We visited here a little under a year ago, and safe to say, a lot's changed since then.

The redeveloped station in Mount Eden's starting to take shape, with the fit out about two thirds of the way complete.

It's just one piece in the puzzle of New Zealand's largest ever transport project.

Taking a look underground, work's come a long way too, with track fully laid and the new stations along the 3.45km twin tunnel nearing completion.

Kuranga-a-Hapi station's been one of the trickiest to build, as the deepest underground.

A lot has progressed since last time, the escalators are in now, a little bit to finish at the top.

These escalators are the longest ones in New Zealand.

Understood they were going to be the longest in Australia, Australasia, but they pipped us up.

Of course they did.

Of course they did.

So this is the fit out here, as we go around you'll see the wall panellings going on, which is the final finish there, there's been some painting on the back of the tunnels, and you'll also see the ceilings going in.

Down here they're putting in the kerbstones for the edge of the platform, the edge of those stones to the trains is important from a safety perspective.

Has to be quite tight right?

Quite tight, the dimensions are really tight.

Cabling's the name of the game currently, with around 1,200km of electrical and communication cables being installed to run the stations and the tunnels.

It's a massive task, it's a fiddly task, it can be very constrained, sometimes you've got five layers of cable trays sitting over the top of each one, sometimes you work in very narrow areas, so that's been a big push for the last six months.

Twenty-three new trains have been ordered for when the CRL opens, the first is being shipped from Mexico at the end of next month.

It'll be rolled onto the tracks shortly after it arrives, but don't get too excited.

The CRL's set to hand the project over to KiwiRail and Auckland Transport next year, when extensive testing will begin.

Passengers can then expect to take a ride sometime in 2026.

Rolling a train down these rails is easy, but all the other equipment around it needs to be working, like tunnel ventilation, train radio, and a lot of the other control systems.

So what we do is, once all the systems are ready, we'll run one train through here very slowly, and that's a series of tests, and if that's successful, you'll run one train through at higher and higher speeds until you get up to operational speed, then they'll start running a multitude of trains through, and if those tests all work out, they'll then start replicating network operations, simulating a fire on a train, emergency stops, a major health event, a terrorist event, all sorts of things that people have to plan how the The City Rail Link's budget blowouts have been no secret.

The project's price tag now sits at around $5.5 billion, part of that due to COVID, but also other revised costs.

Sticking to schedules being niggly too, it's seen workers have to put in plenty of extra hours to get crucial work done on time, but it's nothing new to those working down here.

Nothing ever goes to plan, but the skill as a builder is you make the best plan you can, then you see how you're going, and then you work out the bits that aren't working right, and you do something about it.

And builders are perpetually in a loop of doing a plan, checking how it's going, and then reworking the bits that aren't working well.

The reason these guys who build these are so good is they're so good at overcoming the little problems that land at their feet along the way.

We end our journey in the city centre at TY Horitu Station.

Plenty of progress made, and plenty of progress to be made as the highly anticipated project ticks away.

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