MADRID -- It's 8 a.m. at the Puerto de Atocha train station in central Madrid. Business travelers armed with cellphones and laptops, and pleasure travelers toting cameras and carry-on bags, make their way through security to board the high-speed trains that connect Spain's capital to cities across the nation.

The sprawling station, which dates to the 1890s, serves not only the AVE, or Alta Velocidad Española high-speed trains, but also the city's metro subway and commuter trains. It sits amid a bustling district of offices, hotels, restaurants, museums and other businesses.

This is the vision shared by backers of California's proposed, but controversial, high-speed rail system. And there are lessons -- from both successes and mistakes -- that California can learn from Spain's 20-year history with high-speed trains.

Top among them is just how hard it is to be self-sufficient, even when conditions seem ideal, as they have in Spain.

Despite popular and political support from the very beginning, the AVE rail system faces a tougher future in the midst of Europe's financial crisis.

Already, service between some smaller cities has been cut because too few people ride the trains. Some wonder if it is anything more than a luxury commuter service.

Among the growing fraternity of nations with high-speed trains, Spain is considered the best geographic and cultural analogy to California and its train plans. The long-distance AVE trains and their regional cousins Avant and Alvia, which share the high-speed tracks, connect major urban centers but pass through smaller cities and stretches of rural farmland, just like what is planned for California.

They've gotten people out of their cars and off airplanes, sliced travel times and attracted millions of riders a year -- just what California rail boosters hope will happen here.

Since the late 1980s, Spain has spent about $60 billion to build and equip its high-speed network.

President Barack Obama touted Spain's system as a model for American high-speed rail plans when he announced billions of dollars in federal investments in April 2009.

And Transportation Secretary Ray LaHood voiced admiration for the Spanish network when he visited Spain last summer.

"We know that you are the experts. We know that you have developed a state-of-the-art system here," he said. "It's not lost on anyone that when President Obama proposed this high-speed rail plan, he specifically called out Spain as an example for America to emulate."

Spain's system, however, was launched in conditions much different from what California is experiencing today. Political unity, a thriving economy and the spotlight of international events -- a world exposition in Seville and the Olympic Games in Barcelona -- all provided an impetus for Spain to embark on its high-speed journey.

About the only major point of contention was where the first line from Madrid should go (Seville won over Barcelona), not whether it should happen at all.

While Spain continues to build and expand its system through both good and bad economic times, cost is a key concern in cash-strapped California. Planners are wrestling with a price tag that has doubled over the past two years and grappling with the thorny issue of where to get the money to build it when both state and federal budgets are under strain.

Unlike in California, Spain's high-speed rail effort has not been a public or political punching bag. It's rapidly expanded to become Europe's most extensive high-speed network -- and third only to China and Japan's worldwide -- while facing remarkably little of the NIMBYism, farm opposition or politics fermenting throughout California.