198608 – Standard Radio & Telefon AB – Automatic Train Control Equipment as installed on Swedish State Railways

When the Swedish State Railways (SJ) in cooperation with other Scandinavian Railways decided to introduce a new automatic train control system in mid 1970’ies Standard Radio & Telefon AB (SRT) was chosen as one of the main suppliers.

The system is required to assist the driver, even in high speed trains, by supervising the speed of the trains and effect a brake application if the speed limits, as given by wayside signs and signals are not obeyed. Information to train about speed limits is transmitted at those locations where new information is required, permanently or temporary. Information is transmitted from passive transponders in track or, additionally, via a radio link. Transponders can be connected to the signal via an encoder.

A panel located in front of the driver, will tell the driver the permissible and expected speed limits, give warnings to the driver and provide other means to operate the system.

The units of the system are required to meet the severe environmental conditions and have a high degree of reliability, They are designed for easy installation in track and new vehicles as well as retrofit in older vehicles.

The system has proved to provide a safe and economic control system on a statewide application on various types of vehicles and traction system.

The ATC-units developed and manufactured by SRT are designed by making use of existing and proven technology within the ITT Cooperation, a good understanding of the demands of the application and a close cooperation with the Railway Administration.

The trainborne computer and memorizing equipment is housed in a ruggedized mounting frame and all subunits are housed in individual cassettes, which provide mechanical protection and shielding of the units. The loco antenna with its associated transmission equipment is designed for the rough environment under a locomotive. The track mounted low-profile transponders are designed to withstand the environmental stress that may occur during seasonal changes and track maintenance.

The units were firstly put in full operation 1980. In order to maintain a cost effective production and to follow the changing electronic components market we are regularly reviewing the design of our units. Although the system and its interfaces remain, this active updating allow us to gradually update and enhance the units and still make use of proven technology and design. Examples of such updated units in the ATC system are Power Units, Computers and Transponders.

The system design comprising “2 out of 3” computers has also allowed us to make a system which is easier to perceive and gives you:
– Test and Verification before delivery
– Better indication of faults
– Short start-up time
– Testing via panel output