Rail contacts that respond to the wheel flanges of train wheels occupy anundisputed place in railway safety technology in the form of switching, detection and counting devices. In their simplest application, rail contacts detect an approaching railway vehicle precisely on the spot where the first wheel or the first axle of the vehicle is exactly above the rail contact. Depending on speed and kick-down delay time, one switching operation is output per axle or per train. The operation of level crossing protection systems or warning systems for workmen gangs in the danger area exemplify a number of applications. Two rail contacts, placed a short distance from one another, whose single pulses overlap when traversed, afford a reliable driving direction detection that is independent of speed. These rail contacts, also known as double track switches, are the basis for direction-dependent axle counting in the form of track vacancy detection systems, which have found increasing acceptance over track circuits due to their higher availability. Within a four-year research and development project, based on 25 years of experience in the field of inductive sensor technology, Frauscher GmbH has developed a wheel sensor with out-standing properties. The operating mode of the product with type designation RSR123, which will shortly be ready for certification, is based on a variety of known inductive mechanisms. Following a short description of the various operating principles, the article focuses on the complex effects that are always present and which need to be coped with as tractive efforts increase.