C'mon Civil Beat we've been over this several times already. Rail WAS NEVER PROJECTED TO COST $5.2 BILLION! This is not attributable to inflation. Here are the facts - how quickly we forget how much costs have spiraled out of control. 
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2004: Newly elected mayor Hannemann asserts that 34 miles of rail will cost $2.7 Billion. Mid-2006: Hannemann switches to the Minimum Operating Segment: 20 miles will cost about $3 B. Late-2006: Alternatives Analysis sets the cost at $4.6 B (this figure and all figures below include FTA-mandated contingency funds).
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And on we've gone since then.