SACRAMENTO, Calif.—The new business plan for California's high-speed rail system shows the nation's most ambitious state rail project could cost nearly $100 billion in inflation-adjusted funding over a 20-year construction period, far above the amount originally projected.

The plan, which was shared late Monday with The Associated Press, also shows the system would be profitable even at the lowest ridership estimates and would not require public subsidies to operate.

The report estimates the actual cost at $98.5 billion if the route between San Francisco and Anaheim is completed in 2033. It assumes private investment will account for roughly 20 percent of the final cost.

The initial estimate to build the system when voters approved bond funding for it in 2008 was $43 billion in non-adjusted dollars.