The boss of Auckland's City Rail Link is giving no guarantees it will hit its opening deadline of 2026.
Preliminary work on the 3.4km track, spanning four underground stations, from downtown's Britomart to Mt Eden, began in 2016.
But CRL chief executive Sean Sweeney says reaching that deadline of 2026 - 10 years later - is not guaranteed.
The latest cost projection of the build is $5.49 billion - and once it is up and running, it's is set to cost Auckland ratepayers an estimated $220 million a year to maintain.
It will serve as connecting link between existing rail services , making most of the central city accessible by train.
An engineer, Sean Sweeney has spent four decades working across the world overseeing such big construction jobs.
But as he tells Kathryn Ryan, he believes Auckland is the most expensive place in the world for infrastructure projects.