This paper deals with the determination of the stress propagation in the HH10 type of steel railroad ties under dynamic loads. The HH10 type of steel ties were tested for fatigue at the University of Illinois at Urbana-Champaign. Simultaneously with the laboratory fatigue tests, I was modelling the stress distribution in the tie due to the dynamic loads with using finite-element software ‘ABAQUS’. After the introduction, the laboratory arrangement of the tie fatigue test will described in Chapter 2. Chapter 3 details the steps in building up the finite-element model of the ‘HH’ railroad ties. In Chapter 4, the stress pattern and numerical values for the stresses and displacements of the tie due to dynamic loads as results of the finite-element program will be presented. The most important results will be summarized in Chapter 5.