The train can hold 800 more passengers than current six-car trains, and will initially be used to relieve congestion on Metro Line 1, the city's busiest, Shanghai Metro managers said yesterday.

Over the next three days, the train will operate in the afternoons outside rush hours before going into full operation. This buffering procedure is common for newly rolled out stock.

The second eight-car train is scheduled to come into service on Metro Line 1 before the Spring Festival next month, according to managers.

Another 14 trains will be phased in over the next few years, said Metro officials.

The extra length of the trains will make full use of Metro platforms, which were built to cater to eight carriages.

In September, Metro officials said the extra trains would cut the longest interval between Metro Line 1 trains from the current nine minutes to six.

The new trains are also equipped with a more powerful air-conditioning system and each carriage has a device that allows passengers to talk with the driver in the event of an emergency.

The trains were built by a consortium of France's Alstom SA, Shanghai Alstom Transport Co and Nanjing Puzhen Vehicle Factory.

The city signed a deal for the trains with French President Jacques Chirac during his visit to the city in August 2004.

The eight-car trains are the latest effort by the city's Metro operators to ease heavy traffic flow on Metro lines.

Daily passenger turnover on Metro Line 1, which runs north and south across downtown, stands at 1.1 million. The line opened in 1995.

Trains on Metro Line 1 are up to 25 percent overloaded during rush hours, according to Metro managers.