A contentious KiwiRail report makes the case for a new rail line in Auckland, claiming it would take at least 400 heavy vehicles off the road each week.
KiwiRail has now released the business case in full for a third line between Wiri and Westfield, allowing passenger and freight trains to run on separate tracks.
It also recommends preparing to build a fourth track.
The Ombudsman yesterday criticised the state-owned enterprise for earlier rushing out a redacted version of the report.
The office of Transport Minister Simon Bridges had argued against it being released at all, saying some of it was materially wrong.
The report argues that for about $65 million, KiwiRail would eliminate about 250 hours of delays to freight trains every year.
It would also cut an average three minutes off the travel time for five million rail passengers annually.