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California High Speed Rail Authority

An artist's conception of the bullet train speeding under the Tehachapi Pass.

The anticipated cost to build a high-speed rail line between San Francisco and Los Angeles by 2028 is predicted to drop slightly -- to a grand total of about $67.6 billion, according to a draft business plan released Friday by the California High-Speed Rail Authority.

The revised cost estimate is down by less than 1 percent from the $68.4 billion forecast in the agency's previous business plan, which dates to April 2012. The draft 2014 business plan will be formally presented to the rail authority's board at its meeting Tuesday in Sacramento, and will be subject to public comment -- and, no doubt, criticism -- for a couple of months before a final version is prepared before May 1.

Despite the meager dip in capital costs, the price remains considerably higher than the $33 billion that was touted when Proposition 1A, a $9.9 billion high-speed rail bond measure, was approved by California voters in 2008.

Cost estimates, always a subject of close scrutiny, have been something of a roller coaster ride for the authority and its critics in recent years.

The 2008 version of the business plan predicted that it would cost about $33 billion, in 2008 dollars, to build the 520-mile Phase 1 system from San Francisco to Los Angeles/Anaheim using fully dedicated tracks.

By 2009, in a report to the state Legislature, the authority revised its cost forecast to $34.9 billion in 2008 dollars, or $42.6 million to adjust for inflation for when money was to be spent.

A draft of the 2012 business plan, released in November 2011, nearly caused whiplash for many observers when it predicted construction costs of $65.4 million in 2010 dollars -- or an eye-popping $98.1 billion when adjusted for inflation through 2033.

The most recent business plan, an April 2012 revision of the November draft, scaled down both the plan and the cost. Instead of dedicated tracks for the entire system, the new plan called for sharing existing tracks with the Caltrain commuter rail line in the San Francisco Bay Area and with the Los Angeles region's Metro system. The price tag shrank to $68.4 billion in inflation-adjusted costs, or $53.4 million in 2011 dollars.