TGV Duplex is the name of the double-decker TGV train family used on many French high-speed services.
Alstom developed the Duplex to increase passenger capacity without requiring longer trains or additional paths on busy routes. Each vehicle has two passenger levels, allowing a Duplex set to carry substantially more people than a single-deck TGV while remaining compatible with France’s high-speed network.
The first Duplex trains entered service in 1996. They became especially important on heavily used routes from Paris toward southeastern France, including services associated with the LGV Sud-Est and LGV Méditerranée corridors.
“TGV Duplex” describes a train design and family, not one individual route. Later variants include the Réseau Duplex and Euroduplex. The double-deck design should also not be confused with the single-level TGV Atlantique or TGV Réseau families.