TTCN-3 Testing of Hoorn-Kersenboogerd Railway Interlocking

Railway control systems are safety-critical, so we have to ensure that they are designed and implemented correctly. Testing these systems is a key issue. Prior to system testing, the software of a railway control system is tested separately from the hardware. The interlocking is a layer of railway control systems that guarantees safety. It allows to execute commands given by a user only if they are safe; unsafe commands are rejected. Railway interlockings are central to efficient and safe traffic management for railway infrastructure managers and operators. European integration requires new standards for specification and testing interlockings. Here we propose an approach to testing interlockings with TTCN-3 and give an example for its application. The code of interlockings is simulated during test execution. For assessing the quality of the tests, we propose an approach inspired by the classification tree method