Despite half a million visitors, the Expo Garden was a picture of relative tranquility on Sunday as organizers found ways to rein in the early chaos.

Representatives from 15 of the most popular pavilions met with organizers on Saturday evening to brainstorm better ways of controlling human traffic.

This followed disruptions during the Expo's soft opening last week when surging crowds caused the temporary closure of several pavilions, including Pakistan's, which saw several exhibits smashed on Thursday in a human stampede.

Results of the brainstorming were immediately obvious by lunchtime on Sunday, as people waited patiently for up to four hours in the sun with umbrellas, deckchairs and radios outside the Japanese, Thai and Australian pavilions.

"They provided us with metal fences and fixed security teams and the result was something like magic. I was very surprised. I didn't expect it to happen so fast," said Kreingkrai Kanjanapokin, project director at the Thai Pavilion.

The Expo expects to accommodate an average of 380,000 people a day, but organizers will allow up to 600,000 on busy weekends and special days.

If Sunday was any barometer, the 3.28-square-kilometer site can easily accommodate such numbers.

Visitors entered the Expo Garden within 30 minutes as people began to heed warnings to access it by the less-popular Puxi side. Visitors had plenty of shaded seating in which to eat their packed lunches. Expo Avenue and Expo Boulevard were also easy to navigate, with only buses and funky-looking Expo cars passing along Expo Avenue.

However there was no way to trim long lines outside the most popular pavilions, while the 50,000 reservations for the "Oriental Crown" China Pavilion were gone by 9:20 am. One volunteer told China Daily that people had waited outside the Expo's gates overnight to ensure they got into the China Pavilion.

Visitors also had to wait up to four hours outside the purple cocoon-shaped Japan pavilion, or three hours outside the pavilions of Australia and Saudi Arabia.

These queuing times should shorten when other popular pavilions, like those of the United Kingdom, the United States, the Philippines and Nepal open their doors to the public on May 1. At least a dozen pavilions were not yet open on Sunday.

Fortunately, many visitors kept a sense of humor over the weekend and one elderly Chinese man brought a director's stool and lollipops as he waited outside the Japanese pavilion.

"The guards told us we had to wait four hours, but we've already been here an hour and it looks like we'll be inside within 30 minutes," said the man.

Others gave up after being beaten by the lines and the heat, which reached 19 C around lunchtime. Two 30-year-old ladies with a tour from Hangzhou, in neighboring Zhejiang province, said they were content to shop, eat, soak up the atmosphere and take photos.

The Expo officially opens on Saturday. Meanwhile, technicians were still ironing out glitches at some pavilions on Sunday.

Foreign officials suggested further tweaks were needed to ensure visitors receive the kind of service Shanghai hopes to impress upon the world next month.

"We could do with more public announcements over the speaker system to let people know about the opening and closing times," said Prajade Thiravat, project advisor at the Thai pavilion. "We had people knocking on the gates last night even after we had stopped letting them in, because they didn't realize we were closed."

According to Prajade's colleague Kreingkrai, Shanghai has already seen its manners experience something of a collective makeover in the last decade, with less spitting and honking. He said the Expo could help finish the job.

"The organizers told us that one of the objectives of bringing events like the Expo and the Olympics to China was to introduce Chinese people to international cultures and ways of behaving," said Kreingkrai.

"I think that by the time this ends, we're going to see a huge change in people's behavior."

The trial period for Expo ends on Monday.