Monday, 21 January 2019

Marton New Plymouth Line [0C]: Project Progress Report [2]

Following my last post I have nevertheless pushed on with the maps, making life considerably easier for myself by breaking up the workflows. Instead of having a slow, frustrating and often tedious workflow of doing everything in one go, I have the first pass in pegging out the corridor route, and the second pass filling in all the extra details like stations and bridges etc. I often do fill in yard sidings as part of the first pass for a bit of a break from the routine. By making this change, I have in the last two days pushed the completion of the first pass all the way up to New Plymouth/Waitara, and currently I am working on getting the last bit of aerial photography completed, which is 0.1 metre coverage for New Plymouth and Waitara, and all of what is needed for the Stratford Okahukura Line, the Egmont branch and the Opunake branch.

I'll put a little plug in here for the EnzedTech blog as well, as it covers some of the more technical aspects of the map production, specifically the more backroom sort of work that is needed to make the project come together. There is a specific tag in that blog that relates to NZ Rail Maps development, so here is the URL that will display just those specifically tagged posts:

I haven't actually used that tag more than once so far, so there are in fact several posts on that blog  which I need to go back to and tag so that they are included in that listing.

There is going to be a new post shortly about the script that I use to copy aerial imagery. I will be writing this post today and there will be some previous posts that are getting added to that tag today as well.

Going back to the maps themselves - as soon as I have all the aerial photography in place I can work back putting in all the detail from New Plymouth and Waitara to, first of all, Waipuku and then the Egmont Branch, and then back to Stratford and then working my way up the SOL. There are several yards to be drawn in along the way, so I'm not quite sure when I can start drawing the SOL, but I am really keen to get that started.

Saturday, 19 January 2019

Marton New Plymouth Line [0B]: Progress Report

The last few days working on the MNPL pushing things along towards New Plymouth have been a pretty hard slog, which is reflective of the nature of all the NZ Rail Maps project if I am going to produce full volumes that use current aerial photography as a background. When I first started doing maps in Google Earth I drew in all the routes and a lot of data using Google Earth's tools, which all had to be done from scratch. When it came to Qgis, I used the Linz data layers by default and brought in some traces of closed branch lines from GE. I don't recall there being any other data from GE that was going to be of any use.

When the maps were first done in Qgis it was relatively straightforward as I just assumed the Linz data layers were correct and that was that. But now with the Linz aerial photography and other data sources available I find that correcting the routes to match the aerial photography and fixing up all the other gaps and mistakes is a hard slog. It's almost as much work as doing it from scratch with GE and it effectively does have to be done from scratch for the first time.

As of this moment of writing this, I have just got past Normanby which is 138 km from Marton. That's about two weeks work to get that far. It's a lot of hard work. I would look at the past few days and say I have pushed through about 30 km a day. Extrapolate that to all NZ and it's clear there is going to be a great deal of work if I want to produce all the maps to this standard.

Because of that I am definitely going to stick to what had been planned previously which is on finishing this volume, going back with Volume 5, Volume 7 and Volume 12. Probably at least for this year all that will happen with other volumes is a reprint as diagrams rather than full maps with aerial backgrounds. I don't see any other full map work happening outside that programme because the above listed have been chosen for being especially interesting and by comparison, pushing through 30 km a day of boring farmland doesn't count for anything.

After non stop work over the past few days to get to where I am now, I am going to take a break for a few days before I finish off the rest of this volume. There is 70 km more to reach New Plymouth and then there is the SOL (143 km on its own) and all of the numerous branches. So it will still take until the end of the month or more to complete all of that. And I won't rule out taking a pause from Volume 4 and doing something else for a while. The SOL will be a lot faster to complete because I already did all the extended data on it some time ago, so it would just be alignment on the aerial photography and therefore could go faster than the MNPL itself has gone so far.

Friday, 18 January 2019

Marton New Plymouth Line [3A]: Waitotara - Normanby 1: Bridges 34, 37 and 41 Not used by road traffic

When I first drew maps for the MNPL about five years ago (I had just started to use Qgis but I can't really put a date on it) the NZMS1 maps for the area between Waitotara and Normanby suggested that three bridges around Waitotara and Patea were combined bridges, used by both road and rail traffic. Two in particular, Bridge 37 and Bridge 41, respectively east and west of Patea were explictly labelled as such.

In the course of redrawing these maps I have looked at the information for these bridges again to see if there is any more support for these suggestions. However, I have not been able to find anything that sustains these ideas and have concluded that it is not very likely at this stage that any of these three bridges were designed or used for road traffic as well as their primary rail usage.

If the bridges had been used for both types of traffic there would have been more information available about it because it should have been described in either railway or road documentation for the area, but no such documentation has yet been discovered, whereas other documentation tends to spell against these suggestions.

Here are maps of all three bridges.

Bridge 34 crosses the Waitotara River just west of Waitotara Station at the 78 km peg. A key factor against it being a combined bridge at any time in its life is it being so far from the Waitotara township. It would have been an inconvenient detour from the town to have reached this bridge. On the other hand it is close to the railway station and also close to another road bridge (Limeworks Bridge). At the moment there is nothing to show that the road layout has ever been anything other than what it is today. It appears the abutments of the previous bridge show it was just upstream of the current structure.

Bridge 37 crosses the Whenuakura River just east of Patea. On the one hand, there are overbridges on either side of this one, which would have suited the idea that a main road was sharing the bridge crossing. But on the other hand, in the aerial photography I was able to access, the road that approached on each side was no more than a dirt track, and today is nowhere to be seen. The highway crosses this river a considerable distance upstream. As we do know from previous posts recently, this bridge was severely damaged in flooding in 1922, and was completely replaced in 1930. The photos of the replacement show it was incapable of carrying road traffic. The original probably never did either. Again all I can document here is the location of the previous bridge. The road that did exist was most likely never anything more than a track formed to bring in materials for the new bridge construction in 1930 and any other maintenance needed since then.

Bridge 41 crosses the Patea River just west of Patea. We can state with absolute certainty that the Patea River was bridged for road traffic at Bedford St in the 1870s, the current structure incorporating Bridge 40 being a more modern replacement. There was therefore no compelling reason to need a road being able to cross at this location, which would have been pretty inconvenient for the people living in the township.