Pin-pin resonance is one of the most significant preferred vibration modes of beams, which are supported at equal distances, such as rails at sleepers in railway track structures do. Pin-pin resonance is a vibration that appears in one basic (first) mode and several higher modes, however the basic mode will have the highest amplitudes. In operational conditions of railways, pin-pin resonance only partly influences wheel-rail contact of the train while the speed dependent sleeper-passing frequency is more important. Among other track resonances, pin-pin resonance plays an important role in noise and vibration radiation of the rails and can be used as a meaningful instrument in track system dynamics recognition and optimization. However, existing simple analytic approximations are not sufficiently reliable to perform these recognitions."This will be shown in this paper by means of new tests and simulations that are based on improved models and methods but restricted to ballasted track structures.