When you think about possible routing of suburban trains it becomes apparent that the southern portal of the tunnel needs to work well for both the western line and the link back to Newmarket via Grafton.
I.e. the tunnel will be most efficient if trains run through both ways at the same sorts of headways, like for every train going in one way you need another coming out the other.

The problem with a Morningside deviation is that you’d have only the western line entering the tunnel at the southern portal, while the Eastern and Southern lines plus the Onehunga and Manukau branches would enter at the northern portal. Thats a massive inbalance, as every other line on the network would need to become a western line train. Better to have the southern portal allow access for half of the trains from Newmarket.

About the gradient…straight after kingsland (coming north)split the tracks and the CBD tunnel line swings north and hits the gully which is north western motorway..there’s enuff embankment there for cutting small trench all the way to spagetti in my opinion. Some current MT eden station patrons will be pissed(they have to walk a bit, but come on) the area really getting screwed is a prison LOL (assuming new commuter services skip MT Eden)
Once the train line starts to hit spagetti it goes underground (under sh16..THUS WAHAY ..an even shorter tunnel! Save$$$ and dramatically ease the gradient.

THEN BUILD A TRAM LINE ALL THE WAY UP QUEEN ST AND KEEP GOING TILL EDEN PARK VIA NEWTON ST STATION,(for those residents/workers that area)

I know my idea screws over newton area residents a bit..but I think a tram solves issues.

Think Northland forests coming into harvest over the next 2 decades being freighted into Ports of Auckland via the West line and this new CBD line. More importantly, think of an inland port at Henderson or Kumeu like the just opened Wiri inland port (trucks drop containers off for off-peak railing into port). The reverse freight trip will not be viable if the gradient is what is currently recommended (1:28), and even downhill freight may struggle with stopping!

And of course as the areas passed through are all white-collar office and residential, there should be no freight pickup on the CBD line (whether surface or tunnel route), so the exact track route is not vital, but passenger station locations are. Which is why a Newton station by SH16 from Newton Rd westwards would feed residential areas not covered by Mt Eden. Whereas Kiwirail /ARTA seem to be planning 2 Newton stations (1 replacing old Mt Eden), with a lot of overlap.

Notice too on the Kiwirail presentation to ACC that Kiwirail don’t plan to ask the community what we think til after they have the business case and concept plans ready – meaning they will have ‘done too much work to reconsider routes & station locations’. So we will be able to pick the wallpaper colour. Brief but meaningful consultation should take place at each stage – 1 month won’t kill the project’s timeline.

Matt L has the best comment I reckon (give yaself a chocolate fish Matt):
“Also have they considered lengthening the tunnels at the Mt Eden end to get a slightly better grade?”
The gradients are crucial to this project – even with electric motors, it is 3.5% gradient (ie 1:28, or 1m rise every 28m along). IIRC, that is significantly steeper than the steepest gradient we currently have of around 1:35. Stopping and especially starting up these angles are going to slow even EMUs.

Serious thought must be given to easing the gradient if the economic benefits are going to flow – steep gradients cause more reliability problems (timekeeping and breakdowns, and higher operating costs). Pushing the line back to Kingsland/Morningside would dramatically ease the gradient, and wouldn’t cost more than $150m or so extra. Not much on a $1bn+ project.

That would also allow the route to be pushed from Kingsland a short way across to follow the SH16 corridor, which allows cut’n'cover cuttings rather than tunneling – far cheaper and faster. This could allow the Newton station to be in the gully and service the Ponsonby/Arch Hill area, which would add new population to the catchment (the Newton station adds few people – it overlaps Mt Eden massively and seems to replace it).

Also IIRC, the Elliot St tower hit financial problems, and is highly unlikely to proceed unless the CBD real estate market turn around (very unlikely – vacancy rates shot up after the recession hit). So that would make an excellent building site – they could even build horizontally to make Aotea station – it’s quite an embankment!

So, my two cents – ARTA should pause for breath, and put this route out to public consultation and be prepared to rethink the route. Don’t stall the project, just rethink before we commit to running tracks from the lowest point (Britomart) to the highest point of the inner West line (Mt Eden).

I’m a keen photographer and like architecture and have photographed all the stations. I was traveling along the line one day in 1999 when we stopped at Southwark. That hadn’t happened before. So I hopped off the train for a look. It was the opening day of the station, the staff were as proud as punch, they all had cameras, and they all came outside so I could photograph them in a group outside the station. There is a neat LU logo on a stalk attached to the veranda of the station that I like and they were standing underneath it.