Abstract - The paper describes the low cost solution of a computer-based Level Crossing (L-xing) system. The solution covers typical automatic L-xing system on a single line with a pair of train control signals protecting L-xing. It is besed on the two out of two fail-safe PLC controller produced by Siemens, with duplicated both fail-safe inputs and fail-safe outputs. The concept allows replacement of the expensive signalling relays with the low cost PLC controller and non-vital relays. The same software runs on both PLC units. It is designed using the experience gained from the applications of various L-xing systems in various countries with the aim to achieve both generalization of the software and low cost of the system. The prototype of the Low Cost Computer-Based L-xing System is realized for the application on Yugoslavian Railways.

 Key words - Railway signalling, computer-based fail-safe L-xing system, safety critical software, standardization, generalization, harmonization, low cost solution.