Two Chinese firms have made formal expressions of interest to provide trains for California's $68 billion high-speed rail project.

The California High-Speed Rail Authority, the agency responsible for designing, building and operating what will be the first high-speed rail system in the US, said it has received 10 expressions of interest (EOI) as of Monday.

One of those is from State-owned CNR Corp, its unit Tangshan Railway Vehicle Co and US-based SunGroup USA. Another is from CSR Corp, also a China-based firm. News reports last week indicated that the CNR group would file an EOI.

The other EOIs are from units of Alstom SA of France, AnsaldoBreda S.p.A. of Italy, Bombardier Transit Corp of Canada, Hyundai Rotem of South Korea, Marnell Transportation LLC of the US, Kawasaki of Japan, Siemens AG of Germany and Talgo Inc of Spain.

The legislation approving the California project requires that the trains be manufactured in the US. By year-end or early next year, the authority hopes to solicit requests for proposals for the trains. That will contain specific technical requirements that the trains must meet and include a request for cost estimates.

Stan Feinsod, a rail-industry consultant from San Francisco, said that construction has started already on the project in central California.

"I believe that this expression of interest coupled with the work underway means this project is starting to gather some steam," he told China Daily.

The $68 billion price tag has raised concerns. Cost estimates have risen since initial funding for the project was approved by California voters in 2008.

"I think making cost estimates for such a capital-intensive project over a 15-year period is more an art than a science," Feinsod said. "The bottom line is this current estimate is a good one for this project."