Friday 10 January 2020

Palmerston North Gisborne Line [0K]: Volume 5 Progress Update 11

We are continuing to progress the completion of Volume 5 as quickly as possible. This currently requires a number of steps:
  • The first 92 aerial maps plus a few of individual stations after this point need to be regenerated in the new styles. This is well under way and should be completed shortly.
  • Historic map tiles are needed to be re-imported into Qgis for Gisborne. Along with this, we have created additional tiles for Makaraka, Matawhero, Muriwai, Waipaoa Bridge and a couple of additional sidings in Gisborne itself.
  • We are working on adding historical content for Terrace End, Woodville, Waipukurau and Dannevirke. Additional parts of Napier such as the port were considered, but would take too much time for this stage of the maps.
There is also a script to be produced to enable Volume 5 maps to be uploaded to Google Photos in the correct order, especially when producing the Combined map album that will have aerial and diagram maps interleaved in sequence. This has become all the more important because of the new map styling. In the original design of maps, the aerial and diagram maps only differed in the background, which is the aerial photos and terrain reliefs, respectively. In the updated design, the aerial maps omit a lot of information which can be found only in the diagram maps. Therefore the Combined Maps concept that interleaves aerials and diagrams is important because the aerial and the diagram are both needed to have all the information at one's fingertips. The issue is that Google Photos can only sort by date of the photo. When the maps have been produced, different parts have been done at different times and sometimes not in strict date sequence (the updating of certain areas such as mentioned above being a prime example) so having the script to change the timestamp of the files helps a great deal. 
 
The four maps below are the various stages of the Waipaoa river bridge (Bridge 290) over its first 50 years.

The bridge was first built in the early 1940s. This image is from 1944, the year after the full PNGL opened with the completion of the last section to Gisborne.
 In the mid 1950s, as part of a flood control scheme, the river was straightened and widened. This meant that the bridge was extended at the south end. The extension was constructed on dry land, and the railway was diverted around the extension to allow the work to proceed.
 This is a 1986 photo showing the bridge as it was completed in the 1950s with the extension.
In 1988, Cyclone Bola hit the East Coast of the North Island bringing with it torrential rain and huge flooding. The massive flow in the Waipaoa river ended up washing out the southern end of the bridge. The result was that the southern end of the bridge was further extended. This aerial photo was taken whilst the bridge works were being completed as can be seen with equipment still on the ground. A large pier replaced what was the south end abutment from the 1950s.