Microprocessor-based railway interlocking control with low accident probability

A laboratory model incorporating a microprocessor-based system to control signals and points and to monitor track circuits is described. Approach locking and backlocking controlled through a programmable timer are included. The model consists of a control panel with extrance-exit type control, namely a switch and a pushbutton for each route. Light emitting diodes (LED´s) take the place of signal lamps. Points are simulated by means of three position neutral polar relays. A method of reducing the probability of accidents associated with this type of control is presented. The method consists of duplicating the input channels and utilizing redundant input data.