SNCF TGV Duplex - Innovations

Innovations

Perhaps the most important innovation is the efficiency of the Duplex design. Comparing an original TGV Sud-Est and a Duplex trainset shows that the double-decker design has improvements in both power-to-weight ratio and the weight-per-seat overhead:

In this comparison, "power" refers to installed power, not all of which is used when operating.

• Aluminium bodies - the strict requirement of a 17-tonne (16.7-long-ton; 18.7-short-ton) axle load limit made it imperative to cut down on weight, wherever possible. Extruded aluminum construction (such as used on the German ICE train) made possible a 20% reduction in the weight of the structure.

• Improved styling and aerodynamics - the nose of the power units and the gap between trailers were improved such that a Duplex train at cruise speed of 300 km/h (186 mph) experiences only 4% more drag than a single-level TGV. The nose, the first significant departure from Cooper's original design, was styled by industrial designer Roger Tallon, as was the rest of the trainset.

• Crashworthiness - crush zones and rigid passenger compartments ensure maximum safety in the event of a collision. The power units' frame is designed to take a (steady-state) 500 tonnes (490 long tons; 550 short tons) of force frontal load, and features structural fuses to absorb impact energy.

• Active pantograph - the Faiveley CX used on the Duplex has a pneumatically actuated active control system. Two small gas cylinders in the wiper armature can tune the stiffness of the pantograph's upper stage, to optimize contact at any speed.

• All wheel disc brakes - earlier TGVs (including Eurostar) used disc brakes only on unpowered axles. Weight gains on the Duplex power units allowed the installation of disc brakes directly on the wheels of powered axles (so-called "cheek discs"), instead of using the traditional tread brakes. This does not greatly improve braking performance, but it leaves the wheel tread smooth and considerably reduces rolling noise.

• Quiet roof fans - the cooling fans in TGV power units produce the most noticeable sound (a loud hum) when the train is in a station. The fans, located in the roof of the unit, have been redesigned to be quieter.

• World's Fastest Train - In 2007 a short formation TGV Duplex was fitted with distributed traction as used in the future generation AGV (automotrice à grande vitesse) setting a new speed record of 574.8 km/h (357.2 mph). (see TGV world speed record#Record of 2007)