ASFA

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ASFA balise
ASFA balise reader on a class 319.2 locomotive
Driver's cab of a class 592 railcar with ASFA signaling (top left)

ASFA ( A nuncio de S eñales y F Renado A utomático ; German announcement signals and automatic brakes ) is a Spanish train control system with point-shaped transmission and brake monitoring.

history

The ASFA system was developed in the early 1970s by WABCO (Westinghouse Air Brake Company) based on tender documents from the Spanish railway company RENFE . From May 1972 the system was tested on the Guadalajara – Azuqueca de Henares route. The first public presentation of the system followed on June 23, 1975, together with the inauguration of the electrification of the Madrid – Guadalajara line. But it was not until 1978 that the system on the Madrid – Guadalajara line went into normal operation and RENFE accepted the development.

function

The ASFA system consists of balises on the route and associated vehicle equipment. The balises are containers that contain an oscillating circuit (consisting of an induction coil and an adjustable capacitor ). They are mounted on the track in the direction of travel to the right of the center next to the signals. There are both passive and switchable balises. The passive balises always send out the same resonance frequency , while in the switchable balises the capacitance of the capacitor is changed depending on the display of an associated railway signal. In this way, the resonance frequency of the balise is changed and thus different information is transmitted.

The vehicle equipment contains an exciter magnet that emits a fixed induction frequency of 111.103  Hz ( frecuencia permanente ) and a balise reader. When driving over the balise, this induction frequency excites the resonant circuit of the balise to natural oscillations . The resonance frequency transmitted by the balise is recorded by the balise reader.

The system knows eight resonance frequencies in the frequency band between 50  kHz and 120 kHz, which are assigned to various information such as warning, speed monitoring and emergency braking. The train's vehicle equipment registers the voltage drop in the affected transmitter coil when it is influenced and, depending on the active resonant circuits in the balise, sends the appropriate signals to the driver or triggers emergency braking .

The speed monitoring takes place punctually at a statically defined maximum speed. On the one hand, a speed of 60  km / h , 50 km / h or 35 km / h (depending on the train type) is monitored 300  m in front of the signal and, on the other hand, a speed limit of 180 km / h or 160 km / h can be applied the crossing of a signal with a corresponding signal aspect .

Signal designation Resonance frequency Signal aspect Significance at ASFA 200
L1 60,300 Hz Signal in yellow or green / yellow The driver is warned acoustically and visually that the balise is being passed. He must confirm this within 3 seconds, otherwise an emergency brake is triggered. From the balise onwards, speed monitoring of 160 km / h applies, and if this is exceeded, an emergency brake is also triggered.
L2 64,270 Hz Signal in green flashing The driver is warned acoustically and visually that the balise is being passed. He must confirm this within 3 seconds, otherwise an emergency brake is triggered. 18 seconds after crossing the balise, a speed monitoring of 180 km / h applies and 29 seconds after crossing the balise the speed monitoring of 160 km / h applies. Exceeding these speeds triggers an emergency brake.
L3 68,510 Hz Signal in green The driver is only advised acoustically that the balise is being passed. From the balise onwards, a speed monitoring of 200 km / h applies; if this is exceeded, an emergency brake is triggered.
L4 not used
L5 not used
L6 not used
L7 88,690 Hz Expect signal in red The driver is warned acoustically and visually that the balise is being passed. From the balise onwards, speed monitoring of 60 km / h applies, and if this is exceeded, an emergency brake is triggered.
L8 96,128 Hz Signal in red The driver is warned acoustically and visually that the balise is being driven over and the emergency brake is initiated immediately.

ASFA versions

  • ASFA conventional (suitable up to 160 km / h)
  • ASFA FAC (version for FAC )
  • ASFA 200 (suitable up to 200 km / h)
  • ASFA 200 AVE (version for AVE with larger block sections)
  • ASFA digital

ASFA digital

In 2005, with the development of digital ASFA by Adif started. However, the term digital only refers to the computer-based vehicle device, while the information transfer between the balises and the vehicle equipment continues to take place by magnetic induction, and no digital data is exchanged. However, the frequency table has been redefined and, compared to the old ASFA, can be expanded to enable additional functions. The on-board unit was also adapted to the state of the art, expanded with functions and equipped with a screen in the driver's cab.

With regard to ETCS , ASFA is listed as a class B system (Class B system).

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