Saturday, 24 March 2018

Main North Line [11E]: Addington 5

Well, Friday has been a whole lot more mucking around to make various adjustments to all of the Addington stuff, mainly in the area of adjusting the masking for the partial images. This has resulted in needing to re-render all the partial map tiles which is a relatively slow process. Hence the maps have not been ready in time as expected. There are still more adjustments needed where some of the tracks don't line up, so it will be several more days before mapmaking can really get underway. Here are a couple of sample images that many readers will appreciate for their historical context.

The familiar present day view of Addington with a few extra things drawn in for context.

The historical context with present day roads and tracks.

Main North Line [11F]: Addington 6

Today's not-news is of yet another hold up in mapping.

Because I made the stupendous discovery that some of the tracks aren't lined up between the old and new aerial images.

Unfortunately the nature of historical aerial imagery means that this is a risk. It's my regret that the process I used did not pick up that alignment issues were possible with the tracks in more than one or two places (the edges of the east and west ends of Addington).

Since this affects the middle part and every other part is aligned off it, this means I virtually have to start again from scratch with the middle part and then realign everything else off it.

I hope this won't take too long but the reality is that it could take another week. I will try to see if I can speed things up with two computers at once but I am not at all sure this could happen. 

Letter to the Editor of the New Zealand Railway Observer

Concerning editorial changes made to submitted articles to the New Zealand Railway Observer.

During the last three editions of the New Zealand Railway Observer (No.346-348) I have had published a series of articles entitled "The Geography of the Otago Central Railway". I enjoyed writing these articles and sought in the process of this to provide another look at this railway line and the present day relevance of it. The research behind these articles has been a part of the NZ Rail Maps project, and the maps produced by this project are a key part of the information process that has been used to produce the article series.

I regret however that I must put on record at this point my concern at certain editorial changes that were made to these articles after they were submitted for publication. These changes were made without consultation with me, and in the main are preoccupied with an obvious editorial prejudice against imperial measurements of distance such as miles. There is no legal requirement to use metric measurements of distance in the context of publications such as these, and overzealous conversion of imperial measurements results in many absurdities in written work that I have read from a variety of authors and publishers over many years. In this case the simple metrication of imperial distances fails to understand the historical differences between these measurements as they were used on the railway system of New Zealand.

The articles which I submitted used metric measurements where appropriate, and imperial measurements where appropriate. The following are the key objections I have to the metrication of the entire article:

1. It is impossible to describe a milepost as a "1.6 km post". There is no such thing as a physical post that was put into the ground alongside a railway at 1.6 km intervals. Thus, the line of my article reading for example "Between 38 and 39 miles" which has been changed into "Between 59 and 62 km" refers to actual different locations than the 38 and 39 mile pegs. I can't quite make up my mind whether "59 to 62 km" is better than the direct equivalents of 61.14 and 62.75 km which some publications would have used. Note that "59 to 62 km" in the above appear to be factually wrong. This makes about as much sense as changing the names of official publications that have "1 mile" or similar in their title.

2. The measurements of mileposts and kilometre posts were done at different times, and in the cases of many railway lines, measured actual different distances. These changes have occurred because many railway lines have been deviated or realigned. Historically when deviations or realignments have been made, the original mile or km posts do not get relocated to reflect the change in distance. Instead the engineers have historically made use of a device called a "short" or a "long" mile [1].  For many lines in NZ, "short" and "long" miles persisted until such a time as metrication in 1974 when the lines were remeasured from scratch and the kilometre and half-kilometre pegs put in. It therefore cannot be assumed that distances measured in kilometres will always correspond exactly to distances measured in miles on the same line.

3. The distances shown in the article are official distances from official NZR and its successors' publications. Chiefly these publications are the Working Timetable, and lesser publications include the chainage books which are held by Archives New Zealand. The first metric WT for the Otago Central Railway omitted distances for stations which had closed. For these stations, therefore, the only available and appropriate official distance measurement is the one from a preceding WT measured in miles and chains. Chainage books are all in miles and chains and all distances derived from them have appropriately been expressed in decimal miles. 

Researchers in this area who have made use of the New Zealand Railway and Tramway Atlas, a popular publication which includes distance measurements for the vast majority of railway stations across New Zealand, are aware of discrepancies between these measurements and those found in many of the metric era Working Timetables. We can only assume that the publishers chose to hand convert the imperial distances to metric rather than obtaining new measurements from the metric WTs. For the same reason I have not used the metric distances shown in other publications about the Otago Central Railway for station locations that are not shown in the metric WT. 

4. The maps drawn of the line are marked using the imperial mileposts obtained from chainage charts and in many cases measured from easily verifiable geographical locations shown in the same charts. Whilst there may be some minor discrepancies in actual milepost positions, these measurements offer a reasonable degree of accuracy in the placement of the mileposts on physical positions on the map. The same information is not available for most kilometre posts on the line, a number of which have been removed from the line in any case. Those metric measurements shown are mostly station locations that are in the metric WT. The measurements on the map are those which can be obtained from official railway publications according to the preceding principles and quoting a measurement that has been converted makes no sense in this context because there won't be a corresponding measurement marked on the map itself. 

Reference: [1] NZR DEO’s Office (c.1930-c.1956). Chainage O C B [Otago Central Branch] 0 Miles 00 Chains to 25 Miles 60 Chains. Archives New Zealand, R18524763.