SAN FRANCISCO -- SAN FRANCISCO -- A financial blueprint for linking the San Joaquin Valley to Los Angeles by high-speed trains within 10 years was approved Thursday by the California High-Speed Rail Authority.

The authority's latest business plan, which calls for the eventual construction of a system that connects San Francisco and Los Angeles by way of the Valley, now heads for the Legislature, which must decide whether it will approve using billions in state bond funds for the initial construction between Madera and Bakersfield.

Thursday's board meeting here also marked the possible emergence of a new voice in the contentious high-speed rail debate: young professionals who say the high-speed train represents a transportation choice for their future and urged the authority to approve the plan.

The business plan calls for extending the first construction segments northward to Merced, where the system would link with upgraded and improved Amtrak service to Sacramento and the Bay Area, and southward toward Los Angeles. The southern extensions would head southeast from Bakersfield across the Tehachapi Mountains to Palmdale before turning southwest into the San Fernando Valley.

Until high-speed trains begin running in 2022 from Merced to Burbank, Amtrak trains would be able to run on the dedicated high-speed tracks through Merced, Madera, Fresno, Kings, Tulare and Kern counties. That would free up freight railroad tracks -- now shared with Amtrak -- to handle more cargo without conflicting with passenger trains, authority Chairman Dan Richard said.

In November, an earlier version of the business plan estimated that it would cost more than $98 billion to build a 520-mile line of dedicated, electrified tracks that would be used only by high-speed trains from downtown San Francisco to downtown Los Angeles and on to Anaheim. The plan approved Thursday lops about $30 billion off that price tag. At $68.4 billion, the new version realizes most of its savings by calling for a "blended system" in which high-speed trains would share tracks or right-of-way now used by commuter trains in the Bay Area and Los Angeles Basin.

Another fundamental change is the identification of state "cap and trade" money from the sale of air-pollution credits to industries as a source of money to continue building the project. That provision is intended to answer concerns about how the authority would pay to build beyond the Valley.

The Obama administration has pledged $3.3 billion toward construction starting in the Valley, and the business plan anticipates $20 billion or more in additional federal funding over the next decade. Republicans in Congress, however, have blocked future money for high-speed rail.

Ridership has been a third major concern of critics who fear that too few people will buy tickets for the system to pay its own way, requiring subsidies at the expense of taxpayers.

Kurt Ramey of the accounting firm KPMG, consulting for the rail authority, said that even at the lowest projected ridership levels, the system should generate an operating profit even in its first year.

"The break-even point for revenue is well below the low estimates," Ramey said. With the low ridership and revenue estimates being based on factors that are unfavorable to train travel -- including gasoline prices of $2.60 a gallon in 2022 and airfares that remain at current rates -- the proposed system "just looks like it's got some room in operating performance to it."

Richard, the authority's chairman, said he hopes the plan addresses concerns expressed by legislators over the past five months as they prepare to debate Gov. Jerry Brown's request for $2.7 billion from Proposition 1A in the 2012-13 state budget to begin construction next year. Prop. 1A, approved by California voters in 2008, authorized $9 billion in bonds to help build high-speed rail in the state.