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Alvia Series 120

S-120 electric rail car

In September 2001, Renfe awarded the manufacture of 12, four-car trains with the variable rolling set system designed to provide service on high-speed lines and on the Iberian gauge branches thereof. The contract amounted to 115.5 million euros, and the first of the 12 units began track testing at the beginning of 2005. On 17 May 2006, the first train of the 120 series started service in the Madrid-Barcelona direction under the commercial name of Alvia. This self-propelled train has a variable rolling set system based on Brava bogies (Brava: Bogie de Rodadura de Ancho Variable Autopropulsado [Self-propelled Universal Variable Gauge System Bogies]) developed by CAF, which allow providing service on both high-speed lines and on the Iberian gauge branches, given that the bogies adapt to each track gauge in just 3 seconds. These new self-propelled rail cars with the variable gauge rolling set were manufactured by CAF at its Beasaín factory, and they are high-speed electric trains capable of indistinctly travelling on the two track gauges (Iberian and international), which is a characteristic that makes them the first self-propelled trains that can perform the track change process continuously, without stops or switching. This means a savings of 15 minutes over the traditional gauge changeover operation.

The minimum composition is formed by four power cars joined pneumatically, mechanically and electrically. The maximum composition is two train units, meaning eight cars.



The body structure is self-supporting, and it has been made of a light-weight aluminium alloy. Its design considers the concepts of aerodynamics and drag. It has energy absorption devices on the couplers, deformable structures and anti-overriding devices, so that in the event of a head-on impact, the consequences for passengers and the vehicle itself are reduced.

The lining of the walls and ceiling is phenolic resin. The sides have a slight curvature to improve the aesthetics, and they have fixed windows of reflective glass. Reinforced windows are incorporated, with a shatter-resistant laminate to improve operating safety. The shape of the train is completed by skirting and fairing, on both the top and bottom.

The frame is welded steel, and the body sits on a cross member that is rigidly attached, under which the secondary suspension is installed. Horizontal forces are transmitted by a catch pin.

Each unit has two driver's cabs where the control and driving equipment is installed, distributed on a console and a panel located on the ceiling of the cab.

Access is made through a single vestibule in the centre of each car. Two exterior doors on each side provide access to the vestibule, while two interior doors provide access to the lounges. Each exterior door has a retractable, pneumatically-operated running board that allows access to station platforms of different heights.

Traction and auxiliary systems

From the point of view of the traction and auxiliary generation equipment, the train is conceived as two semi-units. Each one is conceived as a train, such they each have all the necessary energy collection, transformation and transmission elements for operating the train. It could be stated that each unit is autonomous, from energy collection to power transmission to the motors, to the generation of low voltage and the generation of direct current for the control equipment.

Each car sits on two Brava bogies, type A1, with a single motor axle, which means that there are eight motor axles and eight carrying axles that allow changing track gauges at a speed of approximately 30 km/h. Each bogie has two axles, a motor axle and a carrying axle, and they both include disk brakes. The motor axle also includes a reducer gear. The motor axle is driven by a traction motor through a Cardan transmission.

The traction motor, supplied by Alstom, is an asynchronous, 6-pole self-ventilating motor that provides 512 kW of power to the axle. The unit has 8 motors, 2 per car, and each pair of motors is controlled by a traction unit. The IGBT traction converter assures traction and electric braking, with each motor supplying the necessary power. The electric braking can act independently from the existence of voltage on the catenary thanks to the braking rheostats included in each power unit.

The trains incorporate the Cosmos control and supervision system from CAF, whose mission is to manage the complete operation of the train using various inputs and outputs to do so, both digital and analogue.

The system interface with the driver is through a 10" TFT screen that graphically shows the status of the train's various pieces of equipment and allows the driver to enter data and orders. It also shows the incidents that occur and provides the driver with recommendations or actions to take. Finally, the system allows centralised and remote downloading of the fault history from any unit connected to the network. The train also has an anti-slip/anti-slide system.

Compressed air production is provided by rotary compressors located on the two power cars with a cab, which provide an air flow rate of 1350 l/min at 10 bar.

The pantograph elevation equipment is pneumatically operated, for which it has a reserve tank if necessary, plus an auxiliary compressor in the event of insufficient pressure.

The climate control equipment is composed of one compact unit per car that provides 50 kW of cooling power and 26 kW of heating power. Heating convectors on both sides of the passenger compartments reinforce the system, in addition to heating elements for the WCs.

The climate control system includes electronic temperature control.

In order to be able to travel anywhere in the national territory, it incorporates all the existing signalling systems: ASFA 200/98, ASFA AVE and ERTMS.

Bogies and brakes

The bogies are one of the most noteworthy elements of the train. All the bogies of the composition are motor bogies and form a part of the so-called Brava system (Bogie de Rodadura de Ancho Variable Autopropulsado [Self-propelled Universal Variable Gauge System Bogie]) developed by CAF. They are mounted on two axles, one a carrying axle and the other a motor axle, which allow the railway vehicles to adapt to any track gauge. This operation takes place while under way at a changeover station, thereby allowing automatic adaptation to the Iberian gauge or the international gauge in only 3 seconds.

The Brava system consists of two sets of wheels that can move laterally in a pre-established manner, on a non-rotating axle body. While under way, the action of a double safety mechanism prevents the lateral movement of the wheels. The wheels are separated through a blocking-unblocking mechanism, which is automatically operated during the gauge change process.

Moreover, each bogie includes sanders, a pneumatic installation for both the secondary suspension and the brake system, speed and anti-slide sensors, yaw dampers and earth grounds. The bogie of the cab end also has a flange lubricator, rail guards and an ASFA sensor.

Finally, the incorporation of a network of sensors on the body should be noted, called the ATMS system, which monitors various parameters such as the temperatures or the states of the various mechanical parts of the Brava axle.

This series incorporates three brake systems:

  • Mixed electric brake, recovery and rheostatic.
  • Pneumatic disc brake.
  • Parking brake.

The electric brake is the priority system, whose purpose is to reduce the application of the pneumatic brake as much as possible. The pneumatic brake is applied as a complement to the electric brake to reach the requested braking force. In the event of emergency braking, only the pneumatic brake is applied, which will stop the train in a maximum distance of 1000 metres when travelling at 160 km/h and in 2700 metres at a speed is 250 km/h. The wheels are solid, of non-alloyed low carbon steel, with a surface-tempered rim.


The cab cars of this train have automatic Scharfenberg couplers, with an automatic hatch that conceals them. The type of coupling between cars is semi-permanent. This system allows the trains of the 120 series to run in a double composition.

Control systems

This series has the necessary on-board systems for two types of signalling, ERTMS levels 1 and 2 and ASFA, so that it can travel on the two types of lines for which it is designed. The series can be adapted to receive other systems, such as LZB and Ebicab.

The trains of the 120 and 121 series include a train-ground radio communications system and GSM-R, and they also have the Cosmos control and diagnostics system using the TCN communications network.

The series also has a temperature and acceleration monitoring and control system on the bogies.

Technical Specifications

  • Builder: CAF, with an Alstom motor.
  • Units: 12 of S-120 (+ 16 of S-120 and 29 of S-121).
  • Minimum composition: 4 cars, Mc-M-M-Mc.
  • Track gauge: Adaptable between Iberian and international.
  • Voltage: Dual-voltage, 25 kVAC. (international) and 3 kVDC (Iberian).
  • Power: 4000 kW on international gauge and 2500 kW on Iberian gauge.
  • Motors - model: 8 asynchronous - Alstom MTA/550 H.
  • Converters: 4 with IGBT technology (+3 auxiliary).
  • Maximum commercial speed: 250 km/h on international gauge and 220 km/h on Iberian gauge.
  • Number of axles: 8 motor axles + 8 carrying axles.
  • Brake: Electric brake, pneumatic brake and parking brake.
  • Coupling: Scharfenberg.
  • Driver's cabs: 2.
  • Track gauge: 1435 mm/1668 mm.
  • Signalling: ASFA, ERTMS and AVE.
  • Total seating capacity: S-120: 238 (156 Standard class + 81 First class + 1 PRM). S-121: 281 (280 single class + 1 PRM).

Weights and Dimensions

  • Train weight: 247 t.
  • Weight of Standard class power car with cab: 62 t.
  • Weight of intermediate, Standard class power car: 59 t.
  • Weight of intermediate, First class power car: 64 t.
  • Weight of First class power car with cab: 62 t.
  • Total train length: 107.36 m.
  • Length of cars with cab: 27.90 m.
  • Length of intermediate cars: 25.78 m.
  • Width of the body: 2.92 m.

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