Saturday 26 October 2019

Project DIary 2019-10-26: Christchurch Maps

It's been another busy week of gathering research information and a lot of work pulling out map tiles. As noted in previous posts, we spend a lot of time each week, currently around 6 hours, researching all the stations in the Greater Christchurch area. This will involve viewing around 50 files a week and copying mainly track diagrams from them in order to be able to label everything on the maps properly. We have spent most of the time actually just gathering the information and very little lately has been put into maps because the process of creating the historic mosaics and getting map tiles out of them is relatively time intensive. 

So at the moment things appear to progress slowly while the main focus is in these phases of gathering information and investing a lot of work into creating the historical map background images to show the various locations around the Greater Christchurch railway network. This week's research had a look at Linwood Station which was a passenger station on the MSL between Christchurch and Lyttelton. It was located between Linwood Loco Depot and the Wilsons Road crossing and it served exclusively suburban passenger traffic. Like the other suburban stations on the "Port Line", Linwood closed in the early 1970s when the commuter trains to Lyttelton ceased operating, and there is practically no trace of it to be found today. However, NZ Railways Corporation still owns the entire Linwood site that it occupied until the mid 2010s and which is now leased to a number of entities. 

We also took a look at the early history of Linwood Loco, but aren't specifically interested in the entire history of that site, and haven't yet examined all of the records relating specifically to Linwood Loco. We also took a look at Opawa Station, which was the next stop up the line from Linwood and was also passenger specific. Ashley is another small station near Rangiora on the Main North Line and it was between those two stations that a couple of minor realignments of the MNL took place in the 1960s and 1970s relating to the replacement of two bridges, one of which is a major structure crossing the Ashley River. Ashley Station closed in the early 1960s partly as a consequence of the construction of the Ashley Bridge deviation but a siding is still in place for the nearby Canterbury Timber Products factory although disused for some years. Addington Station and also the Way and Works "Plant Zone" and the Signals Depot have been researched and we are currently looking at the numerous private sidings around Addington, including the NZ International Exhibition of 1906 siding which was laid from Riccarton Station across Hagley Park, and the lengthy Fletchers Siding also known as "The Alley" which served many industries and ran from Addington to nearly Riccarton Road.

Map tile production this week has taken in Heathcote and Ferrymead, so that we now have full sets of tiles covering 1940, 1950, 1961, 1970, 1973, 1976, 1985, 1995, 2000, and we also have the Linz aerial coverage for the 2000s, 2015 and some additional Canterbury Maps coverage for updating parts of Heathcote and Ferrymead to 2019. Normally for a smaller station like Heathcote we wouldn't cover such a large number of generations, however the interest for the widest range of coverage is more geared to Ferrymead, which was in significant development from the mid 1960s to the mid 1980s. Now having these full sets of maps will enable work to go ahead particularly with a high priority for Ferrymead; given that we already recently got full map sets for Lyttelton but have done very little with them so far, our actual resources (time) for map drawing itself are a bit scarce at the moment.

A partially completed map of the Ferrymead Railway Moorhouse Village site in relation to the Main South Line in 2019.

The Ferrymead site in 1961, when it was still a dairy farm.

Friday 18 October 2019

Project Diary 2019-10-18: Christchurch Maps

Progress on the maps this week has continued to focus on the Main North Line section of Greater Christchurch. This inches on towards completion with, we estimate, just a week more work to finish it. Quite a bit of work was needed just to add a 1955 aerial image showing the old route between Chaneys and Kaiapoi (deviated in 1958), and the similar but less lengthy realignment between Rangiora and Ashley (1961) is also going to be included. We also expect to show the first couple of km of the Eyreton Branch having found an image dated 1963, one year before the purported closure date. As of this moment, all of Belfast from 1950 to 1985 has been put in, and what is actually left is some of the imagery for Papanui, Styx, Kaiapoi, Eyreton Junction, Southbrook and Ashley. Flaxton isn't currently being mapped, but if I can find anything about it in Archives I may add it.

The extraction of the map tiles for any part of G.C. has proceeded quite slowly. The updates for Lyttelton have been extracted, paving the way to move on to Heathcote / Ferrymead. Once the maps themselves are completed then we can focus our full resources onto extraction. This is quite an involved process as it is not uncommon

Only one day of research has been possible this week, focusing mainly on Addington Station. So far we have avoided looking into Addington Workshops, planning to leave that for another time, but will try and find out if there is any coverage of Plant Zone.

In the wake of the local government elections with the result not showing much potential for the desirable level of change we sought, we are considering what level of campaigning to continue with. Christchurch Transport Blog has more details.

Saturday 12 October 2019

Project Diary 2019-10-12: Christchurch Maps

Local government election results are in and the unfortunate conclusion is we will not see much that improves Public Transport over the next three years in Greater Christchurch. More about this in Christchurch Transport Blog in the next few days.

Meanwhile Greater Christchurch maps are the main focus this week again and in recognition of the time this is taking, a project development schedule post went out earlier this week allowing for several months more work for the rest of the year and possibly the earlier part of next year on completing the GC maps.

The work is continuing on the last section of the Greater Christchurch map tile mosaics which is the section from Riccarton to Ashley. The tile work has been pushed ahead in the last few days. The research is also going ahead quite well with 50 files a week being worked through from Archives New Zealand's local office. However major areas are still to be researched including the stations of Lyttelton, Heathcote, Woolston, Opawa, Linwood, Addington*, Papanui, Belfast, Kaiapoi, Flaxton, Rangiora, Ashley, Middleton, Sockburn, Islington, Templeton. (* Addington has partly been completed, we have not yet looked at either of the Workshops or Plant Zone however and will have to prioritise these). The research has to do a lot of catching up as we only decided to start researching Greater Christchurch stations towards the end of August.

The tiles for most of Lyttelton have now been extracted but a small change put into the mosaic means re-extracting a small number. In the coming week we can expect to see tiles extracted for Heathcote and Ferrymead.

Tuesday 8 October 2019

NZ Rail Maps Project Development Report [2019L]

After reviewing progress for the year so far, the goals that were set back in January and the progress achieved in them, the following decisions have been reached:
  • The maps for Greater Christchurch to be completed as intended, with multiple map generations, for four sections of line - Christchurch to Lyttelton, Christchurch to Lincoln, Christchurch to Burnham and Christchurch to Ashley.
  • Research undertaken at Archives New Zealand for map development purposes will be prioritised to that needed to produce the Greater Christchurch maps.
  • The estimation to complete the Greater Christchurch maps will be the end of 2019 but it is hard to be sure exactly how much time is needed as there is still a considerable amount of work needed to finish them off. The maps themselves are largely complete but the tile sets have to be extracted from every project file, and then checked for accuracy to see if any adjustments are needed. The maps then have to be traced off the tiles, and correlated with research information. This all takes a lot of time, and could well stretch into 2020.
  • After that, work will resume on the schedule published back in January, the priority being Basic maps for all other areas, with Intermediate or Comprehensive in a few areas. The amount of Comprehensive work will be strictly limited as we are running out of disk space in which to store the mosaic tile project files, so probably Basic completion will be prioritised except in Volume 12 which is committed to be completed as Comprehensive.  (To give some perspective, project development files currently occupy 1.5 TB of disk space of which 1.1 TB is mosaic tile projects)
Although the schedule has been pushed back a year by embarking on the Greater Christchurch maps, it was planned as the first year of approximately a 3 year schedule, so there is still a reasonable amount of time in which to push ahead and complete all 12 volumes in 2020. As we now have access to Linz aerial layers off WMTS, this will save greatly on the work needed to download the background aerial imagery for tracing Basic maps, which is quite time consuming. 

However the loss of this year from what was originally planned does mean the overall schedule is going to be reduced. To put it in a nutshell, the plan is that by the end of 2021, the project work will be substantially completed, with maps produced for every part of the national railway network of NZ. This will wind up 14 years of continuous work on the maps project. After that time only maintenance updates will be performed. We haven't yet confirmed this exact schedule for 2020-2021 yet but it will become clearer during 2020 exactly which schedule for project wind down will be appropriate. If 2020 is taken with all 12 volumes to Basic level this leaves 2021 available for Intermediate or Comprehensive level for some of those volumes but not all of them.

Saturday 5 October 2019


The Upper North Island Supply Chain Strategy Working Group, an independent working group established by Cabinet last year to undertake a comprehensive review of NZ’s freight and logistics sector for the upper North Island, has released its second report of three planned. It recommends that Ports of Auckland undergo a managed closure and that Northport at Whangarei be developed as a new major freight port for the Upper North Island, along with options for continued investment in Port of Tauranga as an alternate port for the UNI freight task.

The base assumption in the report is that public pressure in the City of Auckland will force the Port to eventually relocate to a new site outside the City. Whilst Auckland Council has desired to keep the Port within its regional boundary by touting a possible development in the Firth of Thames, the report found on the basis of a Benefit Cost Ratio (BCR) analysis, the development of Northport as the main alternative had a much higher BCR – 2.0 – compared to the Firth of Thames option’s BCR of only 0.2. The option for Northport and Tauranga sharing the existing POAL traffic has a lower BCR of 0.6 than the Northport main alternative scenario,, due to the costs of additional investment at Tauranga, whilst the option for closing POAL and shifting all of its current freight to Tauranga has a BCR of only 0.1. Thus, moving all of the existing freight from POAL to Northport yields by far the strongest financial case in the scenarios that involve closing Ports of Auckland.

The proposal to develop Northport as a main or shared alternate to POAL would require a substantial investment in the North Auckland Line, which has so far had $94 million of upgrade work approved by Government. A much more significant business case that is currently under consideration for Northland’s rail network involves the likely scenario of building the long-mooted spur line from Oakleigh to Marsden Point, an essential missing link in establishing rail freight services to the Northland Region’s major international port. Rail haulage of freight to and from the port has not been possible since it took over from Whangarei around 20 years ago. Significant development of the spur route was undertaken by the Clark Labour Government and Northland Regional Council in the late 2000s but was stopped by the incoming National government, and resumed in 2017. The geotechnical analysis of this route has been completed, and detailed engineering scenarios and costs are currently being developed.

The working group has a third report due out shortly to consider other issues and there are many questions relating to this proposal. The most significant one is that the costs of moving freight into and out of Auckland would be increased. Large volumes of containers can be moved more efficiently by sea than by any form of land based transport. Therefore the onus would fall upon the rail network to develop the most cost effective means of running trains between Northport and Auckland, a distance of around 225 km (port to port). This would entail the development of the highest capacity capability to run the largest trains operated in New Zealand and likely require the full doubling of the existing route over time, and possibly future electrification. Currently the line has numerous tunnel clearance problems and there are some steep grades in a few places that could benefit from easing to increase capacity. The biggest questions of course are political ones, that the Government will need to weigh up before deciding whether to proceed with the overall scenario, or other possibilities.

This scenario overall is more realistic than one that has been floated in some circles, that Northport should be the sole international terminal in NZ with all other locations served by land transport links or coastal shipping. However the number of international container terminals presently in NZ is excessive. The NZ Shippers Council has suggested four ports (two in each island) would be ideal for NZ’s needs. The UNISC scenario reduces the international container ports in the upper half of the North Island from three to two and is a step in the right direction from that perspective at least.

For more information about the Upper North Island Supply Chain Strategy, visit their website at

 The North Auckland Line – 280 km from Auckland (left) to Otiria (right). The former terminus, Opua, is the northern most railway station ever opened in NZ.

Proposed route of the Marsden Point spur between Oakleigh, near Portland, and Northport.

Thursday 3 October 2019

Project Diary 2019-10-03: Christchurch Maps

Well here's another update, and promises, promises, promises.... the last week has slowed things down a bit due to having to deal with other issues, but we are back up to speed now. Plus there have been more than a few issues with Gimp that caused crashes, meaning having to go back and redo stuff and try to find out what wouldn't crash.

The reason there are issues with Gimp and needing a lot of hardware resources (a PC with 32 GB of RAM and a 200 GB SSD swap partition to use for the tile cache), is our preference to use the highest resolution imagery we can. For base imagery that is a resolution of 0.075 metres per pixel (i.e. 7.5 centimetres) and everything snowballs from there. Take for example Lyttelton. We could just do the main railyard but have chosen to cover all the areas where tracks went to, and that means a canvas of 12 tiles wide and 4 tiles high. That translates into a size in pixels of 57600 by 28800, or 1.6 billion pixels total. The highest resolution imagery from Retrolens (usually around 1:4300 scale but occasionally 1:3400) fits in well with that base resolution. By the time we've added in a few eras of historical imagery (from 1940 to 2000 generally) then the result, in this case, is a file size of 21 GiB. It's only since Gimp 2.10 came out that it's been possible for it to handle files greater than 4 GiB in size, which is a real blessing because otherwise multiple files would be needed which would be very inefficient and time consuming. 

We started out some of these Gimp projects covering multiple stations but then as more layers were added (we use a rule of thumb that no project will have more than 100 layers) some of these projects grew too big and had to be split into multiple files. That happened in the case of Lyttelton, which used to have Heathcote along for the ride, which is what was happening earlier this week when everything kept crashing because the system or Gimp hit some sort of limit. Heathcote is a big area to cover because it takes in Ferrymead, so the result was a lot of area to cover and eventually the need to split the files, which we can now recognise because the current version of the Heathcote file is 30 GiB and that is the upper limit of file size we're prepared to work with, from experience. With a file that size it takes ages to load into Gimp, the system will easily use half the total tile cache just to bring it up with no edits, and it can take three hours to save (and Gimp can still crash partway through the save if the file is too big and lose everything). So you can see we are working with some real limits.

The resource issues for doing these highest quality images is the key issue that affects the kind of coverage we do of stations around the country. Christchurch is a particular exception that is going to be the highest quality for all of Greater Christchurch, across multiple generations, and backed up by research as well. That simply can't be justified across NZ, and only major yards will get done to that level. Most sites will be done with just the NZR survey, an example being Bluff that was recently draw up, it was done to high quality but only one generation of historical images. With corridor surveys we can cover the smaller stations as well, but if we can't get coverage of them when they were open, there won't be any. Before we dropped the Midland Line coverage to focus on the Greater Christchurch stuff, we had covered just about all the stations to Kotuku with corridor surveys plus the major stations and some research as well. The same will go through for the MNL and MSL eventually as far as we can get to.

Anyway back onto Greater Christchurch, we only have the MNL from Riccarton through to Ashley to complete. The tiles for the rest will start to get spat out as quickly as we can from here, because map drawing is way behind and really needs to be pushed along as quickly as possible now. So all that MSL stuff will be pushed out as map tiles and then be drawn alongside finishing that stretch of MNL as quickly as possible.