25 years: The final joint in a new $3.7 billion high-speed railway line linking France and Germany will be welded in place on Wednesday to celebrate the quarter of a century anniversary of France's revolutionary TGV (Train a grande vitesse) high-speed train.The first TGV ran between Paris and Lyon on Sept. 22, 1981 after being unveiled by French President Francois Mitterrand. A 666-kilometer (414-mile) journey from Paris to Marseille takes just three hours. In the UK an equivalant journey (London to the admittedly less enticing destination of Aberdeen) takes seven hours.On Monday French rail operators SNCF tested TGV trains on a Mediterranean line with a cruising speed of 362 kilometers per hour (225 mph). Trains currently travel up to 321 kph (200 mph).The TGV network covers 2,010 kilometers (1,250 miles) of track with around 400,000 people using the trains daily for work.In 1990 a TGV set the world speed record for a conventional train at 515.3 kph (320.2 mph). Only Maglev trains in Japan have achieved faster speeds -- including the overall record for railed vehicles of 581 kph (361 mph) .Railway historian Clive Lamming says: "The TGV is Concorde plus commercial success."