A damaged car rests at the roadside on a section of the Shanghai-Chongqing Highway in Chongqing, Southwest China, Nov 6, 2011. Brake failure on a tank truck carrying 9.5 tonne of gasoline is reportedly the cause of a 16-vehicle pile-up, which injured 4 people on Nov 6. The wreck also resulted in traffic congestion that lasted more than four hours. [Photo/CFP]

The 16-vehicle pile-up caused a traffic jam on a section of the Shanghai-Chongqing Highway in Chongqing, Southwest China, Nov 6, 2011. [Photo/CFP]