An improved signalling system will be used on Shanghai's new Metro lines to help improve the system's operational capacity and safety levels, officials said yesterday.

With enough trains in service, the advanced system could reduce operation intervals on the city's Metro lines from the current low of about two minutes to just 90 seconds.

The new system uses the wireless Communication Based Train Control (CBTC) network, which represents the highest level of subway signalling technology in the world now, explained Guan Jingzhi, executive vice president of Alcatel Bell Shanghai Company.

The wireless network enables the real-time transfer of signals between reactors installed around trains and the control terminal. The trains will automatically and instantly react during emergencies to avoid accidents.

It's like the trains now have "a brain, eyes and ears" that work as a group, Guan said.

The system will allow each train to control its speed to keep a safe and most efficient distance from neighboring vehicles.

"The system will help avoid mistakes by the drivers. The trains are able to automatically launch their brakes suddenly and even drive backwards if an emergency is detected, such as passengers being caught by the doors or obstacles appearing on the tracks," Guan said.

The signalling system could work to improve the interval between trains to only 90 seconds, said local Metro constructors. However, they said that the major barrier to this is a serious lack of trains.

The Metro authority said the first phase of the wireless CBTC system had been working smoothly on Lines 6 and 8 as well as the first section of Line 9 since they opened for operation around the end of last year.

The signalling network will also be introduced to the extensions of Line 9, 7 and 10 in the future.

The system is capable of supporting a secure driver-free operation but Metro operators have no plans to adopt such a service mode.

(Shanghai Daily April 2, 2008)