TGV operations fall into two categories: operations on dedicated, TGV-only high-speed lines (LGVs), and operation in mixed traffic on "lignes classiques", conventional lines. Indeed, of the total track length served by TGV trains only about 25% (by route kilometre) is high-speed. In understanding the incident summaries below, it is important to bear this distinction in mind. Most of the serious incidents have occurred on conventional lines, where TGV trains are exposed to the same external risks as any other train. High-speed operation was never a factor in any fatal incident in the history of the TGV until November 14, 2015 when a TGV testing on the new Paris-Strasbourg line derailed violently into a canal, killing eleven and injuring the surviving 42 passengers.