BusinessDesk investigations editor Victoria Young has been investigating how frequently major infrastructure projects go over budget.
An investigative team looked into the first and final costings of 55 major projects.
Of those, 39 came in over budget, 12 were on budget, and just four came in under budget.
The average blowout was $58 million, and with an average initial estimate of $235 million, that equated to a 25% total blowout across the 55 projects.