Chinese authorities blamed a faulty signal system for the subway collision in downtown Shanghai that injured about 260 people on Tuesday, just two months after a high-speed rail crash killed 50 passengers near Wenzhou, also reportedly due to signal failure, the Wall Street Journal reported. About 20 people were seriously injured when one train rear-ended another in a tunnel near Shanghai’s Yu Gardens area, though no fatalities were reported. The operator of the relatively new Line 10, Shanghai Shentong Metro, said that equipment had failed about 40 minutes earlier, requiring trains to switch to manual operations, run at slower speeds and communicate by phone. The crash involved different types of equipment than the July 23 crash in Wenzhou, but the incidents had one supplier in common: Casco Signal, a joint venture of France’s Alstom SA and China Railway Signal & Communication. Casco and Alstom have both rejected involvement with the Wenzhou crash, saying that equipment was “not the root cause.” Casco said Tuesday that initial signs suggested a wider power outage, rather than signal failure, caused the Shanghai collision.