CBD Link May Cost $2.3b


The CBD Rail Link business case cost estimate ranges from $1.99bn to $2.38bn.

The cost of the loop includes property acquisition  costs of about $230m.

At today’s prices in millions estimates include: Construction link and three stations:  $1,861m, Property acquisition: 230m, More rolling stock (24x3car EMUs)  240m, Rail network 100m.

The project is comfortably over a BCR of 1. Lower discount rates are modelled as the NZTA presently models its roads of national significance.

At 8% discount rate 3.5, 6% 4.7 and 4% 6.6.

The proposed CBD Rail Link is an approximately 3.5 km double track underground rail line running beneath the central business district from Britomart to the Western (North Auckland Line) near the existing Mount Eden Station. Britomart will become “through” station and will be modified to suit this new purpose.

Up to three intermediate underground stations are proposed:
  • Aotea (under Albert St between Wellesley and Victoria Sts)
  • Karangahape Rd (under the intersection of Pitt St and Karangahape Rd)
  • Newton (under Symonds St between the intersections with Khyber Pass/ Newton Rd and Mt Eden and New North Roads)
Eastern and western junctions with the North Auckland Line at Mt Eden are proposed. These will provide both operational flexibility and permit a variety of service patterns to be operated.
The CBD Rail Link will result in significant reductions in public transport journey times to the CBD from across the current rail network.
In particular, rail services from the west of Auckland will have a more direct route to the CBD, by eliminating the need to travel via Newmarket as at present.
The topography of central Auckland, together with the operational constraints for rail vehicles, results in the CBD Rail Link having steep gradients and deep underground stations over most of its route. There is an approximate 76 metre difference in elevation between Britomart and the Western line at Mt Eden; in addition, the tunnels have to pass at sufficient depth beneath the Central Motorway Junction to avoid impacting motorway operations.
Twin tunnels, each having an outside diameter of approximately 7 metres, will be provided, and connected by cross passages at a minimum spacing of 240 metres, for evacuation purposes. The tunnels will be constructed by a combination of Tunnel Boring Machines and Cut and Cover construction methods.
The three stations have provision for underground island platforms (maximum 170 metres long or equivalent to a 7 car long train), connected to subsurface concourses via escalators and lifts. The station depths vary between 18 metres below the surface at Aotea and 43 metres below ground at Newton.

Route Selection

The concept of an underground railway through the Auckland CBD has been proposed and studied on several occasions since before the First World War; however, none of these schemes has progressed beyond planning stages. Since Britomart was opened in 2003, a number of studies have been undertaken by the Auckland City Council and subsequently ARTA on the feasibility of connecting Britomart to the Western Line at Mt Eden.

These studies formed the basis for a comprehensive assessment of alternative routes and station locations undertaken during Phase 1 of the CBD Rail Link Study in late 2009, as required under the Resource Management Act for Notice of Requirement Applications.

Eleven technically feasible routes and eleven station locations were developed and subsequently assessed using a two stage multi-criteria assessment process. The criteria were developed from KiwiRail and ARTA‟s objectives for the project and were designed to identify the number and optimal location of stations along the route, taking into account factors such as proximity to surface activities, other transport services, environmental impacts and technical feasibility.


In summary, the CBD Rail Link will:

  • Provide greatly improved penetration of the CBD by rail, with most locations being within 500m of a station
  • Reduce overall journey times for rail trips starting or finishing in the central and southern parts of the CBD
  • Provide a catalyst for land use intensification and regeneration of areas surrounding the new stations in both the CBD and Newton areas, plus facilitating the development of Transit Oriented Developments (TODs) around suburban stations such as Panmure and New Lynn.
  • Enable rationalisation in the number of bus services running into the CBD, by reconfiguring services in areas served by rail (for example New North Rd), to form feeder services to connect with rail services. This will free up CBD road lanes to provide more capacity for bus services from parts of the isthmus and North Shore, not served by rail.

Operational details:

The CBD Rail Link will be suitable for use only by electrically powered passenger trains, due to its steep gradients and long tunnel sections. Freight trains will not use the CBD Rail Link.

KiwiRail has advised that the fire rating of the existing SA/SD carriage trains is not compatible with extended operation in tunnels. Therefore, the assumption used in the CBD Rail Link study is that all services will be operated using Electric Multiple Units (EMUs), either those currently being procured by KiwiRail or those bought in subsequent batches. It is understood that KiwiRail‟s current technical specification for the Auckland EMU‟s requires that these trains must be compatible with the CBD Rail Link. The current maximum train length for the Auckland rail network is 6 carriages (approximately 144 metres long), which is reflected in the concept design for the CBD Rail Link stations.

Although the final number of EMUs to be purchased in the current KiwiRail procurement process has not yet been finalised, KiwiRail and ARTA‟s assumption for the purpose of this Business Case is that, prior to the opening of the CBD Rail Link, all electric train services on the Auckland network will be operated by EMUs.

Operational simulations of the CBD Rail Link by KiwiRail indicate that the theoretical capacity of the rail link between Britomart and Mt Eden, is between 15 and 30 trains per hour in each direction, depending on the configuration of the signalling system.


Watch Len Brown’s news conference

What’s in the business case

Cost and what’s involved
Len Brown -I want it in 7 years
Chinese interest in CBD loop

Loop funding row

Read the full case




  1. joust says:

    more trains as well - the effect on the CBD will be huge! 500m to a station. Fantastic.

  2. greenwelly says:

    The three stations have provision for underground island platforms (maximum 170 metres long or equivalent to a 7 car long train),

    Given that Auckland’s EMU are looking to be 3 car sets of 24m units, the options for platforms are really only 6 car or a 9 car set (2 or 3 sets) @ 140 or 210 metres, buggering around saying they allow a 170m platforms for a 7 car train just seems daft!

  3. Nick R says:

    Greenwelly, 170m is the length of the platforms at Britomart. I guess they are stuck to matching that.

    They are either allowing a bit of leeway for six car consists, or they are leaving open the possibility of seven car consists using 4 car EMUs in the future (i.e 3 car + 4 car).

  4. Matt L says:

    The longer the EMU the less space there is to position it on the platform so trains have to approach slower, you can see this now with the difference in braking between the 4 and 6 car SA sets so having a 170m long platform gives the drivers a little leeway

  5. Ian says:

    What kind of material will they be boring through in the CBD? Would there be much in the way of rock?

  6. Matt L says:

    From memory reading an earlier report it varies quite a bit. Down by the water is reclaimed land, most of the route is sedimentary rock so quite good for tunneling and up by Mt Eden is hard volcanic rock which will be quite difficult.


Leave a Comment


XHTML: You can use these tags:
<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>