Here's why rail is going to cost $12 to $13 billion:
From Honolulu Traffic, March 22, 2017
The Mayor has told us that will take a total of $6.8 billion just to get to Middle Street and $9.5 to get to Ala Moana Center. The difference of $2.7 billion we are told will build the last five miles of the 20-mile line. The cost of the maintenance depot in the first 15 miles is roughly offset by the cost of the more stations per mile iin the last five miles. That works out to be 28.4 percent of the money to build the last 25 percent of the line.
Bear in mind that this section is along crowded Dillingham Boulevard with major electrical utility problems, then Nimitz Highway, which is mostly fill land where each supporting pillar has to be itself supported by 3 to 5 others, and along Halekauwila Street, which is Ground Zero for 'iwi, the native Hawaiian burial sites.
You may also remember that this project started with a rock solid $5.3 billion projection cost. That has already been increased to $9.5 billion and we have not even got to the halfway point. You may also remember that we never predicted that the City would experience any cost overruns before they reached Dillingham Boulevard, the start of the Rail Quagmire, because doing the easy stuff first was why they were starting to build rail out in open fields.
You do not have to be a construction engineer to know that this last section is going to be far more costly than building in the empty fields at Ho'opili. So when Dr. Prevedouros tells us that we should be prepared for total construction costs of $12-$13 billion, you had better believe him.