GUANGZHOU, China: Chan Shao Zhang is in the race of his life.
After four decades of false starts, Mr. Chan, a 67-year-old engineer, is supervising an army of workers operating 60 gargantuan tunneling machines beneath this metropolis in southeastern China. They are building one of the world's largest and most advanced subway systems.
The question is whether the burrowing machines can outrace China's growing love affair with the automobile ? car sales have soared ninefold since 2000. Or are a hundred Los Angeleses destined to bloom?
And even as Mr. Chan labors to bind Guangzhou together with an underground web of steel, the city is spreading out rapidly above ground, like a drop of ink on a paper towel.
The Guangzhou Metro is just part of a much broader surge in mass transit construction across China.
At least 15 cities are building subway lines and a dozen more are planning them. The pace of construction will only accelerate now that Beijing is pushing local and provincial governments to step up their infrastructure spending to offset lost revenue from slumping exports.
"Nobody is building like they are," said Shomik Mehndiratta, a World Bank specialist in urban transport. "The center of construction is really China."
Western mass transit experts applaud China for investing billions in systems that will put less stress on the environment and on cities. But they warn that other Chinese policies, like allowing real estate developers to build sprawling new suburbs, undermine the benefits of the mass transit boom.
"They wind up better than if they did nothing, but it costs them a fortune," said Lee Schipper, a specialist at Stanford in urban transport.
Mr. Chan defended Guangzhou's combination of cars and subways, saying that the city built a subway line to a new Toyota assembly plant to help employees and suppliers reach it.
Subways have been most competitive in cities like New York that have high prices for parking, and tolls for bridges and tunnels, discouraging car use. Few Chinese cities have been willing to do that, other than Shanghai, which charges a fee of several thousand dollars for each license plate.
The cost and physical limitations of subways have discouraged most cities from building new ones. For instance, only Tokyo has a subway system that carries more people than its buses. The buses are cheaper and able to serve far more streets but move more slowly, pollute more and contribute to traffic congestion.
China has reason to worry. It surpassed the United States in total vehicle sales for the first time in January, although the United States remained slightly ahead in car sales. But in February, China overtook the United States in both, in part because the global downturn has hurt auto sales much more in the United States than in China.
Guangzhou, a city of 12 million people that is also the fastest-growing center of auto manufacturing in China, shows both the promise and obstacles of China's subway extravaganza.
Mr. Chan helped set up Guangzhou's subway planning office in 1965, when he was straight out of college. Digging started the next year. But the miners gave up after less than 10 feet when they hit granite.
After that, Mao personally sent China's finest mining and underground construction experts to oversee the digging. But further excavation efforts failed in 1970, 1971, 1974 and 1979. During and immediately after the Cultural Revolution, Communist dogma, poverty and nationalism forced a reliance on inadequate Chinese equipment.
In 1989, when preparations began for successful excavations, city leaders thought it would be enough to have two subway lines, totaling 20 miles, in an X shape bisecting a tightly packed downtown.
"At that point, it was still mostly bicycles and people walking," Mr. Chan said. Then, "in the 21st century, the Guangzhou economy really took off."
Today, Guangzhou has 71 miles of subway lines, most of them opened in the last three years, and yet large areas of the ever-expanding city are still distant from the nearest subway stop.
The city plans to open an additional 83 miles by the end of next year ? and an underground tram system and a high-speed commuter rail system. A long-term plan calls for at least 500 miles of subway and light rail routes, and there are discussions on expanding beyond that.
China now produces much of the equipment to build modern subways, but the country's infrastructure stimulus spending is drawing in imports as well. Most of the tunneling machines here were made by Herrenknecht of Germany. I.B.M. announced on Wednesday that it had signed a consulting contract for computer tracking of Guangzhou Metro's nearly $3 billion in assets, including convenience stores in subway stations and lighting systems.
The digging in Guangzhou proceeds around the clock, every day. Men like Wang Jiangka, a profusely perspiring engineer in charge of one of the steamy tunnels, endure sweltering temperatures at the mine face, where workers put in five 12-hour shifts a week.
"If they don't want to do overtime, we get other workers," Mr. Wang said, standing in a red hard hat next to a Herrenknecht tunneling machine that chewed through the rock more than a one-mile walk from the nearest daylight.
Inexpensive labor ? less than $400 a month ? and the economies of scale created by completing 20 miles of subway lines a year have driven costs steadily down.
Mr. Chan said that it cost about $100 million a mile to build a subway line in Guangzhou, including land acquisition costs for ventilation shafts and station entrances.
By contrast, New York City officials hope to build 1.7 miles of the long-delayed Second Avenue line in eight years at a cost of $3.9 billion, or $2.4 billion a mile. The city expects to use a single tunneling machine.
Owners of land needed for subway construction in Guangzhou have few rights compared with those in New York.
Here, Mr. Chan said, a property surveyor appraises a building and "whatever he says, that's it." But, Mr. Chan added, "because China is now more democratic, if they don't want to move, then you have to take more time."
And time is of the essence. Guangzhou is growing rapidly outward.
Primly dressed in a white silk shirt and light brown slacks, Kerry Li stood under the 30-foot-tall crystal chandelier in the clubhouse lobby at the Hua Nan Country Garden complex and watched as her 10-year-old son played nearby.
A bus leaves her gated community in the suburbs and heads for the city, across the broad, muddy waters of the Pearl River, every 15 minutes. But a recently completed subway line under the river goes nowhere near the compound. Ms. Li's husband, a businessman, drives his own car to work every morning, while his wife stays home.
The lure of cars is hard to resist.
Chen Hao Tian, a 43-year-old economic planner for the Guangzhou municipal government who worries about the need for mass transit, used to spend half an hour riding a free bus for government employees to and from work.
Then he acquired a silver-gray Honda Accord from the local Honda assembly plant and found he could make the trip in 10 minutes ? and run errands along the way for his wife and 13-year-old daughter, and listen to his favorite music.
"On my salary, the maintenance costs are a pressure," he said. "But it gives me great pleasure and the feeling of a higher standard of living."
And few subway rides do that, even for those who build them.