Avondale-Southdown Rail Corridor Full Map

Here is a full map of the corridor route. It is derived from the map in the Wikipedia article.

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The map in the original article will update whenever Trainweb’s server gets around to updating its cache (or may be dependent on your ISP’s caching as well).
Knowing the route a bit more precisely lets me write some sort of route description which is as follows. All the descriptions assume the railway is at the surface at the points referenced.

• From Avondale the line turns to cross New North Road then running through open reserve/parkland to reach a small bridge. Average gradient: 1 in 200
• Continuing to Richardson Road the average gradient has steepened to 1 in 50.
• From there to Sandringham Road the gradient eases to average 1 in 150.
• Gradient is then more or less flat, or can easily be made to be, until reaching Hillsborough Road when it drops at a very steep 1 in 35 to Queenstown Road.
• There is then a more or less flat stretch until Quadrant Road.
• From Quadrant Road the line drops at 1 in 50 to Onehunga Mall.
• After that it averages 1 in 60 down to Victoria Street.
• It eases to about 1 in 80 down to Captain Springs Road.
• It is then more or less flat to Neilson Road.
• From Neilson Road to Westfield it drops at average 1 in 180.

Conclusion is that there would be a substantial amount of gradients averaging 1 in 50, unless it is possible to lower the summit. Since a substantial part of the route is at the summit altitude, or similar to it, this would be very expensive. Probably the best use of earthworks is to average the climb as much as possible so that the steepest 1 in 35 part can get eased out. The total route length would be around 13 km. 1 in 50 grade is simply not seen on newly constructed main lines today for any significant distances. Most of this grade is over the eastward 7 km. The average gradient is around 1 in 100 but in truth it is two climbs separated by a flatter section.

Avondale-Southdown Rail Corridor

Auckland Transport posted on this corridor a couple of weeks back and by coincidence I was looking at it on my map of the NAL today. The idea is that there would be a freight train bypass of the busiest part of the passenger service lines between Avondale and Southdown. The latter has a major freight terminal long established. However, the area which would be served by this freight traffic is primarily Northland which has its rail link currently under review. Scott also says the “incline” of the route limits the length of trains that can be carried on it. Southdown is at around 10 metres altitude and Avondale around 40. This would produce an average gradient around 1 in 400 which is not a big deal. Google Earth data, however, backed up by topo maps, suggests that a train from the Avondale end would have to climb 20 metres in the first (approx) 1.5 km, a 1 in 75 grade which is pretty steep by modern standards. After that the track would be roughly level for a while before it descends on, probably, a similar short sharp grade, and then another longish levelish stretch to the freight yard at Southdown (All numbers are approximate as I haven’t seen any survey data). The line passes close to Mt Roskill, a hilly part of Auckland. The grade could be reduced by substantial earthworks or even tunnelling but this would add greatly to the cost. There has been a designation of the corridor since 1947 but it seems unlikely it will ever be built in the current scenario.

Currently, the Waterview Connection motorway (SH20) is being developed alongside, and probably through, a significant part of the rail corridor. The motorway is going to be tunnelled through some areas where houses have been built, and in other areas houses are being demolished. It is possible that parts of the designated corridor have been reassigned to the motorway as Auckland Transport points out.

This map of the NAL shows an approximate route of the corridor (green line)

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If we zoom in on the Avondale end, we can see that the land designation has had an impact on adjacent properties. A short part of the Avondale end has appeared on my maps for years.

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In spite of that triangle leg going through a carpark, the designation is pretty clear on the map view of Google Maps (click that Map button above and you’ll see it).

Please note that as the map has been updated just today, all alterations may not be visible immediately.

• Avondale-Southdown Line (Auckland Transport)

NZ Rail Maps site changes and updates

I regret to say that a third article in a series about the Seasider is not coming soon. It is at the moment too difficult to juggle the limited amount of time I have for this hobby (at most 1 day a week) with the various interests I have within it. You should go and look at the web album referred to in previous posts and the previous two messages for content about the route of the Seasider. It is just a reality that I don’t have much time at all for rail interests except during the school holidays.

The site has been changed about a bit, the most obvious being that the original layout has been reverted to. This is that all of the files for a particular line, whether new or old, are in their own specific directory, and that the most current version of the file always has the same name. This means I don’t have to maintain a separate directory of files whose names never change for blog postings. A further change just executed today is that all previous versions have been renamed so that they will appear alphabetically lower on a page than current versions. This means all current versions always appear first in the page listing (as they have been changed to sort alphabetically).

Updates continue but are not being publicised specifically here. The major area of update of late has been the Otago area with 7 updates since my holiday at the beginning of April. Some of that relates to that holiday, obviously, and other improvements are relating to the Remnants series of articles. These are also halted at the moment, as they are big efforts that take a lot of time, and at the moment I have just about exhausted the list of lines that have the best GE and (especially) StreetView coverage.

I had hoped to recommend a change detection service for anyone who wants to have updates to the site automatically notified. It doesn’t look like that can be easily implemented at the moment because as it stands the banner ads on Trainweb pages will cause a change notification every time they are updated.