From BIKE PORTLAND some of the most relevant parts:
Smart bureaucrats will always be sure to over-budget construction projects so when they come in under budget the can 'look good'
Four years after the Portland area’s transit agency furiously chopped costs and recruited other local governments to balance the budget for its new $1.5 billion rail line, the price tag so far is tuning out to be more like $1.3 billion.
Though a few remaining bills have yet to be paid, the combination of persistently low interest rates and far more cost-efficient track and systems construction than expected has been so large that TriMet has been searching for new ways to spend some of the unexpected surplus locally.
According to a December 2014 construction report, downward revisions of $64 million from “guideway and track elements,” $42 million from “systems,” $33 million from finance charges and $70 million in unallocated contingency had left the agency with exactly $199,955,869 in “uncommitted” dollars from its $1.5 billion budget.