This month’s report highlights progress mainly in Volumes 10 and 11. Volume 10 work has been on completing a set of maps of the Dunedin-Mosgiel section. But the majority of work has been completed in Volume 11 and has focused around the Roxburgh Branch. Here the goal has been to complete a full set of aerial mosaics for the entire 97 km rail corridor, not just stations as would have been done for other closed branches. This approach was also used for the Moutohora Branch recently and it could be trialed with other branches covered in the future. However, the time needed on just this one branch has been pretty extensive, and whether there is enough opportunity for such an approach for closed corridors all around NZ in the future is hard to ascertain at the present time. To put this in context, closed corridors in NZ amount to something like 2000 km all up, and this makes it very uncertain that such a concept can be pursued to such an extent in future, or as a high priority. Volume 11 has a considerable amount of closed corridor within it, and at the present time it is unlikely that this can be covered to the same extent in other branches. There are also practical problems with aligning coverage between stations simply because of normal issues relating to undulating terrain, for example. In the case of the Roxburgh line, there is quite a lot of such terrain, and correspondingly there has been a lot of difficulty getting accurate registration / alignment of the historical coverage to match the current day basemaps.

On the other hand, the Roxburgh Branch and the Moutohora Branch are both well documented and this provides something of an incentive for producing the full corridor aerial mosaics that are currently being finalised for the Roxburgh corridor. Likewise it is to be expected there will be similar coverage produced for other well documented corridors. As most of the remaining Volume 11 closed corridors are not well documented then so it follows the coverage of them will be lessened, or perhaps produced at a lower standard. The same general principles would be applied to the other volumes. As soon as the current work in both Volumes 10 and 11 is completed, the focus will shift back to Volume 6 and possibly the original plan to complete Volumes 6-9 this year will be invoked, although at this time the Project doesn’t yet have enough aerials to complete the South Island volumes and work is likely to be deferred until resources are available to obtain these. So progress on the previously proposed 2024 timetable set out last year will have to be on a revised schedule.