Palmerston North Gisborne Line [0G]: Volume 5 Progress Update 7

Having created aerial maps and diagram maps for the Moutohora Branch we are currently generating the same for the main line (PN to Gisborne). So far there are 43 individual maps or diagrams for the 54 km from Palmerston North to Dannevirke.

It takes a lot of time to generate each map out of the GIS as each view has to be individually checked for details since it is common to find mistakes at this point. One of the most common issues is for alignments of roads in each map. Linz supplied the source layers for a lot of the information included in the maps and many alignments of transport corridors are significantly different from those depicted in the aerial photos. We assume when these were created their cartographer's brief was to create these large numbers of lines as quickly as possible and were done on a very small scale rendering of the aerial photography due to the alignments being so far off in many cases. Obviously we went to considerable lengths to ensure the alignments matched for the railway but are finding many road alignments need to be corrected as well.

This one fact illustrates why we go to great lengths to download and have available for map use the Linz aerial imagery for each corridor. The experience with Google Earth was the alignments of succeeding generations of aerial images could not be guaranteed or controlled. This led to the earlier Google Earth maps we produced being misaligned and was one of the key factors in progressing past the use of Google Earth. It now appears necessary to factor in downloading the aerial images for each corridor which was something we hoped to avoid in the short term for Basic level maps but is now going to be included and will add probably another week to the production of the Basic maps for each corridor.

The other question that may be raised is the number of maps being produced for each volume. As you can work out, at the current rate and scale there will be hundreds for Volume 5 and people naturally ask questions about how economic a printable version of the map volume would be. After all the first release of maps which is available from our Wordpress.com site was produced in 2014, covers only Napier-Gisborne and it has 118 pages, 107 have maps on them with 2 maps per page so that was 214 maps which is a similar ratio of maps to distance as for the current production so there could be quite a big volume for this corridor.

After considering that conundrum it has been decided the PDF volume (or Intermediate) version of each volume will be a condensed version using smaller scales wherever possible. The maps we are publishing online are generally at a maximum of 1:10000 scale and use larger than this for individual stations and areas where more detail is useful. This is a luxury we can afford for the online edition as we are not paying anything for hosting. For Intermediate level map PDF volumes, smaller scales will be used to a greater extent to reduce the number of maps output, with consequent loss of detail. The other improvement which is also reflected in the online maps is being able to rotate the map view, with a north arrow in the bottom left corner that automatically rotates to show where North is for any angle, which means we can make more efficient use of the physical view captured in each map. Whilst we are not paying anything to host PDF volumes either, the market they are designed for is hardcopy printout which does have an associated cost as well as the physical size of each volume and this is one key reason why there has been no interest in commercial publication from the railfan press.

All in all, there will be a large volume of maps being produced for this volume and as current output so far has only got us over 2 days to 54 km we can see it is quite slow, we would hope to see a lot more output over the next week. As noted above each map view has to be individually composed, which includes rotating to the correct angle, checking the detail and which scale is needed, then after the image is generated a second level of checking at a higher resolution. Fixing a lot of mistakes at this level is adding to the slow progress and we think we will have to spend more time addressing the road alignment issues at the earlier stages of map production to speed this up in future volumes. It could also prove to be the case that 12 basic volumes are going to take up all of the next 12 months with no time left for any other work in the project.

Palmerston North Gisborne Line [0F]: Volume 5 Progress Update 6

This is a brief update to work ongoing to produce Volume 5 to Basic level of maps.

Volume 5 covers the Palmerston North Gisborne Line, which is 390 km long, and two branch lines - Ngatapa Branch and Moutohora Branch - plus associated sidings etc.

The work of mapping the main line corridor and various stations and sidings has been completed, as has the work on the Ngatapa Branch. Work is currently continuing on the Moutohora Branch, currently having been completed as far as Otoko, about two thirds of the complete length of the branch.

The use of the current aerial photography background for all rail corridors - current and historical - necessitates almost complete realignment of mapped data with the aerial photos, as the maps in the past were drawn without access to the aerial photography and therefore often does not line up with what is actually visible on the ground. We also have the benefit of the Retrolens historical aerial imagery at a reasonable scale for mapping general locations of corridor and stations. It is not sufficiently large scale in most cases for drawing track layouts but that is not an issue at Basic level, and features can be copied into the map by hand.

The pictures for today are all comparisons from the Moutohora Branch. The historical aerial photography dates from the late 1940s or early 1950s, when the line was still open (it closed 1959). The route followed by the Moutohora Branch was rugged backblocks country with a lot of hills to be traversed and, by railway standards, extremely challenging gradients and curves made this a difficult route to operate, with inclines of 1 in 30 in places. There were four tunnels, all of which still exist today in some form. The main road of the area was similarly very cheaply constructed, and after the branch line closed, not too many years passed before major highway improvements saw much of the railway formation taken over and repurposed. This makes it difficult to trace the entire route today.

All the historical views below are from 1952 and compared with the 2015 aerial photography as viewed in the maps, with various historical features drawn in.

Waikohu station was 23 miles from Gisborne (near the intersection of SH2 and Whakarau Road) and was approached from the east by crossing a combined bridge - the only example of such on the Moutohora line. The bridge remained in use for some years after the line closed until the highway was realigned with its new bridge. The goods shed still exists as a historical relic at Waikohu.

 At the Waihuka River No.3 highway bridge between Waikohu (23 miles) and Otoko (31 miles) and at the confluence of the Waihuka River and Hihiroa Stream, the highway formerly took a series of sharp curves to go around the side of a hill and crossed the railway line on the eastern side, then the railway passed underneath the highway at the western side by means of Tunnel 3. When the highway was straightened and cut through the hillside, the Waihuka River was diverted and the old river bed and site of the railway bridge were filled in. This is now one end of the Otoko Walkway which follows the old railway. The bridge is believed to be the one shown in the Auckland Weekly News photo below taken in March 1910 ("Dreadnought Bridge"). (Photo from Sir George Grey Special Collections, Auckland Libraries)

Otoko (31 miles) was approached from the east after crossing a large steel viaduct of a similar design to those constructed on the North Island Main Trunk in a similar timeframe (c.1910). The highway in the 1950s passed under the west end of the viaduct before looping around two sharp bends around what were probably railway houses. The highway then followed the route of what is now Makaretu Road. After the line closed, the railway formation was taken over by the highway for several kilometres to the west. The old railway buildings were relocated onto a nearby farm as shown. When the railway was demolished the viaduct piers were purchased by a concrete company in the Gisborne area, but one of the piers was abandoned in place and can still be seen at the site today.

NZ Rail Maps Project Development Report [2020A]: Work Programme For 2020

Welcome to the new year of 2020. This article is really just a summary of previous recent posts setting out our development priorities for the NZ Rail Maps project for 2020. As noted in those posts, it is mainly a rehash of the 2019 vision, which was largely not completed as planned, but is now being given a much greater priority due to resource prioritisation.

The key achievement expected and the highest priority expected in 2020 is to complete all 12 volumes of the maps to a Basic level. For most volumes this will be a relatively straightforward task and these volumes should all be completed by about the middle of the year. For Volume 12, part of the information in that volume relies on Comprehensive level development of part of a rail corridor, so it will be slower to be completed. 

After that, completing all 12 volumes at the Intermediate level is the second priority, and is also highly likely to be finished in 2020, probably towards the end of the year.

The third priority is Comprehensive level development of some areas. This includes the area of Greater Christchurch, where a significant number of Comprehensive maps have already been made. These will be completed as quickly as possible, but the impetus of generating a reference source of historical imagery of the Greater Christchurch area is not as great as it was last year because the work of Christchurch Transport Blog has been downgraded. However, maps for most stations are currently so close to being completed that it should be possible to create these maps quite quickly but in general they are still third priority. Fourth priority is the Comprehensive level maps for Volume 12 (the Otago Central corridor in particular) and fifth priority is Comprehensive level for all other areas around the country. The historical research in Christchurch for the Comprehensive level maps is nearly complete and will be prioritised for completion as quickly as possible.

In 2020, we also plan to change the project's web site and online resource utilisation. At the moment our domain name redirects to our old Trainweb site, but in the short term the redirection will be changed to our Wordpress site. Depending on funding we may move to a fully hosted Wordpress site this year, but that is not certain at the moment. Google Photos remains our key online resource for map publication with most other third party site use being deprecated, as there is enough space on our free Wordpress site to host the PDFs from the Intermediate level.