For anyone out there thinking “why not extend existing heavy rail to the airport?” in Auckland:

Winston Peter’s suggestion that a heavy rail spur from Puhinui would be less expensive and/or better for rail users is.... not correct.

Firstly: one of the key benefits of a new line through the isthmus and Mangere is that it will add significant overall rail capacity to the city.

Not long after CRL opens, the existing heavy rail network (especially the southern line) will basically already be at capacity.

Auckland public transport has been growing rapidly (notwithstanding Covid) and as we increase frequency and reliability, it will grow even faster. We will need more capacity in the medium term.

Secondly: branching reduces frequency. A spur off Puhinui could not support frequent services to the airport, and would REDUCE the frequency of services run on the Southern Line.

Thirdly: the heavy rail spur would be outrageously more expensive than the frequent bus connection we are putting in from the airport to Puhinui, as well as being less frequent!

So what WP and NZFirst are claiming is a sensible solution for airport mass transit would mean:

Less rail capacity across the city
Reduced frequency of trains
More expensive for worse service