The first two stretches of California's proposed high-speed train system in the San Joaquin Valley would close dozens of roads, displace hundreds of homes and businesses, affect thousands of acres of farmland, and cost billions more to build than originally anticipated.

But environmental impact reports released Tuesday for the Merced-to-Fresno and Fresno-to-Bakersfield segments say the statewide project would save more than $100 billion in new and expanded freeways and airport construction over the next 25 years, reduce automobile traffic and help improve air quality in the Valley and the state.

The California High-Speed Rail Authority's long-awaited release of the reports, about six months behind schedule, kicks off a public-comment period that runs through Sept. 28.

Over the next month and a half, the authority and its consultants will hold workshops and public hearings where local officials, residents and business owners can learn more about the project or voice their complaints or concerns.

The comments will steer the authority toward the selection of a final route from among several options in a final version of the reports, expected in early 2012.

California High-Speed Rail Authority CEO Roelof van Ark said the reports provide the most detail so far about route options, their effects on nearby communities -- and how much the project will cost.

"The information contained in these reports will ensure we can successfully go to bid for the initial construction segment next year," van Ark said Tuesday.

The two reports, amounting to more than 10,000 pages, assess how various route options will affect communities, businesses, farms and historic and wildlife resources along the 190-mile stretch from a proposed station in downtown Merced, through downtown Fresno, to a station in downtown Bakersfield.

They also spell out the measures the authority needs to take to make up for those effects.

Route options

Between Merced and Fresno, two main route options remain in consideration: one along the Union Pacific Railroad tracks near Highway 99 through Merced, Chowchilla and Madera; and one along the Burlington Northern Santa Fe tracks a few miles east of the cities and the freeway. A third option is a combination of the Union Pacific and Burlington Northern routes. The route lengths vary from 74 to 95 miles between downtown Merced and downtown Fresno.

Among the Merced-to-Fresno highlights:

- Engineers say building the line is expected to cost $3.8 billion to $6.9 billion between Merced and Fresno, depending on which route is chosen. This is the first time the authority has produced a breakdown of costs by segment.

- Between 291 and 343 homes would be displaced, forcing the relocation of 900 to 1,100 residents.

- Anywhere from 228 to 323 businesses would be relocated, affecting 6,500 to 8,200 employees.

-Between 1,037 and 1,481 acres of "important farmland" would be lost to the rail alignment. Important farmland is land designated either as prime, of statewide or local importance, or unique.

From downtown Fresno to downtown Bakersfield, only one 114-mile main route is in play, from a proposed downtown station along the Union Pacific tracks near Chinatown to the south end of Fresno, then south along the Burlington Northern Santa Fe tracks into downtown Bakersfield. The route veers from the freight rail tracks in Kings County to bypass Hanford on the east.

In Kings, Tulare and Kern counties, the route includes options for bypasses around the towns of Corcoran, Allensworth, Wasco and Shafter.