Key Points:

Government agency Ontrack is being warned against rushing into a costly route protection study for a $1 billion to $1.5 billion inner Auckland rail tunnel ahead of a strategic assessment of regional passenger needs.

Auckland Regional Council member Joel Cayford says tender documentation for the $5 million study, for which bids close next month, points too strongly to a tunnel beneath Albert St to Mt Eden without due regard to large population bases such as the university and hospital quarters.

The former chairman of Auckland's two regional transport committees agrees with Ontrack that the priority must be an underground station near Aotea Square - with a greater potential passenger turnover than Britomart.

But instead of starting with a link from Britomart to a proposed Aotea station, which Ontrack expects will be 18m below Albert St, he says consideration should be given to tunnelling to the square from Parnell, via the Domain. That would give the benefit of two terminal stations initially, overcoming capacity problems at Britomart while letting links be added later through Aotea Square to destinations like North Shore and Mt Eden.

Dr Cayford, whose thinking evolved from a paper he prepared in October for a postgraduate degree, is concerned Ontrack is wedded to a route proposed in 1923 by Railways Minister Gordon Coates.

Ontrack's documentation for a contract to prepare for a notice of requirement over a preferred route early next year says an alignment from Britomart to the proposed Aotea Station has been "generally determined".

Although no date has been set for construction, Ontrack expects it to be before 2020, given that Britomart will reach its capacity by then.

But Dr Cayford said the documentation appeared to leave little room for any alternative, being more concerned about addressing the geotechnical challenges of a Britomart-Mt Eden route.

It was disturbing that the Auckland Regional Policy Statement, which embodies a legal requirement to tie together transport and land use planning, was not mentioned in the tender documentation.

Although the project will be managed by the Auckland Regional Transport Authority as well as Ontrack, he was concerned at the absence of the city and regional councils from key oversight roles.

He was also disappointed that the documentation says only that a region-wide network planning assessment to be undertaken by Ontrack and the transport authority as a separate exercise "may" need to be taken into consideration by the successful consultancy.

An Ontrack spokeswoman said it accepted the importance of considering alternative routes before a designation was sought.

"We are working closely with ARTA and Auckland City, as the territorial authority on this matter."