Have you ever had a hard look at the state of the rail lines north of Auckland, go to Helensville, Maungaturoto or anywhere , that rail line was not meant to carry heavy container traffic.
Last year the PoA handled 900,000 + containers landed as well as exporting the same number, Marsden Port simply cannot handle that amount of heavy volume, END OF STORY !@!
So NZTA /NZRail in order for containers to fit through the tunnels ( as they didnt fit ) LOWERED the tracks leading into,inside and outside the tunnels !! another great piece of N Z engineering practice, so much for this countries world leading infrustructural engineering ideas, would only happen in NZ and we wonder why the roads, rail, bridges etc get washed away in a storm !!