Ladies can expect relief from long queues at the Expo Park as the organizer has decided on the one-male-toilet-to-2.5-female-toilets proportion.

The ratio of toilet seats for male and female in one detached toilet is will be 1:2.2 or 1:2.5 while 1:0.5 in pavilions (equipped with two squat toilets and one urinal in men's room, and two squat toilets in ladies' room).

According to Zhou Minhua, director of technical service department of Shanghai Expo, a tracking survey on toilet usage was conducted in the last decade.

Carried out at large-scale automobile exhibitions, open-air events and the previous two World Expos, the survey shows that it takes men 48 seconds to urinate and on average 114 seconds for women. 10 –12 a.m. and 1-5 p.m. are the peak demand hours.

Much like the better toilet campaign enacted in Beijing before the Olympics, Shanghai is accelerating and upgrading its public restrooms in time for the World Expo.

The host has cleaned up and renovated more than 11,000 public toilets in and around the 5.28-sq-km Expo site to meet the "urgent needs" of roughly 70 million expected Expo visitors.

These public toilets guarantee about 8,000 visitors at a time. Using water supplied partly by rainwater collected in the "Sun Valley", some of the toilets are adjustable according to the ratio of female and male users.

Portable toilets will meet the urgent needs in the heavily crowded areas. "They drive away as soon as they grow beyond capacity," Zhou said.

There are more than 10 such portable toilet vehicles in the city, one third of which will be used at the Expo site.

"Public toilets at Aichi World Expo in 2005 were thought to be a humanized design, yet the problem of inadequate toilets came into focus," Zhou said, remarking that it took women about 15 minutes to queue for a toilet seat.