In a move that strikes us as both logical and responsible, Rep. Kevin McCarthy of Bakersfield recently asked the U.S. Government Accountability Office to study and report on the California High-Speed Rail Authority's project cost estimates. McCarthy, a stringent opponent of the $68 billion bullet train, probably didn't expect the answers he received.

The GAO reported that the rail authority's ridership and revenue forecasts are in fact reasonable. The report did call for periodic updates "to refine the revenue and ridership model for the 2014 business plan," and it took issue with the cost estimates provided by the Federal Railroad Administration.

The GAO also expressed concern about the project's future funding sources. It specifically mentioned congressional support for additional funding as "one of the biggest challenges to completing this project." Opposition to that federal funding could be a substantial barrier to completion of the project, according to the GAO report.

But, all told, the report portrayed HSR as a generally realistic undertaking.

McCarthy seems to have not expected the positive news about HSR's likely viability, but as might have been expected, he found areas that merit concern. "Apart from the questionable business plan, fluctuating cost estimates and lack of public support, the California High-Speed Rail Authority's continued reliance on additional federal spending is naive and misguided at best. The authority's plan is irresponsible and reckless, and that is why I am developing legislation to stop more hard-earned taxpayer dollars from being wasted on California high-speed rail," McCarthy said in a recent statement. So we shouldn't expect to see him jump on board anytime soon.

But the GAO report seems to reject a major contention of bullet train opponents like McCarthy and Rep. Jeff Denham of Modesto, who contend that the system will not attract enough riders to cover operating costs.

It also notes the value of private-sector involvement that is likely to contribute funding. "Based on our past work on high-speed rail," the report states, "successful projects require significant and sustained financial commitments from the public sector before private investors will participate, and the authority's plan reflects this funding model."

Another potential source of funding is the rail authority's plan to sell an operating concession, similar to models used in other countries, with proceeds from the sale going toward completion of the system.

Politics are not part of the GAO's duties; it is an independent, nonpartisan office. But the politics are this: the California high-speed rail system is a centerpiece of the Obama administration's proposal for a nationwide network of railways. That plan has fed a contentious debate between Republicans and Democrats that likely will not subside anytime soon.

It's worth noting, though, that California HSR has much in common with the Federal-Aid Highway Act of 1956, which authorized construction of the interstate highway system, and the Pacific Railway Act of 1862, which resulted in building of the transcontinental railroad. Both of those projects, substantially funded by the public sector, were massive in scope and constructed in phases -- and they, too, changed America for the better. They, too, encountered opposition from politicians who proved to be on the wrong side of history.