A system to prevent subway collisions will be put into operation on Line 11 trains in Shanghai in a pilot program from June following a number of accidents caused by defective signaling systems.

According to a report by Oriental Morning Post on Thursday, the collision avoidance system, called BatTrain, was developed by Shanghai Shentong Metro Group and Shanghai Advanced Research Institute under the Chinese Academy of Sciences. There are hopes it will be expanded to other lines.

The system, revealed at a metro equipment fair in Shanghai on Wednesday, attracted much attention after a signaling failure caused a rear-end crash between two trains on subway Line 10 last September. More than 280 people were injured.

Signal failure also caused a crash last July of two bullet trains near Wenzhou in East China's Zhejiang province, killing 40 people and injuring 177 others.

According to Deng Qi, a technician from Shentong who took part in the fair, the system is designed to serve as an "assistant measure" that will take effect when there is a problem with a subway train's regular signaling system.

The new system, adopting the technology of sound propagation and signal tracing, is able to detect other trains, measure the distance and fix their positions via on-board equipment similar to a set top box used at home.

The newspaper cited Deng as saying that the safety distance between two trains in Shanghai's subway system is designed to be 300 meters. When the distance of two trains is shorter than that an alarm will automatically sound.

There is also an emergency braking system that will function automatically on the following train if two trains are extremely close.

Designers said the system was inexpensive and easy to maintain.