The French TGV high-speed railway (French: train à grande vitesse), also known as TGV, is a high-speed railway system designed and built by Alstom and SNCF and operated by the latter. In 1981, TGV opened between Paris and Lyon, and now it has formed a railway network with Paris as the center and radiating to various cities in France and surrounding countries. On April 3, 2007, TGV set the fastest record for wheel-rail trains with a speed of 574.8 kilometers per hour. At the same time, TGV is also the fastest average speed among scheduled wheel-rail passenger trains in the world. "TGV" is a registered trademark of France Railways.