The California High-Speed Rail Authority is pushing back Friday's deadline for contractors to submit their bids to design and build the first stretch of high-speed rail line through Fresno and the central San Joaquin Valley.

Authority CEO Jeffrey Morales said Tuesday that questions from five consortiums of building firms have prompted the authority to set Jan. 18 as the new date by which bids must be submitted for a 28-mile stretch of the high-speed rail line from Avenue 17, northeast of Madera, to American Avenue at the south end of Fresno.

"The bidders have been asking for more information and more time to analyze the information," Morales said. "If we take our time at the front end to get it right, it will ultimately be to the benefit of the project" through better bids and possibly lower prices.

The rail authority estimates that this construction segment will cost between $1.2 billion and $1.8 billion. Morales said the agency now anticipates awarding a contract and beginning construction by June 2013.

The Madera-Fresno section is the first of four construction segments from Madera to just north of Bakersfield that, because of federal funding requirements, must be completed by Sept. 30, 2017. Morales said he remains confident that all four sections can be done by that time.