Case study description

The TTCN-3 railway case study is devoted to testing railway interlockings with TTCN-3. An interlocking is a layer of a railway control system that guarantees no train collisions or derailments happen. If the interlocking considers a command given by a human expert as unsafe, the execution of the command is postponed until the command can be safely executed or discarded. Thus it is responsible for the safety of the railway system. Therefore, the interlocking has to be thoroughly tested.

Starting from general safety requirements defined by CENELEC standards EN 50126/50128/50129, we have developed a test suite for testing the interlocking of Hoorn-Kersenboogerd station. We have implemented a TTCN-3 test system with simulated time for executing this test suite. In this case study, we have provided a complete approach to testing railway interlockings: starting from developing test cases, proceeding with implementing the test system and finally automatically executing tests and interpreting results. This experience shows that TTCN-3 is suitable to provide standard solutions for testing railway control systems.