This week the main work done in the Project has been in the Midland Line. The mosaic of Greymouth in 1945 was completed and has been used in mapping. It is fair to say the planned release of Volume 9 is a bit behind schedule. For reasons explained below, the release of what has been completed to date will now be effected, which will be mostly the mainline section. This will be finalised and produced next week.

The second thing that has been going on this week is reorganising the volume structure for the maps. This is the fourth and, it is confidently expected, last volume reorganisation. It is useful to look at why the project is divided into volumes. For the webmaps and the image based maps it actually does not matter at all which volume they are in. The volume structure was originally conceived for the purpose of producing books or PDF files of a collection of maps together. Currently this format is not being maintained, but it certainly is still planned to output these physical volumes as part of map production in future.

Apart from physical volumes, the main reason a volume structure is implemented is for the following reasons:

• For the reason of project organisation / structure. Instead of having all the maps in one big project, having them split into a number of projects is important for effectively managing the map data. It helps to create redundancy in the data which limits the impact that file corruption can have on the various datafiles.
• For the reason of organising GPX files. Some GPS devices are limited to 1000 locational points that they can store in a file at one time. This means that the project’s GPX files will be structured to work with this limitation. So it is not possible to put all of the locational points in the entire project into one GPX file because that would be a much greater number than 1000 (there is currently about 4000 km of operating track in NZ right now, so that is well over 4000 points that would have to be stored).

This week’s changes have been along the lines of equalising the size of volumes. It turns out that NZ has had 6000 km of railways historically. Kiwirail has records of around 4000 kilometre posts although not all of it is open, but they will include mothballed lines. Taking the 6000 km and dividing it by 12 volumes gives 500 km per volume. So the volumes are being reorganised to each be 500 km approximately. This is better than the previous absurdity of volumes being different lengths from 110 to 990 km.

Because of this change, Volume 9 is no longer Volume 9. In the future, Volume 9 will cover Christchurch and parts to the south. The new volume for the Midland Line will be Volume 7 and it will include all of the railway lines on the West Coast in the same volume. The table below shows what is actually in each of the new volume definitions. Making each volume more or less consistent in size will have the advantage of making all the printed volumes more or less the same size so that their production and distribution costs are the same. It also means each GPX file will have plenty of room in it to store around 500 km pegs as well as all the stations within that area. Thirdly, it makes it easier to estimate how much time is needed to complete each volume consistently if they are all of a very similar size.

The Project realises this change will not suit everyone but there is in reality no actual perfect way of organising the map volumes that will serve every possible situation or purpose. What is relevant is that this structure will not affect the way image based maps or webmaps are produced. The webmaps will continue to be completely seamless i.e. a single map, whilst the image maps will still be output the way they are now organised by the name of the railway line that they cover. In fact the Project is considering changing the downloads pages into ones that are organised by line name rather than volume name. Because of the changes, the existing volume categories will all be removed, as they are now out of date in a lot of cases, and the post captions will be altered.

What’s relevant for the here and now is that Volume 7 will not be completed this year so there is now not going to be a full release of the volume that contains the Midland Line. For this reason and also because of the need to get the Midland Line maps produced as soon as possible, the part of Volume 7 that includes the main line from Rolleston to Greymouth will be finalised and released ASAP. The part that includes Midland Line branches will be finalised and released sometime later this year.

Volume Definitions as at 2023-07-01