The bid was the lowest of the five submitted for the contract in January, well below the expected $US 1.2-1.4bn price tag, but had the lowest technical and safety ratings of those submitted.

The bidding process subsequently courted controversy after it was revealed in April that the authority changed its rules for selecting the winning bidder without approval from the board which would allow it to select the cheapest bid. CHRSA said at the time the authority was worried that their previous methodology, which would consider only the three bids with the highest technical ratings "could have left hundreds of millions of taxpayer dollars on the table."

However, following an hour-long session of questions by the board to CHSRA staff, members were satisfied and voted 6-0 to accept the bid, with board chairman Mr Dan Richard abstaining because he had previously worked for one of the companies involved. The successful vote paves the way for work to begin this summer after the contract is formally signed in the next few weeks.

"The questions really boil down to, can the successful bidder do the job, and will they do it within the confines of the contract as contemplated by the authority," said board member Mr Jim Hartnett. "The questions that I had were answered to my satisfaction."

Opponents of California's $US 68bn high-speed rail project, which will eventually link San Francisco and Los Angeles, raised questions at the meeting about possible cost overruns and the financial health of the lead company, Tutor Perini. Tutor CEO Mr Ron Tutor dismissed these criticisms.

"Like most of the uneducated opinions you hear where we can't rebut them, they are not based on anything factual or real," Tutor said. "We've built more large civil works programmes in this state than anyone else, virtually all of them successfully and without the cost overruns they all allude to."