The dynamic behaviour of a crane runway girder and its supporting structure under different situations of vertical moving load is investigated analytically and experimentally. The results of the strain measurements confirm the finite-element analysis and the approximate formulae as well. The dynamic load factors calculated from the measured strains are about 5% smaller than the values according to DIN4132. The strain measurements and the calculations show that the dynamic load factor is not decreasing from the runway girder to the supporting structure, as it would be anticipated from DIN4132. From the analysis the maximum values of the dynamic load factors are obtained for lifting of the load whereas because of the flexibility of the load from the measurements they are obtained for different situations.