With more than one-third of visitors choosing to ferry their way to Expo 2010 Shanghai, waterway transportation in the city is being seriously tested.

Before the Expo rolled out the carpet, organizers estimated that only 5 percent of visitors would enter the Expo Garden through its water gates, or travel between the Expo's Puxi and Pudong sections across the Huangpu River.

However, Qu Chun, assistant director of the Shanghai Maritime Affairs Bureau's Expo office, said the Expo's water traffic has been far more than expected, with the highest daily volume reaching 185,000 people.

More than 17 million Expo visitors have now traveled to the site by ferry, making up about 35 percent of the entire tourist flow, according to the Shanghai Maritime Affairs Bureau.

That is putting big pressure on local maritime management. Along the 7.2-km of the Huangpu River's banks weaving through downtown Shanghai, about 150 Expo passenger ferry trips add to the 653 trips of other ships traveling either along or across the river every day.

"We don't have anyone to learn from, as the Shanghai Expo is the first Expo to use a ferry for public transport," said Qu. "Apart from security concerns, we have to make sure the waterway can be used to transport coal, electricity and oil supplies."

There are three levels of waterway security, according to the Shanghai Maritime Affairs Bureau's Expo office. "At the current stage, we're on the lowest one, which means ships that transport dangerous goods are allowed to pass the core waterway of the Expo area every day from 4 am to 8 am," said Tang Wu, an officer with the Shanghai Maritime Affairs Bureau.

"The opening and closing ceremonies are under the strictest level, which means no fishing boats, yachts or cruises are allowed. Only special Expo boats and marine police have the privilege of traveling by water during those periods," he said.

The city's maritime affairs bureau strengthened its administration during the six-month event by establishing the new Expo office before the world fair drew its curtain on May 1.

Seven patrol craft and 108 officers share duties 24 hours a day, seven days a week to guarantee safety.

Thanks to their hard work, no boat-related accidents have happened since the opening of the Expo. However, marine police have encountered 18 dangerous cases such as drunken operation of a vessel and the potential for boats to run aground.

In the case involving alcohol, the captain had been drinking and came to the attention of marine police when he was slow to dodge other boats.

"All ships on the Expo waterway have to follow the speed limit," said Tang. "They can't sail too fast, or they might cause accidents. They can't sail too slow either, or there would be traffic jams."