As we know, to be able to draw my maps, I have made extensive use of aerial photography. Retrolens is where most of this is coming from these days as I have wound down getting contact prints scanned from Archives NZ to reduce cost.
There are a few areas I have not yet got coverage for because they are still being scanned. Here are some illustrations of why that is.
This is how much of the line was covered by imagery with a scale of less than 1:12000 in the 1930s. In short, nowhere near as much as I would have liked.
1940s large scale coverage.
1950s hi res coverage is mostly along SH85.
1960s hi res coverage is mostly SH8, SH85, SH87 and the Clyde hydro development. Covers a fair amount but there are obvious gaps.
At least for the 1970s we can get some of Ranfurly and Waipiata that isn't covered much in the other surveys, and the Clyde hydro area is well covered as well.
For the 1980s it's pretty much SH85 and SH87 again.
This reality means there are some unavoidable black spots for coverage. Here are the challenged areas in particular:
- Galloway: Officially, there is no large scale coverage of this station. Unofficially, due to survey drift, there may actually be some inclusion in survey 5800 of 1980, but the station actually did close in 1978. Hence I have only been able to source small scale so far. This is close enough though.
- Auripo: Survey 112 does cover this area at 1:12000 and dated 1939. This is the only survey during the period that the station was open. At the time of writing survey 112 was not fully scanned.
- Ida Valley: Survey 112 mentioned above is again the only large scale survey for the period that the station was opened. Not yet scanned for the area.
- Ranfurly: There are actually a number of suitable surveys for Ranfurly, just not ones that have been scanned yet, because of it being on SH85. Survey 112 officially doesn't cover the area, but it is possible that with survey drift it will cover the station area. Survey 890 of 1956 and Survey 1745 of 1965 do cover Ranfurly and so it should be possible to see the old loco depot area if the survey boundaries are correct. Surveys 2833 of 1975 and 5800 of 1980 will also be of use once they come online.
- Waipiata: Waipiata is a blackspot because of it being in the middle of a triangle between SH85 and SH87. Still, it should be well covered by Survey 2833, giving us some 1975 era views, when the station was still fully open.
- Hyde Ballast Pit: There isn't any large scale coverage of the area until Survey 1916 of 1966, so there just isn't anything that will show us tracks on the ground in the ballast pit, which closed in 1952. Smaller scale stuff from the mid 1950s isn't able to help much.
- Middlemarch: Survey 1915 of 1966 is the first large scale coverage and has very recently been added to Retrolens. Expect to see a posting about Middlemarch very soon.
- Pukerangi-Taioma: This is understandable black spot territory given the sparse population and distance off SH87 and there is in fact no large scale coverage at all in the Linz database. However, there is coverage of different parts of these areas in different surveys at smaller scales.
- Taioma-Christmas Creek is covered by Survey 1435 of 1963 at 1:18100, which has not yet been added to Retrolens.
- Christmas Creek-Pukerangi is covered by various surveys around 1:23000 or 1:25000. I have seen some of this coverage and generally it is fairly fuzzy.
- Wingatui - Taioma: Coverage starts from 1949 onwards. At the time of writing not yet in Retrolens. (In reality this will only be Taieri Aerodrome, Salisbury and the 2nd Taioma station of interest)
Looking at the gaps particularly the Taieri Gorge I have had to weigh up the pros and cons of various options for closing those gaps and have decided pretty much to focus on getting the chainage charts copied from Archives New Zealand for the first 25 miles (I already have them for 25 to 146 miles) and waiting for more coverage to come online. The chainage charts should have sufficiently good yard plans for all the Taieri Gorge stations from the first construction of the line and it would take too much time or cost to get plans of these stations from the individual files. In any case actual yard plans often aren't as detailed as the chainage charts with distance markings. So it is likely the full maps will not be completed for the series of articles and updates may well be sent in at later times.