Reports on the environmental effects of high-speed trains in the Valley will be delayed for several months as engineers seek less costly ways to build the project.

The delay will not postpone the anticipated start of construction in late 2012, the California High-Speed Rail Authority said. But it will push the environmental assessments beyond a fall deadline in the state's agreement for billions in federal dollars.

"Only the estimated schedule for environmental milestones has changed," authority CEO Roelof van Ark said this week. "The schedule for construction has not."

A 120-mile stretch of high-speed tracks between Fresno and Bakersfield is tabbed to be the first portion built for California's high-speed train system.

The project is ultimately planned as an 800-mile system connecting the state's major cities with trains carrying passengers at speeds up to 220 mph.

Draft environmental reports originally were expected to be published in January for two Valley sections of the line, Merced-Fresno and Fresno-Bakersfield. Now, engineers don't expect to release those draft reports until June for public comment.

"There's a bit of a delay, five to six months on each of the segments, that's the bad news," authority Vice Chairman Tom Umberg said at the board's meeting Thursday in Los Angeles.

But the good news, Umberg said, is that the delay will give engineers time to reconsider miles of track that were proposed to be elevated high above the landscape, including about seven to eight miles of track rising about 60 feet over the heart of Fresno.

A ground-level track originally was among the options being considered, but was abandoned because engineers believed it would not be feasible, a state official said.

"A number of the aerial structures that were proposed in the Central Valley now can be eliminated," Umberg said. "That track can be at grade rather than on aerial structures."

Over the past couple of months, van Ark said, engineers have been looking at route options "to identify opportunities to minimize environmental impacts and also to take a hard look to see if there are reasonable ways to reduce project costs."

The exact savings aren't known, but reducing the amount of elevated tracks could shave tens of millions from the price of the Fresno-Bakersfield section, estimated at about $5.5 billion.

The Federal Railroad Administration has committed nearly $3 billion to California for initial construction of high-speed rail in the Valley. A December grant agreement required that environmental studies be completed and certified by September for the sections from Merced to Bakersfield.

The revised schedule now calls for environmental certification and selection of a final route in February 2012.

The new timeline won't jeopardize the federal funds because the state has the blessing of the Federal Railroad Administration, said Rachel Wall, the state authority's press secretary.

"Everything we do is in partnership with FRA," Wall said. "They're aware and they're involved in planning progress."