Chinese authorities blamed a signal breakdown for a subway collision in Shanghai that injured? 271 passengers yesterday afternoon. The crash occurred on the city's Line 10 subway, China's largest fully automated line, when one train rammed into the back of another.

The signal systems used on the line are made by Casco Signal Ltd., a joint venture between China Railway Signal and Communication Corp. and French power and transport engineering group Alstom (ALSO.PA).

The Alstom website says Casco supplied signaling equipment for Line 10, noting that it was designed to be China's largest driverless subway line.

Apart from Line 10 in Shanghai, the system has been used in Beijing's subway Line 2 and the line linking the airport with the downtown area.

Casco imported the Urbalis888 CBTC, an automatic train control system based on high-speed wireless communication technology, from its parent, Alstom Transport, said the company on its official website.?The company?has been involved in more than 28 subway signaling projects across China, including lines in Beijing, Shanghai, Tianjin, Shenzhen and Kunming.

The Shanghai metro has been plagued by minor incidents as it has undergone rapid expansion in the past few years. In July, a subway train on Line 10 took a wrong turn during peak traffic because of a signalling error but managed to avoid a crash, while in December 2009 a technical glitch in the metro signalling system caused two trains to crash, in an incident that was blamed on Casco at the time. No one was hurt in either incident.?

Alstom, which describes itself as “the world’s leading energy solutions and transport company,” didn’t have any statement about the Shanghai crash at its website this morning.