scans of the original negative and not orthorectified in any way so especially on hilly terrain you will see such variations. But on what is a fairly flat part of Clyde over 1 mile there wouldn't be expected to be the amount of variation seen and which wasn't seen on the other generations of aerial photos. The result was something like 30 metres displacement in one particular area which is a lot. It took all day yesterday to find a workable solution with a different image of most of the area to the one that was first used.

Here are the two images for 1972/77. The first one is the original, and the second one is the corrected one.

Now that the 1972 series has been fixed, I found that the rail corridor on the 1962 series does not line up with 1972 series, so that also has to be adjusted.

Otago Central Railway [61Y]: Alexandra-Cromwell 22 - 2nd Clyde Station 1

So back to Volume 12, this time back to working on the Otago Central again. Having done the maps last month for the first Clyde station, now I have to get to work again on the 2nd station. The mosaic has turned out to have an issue with the section particularly relating to 1977, that has to be fixed, so that will take a part of today before I can update the maps for that area. Here are a range of views of this area - 1962, 1978, 1985 and present.

Otago Central Railway [61X]: Alexandra-Cromwell 21 (Clyde 1972)

1st Clyde station in 1972.

Otago Central Railway [61W]: Alexandra-Cromwell 20

Last time I was talking about the challenge of aerial maps of the north part of Lake Dunstan. All of Lake Dunstan is of interest for historical purposes due to the hydro development resulting in indundation of a considerable area of land. Just as an aside I am about to do a map of Lake Karapiro which is an interesting one because it submerged the Horahora power station in the lake.

Anyway carrying on with Central Otago here is a sample of Clyde. The new Clyde mosaic is the second largest ever (north Lake Dunstan is the largest) that I have worked on. 8.9 GB and that is much increased from the previous version of Clyde which is only 1.9 GB. That's essentially what it takes to do the maps at the higher resolution and quality with the LINZ tiles doubled in pixels in each direction therefore four times as many pixels overall, and in this case enough imagery to depict eight different periods: 1962, 1972, 1978, 1979, 1981, 1985, 1991 and 2014. As it happens there isn't always aerial photography for the whole area for every single one of those periods so they can be made up of images from two slightly different periods.

So this image and others of the same series will be labelled "1962" but in fact the 1962 stuff I have only covers the main part of the first Clyde station. The part coming down into the 2nd station site is actually lower resolution stuff from 1958, but the 1962 survey isn't fully online yet, only the parts I previously paid to have scanned from Archives New Zealand are useful to me.

Another mishmash example is 1972 which is the NZR surveys of the 1st Clyde station combined with some 1977 stuff.I have however checked what I can get from 1974 and 1976 and am reasonably confident that this so-called "1972" stuff is reasonably close to what was actually there in 1972 across the 2nd site. There wasn't enough difference between 1972 and 1977 across the 1st Clyde station to justify a different era of imagery for that site.

Anyway all the tiles have been made and imported into the maps ready to go.

Otago Central Railway [61V]: Alexandra-Cromwell 19

So I have been working on two mosaics in particular, the ones of Lake Dunstan from Cromwell to Luggate, and the ones of Clyde, over the past week but not as much as the previous week but that is what happens with ebb and flow of different time commitments etc.

The Lake Dunstan ones are complete. I am not going to show any more previews at the moment but just talk about the challenges as they have involved 72 current aerial photography layers from Linz in a matrix 8 wide and 9 high, plus three historical layers from Retrolens - a total of 75 layes. When you work out the numbers that is around 2,000,000,000 pixels which is a lot, and in the XCF file that is a 12 GB file. That is easily the largest GIMP project I have ever worked with, and very much tested the limits of my dedicated graphics computer with its 16 GB of RAM. When it came to rendering out the aerial maps for Qgis, they have been divided into six large tiles each of which consists of 12 of the original tiles (4 wide and 3 high) and these tiles are up to 200 MB each in size as a JPEG at 100 quality. The resource demands were such that I could only crop and render one of these six tiles at a time before Gimp ran out of resources and crashed (when the CPU, memory and swap meters were all maxed out) so I had to keep closing Gimp and reopening it to do the next tile. Qgis also has trouble handling them even on the map drawing computer with 32 GB of RAM and again I am seeing maxed out CPU, memory and swap and have had to put these images into a separate project just for this section. The next thing of course is to draw the map details and then produce the final images.

The main intention of this post as far as pictures go is to show the progress on Clyde. This image is from the Gimp project to re-mosaic the Clyde historic aerial imagery at a higher quality by scaling up the Linz layers to four times as many pixels so that we don't have to scale down the historical images so drastically and lose so much of their high quality (mostly the NZR surveys which they intended to show a very high level of detail on the ground).

The second Clyde station with the turntable and engine shed upper left and the freight shed upper right. All of these features still exist today.

Part of the old station site with at far left the engine shed foundations (not sure when this closed) and towards the right hand side you have the turntable pit and one of the houses at this end of the station yard. The railway precinct at Clyde covered a significant area compared to some of the other stations, perhaps reflecting the fact that it was originally expected to be the railhead. There were at least two areas of housing in the yard and at least six houses of which several remain today, but there is no obvious trace of the turntable or engine shed foundations on aerial photography and a considerable amount of the station yard has been built over since the station closed in 1980.

I am still doing the rest of the mosaic which will cover up to 1991 when completed and I expect it will be completed today so that the map tiles can be produced and brought into the maps.

Otago Central Railway [61U]: Alexandra-Cromwell 18

Not the railway, but this is what I have been working on for the Clutha valley north of Cromwell.

The area on the left is called Lowburn and on the right is Northburn.

The Lowburn bridge was built in the mid 1930s and replaced a punt.

The old NZMS1 map of the Clutha valley from Cromwell north. Lake Dunstan covers about 1/3rd of the distance from Cromwell to Wanaka, the river's source. There have been in the past plans for hydro development at Queensberry and Luggate but nothing has eventuated. The Clutha is further dammed downstream of Clyde, at Roxburgh, which was built in the 1950s. 

After 60 years of faithfully serving the local community, the Lowburn Bridge was submerged beneath the rising waters of Lake Dunstan as the sluice gates on the Clyde Dam were closed to fill the hydro lake. The bridge is still there at the bottom of the lake with an old car sitting in the middle of it.

Otago Central Railway [61T]: Alexandra-Cromwell 17

In the past few days I have been doing newer higher resolution aerial mosaics for Clyde. Here are screen dumps of what has been completed so far.

Clyde in the 1960s.

  

Clyde in the 1970s.

 Clyde in 2015.

The main work still to be done is for 1978-1991 which includes the following changes:

• 1978: Work started on the 2nd station site
• 1979: 
• The main line was diverted and linked to the original line to the 1st station and Cromwell. 
• The new highway occupying the original railway corridor through the south of Clyde was under construction.
• 1981: 
• The 2nd station was open and the original line to Cromwell was lifted. 
• Highway completed.
• 198x: The 1st station site saw the goods shed relocated to the museum site nearby.
• 1991: The 2nd station was closed and the line lifted.

The remaining aerial photos will be added today and the maps redrawn. I have spent a lot more work on these maps than on the originals and of course I have the high resolution aerial photography and are using double size LDS tiles so the quality will be higher particularly with the NZR survey of Clyde incorporated in the 1970s generation.

Otago Central Railway [61S]: Alexandra-Cromwell 16

So the Cromwell maps took a little longer because I had to make bridge tiles to bridge the gap between the new aerial imagery and the old stuff I have for the rest of the gorge. So that there is a fairly seamless join between the new tiles and the existing ones. The bridge tiles are a regular 9600 pixel width (LINZ's 4800 width tiles doubled in each direction) but a special height of 9599 pixels to line up with the existing tiles, and why this odd size? Well, the existing tiles are funny hybrid ones which were originally 0.75 metres resolution and I found some way of scaling 0.4 metre tiles to overlay on them to update the base imagery to a higher resolution without having to redo everything from scratch. And because of that the 0.4 metre tiles don't line up perfectly with them when you mix 0.4 metre and 0.75 metre derived tiles in the same map. So the bridge tiles have had to be cropped to a specific size that will fit exactly in the gap and part of that was to overlay another 1965 aerial photo over the old 1962 ones and make it line up almost perfectly at the join.

So here are the completed maps for Cromwell. The next stage is Clyde which will be started today, and then Alexandra which will include the aerial photo for the Fulton Hogan siding. At the same time I am working on the head of the lake mosaics as there is enough imagery to get to Lowburn for a start (another drowned bridge there) and hopefully there will be enough good stuff to get all the way up to Mount Pisa where the lake turns back into a river.

I still have to muck around with the masking and the lake and riverbed layers to get them the same as what I did with the older aerial photography. I also got a low res 1958 layer to give me the position of the original goods shed.

Otago Central Railway [61R]: Alexandra-Cromwell 15

As mentioned yesterday I am now working on new maps of Cromwell and hope to get some coverage that will also give me the valley going to the top of Lake Dunstan in conjunction with the Cromwell Museum to have full coverage of the historical appearance of that area. 

After some experimentation I am doing new mosaics with much larger geojpeg tiles for Qgis because the new imagery is of such a high resolution that scaling it down to fit the old mosaic tiles lost far too much detail. This entails getting the highest resolution tiles available from Linz Data Service and scaling them up so there is more of a match in size for the Retrolens stuff to drastically reduce the scale down and loss of quality on the latter.

This will be for Cromwell station and Clyde station only. I am not redoing the gorge which would take much too long, instead I will use the existing Gorge stuff that I have as it does not need to be at a higher resolution as there is not much detail on the ground.

The mosaic so far is looking extremely good with the quality of Cromwell Station being very high, almost as good as what was in the previous post, and it means maps will be able to be of much higher quality for that yard. The same approach will be followed for other yards that I have this high quality NZR survey imagery for. These include:

• Clyde - both 1st and 2nd stations
• Alexandra - in addition to the early 1980s NZR survey an older one from the early 1970s has turned up.
• Omakau
• Ranfurly
• Waipiata
• Middlemarch

I expect to finish the Cromwell mosaic today and probably start the Clyde one tomorrow, then redrawing the maps will be quite fast so this is not going to slow things down much.