Guest Post: If we’re going to tunnel light rail, do it right!

Guest Post by Matthew Beardsworth – North Shore urbanist, transit user, & disabled advocate

On Friday 28 January 2022, the New Zealand Government selected tunnelled light rail option for the City Centre to Mangere mass transit corridor. To quote Douglas Adams, “this has made a lot of people very angry and (at least within the transit advocacy community) been widely regarded as a bad move.”

(The official route proposal by the Auckland Light Rail Group.

To sum up the issue briefly: the government has chosen the most indirect route to Mangere; one which runs through less homogenous rock types1 and a swampy flood plain2; one which does little to resolve the bus crowding & congestion issues in the inner city; one which will apparently cost the better part of $15 billion if not more and yet still incorporates street-running surface light rail in Mangere – something that will hinder or complicate future capacity growth and upgrades.

This decision reeks of flawed economic modelling instead of actual transit planning, and of a government pandering to affluent isthmus NIMBYs who kick up a fuss at the mere suggestion of giving up any lanes for a higher-capacity transit mode. It’s a far cry from the ~$2-3 billion surface light rail CC2M line originally proposed by AT in 2016, and I for one do not believe the new plan will deliver optimal transit outcomes for Tamaki Makaurau.

Others have covered a return to the original surface light rail proposal – Greater Auckland3 and Women in Urbanism Aotearoa4 make strong cases on the grounds of cost, accessibility, and quicker carbon reductions. Brendon Harre and others point out that $15 billion could easily go towards extensive surface light rail networks in Aotearoa’s 3 biggest cities; Auckland, Wellington, and Christchurch – instead of just a single line in Auckland.

Arguably surface light rail would benefit far more people and be quicker to deliver; the only compromises being with speed, some capacity, and private vehicle space allocation – the latter isn’t actually a bad thing when you consider the need to drastically reduce transport emissions within the next 10 years. 

What was originally proposed; surface light rail down Dominion Rd.

But what if there is a case for building a grade-separate, higher-capacity line now? Even a maxed-out surface light rail system is outstripped capacity-wise by metro rail, and it’s not far-fetched that Auckland will need that greater capacity at some point in the future. The Auckland Light Rail Group and the Transport Minister Michael Wood have made the arguments that an underground light rail option is better future-proofed for expansion into a whole new RTN network – let’s assume that holds up. Is it worth $15 billion dollars? I still don’t think so.

If the government is dead-set on underground mass transit, and as they say maximising capacity and future extension potential – then Auckland Light Rail needs to be both more ambitious and less expensive. Contrary statements? Maybe not.

First up – the tunnelled light rail option. It’s suboptimal, no doubt about it. Tunnelled light rail is essentially putting trams underground – and not even entirely underground at that. The surface running section proposed between Onehunga and Mangere Town Centre will limit light rail consist lengths, service frequencies, and therefore capacities; not to mention longer journey times. Even international transit advocates5 have weighed in on the matter. There are few if any cities overseas that drive light rail underground for such significant lengths.

If tunnelling is a given, then the line should be tunnelled (or fully grade-separated, somehow) all the way from city centre to Mangere. Complete grade separation opens the door to larger, longer, driverless trains running more often and at higher speeds – light metro. Light metro systems can already be found in Vancouver, Copenhagen, London, Kuala Lumpur, Taipei;  and soon in Montreal & Honolulu – amongst other cities.

The Vancouver SkyTrain (photo credit)

The Government and Auckland Light Rail group do appear to be aware of light metro, at least. The ALR Indicative Business Case found light metro would be only 10-15% more expensive than tunnelled light rail while offering nearly twice the maximum capacity; suspiciously though the detailed assessments dramatically reduced light metro’s capacity compared to what’s actually possible, apparently stacking the business case in favour of tunnelled light rail.

From ALR Indicative Business Case Table 7, Page 83

Speaking of expense – the escalation of costings for Auckland’s light rail project (an eightfold increase since the initial 2016-2017 proposal) is bizarre and concerning – completely out of line with international standards. The tunnelled light rail proposal is costed at $14.6 billion for 24km of route – that’s $608 million per km ($430 million per km in today’s money without forecast inflation). By comparison, light metros in Vancouver & Copenhagen (fully tunnelled or elevated) have variously costed between $150 million NZD and $300 million NZD per km.

NetworkLengthTotal CostCost per km (NZD)
Montreal REM67km$6.9 billion Canadian $8.14 billion NZD (2021)$121 million per km
Vancouver Skytrain Canada Line19.2km$2.54 billion Canadian $3.00 billion NZD (2021)$156 million per km
Taipei Metro Circular Line15.4km$3 billion NZD approx..$195 million per km
Macau Light Rapid Transit9.3km$1.71 billion USD $2.58 billion NZD$277 million per km
Copenhagen Metro M315.5kmKr24.0 billion $5.53 billion NZD$369 million per km
International average cost for underground rail/metro ($300 million USD per km  $450 million NZD
ALR costing (2021)24km$12.8-15 billion NZD$533-$625 million per km

Figures sourced from Wikipedia

Based on those figures, I would expect a fully tunnelled light metro here to cost in the range of $5-7.5 billion – half or even a third of the official costing. Costs could perhaps be further reduced by allowing for more surface or elevated right-of-way, particularly across the more level terrain through Mangere – elevated rail has less visual impact than elevated motorways, and I could see potential for an elevated route skirting Moyle Park & David Lange Park, well linked into green space. 6

The Copenhagen Metro on an elevated section through the Grønnigen Hundegard. A future vista for Mangere Town Centre?

Onto routing – the official selected route is via Sandringham Rd. As mentioned before this is the longest, most indirect route to Mangere, and it appears to have been chosen in an attempt to achieve too many goals in one project. It also runs through a variety of varied rock types 1 and the floodplain of the streams that once fed Cabbage Tree Swamp (now the Eden Park stadium). 2

Manukau Rd offers a routing 5km shorter from City to Mangere; through more homogenous rock types that would be easier to cut-&-cover or bore through at a shallower depth. It has a wider road corridor, so elevated metro may be more feasible here – further decreasing costs compared with tunnelling. If cost is a primary concern, perhaps Aucklanders should reconsider their stance on elevated metro; the process of transit-oriented intensification could very well create a wider street corridor.

Example of Vancouver Skytrain elevated along a 25m wide arterial route. In the case of Manukau Rd fewer lanes would be desirable – accordingly the pedestrian sidewalk could be widened in place of the street parking & perhaps leftmost lane in this streetview. (GoogleMaps)

Manukau Rd serves major nodes and densely-zoned isthmus areas such as Auckland City Hospital, Newmarket, Epsom, and Royal Oak; these existing centres have ample potential for further high-density transit-oriented development around light metro A Manukau Rd-routed CC2M would connect schools and universities, hospitals, parks, residential, and employment areas – catering to all sorts of trips, exactly what transit needs to do to replace car trips.

But Matthew, I hear you say, a Manukau Rd route doesn’t solve the bus issues or serve Mt Roskill! That’s admittedly true. But why does everything have to be done in a single, compromised project?

If we’re going to have this sort of broad vision, if we’re assuming that the Government is willing to spend $15 billion on mass transit in Auckland – why not build both grade-separate light metro for Mangere and surface light rail for the western Isthmus? There are two distinct purposes here – mass rapid transit to the Southwest and high-capacity inner city coverage. A higher-speed, fewer-stops transit mode is not going to serve a dense inner city as adequately; this has long been one of the primary criticisms of light metro proposals in Auckland.

Separating CC2M from the need to improve transit to Mt Roskill and Wesley allows each project to be optimised to suit its individual needs – higher speeds to Mangere, closer-spaced stops and more coverage for the western Isthmus.

What $15 billion spent just on the Auckland Isthmus could/should be able to achieve. Light Metro to Mangere, the Northwest, & North Shore; modern trams on Sandringham Rd AND Dominion Rd; and a crosstown mass transit line chucked in for good measure. My own work.

The potential savings of the shorter Manukau Rd routing over the Sandringham Rd routing could even be enough to cover 16km of street-median modern tram line, costing $<1 billion if we assume $30-$60 million per km costing as were achieved in Tampere, Finland and Canberra, Australia – coincidentally, enough to cover light rail from the Waterfront along both Sandringham Rd and Dominion Rd. Two major bus routes into the city could be entirely replaced, freeing up capacity along Symonds St and Wellesley St to allow other bus routes (e.g. New North Rd, Mt Eden Rd) to run more frequently and more reliably; benefitting people along those arterial routes too.

The Odense Letbane, in Denmark. 15km of light rail for $750 million NZD. (

And how about the urban growth potential – light rail along Dominion & Sandringham would offer triple the capacity of the present bus routes, and kickstart intensification along continuous corridors from Wesley & Mt Roskill into the city. 6+ storeys along 10km of combined route – tens of thousands of new affordable car-free dwellings. Compare that with what ALR are proposing: no more than 3 stations between Kingsland & Mt Roskill, only serving existing densely-zoned residential nodes.

Building both light rail and light metro would tie into a grander, broader vision for Auckland’s rapid transit network – and reducing the costs should allow for more to be done with $15 billion. Even conservatively after building Manukau Rd light metro & Sandringham + Dominion light rail there could be $5 billion free for another mass transit project; optimistically up to $10 billion. We could accelerate the Airport-Botany mass transit, bring forward light metro to Huapai, build a crosstown light rail line utilising the Avondale-Southdown designation; make an earlier start on AWHC and light metro to the North Shore – even accelerate projects as “mundane” as bus lanes, cycleways, and high-frequency buses all across Auckland.

That’s something many could agree on I think – that there are better ways to spend $15 billion on transport in Tāmaki Makaurau, in Aotearoa, than on a single project in one city.

It is at least somewhat heartening that the government is keeping rapid transit to the North Shore & Northwest in mind, recognising at least some of the need for long-term transit planning – but I think the vision needs to be broader than the 3 radial corridors into the city centre. It needs to encompass future-proofing light metro for even more potential lines, for upgrading busways and light rail to metro when demand outstrips those modes capacity. Underground CC2M should include provisions for junctions – at Victoria Park for a Northwest line under Ponsonby, at Grafton Gully for a potential Northern line under Devonport and Takapuna, at Newmarket for an Eastern Line, at Onehunga for a crosstown line. I’m sure the list could be even larger, with more out-of-the-box thinking regarding routing & development patterns.

Possible alignment variations for light metro underneath Central Auckland – the dashed line routes should be future-proofed for. (My own work)

Call it Option Ultimate, if you will. A new Congestion Free Network, futureproofed for the end of the century. Futureproofing demands flexibility; the ability to adapt plans based on how Auckland grows and develops. Flexibility can be spun off short term staging, keeping costs even lower by building lines in manageable, quicker-to-deliver chunks. Because while we mustn’t forget the long-term goals, we also mustn’t forget that it is vital to enable a large-scale mode shift away from private vehicles and reduce transport emissions fast.

“Option Ultimate” – a late-century metro system spanning Tāmaki Makaurau, with modern trams replacing buses on the Isthmus arterials. The Eastern Busway, Airport-Botany, Upper Harbour BRT, and other corridors would be converted to metro as patronage demanded it. (My own work).

In summary – if the primary concern is cost then I believe the government should return to surface light rail, and spread the mass transit budget over more of Auckland (and Wellington, Christchurch too). If the primary concern is future-proofing, however, then I believe the government should skip tunnelled light rail and go straight to light metro, without ruling out modern trams for the Isthmus arterial corridors.

Imagine, in a decade or two’s time, automated metros every couple of minutes 24/7 at all stations; fast and frequent. Imagine sitting at the front of the carriage and looking out the front windows, at kaleidoscopic wormhole-like light displays in tunnels, or at the iconic Auckland skyline and maunga going by from elevated viaducts. Imagine modern trams, too, spanning the Isthmus, gliding on grass-bordered green tracks through lush tree-lined streets and between tall, lively mixed-use towers.

Manukau Rd with elevated light metro between mid-rise development & above green planted boulevards? (My own work)

Make the right infrastructure choices today, and that can be a reality.

If we’re going to tunnel light rail – do it right. Commit to light metro, and see if we can’t have some surface light rail on the side as well.






5 (RMTransit)


2 thoughts on “Guest Post: If we’re going to tunnel light rail, do it right!

    1. Thanks John!

      It’s almost enough to drive an urbanist to conspiracy, isn’t it. A proposal that doesn’t reduce car volumes on the surface, limits intensification & station locations to existing dense zones and development sites, has the most indirect route to Mangere and is incredibly expensive yet still uses low-floor trams and street-running sections… it seems to hint at either incompetence or an agenda.

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