UNLESS absolutely necessary, Xie Yiqing would never walk along the interchange passage between metro lines 1 and 2 at People's Square station.

"No matter whether it's peak time or not, the passage is always crowded with throngs of people, most of them walking too fast and being rude," she said. "It makes me feel extremely uncomfortable, sick and headache to be among so many people."

Most commuters who depend on the metro to get to work and who have to walk along the interchange passage every day have similar feelings about the experience.

"I feel it is a little dangerous to walk along the passage in the rush hour," said Xu Limin who works in Lujiazui and who has to take the metro every day. "If there is a fire or if something goes wrong with the escalator, people will find it difficult to get out of danger."

Excessive crowds

When Metro Line 1 was first put into operation in 1993, it played only a minor role in public transport because most people were used to taking a bus or riding a bike.

But now, the three metro lines have a major role in public transport and passenger flow records are being broken year after year. In 2001, underground rail traffic carried 774,000 people each day and the figure rose to 1.23 million last year.

The huge throng of passengers has caused the whole metro system to become overloaded for some years. Each train carriage is designed to carry a maximum of 310 passengers but today they each contain about 400 passengers, one third more than they were designed to hold.

According to the metro construction schedule, the present 65 kilometres of subway lines will be extended to 200 kilometres within five years. Underground rail traffic will carry about 25 per cent of the city's commuters instead of the current 10 per cent.

With the increasing number of passenger and as more communities are built along the metro lines, the passenger flow will increase markedly in the interchange passage linking the two metro lines at People's Square.

At present, the number of people using the passage is about 120,000 each day although it can sometimes exceed 240,000, according to statistics collected by the Shanghai Metro Operation Co Ltd. This compares with fewer than 100,000 a day in 2002.

"The interchange passage is under great pressure from the huge flow of passengers," said Yin Wei, an official with the company. However, since metro line 2 began operations in 1999, no accident has been reported in the interchange passage. Yin said the company closely monitored the situation in the passage.

In Miyun County in Beijing on February 5, an accident set off an alarm bell on an overcrowded bridge in a park during the Lantern Festival and 37 people were killed in the crush.

"We should be prepared before any possible problem arises here," Yin said.

Inconvenient transfer

People's Square, the only transfer point between metro lines 1 and 2, has two interchange passages. The northern one is 90 metres long and the southern, 300 metres. The longer one was opened at the beginning of last year but fewer people like to use it, especially in the morning when most people are hurrying to work. So it is estimated that about 90 per cent of commuters use the shorter passage.

"Of course, there are some shortcomings in the design of the interchange passage - the designers didn't have the correct predictions about passenger flow," Yin said.

"The complaints about the inconvenience in transferring between Metro Line 1 and Metro Line 2 have never stopped since it was put into use," said Chen Xiaohong, a professor from the School of Transportation Engineering at Tongji University.

"Admittedly, such a long distance between the two metro stations reveals certain flaws in the city's original planning," Chen said.

However, she said the city had thought about the transfer problem from when the subway project was first raised.

The best way was to construct one big station at the transfer point for the two lines instead of two stations which are separated and linked by the long interchange passage.

Due to a lack of funds, the city couldn't construct the two lines simultaneously. When the city started construction of Metro Line 1 in 1989, Metro Line 2 had not been thought of.

"The measure taken, introducing a one-way flow during rush hour, is just a temporary method to decrease the crush in the short passage and prevent crowds of passengers coming from different directions colliding with one another," Yin said. "To solve the problem thoroughly, the city should wait for the construction of Metro Line 8 which will also intersect at People's Square Station."

With the completion of the new metro line, the interchange passage will be broadened and a new plaza built which will help disperse metro passengers. But the official didn't reveal the timing for the completion of Metro Line 8.

Yet in Chen's eyes, the biggest problem with the subway transfer is not the long distance between the two stations. Instead, it is the poor work the metro has done in telling people how to transfer from one line to the other.

The indication boards are not clear. It is often the case that new passengers don't know for sure if they are going the right way to get to the other metro line.

In some foreign countries, transferring between two lines may also cover a long distance but people can easily follow the instructions telling them which way to go.