This is a guest post by Darren Davis. It originally appeared on his excellent blog, Adventures in Transitland, which we encourage you to check out. It is shared by kind permission.
Prologue
It’s been 25 years since the Bay of Plenty has had a regular passenger service in the form of the Kaimai Express. And May 2026’s Glenbrook Vintage Railway excursion train was apparently the first passenger train to enter the Bay of Plenty in over a decade. And it sold out in record time – less than two days – with minimal publicity. Which kinda shows some sort of latent demand for interregional passenger rail in Aotearoa.
What shouldn’t be a once in a decade plus shot – a passenger train boarding actual passengers at the east facing platform at Hamilton Frankton Station. Photo credit: Darren Davis
This absence of regular passenger rail service is in spite of the fact that the Bay of Plenty forms one leg of the Upper North Island’s Golden Triangle, home to 40 per cent of Aotearoa’s population, whose rail network carries 30 per cent of Aotearoa’s rail freight.
And as a reminder that such a thing actually existed back in the day, below is the timetable of the dear departed Kaimai Express, which ran until 2001.
Kaimai Express timetable up to its enforced demise in 2001
I have previously written about the case for restoring passenger rail to Toi Moana/ Bay of Plenty here. So worth having a read of this for my views on the case for rail to the Bay of Plenty and a possible Te Huia based option.
What are the options for restoring passenger rail to Tauranga?
So what would it take to get passenger rail back to the Bay of Plenty? Quite a lot in fact. The elephant in the room is the constraint presented by the Kaimai Tunnel as well as the cost of addressing decades of underinvestment in passenger rail in Aotearoa.
But that doesn’t mean that it’s impossible, just difficult and likely expensive. As I see it, there are two basic options:
- Extending the current Auckland to Hamilton Te Huia service to Tauranga
- New battery electric multiple unit service
Both options would require work on the Kaimai Tunnel to make it safer for train passengers and rail crew. So let’s dive into the options.
Te Huia to Tauranga
I have covered this in my earlier piece so in case this content looks familiar, it is as it paraphrased from my previous blog post on the subject.
Extending Te Huia to Tauranga is the (multi) million dollar question, and we shouldn’t kid ourselves that this will come cheap. The five-year trial of Te Huia between Hamilton and Auckland – now extended for a sixth year – ended up costing $98 million. But it also set a solid basis for building on this investment and extending its benefits to Tauranga and the Bay of Plenty, assuming of course that the service becomes permanent in 2027.
So the logical way to go is to build on what we’ve got and take it further – to Tauranga. And this means an extension of Te Huia to the Bay of Plenty.
Let’s assume for the sake of argument that the current 9:30am Te Huia departure on Thursdays and Fridays become Monday to Friday services (i.e. adding in Monday to Wednesday trips), then an extended service could start in Tauranga at 8:00am and get to Auckland Strand at 11:54am. The return trip could be an extension of the current weekday 5:45pm departure from Auckland Strand would arrive in Tauranga around 9:50pm.
My hypothetical Te Huia to Tauranga timetable
At weekends, based on extending current services in the Te Huia timetable, this could be a 7:30am departure from Tauranga on Saturdays and a 1:15pm departure on Sundays and public holidays. Return trips would leave Auckland at 5:30pm on Saturday and 6:15pm on Sundays and public holidays with late evening arrivals into Tauranga.
These are not absolutely ideal times, especially the late arrivals into Tauranga, but we need to be careful not to make perfect the enemy of good. But to make this work, we would need to address the 8.879 kilometre long elephant in the room – the Kaimai Tunnel. At the moment, a combination of a large number of daily trains from the Port of Tauranga to Metroport in Southdown in Auckland and the time required to clear the tunnel of diesel exhaust emissions severely constrains the potential slots available to operate passenger trains through the tunnel. More on this later.
Battery electric train option
The simple logic of this option is that Aotearoa is investing $900 million in battery electric trains to run improved, and hopefully faster, services on the Wairarapa and Manawatū lines in the Lower North Island. There is a narrow window of opportunity for the Upper North Island to add its requirements to this order, to achieve some economies of scale in terms of the size of the train order.
Render of interior of Tūhono Lower North Island battery electric trains. Image source: Horizons Regional Council
There are some technical differences to address, such as differences in platform heights between stations in the lower and upper North Island (why a country as small as Aotearoa can’t standardise platform heights is quite beyond me), but I have been advised by people with rail technical know-how that this is far from an unresolvable issues.
But the biggest technical difficulty is that the current battery range of around 80 kilometres would require the approximately 76 kilometre gap in North Island Main Trunk electrification between Pukekohe and Hamilton to be closed first, and probably extended as far as Morrinsville on the East Coast Main Trunk from Hamilton along with the ability to fully charge up the train battery overnight in Tauranga.
KiwiRail has done a lot of work on the electrification of the Golden Triangle rail network in the Upper North Island which I have previously covered in this blog post which I recommend reading.
In a presentation to the Waikato Regional Transport Committee on 9th March 2026, KiwiRail outlined the following updates to this work.
- Currently completing the Detailed Business Case to identify the best and preferred electric solution plus the staged delivery pathway.
- After this it is expected that further work on the funding options will be discussed with key stakeholders. This will include exploring funding options for the delivery stages from within KiwiRail and potential Government budget bids.
- It is also likely that further technical work will be recommended on the preferred option to further increase confidence in the programme estimates and help narrow the risk contingency range.
It’s clear from this that Golden Triangle electrification does not seem to be anyone’s fast track. And as this electrification is a precursor to a battery electric train option to Tauranga (which notably is a viable option for replacing Te Huia between Auckland and Hamilton as the electrification gap is around 76 kilometres, within battery range), extending the current Te Huia diesel train service to Tauranga seems to be the only viable shorter term option.
The elephant in the tunnel
The elephant in the room is the Kaimai Tunnel. While passenger trains do run through similar length tunnels around 9 kilometres long (Remutaka Tunnel for the Wairarapa Line and the Otira Tunnel for the Tranz Alpine train) with a range of precautionary safety measures in place, the issues with ventilating the Kaimai Tunnel requires lengthy gaps between trains to clear out the exhaust emissions in the tunnel. These lengthy gaps were in play for the recent Glenbrook Vintage Railway excursion, requiring a late departure from Tauranga to fit in with an available tunnel slot.
Freight train emerging from the Kaimai Tunnel.
Given that the ventilation issues in the Kaimai Tunnel are a clear and present health and safety risk for the KiwiRail locomotive engineers and maintenance staff whose work involves the tunnel, it would seem that addressing those issues would deliver a win-win for both KiwiRail’s freight operation, which would have more slots available and equally a win for slots for passenger rail, not contingent on waiting for an available gap around a busy schedule of freight trains.
Final thoughts
While advocacy groups such as Future is Rail and Tauranga Connect have been energetic in their advocacy for passenger rail in the Bay of Plenty, elected members at all tiers of government have been rather less energetic in their advocacy. Without this political drive and momentum, noting a forthcoming national election in early November 2026, it is hard to see much action forthcoming unless it becomes an election issue.
It took the Waikato a decade of solid and highly energetic political advocacy to get Te Huia off the ground between Hamilton and Auckland. And it’s going to take solid and highly energetic political advocacy in the Bay of Plenty to get passenger rail restored east of the Kaimai Ranges in the Bay of Plenty.
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Some second-hand railcars from Aus / Asia would probably do the job
InterCity run a bus at 7.35, reaching Auckland at 11.15, so how much demand would there be for a train leaving 25 min later and arriving 39 min later? Until 2001 trains left 30 min later and arrived 25 min later, but still there weren’t enough passengers to keep it going. It’s 237km by rail, but only 200km via SH2 for a car journey of under 3hr. The Paeroa to Pōkeno link would have cut the rail distance to about 217km, but until electrification brings faster speeds, how likely is it that a train once a day is going to succeed? Billions have been spent on the roads. A fraction of that spending would produce a railway able to compete.
Whilst scenic, the road trip either way is congested , and often delayed. But yes , they really need to cut a 1/2 hour out of the Hamilton – Auckland time.
Inclined to agree, I think it will need a pretty bold vision to make something like this successful. Half-hearted and slow rail is not going to do it.
Part of the resistance to passenger numbers will be the fact that Ham and Tga don’t have great public transport, and are highly car orientated cities. That means we aren’t designing a network that links up metro systems, but rather are trying to compete with the cars that probably ~90% of the adult population of each city already owns. Given that te huia is already slower and more costly than driving, the pool of users for intercity rail remains fairly small.
The uncomfortable reality is that to get a from my place in Hamilton to the train station using PT is about a 45min trip if being realistic (walking to the bus stop, margin for error, etc). By that time a car would already be closing in on the bombay hills. The ~$30 per person fare would be more than the fuel cost, which when you have high car ownership is the only marginal cost that people consider.
Not trying to be antagonistic, just stating some facts. Since the late 1990s car ownership per 1000 people has gone from 600 to 850 and this is a massive headwind for trying to get non-urban PT projects moving. I would love to see us go back to ~600 cars per 1000 people, where non-car ownership was normal and households had just one car, but it won’t happen overnight.
Unfortunately our cities have already been built for cars (sprawl), which makes it difficult to get anywhere without using a car. For rail services to be competitive, dense housing need to be built close to station catchments, not way out in the suburbs like has been done in Auckland.
There are five to eight return plane flights between Tauranga and Auckland each day. The lack of great public transport doesn’t seem to stop people catching planes.
Despite it’s slow speed Te Huia is getting around 60 people per train on average. When the last services between Auckland and Hamilton ran it was in single figures, despite them being quicker.
While there is room for improvement, the populations have all grown significantly during that period and I think there is plenty of evidence for demand for intercity public transport.
You wonder how much either shade of government is holding back on rail infrastructure in this area because services might well cannabalise Air NZ, resulting in bail out/additional support money further down the track. A double-cost, if you will.
Electrification of the Kaimai tunnel is required regardless of any passenger services.
Required just to remove the health hazard of diesel fumes on railways staff in the tunnel and remove the current limitation these impose on frequency of rail operations.
Completing the electrification of the Golden Triangle would be a huge enabler of unlocking the unrealised potential for moving both freight and people in the most populous part of our country.
But it would work very much against the interests of those hidden submitters to the bill to remove climate change liabilities from big polluters.
You would think electrifying the tunnel section loop to loop , or to Whararoa ( to pick up a power feed ) wouldnt be too expensive. Just have an EF tow all trains through .
Don R – Kiwirail is developing a business case called Golden Triangle Electrification Programme – (GTEP) for its shareholder – the government, to electricfy Pukekohe to Frankton to Ruakura or Morrinsville, installing ETCS 2 train control, using battery’ electric locomotive’s similar to Stadler’s EURO9000, with battery recharging locations at Southdown (Auckland), Mission Bush Steel Mill (Auckland), Te Rapa, Hautapu, Waitoa, Tauranga, Kinleith, Kawerau and Murupara.
This would help in the introduction of battery/electric (25kva) passenger train services between Auckland, Hamilton, Tokoroa, Te Kuiti and Tauranga/Te Puke and between Hamilton and Palmerston North from 2035.
KiwiRail needs to be more active, and visible in selling this to political parties, especially the two majors, the local authorities, and to the public.
Public pressure can translate into political pressure, as the really quite spectacular progress in Auckland Commuter Rail has demonstrated over the last three decades.
Likewise, for firstly just the retention of regional rail, and then expansion and upgrades out of Wellington in the same period.
Don R – Under the current business model of Kiwirail Holdings Ltd T/A as Kiwirail, being a rail freight and logistics operator, I don’t see Kiwirail going into subsidised ‘public transport’ style and/or non-subsidised ‘book & travel’ passenger rail, as they are currently happy with their Great Journeys NZ ‘scenic’ passenger rail operation.
Subsidised ‘public transport’ style intra/inter regional passenger train services like the business and operating model of Te Huia and lessor extent the Capital Connection, will be up to the 13 regional public transport operating authority’s to develop, plan, fund with central government finance and rate payer assistance, as seen with Te Huia and the revamped Capital Connection train services using new ‘Tuhono’ Class battery/electric train sets from 2029.
With regards to non-subsidised, commercialised ‘book & travel’ long distance passenger day/night train services between Auckland and Wellington, Picton and Dunedin or Christchurch , Dunedin and Invercargill would be owned and operated by a private ‘for profit’ train operator.
Can’t they use tri-mode or just diesel-electric with enough battery pack to get through the tunnel (~10km of range, not 80km)
Ideally full electrification of the main lines between Akl-Ham-TGA, but seems like replacing the locomotives/engine units is a relatively low hanging fruit that is much more likely to be done in the short to medium term, and if tri-mode is selected, they can be kept and get more efficient over time as more of the of easy to electrify sections are completed.
The Central Rail Link is supposedly our biggest ever infrastructure investment. I personally think the constant refurbishment and upgrades to our road network are a much greater waste of time and money than a nice little subway extension that will make train travel direct competition to the motorway.
What would be the logical next step? Given we have a very successful passenger service from Tamaki to Kirikiriroa, Tauranga makes sense. We contain between us perhaps half or more of the people in our motu, so we are responsible for more evil emissions than the farmers, although cows balance us out in terms of evil.
We cannot change the reliance of our economy on farms easily, but we could easily make travelling by train more easy.
Connect the dots. Tauranga next. Three highly populated cities connected by a modern transport network (also a not so modern transport network).
Less car crashes, less motorbike crashes, less truck crashes, less cycle crashes, less pedestrian mortality: LESS CRASHES.
Less life lost. Less drunk in charge of a vehicle, again, and again and again.
Quality of life improved, chance of death lowered.
Who could argue against such an outcome?
bah humbug
Next time we have a tunneling machine in the country drill another tunnel then build another line to take fast passenger trains .These are needed to be a lot faster than the freight trains and more frequent .Yes it would be a big INVESTMENT but would be cheaper than 4 lane RON money pits .
No need for a second tunnel at the moment. With the right signalling and ventilation (or electrification) the tunnel could handle 4 tph. This is more than enough for passenger train each way every hour.
We had a TBM and tunnellers in New Zealand to dig CRL in 2019-22. The sensible thing would have been to use this skill and equipement for the next generation of rail tunnels, e.g.
– Bombay Hills base tunnel (cutting off three sides of a square via Pukekohe)
– Second Kaimai tunnel (for higher capacity and to allow both bores to be electrified without disrupting services)
– Paekākāriki tunnels – replacement with long, double-track tunnel under the Pukerua saddle
– Straightening out wiggly bits of line (practically everywhere in New Zealand)
Instead all the tunnellers have left NZ and it’d be an expensive effort to get them all to come back to dig again.
A regular TBM is not that expensive, ($30-$50m) but are usually bespoke based on the type of ground they are chewing through,
You can get multiple condition ones, but they tend to be much more expensive, and in terns of the cost of a tunnel the main cost is not the machine, its the army of people running them and all the stuff like the 1000s of concrete curves they install as they progress..
Unless NZ can create a tunnel “pipeline” of continues work, its always going to be a case of being a series of one off jobs..
I have suggested it before but for sake of consistency I will post it again. Run the existing sets to Matamata with connecting buses to Tauranga and Rotorua.At least there is a platform there. And yes Kris I know Kiwirail don’t want to run the DF driving end first but there is an option to turn the train on the triangle at Waharoa. And you have talked about them using upgraded DL’s. I suppose Kiwirail could even find another excuse why they couldn’t do it. How about we can’t reverse at Matamata. We can’t run the locomotive around the train because the crossing sidings have been removed. My point is we need to start somewhere. The tunnel is difficult I get that hence the compromise. At least doing this picks up two destinations instead of one plus two smaller Waikato towns. Although the next move for Te Huia should be stations at Pokeno, Tuakau and Te Kauwhata. Doing it this way keeps the train part of the journey in the Waikato so no need to involve bay of Plenty too much although they could integrate the buses with there own bus networks.Use the existing slots in Auckland network means no involvement of AT other than what they grudgingly already give is needed.
Who wants to get a bus over the Kaimai Ranges? Part of the appeal of the rail tunnel is that it’s completely flat – a much nicer journey*.
Also, going by train eliminates the nead to use Tauranga’s road system, which is always a good thing.
*See also: Remutaka Tunnel
Royce – Once the CRL is operating, the DFB’s will not be allowed to operate on the Auckland metro rail corridor’s as they will not have ETCS 1 train control system fitted, hence the DL fleet is in the process of being fitted with ETCS 1 system’s allowing them to operated on the corridor’s after CRL is open.
Te Huia’s current two 4 or possibly 5 carriage DL hauled consists will be required to operate between Hamilton and The Strand hopefully from August 2026 with a new Te Huia’s new timetable and increased frequencies hopefully from June 2027 under the new funding cycle and the release of additional path slots from AT and AOR.
Any frequent inter-regional ‘tap & travel’ passenger train services between Auckland, Hamilton, Tauranga/Te Puke, Tokoroa and Te Kuiti will be battery/electric (25kva) train sets based on the final production specification’s of Wellington’s new ‘Tuhono’ Class battery/electric train sets, if DBFMO (design, build. finance, maintain and operate) PPP procurement is approved by late 2028 for delivery of the first train sets from 2035.
KR’s long term loco plans appear to be to dump a fair chunk of the DLs,
It looks like they currently have 5 DLs with ETCS retrofitted , but the ride results weren’t great …
Longer term KR said they intend to use 19 of the new DMs in Auckland as they will have ETCS factory fitted…
https://www.kiwirail.co.nz/media/kiwirail-partners-with-stadler-for-new-low-emissions-locomotives/
DL ride above 80km is abysmal. National brought junk that Kiwirail are currently trying to flog off overseas as they were so bad (10+ DLs laid up already).
“What needs to happen” is largely dependant on purpose, i.e. who will the passengers be? If its tourists and the elderly who may enjoy a slow scenic train ride, then organising and marketing repeats of the Glenbrook excursion train could be done at little cost.
Otherwise, it must compete with cars, buses and flying, where time and point to point convenience are important.
The point to point will in most cases be provided metro rail and bus connections, with limited transfers to higher speed intercity rail.
A typical base load of passengers is Auckland Airport, where it should stop to minimise luggage transfer.
Service should run Britomart & Aotea for PT connections & hotels etc, Auckland airport, Pukekohe, Huntly, Hamilton, Morrinsville, Tauranga.
Time means nothing less than tilt trains and minimum 160kmh, requiring grade separation, ETCS, triple/quad tracking metro networks to allow express passenger service, and seperate freight movements.
Staged construction will be needed where possible with this end goal in mind in order to keep costs palatable and I’d expect this to start with the Auckland metro network.
Intercity trains will never go to Te Wai Horotiu, Waitemata potentially but definitely not through the CRL.
Stadler FLIRT Akku has a battery range of 150km (with a 3-car formation having a world record of 224km in winter conditions – 0c). It has a stated recharge of 15mins (although it is unclear what that was – but I thought I read previously it was 0 to 80% just can’t find that anymore).
I think you could avoid electrification of the entire line by developing several charging islands as safe guards.
* electrification from Rotokauri to Te Rapa (2kms) plus electrification of the ECMT platform at Frankton… this would give a decent run under overhead wires to top up the battery before the run north to Pukekohe or east to TRG. (plus the dwell times at Rotokauri and Frankton).
* you could electrify Morrisnville station, again offering a few minutes top up while stopped.
* build a charging island of 5kms near Waharoa, to again top up the battery after the climb from TRG through the tunnel or while waiting for the tunnel to clear.
Whether something like the Stadler Class 93 (tri-mode) to haul freight could solve the emissions issue for the Kamai tunnel is unclear… but I’m sure in a few years there could be more feasible options. (spending billions on full electrification might become unnecessary in the next few years)
The main issue not raised here is that this line is single track, and freight to Port of Tauranga will always have priority. Will passengers tolerate sitting at a loop while freight trains pass? Will the freight and passenger timetables be reliable enough to allow a clean run in the required direction? I think this is a much bigger issue than the tunnel.
Not optimal, but not a deal breaker either. There is a freight train roughly every two hours between Hamilton and Tauranga, so a passenger train would generally cross one freight service.
As passenger services grow it will help build the case for double tracking sections and also giving trains with passengers priority over trains with generally non-time-sensitive containers or log wagons.
AMF – Under Kiwirail’s ‘Golden Triangle Electrification Programme’ it is planned to operate ETCS 2 train control management system from Pukekohe to Hamilton to Tauranga to allow increase train movements to/from Tauranga including the Port of Tauranga.
Break it up into stages, like the RoNS geniuses do.
Extend the current service out to include Hamilton Central, Morrinsville and Waharoa stations, the latter setting up the route south to Matamata and east to Tauranga. At the same time, sort out the plan for the Kaimai Tunnel. At some time during that process, start Te Puke to Tauranga from the other end (that would presumably be useful in its own right) given all the development between the two (Papamoa).
To do that though, you need the central government committment to a building programme over the next 10yrs. Doubt that will happen under this government, unless Bishop agrees to it under the bipartisan infrastructure plan with Labour, to ensure his own projects don’t get binned next time they are in opposition.
Ok Kris so we wait maybe I won’t see it. I wonder if the Te Huia sets will last the distance. Maybe the answer is just to extend the electrified tracks in sections to Hamilton and damm the artificial barriers the regional based public transport governence puts on us. Presumably we can buy more AM sets. You would have to hope they electrify 10 or 15 Kilometres a year. With all due respect to Greater Auckland my opinion is full electrification to Tauranga would have being a more worthy project than the CRL so there you go. I think there will be demand if a reasonable service can be provided. Have a look at the park n ride in Pukekohe It’s full with many more parked on local streets. It’s a pity but Kiwirail won’t compromise on only operating gold plated services so that’s that. Maybe things might be a bit clearer after the election. I haven’t heard anything from any party yet
Royce, the cars all come from Pokeno/Mercer, you and I both know that.
Stations at those two places would drastically increase Te Huia ridership.
Is this April Fool’s Day?
Do we know how they managed to get from papakura to Auckland Central in 35 minutes and now the trip to Waitemata takes 53? Were there just no local commuter trains back then between 11 and 12 so that the long distance rail could speed through all the stations?