Progress in developing high-speed train service between Northern and Southern California has been chugging along for more than a decade. And it could be 20 more years before a bullet train streaks from Los Angeles to Silicon Valley.

But a key question will be answered over the next year: How should the trains enter the Bay Area from the Central Valley? Should they cross the Diablo Range near Pacheco Pass and head north through Gilroy and San Jose? Or should they turn east near Tracy and come over the Altamont Pass?

The answer should be Pacheco Pass. It's the only way to serve Silicon Valley and San Francisco tech and tourism industries efficiently enough to be practical.

This is no small regional matter. Folks in Sacramento and the East Bay, along with some environmental groups, favor the Altamont Pass. South Bay leaders and some transit experts insist that the Pacheco/Gilroy route is the only way to ensure statewide high-speed rail success.

More study must be done on environmental questions, such as ways to protect the wilderness areas east of Gilroy, including Henry Coe State Park. But based on logic -- just look at a map -- the route to San Jose makes the most sense. From San Jose, trains would continue in two directions -- north along the Caltrain corridor to San Francisco or northeast to Oakland.

Using the Altamont Pass, trains from the south would stop in the Fremont-Union City area and then send spurs in three directions to San Jose, San Francisco and Oakland. That makes no sense. The line would end up being nothing more than a very expensive commuter option for folks in the Central Valley. Rail options already exist for this.

In November, the state High Speed Rail Authority approved a general environmental impact report on the basic plan for the 700-mile line linking San Diego, Los Angeles and the Bay Area. Trains are expected to travel at 220 mph, which would mean about a two-hour ride between Los Angeles and San Jose if the Pacheco Pass route is selected. The cost of the project has risen repeatedly, with estimates now as high as $38 billion.

More detailed studies will now be launched for the southern section, with hopes of opening a segment by 2016. Meanwhile, the rail authority will spend this year gathering more specific cost, ridership and environmental information on the Altamont Pass and Pacheco/Gilroy alternatives. There will be more public hearings, with the goal of a decision by spring 2007.

A bond measure to help pay for the project is scheduled to go before voters in November but will probably be postponed, as it was in 2004, while more details are worked out. At best, we'll be able to ride a bullet train to L.A. by the mid-2020s.

At one point, the decision to bring the trains through Gilroy and San Jose appeared to have been made. Altamont advocates forced a re-examination. This time, let's make sure the studies are definitive and the decision final.

The San Jose area and San Francisco are the economic hubs of this region. A faster and more direct link between them and Southern California would almost surely generate higher ridership than trains to the East Bay and Sacramento.

ON THE WEB: To learn more about the high-speed rail project, go to www.cahighspeedrail.ca.gov.