TGV Duplex
| Company type | Train model |
|---|---|
| Industry | Rail transport |
| Founded | 1995 |
| Founder | Alstom, SNCF |
| Headquarters | France |
| Products | High-speed double-deck trains |
| Parent | SNCF |
The TGV Duplex represents a French high-speed train within the TGV series, constructed by Alstom and managed by the national railway operator SNCF. It was the inaugural TGV model to incorporate double-deck passenger coaches, which boosted seating capacity to 508 passengers, effectively meeting the demand on heavily trafficked high-speed lines. Although initially a smaller portion of the fleet, the Duplex has grown to become a crucial element in SNCF's service offerings.
In total, 160 trainsets were manufactured: 89 original Duplex units beginning in 1995; 19 Réseau Duplex sets launched in 2006 as part of the TGV POS fleet expansion; and 52 second-generation Dasye trainsets delivered from 2007 onward, equipped with upgraded traction motors and advanced safety features.
This design further progressed into the third-generation model known as the Euroduplex.
Purpose
The LGV Sud-Est corridor connecting Paris and Lyon holds the distinction of being France’s most heavily utilized high-speed route. Following its inauguration in 1981, passenger capacity rapidly reached its limit. Potential solutions to increase throughput included reducing intervals between trains to three minutes; however, signalling complexities and braking constraints limited this approach. Expanding train width was unfeasible due to loading gauge restrictions, while coupling two trainsets demanded excessively long platforms. The practical alternative was adopting a bi-level configuration, which increased seating capacity by approximately 45% without altering train length or width. TGV Duplex sets frequently operate coupled alongside single-deck Réseau or other Duplex units.
History
The feasibility assessment for the Duplex concept concluded in 1987. In 1988, a full-scale prototype was created to evaluate passenger acceptance of the double-decker layout—a novel approach for high-speed intercity trains. A modified TGV Sud-Est trailer was used in regular service to replicate the lower deck arrangement, while another train underwent testing to analyze dynamic effects caused by an elevated center of gravity. Negotiations with GEC-Alstom culminated in a contract signed in July 1990 to develop the "TGV-2N". The official procurement followed in early 1991. Initial trials of bi-level trainsets took place in November 1994, initially powered by TGV Réseau locomotives until dedicated Duplex power cars became available. The first pairing of a Duplex power car with double-deck trailers occurred on 21 June 1995.
Innovations
The principal advancements focus on enhancing efficiency and operational performance relative to earlier models:
| Power-to-weight ratio (kW/tonne) |
Weight/seat (tonne) |
Power/seat (kW) | |
|---|---|---|---|
| TGV Sud-Est | 17 | 1.10 | 18.34 |
| TGV Duplex | 23 | 0.7 | 16.15 |
- Aluminium construction: To comply with axle load restrictions on French high-speed tracks, Alstom employed extensive extruded aluminium components to minimize weight for the larger double-decker trains.
- Enhanced aerodynamics: The redesigned nose shape and reduced gaps between trailers limit aerodynamic drag increases to only 4% at , compared with single-level TGVs. This nose design, differing from Cooper’s original style, was crafted by industrial designer Roger Tallon.
- Crash protection: Locomotives incorporate crush zones, reinforced passenger compartments, and frames engineered to withstand frontal impacts up to , featuring structural fuses that absorb collision energy.
- Active pantograph system: The Faiveley CX pantograph utilizes pneumatic controls to maintain optimal contact with overhead lines across all speeds.
- Disc brakes on all wheels: The increased weight allowance enabled fitting disc brakes on powered axles ("cheek discs"), which reduce wheel wear and noise without compromising braking effectiveness.
- Low-noise roof fans: Cooling fans were redesigned to significantly decrease noise levels at stations.
- Speed achievement: In 2007, a shortened TGV Duplex set equipped with distributed traction established a speed record of , influencing subsequent AGV train designs.
Moreover, the bar car’s lower deck contains technical equipment, thereby maximizing passenger space—a distinctive feature among TGV layouts.
Réseau Duplex
The Réseau Duplex emerged as an extension of the TGV Duplex series within the framework of the TGV POS initiative. In 2006, Alstom supplied SNCF with 38 tri-system power cars alongside 19 double-deck Duplex passenger sets.
To assemble Réseau Duplex train formations, newly manufactured Duplex coaches were combined with 38 older dual-system power cars originating from the initial TGV Réseau fleet. Concurrently, the 38 new tri-system power cars were paired with 19 pre-existing single-level Réseau coach sets, resulting in hybrid POS trainsets designed for international service.
The tri-system functionality was crucial for operations on the LGV Est, which connects to Germany’s 15 kV AC rail network. Introducing Duplex coaches on heavily trafficked domestic lines also enhanced seating capacity on busy routes.
This approach allowed SNCF to deploy tri-system equipment for the LGV Est launch without postponing the production schedule of Duplex trainsets.
Dasye
Dasye (Duplex Asynchronous ERTMS) constitutes the second generation of Duplex trains, maintaining a comparable exterior and cabin layout but incorporating two significant improvements in the power cars: asynchronous traction motors (initially implemented on the Eurostar e300) that enable isolation of defective bogie motors, and integration of the European Rail Traffic Management System (ERTMS).
A total of fifty Dasye trainsets were commissioned; a prototype power car was delivered at the end of 2006, with commercial operations beginning on 14 February 2008.
Starting in 2013, numerous Dasye units were adapted for SNCF's budget-friendly Ouigo service by adopting a high-density interior configuration that boosted capacity by 20% to 644 passengers through removal of bar and first-class compartments and installation of slim-profile seats. By 2021, 38 trainsets had undergone conversion for Ouigo, with plans to complete all 50 by 2025.
Eurotrain
Eurotrain was a joint venture established by Siemens and GEC-Alsthom (now Alstom) in 1996 to promote high-speed rail technology across Asia. In 1997, it was selected as the preferred bidder to provide the core system for Taiwan High Speed Rail (THSR).
In early 1998, Eurotrain assembled a demonstration train by merging components from French and German high-speed trains: intermediate cars from TGV Duplex set #224 were coupled with German Railways ICE 2 power units numbered 402 042 and 402 046. On 4 May 1998, this train operated on Germany's Hanover–Würzburg high-speed railway, achieving a maximum velocity of .
Despite this achievement, in December 2000 THSRC awarded the contract to the competing Taiwan Shinkansen Consortium, leading to legal proceedings that culminated in compensation payments to Eurotrain in 2004.