A 50% overrun would be a bargain. This train will cost at least 3 times the estimates. The whole states economics are to be hijacked for the sake of union pensions and that is the whole story in one sentence.
The purpose of ANY public works project is to put money in motion so that it can be stolen. If money sits in a stack, and tomorrow the stack is thinner than it is today, then it is easy to determine that some of it has been pilfered.
Put that money in motion, start passing it from account to account, person to person, agency to company, and there are unlimited opportunities for it to be stolen through bribes, bill padding, extortion, campaign contributions, community groups, etc.
If at the end of the process something useful accidentally gets built and the public benefits, just know that that that was completely incidental.