Plans for an underground rail loop from Britomart southward underneath the CBD to Mt Eden have been mooted for the best part of a century.
The CBD rail loop has been variously spruiked as a transformational economic development project at the centre of the new Super City (John Banks) and
a key element in a rapid transit plan (Len Brown).
Right now a considerable amount of work is being done on the concept designs and business case for an underground loop on the preferred route identified by consultants acting on behalf of ARTA (about to morph into Auckland Transport) and KiwiRail.
The tunnel would run between Mt Eden and Britomart, taking in Khyber Pass road, Symonds St and K Rd, with the opportunity for three train station locations at Symonds St/Khyber Pass Rd; K Rd/Pitt St and on Albert St between Victoria and Wellesley Sts.
KiwiRail chief executive Jim Quinn says the project will be "quite a phenomenal bit of work".
The height difference between Britomart and Mt Eden is approximately 70m.
"I pick it will be done eventually and at the right time," says Quinn. "It is an enabler for Auckland, but it will come down to affordability."
Other plans will have to come into play if the project is overly delayed to ensure that Britmart doesn't "choke".
"I expect the business case as it works through will do the counter-factual as well. No one is going to want the network to choke."
Under the preferred option, three stations will be located under public roads, optimising redevelopment and growth opportunities for economic productivity and patronage; the lowest number of curves which means lower costs for the tunnel boring machine, and better operational speed for trains thus reducing operational costs.
ARTA says an estimated 44,500 people work within 500m of the proposed Aotea Station site, while the K Rd and Symonds St sites both have approximately 7000 people working within a 500m radius.
KiwiRail and ARTA have commissioned the APB&B group of consultants, comprising AECOM, Parsons Brinckerhoff, Beca and Hassell The approximately 3km twin tracked tunnel will be up to 40m underground and is expected to take seven to 10 years to design and build.
Currently almost 58,000 people travel into Auckland's CBD for work and education every week day morning at peak, with almost 33,000 of them using public transport.
The Project Auckland series looks at the challenges facing Auckland as it seeks to become a world-class city.