Wheel detection and axle counting systems provide the basic information for track vacancy detection, for controlling level crossing systems and a range of switching tasks or trigger functions. This technology is established throughout the world for standard gauge railways and is increasingly replacing track circuits. The requirements and the framework conditions in rail-based public transportation systems do, however, differ significantly from those in the standard-gauge railway and long distance track sectors. Nevertheless, in this segment too there is a clear trend towards wheel detection and axle counting systems. New lines and projects are increasingly being equipped with modern axle counting systems due to the benefits in terms of functionality and operating costs. Nowadays even in railed public transport systems, there is a clear move from track circuit systems to wheel detection and axle counting technology.