Beijing —- Since 2001, when China won the right to host this year's Summer Olympics, Beijing rarely has rested. Construction has been nearly constant, and as residents have gotten richer, roads have become gridlocked and pollution has worsened.

But on Sunday, Beijing was strangely calm: Traffic flowed smoothly, the general din of building had ceased, and even the air —- often a noxious stew of car exhaust, industrial fumes and whirling dust —- seemed cleaner.

The shift highlighted a Herculean —- and sometimes draconian —- effort by Chinese officials to make Beijing presentable for 10,500 Olympic athletes and 1.5 million visitors expected at the Games next month. Starting Sunday morning, Beijing barred half of the city's 3.3 million private cars from the city's roads and ordered all large construction projects halted until Sept. 20, shortly after the closing ceremony for the Paralympics.

Those rules came on top of dozens of recent regulations governing everything from what people eat to how they celebrate. Among other things, Beijing has recently banned pouring concrete, launching fireworks and using spray paint.

To avoid upsetting nonsmokers, Beijing expanded a smoking ban in May to include "fitness centers, cultural relic sites, offices, meeting rooms, dining halls, toilets, and aisles and lifts in buildings belonging to government or private institutions," the state-run Xinhua News Agency reported.

To avoid angering canine-friendly visitors, the city will ban the sale of dog meat —- traditional fare in some Chinese provinces —- at officially designated Olympic restaurants and will encourage other businesses to keep dog off their menus during the games.

In a city sometimes called "Grayjing," pollution is a bigger concern for Games organizers, and beyond the ban on private cars, more than 300,000 "high-emission" vehicles —- mostly freight trucks —- have been forbidden to enter Beijing, a regulation that has driven up food prices.

Coal-burning power plants have been ordered to reduce their emissions and farmers to refrain from burning straw. Hundreds of factories have been told to suspend operations.

Together, the regulations have changed the face of Beijing, and on Sunday residents were surprised by the city's relative peace.

"It doesn't seem like Beijing at all," taxi driver Wang Jiming said as he zipped along an avenue lined with "Beijing 2008" flags and posters emblazoned with the Olympic motto "One World, One Dream."

"I don't remember it ever being so quiet," he said.

As Beijing's army of migrant construction workers —- a group estimated to number more than 1 million —- leaves the city, Beijing is likely to become even quieter, at least until crowds begin arriving for the games. On Sunday, thousands of suddenly unemployed workers waited for trains at the Beijing Railway Station, many of them carrying duffel bags stuffed with everything they had brought from their distant homes.

"It's strange to have to leave, but because of the Olympics there aren't any [construction] jobs," said Li Liuxue, a 49-year-old laborer from northern China who had worked in the city for three years. "Maybe I'll come back in September."

The regulations have cut into profits for some businesses. At a Home Depot store in the city, sales have fallen by nearly half over recent weeks because of the bans on construction and deliveries, manager Zhou Xiaolong said.

Liu Li, one of a handful of shoppers in the warehouse-size store, said she had planned to buy floor tiles but because of the delivery restrictions would wait until after the Games.

The Atlanta-based company has advised Beijing customers "to focus on less complicated home improvement projects during the Games period, such as installing lights and curtains," Home Depot spokesman John Hong said.

At least some Beijing residents have been angered by the multitude of rules. Residents in a neighborhood near the Forbidden City complained that the ban on trucks had driven up the cost of food. The price of cabbage, for example, has risen 66 percent because of reduced supply, state media reported last week.

"Everyone supports the Olympics, but we shouldn't have to pay more for it," said Chen Longxin, a driver living in the neighborhood.

At a nearby newsstand, owner Liu Haisi predicted his sales would plummet during the Games because a large construction project had been halted and local office employees would work from home to avoid public transportation.

"The Olympics is good for the government, but it's an inconvenience for average citizens," he said.